Medicinal and Aromatic Plant Series, Nu, 8 CITRON ELLA (Gym bopogon nardus) lSSN 1391-5622 ISBN Information Services Centre Industrial Technology Institute (Successor to CISIR) Colombo ,: 1. --- Sri a Lanka '- ,p3R"T.\- , . -*.$g . ' . ~ - . f f % -- " - ,-a . . ,," r - 2 5,; ; '" V,,/ \ PJedicinal and Aromatic Plant Series, No. 8 b ,v ?'I , ' P ,- 'I SCT ;;;z r 2 , Citrsraeila - a hiterature survey -. Compiled by : Purnlma Sayasinha Supervised by : Dilmani Warrlasuriya and Harshani Dissanayake National Science Foundation Grant RG/IS/96/01 Published by : fndormation Services Centre industrial Technology hstitute 363 Baudhaloka Mawatha, Colombo 7, Sri Lanka O Industrial Technology Institute (CISPR) & National Science Foundation First Published in 1999 National Library of Sri Lanka - Cataloguing - In - Publication Data Jayasinha, Purnima Citronella (Cy~nbopogon nardus) / Purnima Jayasinha; Dilrnani Warnasuriya; Harshani Dissanayake .- Colombo : Information Services Centre, Industrial Technology Institute, 1999 Vol. 53 .- p. ; 2Scm. .- (Medicinal and aromatic plants series) ISBN 955-8394-08-4 Price : Rs.200.00 i. 615.321 DDC 21 ii. Title iii. Series iv. Warnasuriya, Dilmani jt. au. v. Dissanayake, Marshani jt.au. 1. Aromatic plants 2. Botany, Medical ISSN 1391-5622 ISBN 955-8394-08-4 Published by Information Services Centre, Industrial Technology lnstitute The Information provided in this monograph is taken from available scientific literature. The authors accept no liability for any damages arising from any claims contained in this text. Acknowledgements The financial assistance by the National Science Foundation (grant number RGAS/96/01) for the project is gratefully acknowledged. Sincere thanks are due to Mrs. Wathmanel Senexiratne and Mrs. Neranjani Mohottala for 2reparing tlx database Gratefbl thanks are also due to Dr. U M. Senanayake for editing. The assistance and support given by the industries during visits are greatly appreciated. The secretarial assistance of Mrs. Ramani Kapurubandara is acknowledged 'Thanks ?,re also due to Ms. Roshani Fernando for designing the cover. Contents Pwge Introduction Botany 3.1 Taxonomy 3.2 Plant Description Habitat Agronomy 5.1 Soil and 2imate 5.2 Preparation of Land 5.3 Fertilizer 5 4 Weeding 5 5 Irrigation 5.6 Diseases and Pests 5 7 Yarvesting and Yield Processing 6.1 Primary Processing of Leaves 6.2 Distillation 6.2.1 Distillation Time 6.2.2 Cooling System 6.2.3 Oil Separator Packing and Storage Chemistry of Grass 8.1 Physico-chemical characteristics 8.1.1 Essential oil 8.1.2 Cohobation water 8.1.3 Distillztion residue 8.1.4 Spent grass 8.2 Chemical Constituents of Grass 8.3 Biocharacteristics Analysis of Citronellr oil 9.1 Chromatography 9.2 Spectroscopy 9.3 Determination of Total Gerartiol 9.4 Determination of Citronella1 10. Chemicals from the oil 1 1. Standards and Specifications 11. I Standards 1 1 2 Adulterants 1 1.2.1 Detection of Addterants 12. Production and Trade 13. Uses 13.1 PeAmery 13.2 Pesticide 13.3 Food 13.4 Miscellaneous Uses Bibliography 1.0 INTRODUCTION Citronella is a kind of a grass with narrow, long leaves. It is an economically valuable herb as it produces a very important natural essential oil named citronella oil. The main constituents of this essential oil, citronellal, citronellol and geraniol are widely used in soap, perfumery, cosmetic and flavouring industries throughout the world. Citronella oil is classified in trade into two types - Ceylon citronella oii, obtained from Cymbopogon nardus Rendle, and the Java type citronella oil obtained from Cymbopogon winterzanus Jowitt. Java citronella is considered to be superior to Ceylon citronella. Both of these have probably originated from Mana Grass of Sri Lanka, whlch according to Finnemore (1962) occurs today in two wild forms - Cymbopogon nardus var. linnnei (typicus) and Cymbopogon nardus var. confertzflorus. Both of these forms are not known to be used for distillation to any appreciable extent. The Java citronella, which is called 'Maha Pangeri' in Sri Lanka is the result of selection from the Ceylon citronella The name Cymbopogen winferimus is given to commemorate Mr. Winter an important citronella oil distiller of Sri Lanka, who first cultivated and distilled Maha Pangeri type of citronella in Sri Lanka. Cymbopogen nardus Rendle, which is called 'Heen Pageri' or 'Lena batu' is Sri Lanka, is the source of Ceylon citronella oil. It is widely grown in Sri Lanka due to its drought resistant and hardy qualities, which makes it ideal for the climate in the Hambantcta District. 2.0 HISTORY Citronella is one of the oldest industrial crops in Sri Lanka. Two Dutch surgeons Paul Hermann and Nichola Grim introduced it to this country in the 17 '~ century. In the early 18" century the first shipment of 'Oleurn Siree' was sent to England and in 1851 and 1855 samples of the oil were displayed at the world fairs in London. In 1885, Lenabatu was first discovered in Matara and five years later in 1890, a primitive still which was being used for distilling the wild grass in Java was discovered by A.K.J. Happer. He later grew Java citronella OP an experimental scale, in his fields. At this time Sri Lanka was the sole exporter for citronella and had about 50,000 acres of citronella ia the Southern province of Sri Lanka. Maha pengiri was introduced to Java from Sri Lanka in 1899. Subsequently Java replaced Sri Lanlca as the major producer of citronella to the world. In 1901, citronella was replaced by tea at Akuressa and Baddegama in Sri Lanka. Although the first experiments with the systematic botanist, Simpson, started citronella, in 1936, in Sri Lanka, the citronella industry started to drop. In 1959, with establishment s f the Coconut Cultivation Board and the lower price quoting from the traders to the farmers, gradually drop in citronella cultivation was seen. By late 1960's nearly 20,000 acres of citronella were replaced by coconut and other cultivation. Citronella cultivation went down drastically during last four decades mainly due to the price instability. There were numerous malpractices in the testing and grading of oil at the dealer's collection centres whereby good quality oil was sometimes declared as the small farmers was the method of buying the oil by the dealers. The unit of payment to the farmer was on a "per bottle - containing 24 ounces of oil" basis. As mentioned above, a few private dealers dominated the whole marketing structure in the absence of government institutions for purchasing citronella oil. This made unsatisfied farmers give up citronella plantation and start on new sources of revenue. The other main problem the farmers were facing was, the difficulty in renovating or repairing their units due to high cost of spare parts. In 1972 after the formation of Department of Minor Export Crops, special attention was given to citronella. From 1975 onwards ioans were given to the farmers to replant citronella and to repair the distilleries that are not in a working condition. 3.1 TAXONOMY The genus Cpzbopogon comprises about 140 species. The grasses, many of which have a pleasant aroma, yield essential oils, which are of commercial importance. Formerly, Cymbopogon was classified as a sub-genus of Andropogon, but today, it is considered as a separate genus. Family . Graminae Genus : C'jimbopogon Species : nardus winterianus Other Names : Cymbopogon nardus Sinhala : Lenabatu, Heenpengiri Tamil : Vaanaipul, Kamachipillu English : Citronella Sanskrit : Guchcha 3.2 PLANT DESCRIPTION Cym bopogon nurdiis: This is said to be a hybrid of Cymbopogon wznferzanus and Cymbopogon confertzflorus. It is a perennial herb, up to about 2-2.5m high, with rhizome, whitish, sometimes tinged with purplish red, nodes often swollen, tips drooping. Leaf sheath glabrous, often auricled; basal sheath purplish red outside. Leaf blades up to Im long, 5-20 mm wide, the upper smaller, edges and surface rough, glabrous except near the base. Spathate panicle decompound, internode up to 1 mm long, ultimate branches slender, zig-zag. Racemes 15-17 mm long. Sessile spikelets 4-4.5 mm long. Lower glulne glabrous, flat, acuminate, narrowly winged on the keels towards the back. Wings minutely toothed, 2-4 nerved between keels; edges narrowly inflexed throughout. 'Jpper glume boat shaped, one-nerved, keel toothed towards back, lower lemma. 3mm long, thin, fringed, nerveless, upper lemma shorter, thin, fringed, apex shorter, bilobed with bristiles in the notch. Anthers 1-4 mm long, pedicelled spikelets smaller to slightly smaller; upper floret male without lemme. @~bopogon winterianus A tufted, aromatic, perennial herb over 2 m in height. Leaf blades up to 1 m long, 10-50 m wide, usually light green, glabrous, smooth on the upper surface, slightly rwgh below and along margins, leaf sheath glabrous, yellowish green, basal sheath glabrous, green to reddish Inflorescence a very large 30cm long decompounded panicle, racemes 20 rnm long, one sessile or short and the other longer-pedicelled with two lower spikelits. Cym bopogon confertrflorus: This grass is said to be the parent plant of the citronella species. The leaves and stems are similar to those of C'mbopogon nardus, but the plants are larger. 4.0 HABITAT Cym hopogon nardus It is found mainly in Sri Lanka In Zndia it has been grown on an experimental basis. It also grows in Seychelles. Cymbopogon winteriarzus It is found mainly in Indonesia, Taiwan and Guatemala, also found to a small extent in Sri Lanka, East and Central regions of Africa, Argentina, Brazil, Burma, China, Comoros, Dominican Republic, Ecuador, El Salvador, Fiji, Haiti, Honduras, India, Leeward Isiands, Madagascar, Malaysia, Mexico, Nicaragua, Philippines, Seychelles, Tanzania, West Indies and Zaire. Cj/m bopogon confert~fZorus Occurs wild in Sri Lanka. Also found in South India. 5.1 SOLL AND CLIMATE Cym hopogon nardus A hardy plant, which requires little care and not much moisture. It can be grown on any soil with an altitude below 610 rn. In Sri Lanka, it is usually grown on infertile poor soils in coastal regions. It is sometimes planted on slopes on hills, to prevent soil erosion. Requires a hot, moist climate and a rainfall of 1.5 - 1.8 rn per year. Cjlmbopogon winterianus: The plant grows well under varying soil conditions. Rich sandy loam soil is most preferable. It grows well at the altitudes between 1000 m and 1500 m, but an altitude of 180-27 5 m is the optimum. The plant grows well under wide range of pH, acidic (5.8) to slightly alkaline (8.0). However pH 6.0 is optimum for this crop. The plant is very sensitive to water logging which should be avoided to obtain maximum growth When calcerous soils containing a thin layer of sand were used, good yields of grass and oil were obtained at first, but when the roots reached the lime sub-soil, the citronella content of the leaves decreased. Requires a warm climate, with plenty of sunlight. When grown in the shade, fewer shoots and growth was retarded, and the leaf blades often became hard and woody. It was also found that oil yields and total geraniol content of grass grown in the shade, were low. High atmospheric humidity (73-90%) is more favourable to crop growth than high soil moisture and also well distributed rainfall of approximately 200-250 cm. The soil is prepared by burning old grass and weeds followed by ploughing, harrowing and planking twice. In areas where soil insects are a problem endrin or heptachlor (5% dust) at the rate of 50kg per ha. should be applied at the time of last harrowing to protect against soil-borne insect pests. Although the planting can be started any time during the year, it is ideal to plant in Yala and Maha seasons with the rain. Planting material consists of stools of fully-grown healthy plants. Each stool should contain at least 1-3 tillers. The fibrous roots and leaves are trimmed off the stools before planting. If the planting is delayed, the stools may partially dry up which will result in poor plant population. The stools are planted vertically, about lOcm deep, and at a distance of 60 cm in rows, spaced 60 cm apart. However in areas where the soil is fertile and the climate conditions support luxurious growth, a spacing of 90x 90cm may be kept. In general there can be 35,000 stools per hectare of land. Green manuring is ons side red beneficiai to the crop Since the plant is soil exhausting, liberal use of chemical fertilizers is recommended The fertilizer requirements will vary accol-ding to the ievel of soil fertility The results of most fertilizer trials in the literature suggest that the crop responds well to N application, particularly during the early years. A good crop of citronella requires N-P-K mixture of 125kg N; 62kg PzOs and 50 kg K20 per hectare per year. N is applied in 4 or 6 equal split doses but the entire quantity of P285 and K20 may be applied at the time of planting as basal dose. In recent studies, it has shown that 4 split dose application of KzO has better results than basal application. Foliar application of a solution of urea (1%) at fortnightly intervals throughout the growth of the plant is recommended. Urea supergranules increase the herb yield by 25% over the prilled urea. In many cases, both herbage yield and oil yield increased with increasing N. The effect of phosphoms and potash on yield is not appreciable, although phosphorus appears to influence fillering. Too much application of N increases the green matter but reduces the oil content. The residue grass (spent grassj left after distillation of the oil or the ash from spent grass which had been used as a hel , is applied twice a year, between bushes, as a green manure. Plants that had been used as green manure for the Java citronella include. Tephrosla vogeh~, Tephrosza catzdzda, Crotolarza and Mzmosa species. These were applied after 5 years, in order to regenerate the soil Farmyard manure has also been used The micro-nutrients such as Cu, B, Fe, Zn, Nrn also has a effect on herbage yield and on diseases. Fertilizer recommendations in the literature, are summerised below: Sri Lanka: Mixture Grass mixt~re 17: 1 1 : ! 4 (N:P205:K.28) Dose 750 kg/ha Nutrients 1 2 8 kg Nlha 83 kg P2051ha 105 kg KzOIha Rate of application : kglha Yala Maha 1' year 190 190 2nd year and later 3 75 3 75 India: Bangalore: Nutrients: 450kg Nlha 100kg P205/ha 125kg KzOIha Rate of application : six split doses on a 3 year's rota~ion North Bengal N - 200kg/ha/year P28 j - 25 kglhdyear K 2 0 - 60kg/ha/year Jammu N - 250-340kg/ha/year, applied in 3 to 5 split doses The citronella plantation should be kept weed-free. When the plants have established themselves and formed bushes, the problem is not so severe because of the very nature of growth of the bushes. However, in the newly established plantations and after each harvest, the weeds grow in the inter-row spaces and weeding becomes essential. To keep the land free from weeds for the first 60 days is very important. This enhances t;llerirg and leaf-growth Weeding should be done two-four times during the first year and there aRer once a year, after each harvest. !n a recent research carried out at ZIMAP Regional Centre, Hyderabad, India have showed that hand weeding, mulching with spent grass (5.0 tlha), close spacing (30 cm x 30 em) and preplanting application s f herbicides like atrazine (1.0 kg a.i./ha) fluchloralin (0.7 kg a.i.lha) and butachlor (1.0 kg a.i./ha) produced higher biomass, essential oil yields and essential oil content in citronella in comparison to unweeded control. Effective control of weeds after 45 days of application of 2,4-D with cane sugar (1.5%) controls Cyperus rotundus successfully. But 2,4-D sodium salt lowered the yields and essential oil content Application of Diuron and Sirnazine (2kg a.i/ha) have been observed to control the weeds. The plant requires adequate moisture for good growth and yield of leaves. In the areas where annual rainfall is about 200-250cm, well distributed over the year and the humidity is high, supplemental irrigation is not necessary. In the drier months, however, the irrigation may be provided and this increases the yield. Leaf blight d' ~sease: The fungi, Curvularza andropogonis (Zimm) Boedijin, cause this disease. It appears in the form of small brownish spots, which enlarge into long patches along the tips and margins of the leaves. The yellowing leaves then starts leading to complete drying of leaves. As a result of this infection, there is considerable decrease in leaf and oil production. This can be controlled by prophylactic spraying of any dithiocarbamates, namely, rnancozels and zinab at an interval of 10-15 days during the growing period. Recently, in India, three leaf spots (Purple, Grey & Brown) were observed on Cymbopogon winteria,vl~l.s at various cultivation centres. Eleven hng i were found to be associated with these spots, viz. Colletotrichzrrn graminicoln, Periconia hyssoides, Spegazznia tessarthra, C~rvularia andropogonis, Alternarza alternata, C~ladosporium herbarum, Gyrothrix podosperma, Arthrobotyrzm cymbopogonis, Monochaetiella cymbopogonis, Drechslera sacchari and Tet~aploa aristata. Collar rot and wilt disease: This was found is corrmercial plantations of Java citronella in India, Patnagar and the adjoining areas in Uttar Pradesh, in 1992-1993. The causal organism was identified as F. razonil$orme (Gibhernlla fijikzrroi) In the northern part of India, P. aphnnidermaiurn was a predominant hngus recovered from roots of Cymbopogon winterianus, showing lethal yellowing. This disease occurred most frequently between July and October. Roots of infected plants showed marked discolouration and sloughed from the vascular tissue. Diseased plants were chlorotic and stunted. Rotting was often found to spread from roots to stem, leading to severe chlorosis and death of the infected plants. Anthracnose: This disease occurs generally in South India and is caused by the fungus Colletotrichum p-aminicola The symptoms consist of brownish spots, which enlarge with age during monsoon. The spots are dotted with fruiting bodies of the fungus. The disease can be controlled by application of Dithiocarbamate. Yellowing and Crinkling of leaves: The leaves of the plant crinkle and turn yellow in some stage of growth. The winter months @ec.-Jan.) are more congenial for this abnormality. The cause is unknown h t certainly it is related with the nutritional imbalance in the plants ontogenetic development. It is noted that oil yields are drastically lowered in yellow crinkled leaves. Folier feeding with area (1%) and magnesium sulphate (0.5%) eliminates yellowing and crinkling. Chlorosis: The chlorosis in Java citronella grass was caused by trace element deficiencies in soil, especially, those of Fe and Zn. A probability also exists that chlorosis maybe caused by S and other element deficiencies. Two or three foliar sprays of a mixture of these micro-nutrients at fortnightly intervals is recommended to combat that deficiency. Insect Pests: Cock-chaffer gmbs, termites and white ants cause damage to the plant during June- November. The attack is more pronounced in the lighter type of soil compared to heavier type of soil. This is oossibly due to less compactness more aeration and less water holding capacity in lighter type as compared to heavier type of soil. The roots were attached first which results in yellowing of leaves and death of plants. b-eavy infestation of citronella plants due to stem and shoot bores has also been observed causing about 20% damage from 2nd year onwards. This can be controlled by spraying ' follidol' at 0.02% concentration, soon after harvest. The pysalid, Stemmutophorn fusciknsalis was recorded damaging the aromatic perennial herb, citronella in Andhra Pradesh, India for the first time in 1990. Usually the crop is ready for harvest aRer 6-8 months of planting. Subsequent harvestings can be done at an interval of 90-120 days The numbers of harvest, however, depend upon the growth of plants Harvesting can be done 3-4 times a year under favourable conditions The best time of harvest appears to be that when the stem bears 6 adult leaves, with the 7'h leaf in a rolled up position. Harvesting too early or too late has an adverse effect on the quality of the oil. Only leaf blades are cut leaving behind 15-20cm of the sheath It is usually harvested early in the morning. The plants should not be cut during rains 3nce it is harvested it is allowed to dry in the field for a day or two. The dry leaves are removed with the nand or fork at the time of each harvest. The leaf-blade excluding the leaf sheath is the only portion of plant that yields oil of standard quality. Other than the leaf-blade, the different parts of the plants are deficient in citronella and geraniol, although the content of citronella is higher in infloresence asd leaf-sheath. The yield of herbage and the oil varies with the season, fertility of the soil and method of distillation. Under favourable conditions, fresh herbage yields up to 10-12 tonneslha in first year and about 15-20 tonneslha for next seven years. Thereafter yield starts to decrease. On an average, the oil content is 1% (fresh weight basis). In Sri Lanka an annual yield of 10 tonneslhalyear is obtained. The chemicals in most of the essential oils are volatile and also prone to chemical transformations. Improper post-harvest handling will not only cause losses of these valuable chemicals but may give rise to undesired compounds. The leaves should be spread out and dried in the shade. Direct drying in the hot sun should be avoided as far as possible. The period of drying depends on the sunshine and atmospheric conditions.lt has been reported that the best oil is obtained from grass dried in the shade for 24 hours. During wet weather, the grass is dried on racks under shelter and turned frequently to prevent fermentation and mould formation, which will effect the quality of the oil. After drying, dry leaves and foreign matter such as soil are removed and the grass tied into bundles of about 22 kg each. 6.0 PROCESSING 6.1 PRIMARY PROCESSmG OF LEAVES 29,52 Primary processing involves a wilting or drying operation, Drying of some form is necessary to lower the water content and to increase difhsibility constituents of the oil. Citronella leaves, which have terpene oils needs only 24-36h, wilting. At this time rnoisture content is 30-40%. In distillation, insufficientiy dried leaves leads to a low rate of oil recovery and smaller quantities of oil per distillation, although oil recovered, on dry basis, may be slightly greater. Essential oils are mixtures of volatile liquid (and solid) compounds, which vary widely in regard to chemical composition and boiling point. Every substance possesses a definite vapour pressure, at a given temperature which depends upon the prevailing temperature. Two methods are used for the distillation of the essential oil from the grass. These are (a) water and steam distillation, where the plant material is supported on a grid, above boiling water, and (b) steam distillation, where the steam is passed over the plant material which is supported on a grid. The former involves direct heating of the still, while in the latter, the steam is generated in a boiler, away from the still. Higher yields have been obtained using steam distillation. There are diflerent types of distillation units used for the field distillation of essential oils in Sri Lanka. he most common type used for distillation of citronella oil is traditional type C. These stills are used in the region fiom Galle to Harnbantota. The boiler is of the horizontal type, insulated by a bank of mud. It is fired by a krnace, which extends almost through its length and should theoretically produce a high rate of steam. Steam should be introduced into the still under pressure, to enable it to rise through the charge with sullicient force and penetrate all parts evenly. A steam pressure of 1-2 atmospheres has been recommended. Under these conditions yields are slightly lower, but the resuiting oil has a higher geranio~ cor;itent. Yields are higher with steam pressure of 3-4 atmospheres but the geranio! and citronellal contents of the oil are lower Prolonged contact with steam may cause decomposition of the oil Stills are made of galvanized iron, with a diameter of about 135 cm and height of about 240 cm. Most frequently double still bodies are used in each unit so that they can be used alternately. Such still bodies, have a capacity for about 50 kg of grass. The stills are insulated to prevent heat losses They are embedded in a stone hearth or surrounded by a layer of kieselguhr or finely chopped citronella grass The grass is cut before being charged into the still to enable even distribution in the still and thus prevent steam cha:~nelling. Cut grass has been found to yield a higher percentage of oil when compared with uncut grass. When loaded into the still, the grass is trampled down tightly COOL WATEZ SUP - - p,, i i O DISTILLIIVG TAIJKS - COOL WATER SUPPLY TAN6 +---- DISTILLED HOT STEAM DOWN PIPE COGLING COIL OIL COLLtCTlNG JAF Figure 1 : Simple distillation apparatus 6.2.1 DISTILLATION TIME Eistillation times vary with th\: weight of the charge It takes about 2 hours to complete the distillation of 500-600 kg of charge and 3-4 hours to 1000-1500 kg charge. It was found that 80% of the oil is distilled during the first hours, 19% in the second hour and 5% in the third hour If the distillation is extended till the grass is completely exhausted, an inferior oil with low citronellal is obtained. If the distillation is stopped early, the oil contains a higher content of citronellal The order in which the various constituents are distilled is low boiling terpenes, citronellal, mixture of citronellal and geraniol, alcohols and esters, geraniol and sesquiterpenes, sesquiterpene alcohols. 6.2.2 COOLING SYSTEM (Condenser) As the name suggests the responsibility of the condenser is to change the phase of oil and water vapour back into liquid so that as immiscible liquid, they can be separated. Usually a condenser is a tube or a series of tubes that are water cooled, so that the vapour emerging fiom the vapour tube will rapidly change into liquid phase. Condenser tubes are made out of lead, aluminium or stainless steel. Copper tubes are avoided, since they tend to colour the oil. Unsatisfactory cooling can cause resinification of the oil. 6.2.3 OIL SEPARATOR Once the oil and water have conde~sed, the oil droplets must have time to coalesce. This is done in a separating can or Florentine flask made of aluminium. Oils separate from water according to their density because they are immiscible or only sparingly soluble. The most important factor of an oil separator is that it must be large enough to give the coalescing oil particles, time to form distinct oil droplets that readily separate from the oil If a green coIour is present, after the water layer is drained off, it is removed by treatment with dilute acids, especially tartaric acid. The separated oil is then filtered twice, to remove any minute particles or debris that have unobtrusively found their way into the oil. Security: Since the oil is very expensive, the distillers take strict security measures. The oil separator and the container holding the separated oil are oRen placed in an underground room, which is locked. The entire distillation unit may be housed within walls and protected by a protruding roof. Table 1 : Distribution of Citronella oil stills in Sri Lanka. 1. Kirambe -Katuwana 2. WalasmuUa - Weeraketiya 3. Beliatta 4. Tangalla - R a m Area 7.0 PACKAGING AND STORAGE 24, 52 No. of Stills Citronella oil must be packed in air tight containers which are completely filled, without any air space. Glass, tin-lined or aluminium containers may be used, or galvanized iron drums. Jayawardena, A.L. et.al. found that of the metals, aluminium and zinc remained partically unattacked by citronella oil for a short period of time: like for export containers. The containers are stored in a cool place away from light. Guenther (1940) reported that on storage, the specific gravity of citronella oil increased and solubility in 80% alcohol decreased. When exposed to light and air; the oil may change colour, Eom yellow to green. Long periods of storage may cause the oil to become dark brown in colour, due to oxidation. The oil may become more viscous on storage. Waterrnan and Elsbach found that on keeping, in a closed bottle, the refractive index of Java citronella oil changed only slightly in 7 months, from n~ 1.4688 to n~ 1.464. When stored in open tube the regactive index increased to a larger extent, the increase being greater for the Ceylon citronella oil than for Java citronella oil. The greater stability of the java oil, it was claimed, was probably due to a higher geraniol content The geraniol prevsnted oxidation to citronellic acid 8.0 CHEMISTRY OF G M S S 27,52 8.1 PHYSIC0 - CHEMICAL CHARACTERISTICS 8.1.1 ESSENTIAL OIL Colour: Ceylon type - Pale yellow to brownish liquid Java type - Yellow to pale brown Density: Ceylon type - 0.894 - 0.910 Java type - 0.850 - 0.895 Dielectric constant: Italian ~ i l - at 16 O C 3.233 at 2'7 "C 0.326 Flash point - 84 OC for unadulterated oil Moisture content: Ceylon oil 0.4% after 1 year Java oil 1.1% After saturation with water: Ceylon oil 0.9% Java oil 1.4% adour: Rose or lemon-like. odour of Java oil is said to be superior to that of Ceylon oil. Refractive index: Ceylon oil - 1.479 - i ,487 iava oil - 1.466 - 1.473 Solubility in water . Surface tension Albert has shown that soap assists in increasing the water solubility of citronella oil Citronella oil (25 ml) + 0.88 ammonia (8.5 ml) + soap solution (50% amrnonixm ricinoleo-sulphate) to give 100ml. Citronella oil (20 ml) + cydohexanol (7.5 ml) + potassium linoleate solution (20%) to give 100 ml Citroriella oil (33 ml) + 25% sodium chloride (6 5 ml) + 33% potassium ricinoleate solution to give 100ml. Citronella oil (40 ml) + Basic triethanolamine ricinoleate to give 100 ml. Ceylon oil 28.7 (density 0.9) Java oil 29.2 (density 0.5896) Java oil 27.7 (density 0.887) Using the capillariscopic method, the following values have been obtained for the increase in diameter of the oil spot during the first minute of observation (k) and the original diameter of the oil spot (d) : Ceylon oil k = 0.4136 d = 3.82 Java oil k - 0.4248 d = 2.71 Ultrasonic velocity: 1076 rnlsec at 29 ' and frequency 10.02 Mc/s Viscosity: Ceylon oil 5.464 (at 20 'c) (density 0.90) Java oil 5.467 (density 0.8896) Java oil 5.549 (density 0.887) It was found that there is no relationship between viscosity and the citronella content of the crude and rectified oil (Java variety). X-ray diffraction: Inter-planar distance (d) for citronella oil : 4.92 A' 8.1.2 GOHOBATTON WATER : ESSENTIAL 01L 37 Cohobation of distillation water obtained on steam distillation of Ceylon citronella, yielded 0 05% essentiai oil When the distillation water were re-distilled, the distillate concentrated and the free oil separated by decantation, and by extraction of the residual waters with ether, the mixture of these oils, had the following physical characteristics. dzo 0.913at20°C n~ 1.4829 at 20 'C Acid value 0.3 Ester value 1 8.1 Ester value after acefylation 83.2 Carbonyls as CloHlsO 38.2% The chemical composition of this was: I-carvotan acetone 10.7% Geraniol 20.0% d-citronella1 4.2% Geranyl acetate 6.25% Ethyl alcohol 2.5% Perillaldehyde 12.1% Furhral 2.3% Phellandrene 8.43% 8.1.3 DISTILLATION RESIDUE 52 This is a liquid, which comprises the oxidation and polymerization products that are non-volatile. In the case of Java oil, this residue was 0.5-3%. In Sri Lanka, this residue is referred to as 'Goda'. 8.1.4 SPENT GRASS 24,52 The residue thrown out after extracting the oil is termed as 'spent grass'. It was found to have high moisture content of 82.68%. The dry matter content was 17 32% of which, 84.09% was organic matter. The following analysis has been reported for decayed spent grass of Ceylon citronella. Grganic matter 84.09% (contains 2.24% N) Oxides of Fe & hi 0.97% Phosphoric acid 0.30% Lime 0.61% Potash 0.09% Other constituents 0.74% Pandittesekera obtained the following figures for Ceylon citronella grass ash: Lime - 3.28% '3hosphoric acid - 1 39% Potash - 7.06% Georgi gave the following figures for dry spent grass from Cymbopogon winterzanus grown in Malaysia. Ash - 5 6% Organic & 'Jolatile - 94 4% matter Nitrogen 1.11% Potash (as K20) 1.23% Phosphoric acid - 0.13% (as P2O5) It has been reoorted that spent grass is an excellent source of manure. It is applied either after composting or in the form of ash by burning. There is a report fi-om Puerto f i c o that spent grass is dried and ground to a powder and then mixed with molasses and soya proteins which form a good feed for the r,attIe The dried spent grass is also used as fuel for the distillation of the oil. The spent grass can also be used as cheap material for packing glassware. It is also reported that spent grass can be used for manufacture of paper and cardboard. 8.2 CHEMICAL CONSTITUENTS OF GRASS 14,26-23,37,38,58,76,99,102 The main chemical differences between the oil fi-om the two varieties, Cyvnbopogon nardus (L) Rendel and Cymbcpogon wznterianu,~ Yowitt were the relative amounts of total acetylisables. The Java type oil were characterized by low concentrations of monoterpenes (2.9-3.8%) and high concentrations sf citronella1 (34.8-3 6.6%), citronellol(9.9-11.5%) and geraniol (22.1-25 4%) as compared to the Ceylon type. The Ceylon type contained 23.8% monoterpenes, 13.3% Citronella and 6.2% citronellol. The concentration of geraniol was slightly lower than the Java type at 20.9%. The Ceylon types contained significant amounts of borneol (5.2%), methyl euge~ol (8.42%). Bornyl acetate was also present in the Ceylon type. These compounds were either not detected in the Java-type or were present at much lower levels. The Java- type contained 0 13-0.17% citronellic acid which, was not detected in the Ceylon type. The Java citronella oil has been characterized as fresh and sweet revealing the high content of citronellal, geraniol and citronellol. These compounds are not predominant in the odour of the Ceylon type oil, which is characterized by the comphene-borneol- methyl engenol complex. Table 2 : Chemical Constituents of Cymbopogon nardus. Constitutent Percentage T-amorphol / bulnesoI Renzylacetate K-Bergamc7tene Borneo1 Bornyl acetate Bourbonene y-cadinene 6--cadinene Camphene Camphene Carene 8-3 -carene Caryophyllene Caryophyllene oxide 1, 8-Cineole Citronella1 Citronellyl acetate Citronellol Citronellyl butyrate a-cabaene P-cubebene p-cymene Decanal 3,3-dimethyl bicycfo [2.2.1] heptan-2-one Dipentene a-elernene p-elemene 6-elemene Elemicin Elemol l 0-epi-y-eudesmol Farnesol Cis a -famesol Trans a - farnesol 0.55 0.5 1 .o 4.8 - 6.6 0.5 1 .o 1.02 0.6 6.6-3 1 0.5 trace 0.12 0.9 - 3.2 0.1 - 0.3 13.3 - 14.7 1.1 - 1.2 6.2 - 6.5 trace 0.04 3.77 0.1 0.18 0.07 Geraniol Geranyl acetate Geranyl butyrate Geranyl formate Hexanol a-humulene Lirnonene Linalool Linalyl acetate Melonal (2,6-dimethyl-2-heptenal) Menthol Methyl eugenol Cis-methyl isoeugensl Methyl heptenone 6-methyl-5-hepteq-2-one a - muurolene 6 - muurolene Trans-muurolol Myrcene N erol Nerolidol Neryl acetate Cis-ocimene Trans-ocimene Pelargonaldehyde a- Phellandrene p- Phellandrene a- Pinene p- Picme Iso - pulegol Iso(iso) pulegol Sabinene Scadinene Sesqui citrocellene a - Terpinene 6 - Terpinene a - Terpineol Terpinen-4-0 1 a - terpineol Terpinolene a - terpinyl acetate a - thujene Thujyl alcohol Tricyclene Iso - valeraldehyde 17.5-40 2.1 0.6-1.5 0.2-4.2 0.1 0.21 9.7-44.5 0.5-1.2 0.8 0.11 trace 1.7 10.1-11.3 0.2 0.16 0.46 0.36 0.33 0.8-2.4 0.6-0.9 0.3 0.10 2.1 '.1 0.06 trace 0.7-1.2 0.5-1.2 0.6-0.7 0.4 0.02 Table 3 : Chemical constituents of C,>mbopogon winteriaaaus Constituents Percentage T- arnorphol 1 bulnesol Benzaldehyde a - Rergatomene Borneo1 p - Bourbonene Cadina-1,4-diene p - cadinal y - cadinene 6 - cadinene a - cadinol 6 - cadinol Epi- a- cadinol Calaminene 6 - 3 - carene Camphene Carvone j3 - caryophyllene a - Celanene Chavicol Citral Citronella1 Citronellic acid Citronellol Citronellyl acetate Citronellyl butyrate Citronellyl citronellate a - copaene p - Cubebene Cyrnbopol p- cymene Decanal Dicitronelloxide Dipentene p - elemene 6 -elernene Elemol 10 - epi - y - eudesmol a - eudesmol p - eudesmol Eugenol (Z,E) farnesol (E,E) farnesol Furfural Geronial Geraniol Geranyl acetate Geranyl butyrate Geranyl formate trace - 2.3 0.2 0.1 - 0.39 0.05 13.4 - 15.7 0.9 - 7.3 trace 2 - 4 0.08 2.25 Hexanol 2 Hexene - 1 - 01 3 Hexene - 1 - 01 a - Humulene ISO - amyl alcohol Iso - butyl alcohol Iso pxlegol Juniper camphor Limonene Linalyl acetate Linalool Melo nal Menthone 1 - methyl - 3 - cyclohexanone Methyl eugenol Methyl isoeugenol Methyl heptenone 6 - methyl - hept - 5 - en - 2 - ene 1 - methyl pentanal a - muurolene y - muurolene Myrcene Neral Nerol Neryl acetate ( Z ) - j3 - ocirnene (E) - P - ocimere Octanal a - phellaqdrene J3 - phellandrene a - F'inene p -Pinene Pulegone Rose oxide Sabinene Selinene Sesquicitroneliene a - ter2inene Terpinolene Terpinen - 4 - 01 a - terpineol Tricyclene Thujyl alcohol Vanillin trace 2 0.47 0.67 0.72 - 1.3 1 .o 1.0 -7.7 trace 0.08 - 0.3 0.14 - 0.4 0.2 0.1 3.4 0.2 0.5 0.03 Table 4 : Chemical constituents of Cymhopogon Confertzflorus: Constituent Percentage Total alcohols Geraniol Citronellal Table 5 : Chemical const ituents of Andropogon schoenanthus: Constituent Percentage Geraniol Citronella1 Citrai Table 6 : Chemical Composition of Various Commercial Citronella Oils Compound China Argentina S.America Java Ceylon - .- Cis-3-hexenol* 0.02 0.01 0.01 0.01 Tricyclene 0.01 1.09 a-thuj ene * 0.0 1 0.01 1.09 a-pinene 0.01 0.02 0.01 0.05 1.87 Camphene - 0.04 6.97 Sabinene 0.07 0.09 0.05 0.07 0.06 6-methyl-5-hepten-2-one 0.01 0.01 0.01 0.01 0.16 P-pinene 0.03 0.01 0.01 0.06 Myrcene 0.07 0.08 0.08 0.09 0.83 a-phellandrene - - 0.12 6-3-carene 0.01 0.01 0.01 0.01 0.12 a-terpinene 0.01 0.01 0.01 0.01 0.06 p-cymene 0.01 0.01 0.01 0.12 P-phellandrene/l,8-cineole 0.05 0.05 0.06 0.07 0.06 Limonene 2.62 3.2 1 2.93 2.8 1 8.66 cis-p-ocimene 0.01 0.01 0.37 1.92 Melonal 0.09 0.09 0.07 0.09 0.11 Trans-P-ocimene 0.02 0.0 1 0.02 0.19 1.07 3,3-dimethyl b ic~~c lo 12.2. I ] 0.01 0.01 0.01 0.07 heptan-2-one* Terpinolene 0.05 0.06 0.06 0.06 0.74 Linalool 0.77 0.86 0.47 0.72 0.56 Citronella1 35.27 36.63 36.39 34.79 6.09 Iso (iso)pulegol* 0.29 0.41 0.34 0.22 0.87 Borneo1 0.06 0.08 0.06 0.05 5.23 Terpinen-4-01 0.04 0.05 0.04 0.04 0.65 a-terpineol 0.06 0.06 0.06 0.05 1.05 Decanal 0.10 0.09 0.12 0.10 0.18 Citronellol 9.92 11.47 10.63 11.19 6.15 Compound Geraniol I Bornyl acetate Citronellic acid a-terpinyl acetate Citronellyl acetate Eugenol Neryl acetate 6-elemene* Geranyl acetate Methyl eugenol a-copaene* P-bourbonene P-elemene P-caryop hyllene Cis-methyl isoeugenol a-humulene Trans-methyl ~soeugenol P-cubebene* a-muurolene* y-muurolene* y-cadinene Elemol 6-cadinet~e Cis-a-farnesol* 10-epi-y-eudesmol* Trans-muurolol T-amorphol*/bulnesol* Trans-a-famesol * Total % of oil 1 S.America 1 Java Ceylon China Legend: * = Not previously reported in citronella oil The P-phelfandrene/l,8-cineole and T-amorphoVbulneso1 peaks did not consistently separate. Argentina Citronelloi Chemical structure of Citronelloll Chemical structure sf Citronella1 Geraniol Chemical strucuture of Geranioll Lirnonene Chemical structure of Limonene Camphene Chemical structure of Camphene (+) form Borneol Chemical strucl~rre of Borneol (+) form a-Pinene Chemical structure of a-Pinene p-ocimene Chemica! structure or p-ocimene Chemical structure of Terginollene Figure 2 ; Coe~stituents of Citronella Antibacterial activity: The vapour of citronella oil inhibits the growth of gram-positive organisms. The oil shows antibacterial activity against pathogenic bacteria such as Escherichin cdi , Bacilius m~coides, Hucilllis pitmilus, Sarcinaluteu and Sh~geZka nigesb. It has been repohted that citronella oil inhibits the growth ofMicrococcuspyoget~es var. azlreus. At a dilution of 1 : ! 6,000, Okslzaki and Oshima found citronella oil effective against avian Mycobucterir~rn tubercz4losis. The Formosan citronella oil had antibacterial activity against Hacillzrs suhtilis var. nterrinzzls. Using Bacillzrs typhos1r.s as the test organism, obtained the following values for citronella oil. Rideal Walker coefticiene = 10.0 Phenol coefficient (Garrod's tzst) = 4 4 Anti-fungal activity: The oil of citronella exhibits a very good antifungal activity. Dube Gita et. al. found that it shows good antifiinga! activity against Aspergllus niger, Aspergillus fzavus, Aspergillus fumigatus and Fzcsariz~m oxyslporum. Cymbopogon nardus strongly inhibited germination of fbngi, Sclerotium rolfsii, Rhizoctonia oqzae-sativoe and Sclerotlum hydrophyllum. Insect repellent activity: Citronella oil isolated from Cymbopogon nardus at 1.0 concentration exhibited significant insect repellent activity against two stored grain pests viz., Triholzum castaenum and Bruchus chinensis and a household pests, cockroaches and mosquitoes. It was found the repellant and toxic effects of citronella oil against Sztotroga cerealella (Olivier) an important pest of stored paddy in Sri Lanka They hrther showed that f3- pinene was the most effective repellent followed by p-cymene, camphene, a - phallandrene and a -pinene when the terpene hydrocarbons were examined individually, p-cymene was found to be the most effective at causing inactivation and mortality. Larvicidal activity: The essential oil of Ceylon citronella shows a significant activity (6.3mVl) against Culex yuinquefasciatus and lesser activity against Aedes aegypti (9.3 mgll). Ratnaweera et. al. found that myrcene was the major active principle of hydrocarbon fractions responsible for the larvicidal activity. y-terpinene also shows has considerable activity. Skin irritation: Citronella oil when tested at a concentration of 8% in petrolatum, in a 48-hour closed patch test, on 25 human subjects, did not cause irritation. There have been a few reports of eczematous, contact-type hypersensitivity, folliculitis of the acne form, papulovesicular eczema of the hands, fingers and forearms, caused by citronella oil. Citronella1 is said to be the allergen in the oil. Citronella oil has received listing as a primary irritant in perhrnes by some authors. Toxicity: The acute oral LD50 of citronella oil in rats in greater than 5gIkg The acute dermal L D s ~ in rabbits is 4.7ml.kg. 9.0 ANALYSIS OF CITRONELLA OIL 52,94,99 Gas liquid Chromatography Gas or gas liquid chromatography is a method of separating a volatile complex mixture into its separating a volatile complex mixture into its separate components by making use of the different partitions of the components between a mobile gas phase and a stationary liquid phase. A stream of an inert 'carrier gas' like Argon, Feliurn or Nitrogen flows by way of a pressure value, through the chromatographic column which is maintained in an oven compartment. The sample to be analysed is injected into the injection port where it is flash volatilised i ~ . t o the stream of carrier gas prior to entering the column. The column is a coiled tube, which contains the liquid ' stationary phase'. Columns are of two main types viz: packed columns and open tubular columns. Open - tubular columns have much greater powers of resolution. They are more sensitive than packed columns, but can tolerate only minute doses of material. The selection of the type of column, the appropriate stationary phases and its temperature, play an important role in the success of analyses by GLC. Some stationary phases that have given particular good results are Carbowax 20h.1, FFAi', SE 30, OV 101 and OV 225. In order to achieve optimum separation the temperature of the column compartment has to be gradually increased during analysis. The separated constituents of an essential oil emerging from the column enters the 'detectors' which monitors the entry of each compound. The emergence of each separated constituent alters the electrical conductivity with respect to that of the carrier gas. These variations in each case are converted into electrical signals and recorded on a strip chart recorder. This 'gas chromatogram', takes the form of a series of peaks which correspond to each component separated by the column. Please refer SLS 572 : Part 3 : 1984; I S 0 7359 and IS9 7609. Thin layer chromatography (TLC) TLC is a simple separation technique where a mixture is separated on a glass plate coated with a layer of silica gel powder, aluminium powder or cellulose powder. Silica gel is the most useful matrix for analysis of essential oil components. The mixture is applied to the lower edge of the coated plate of glass and then developed in a suitable solvent by being placed in a glass tank. The solvent will ascend along the plate and when a distance of about 15cm is covered the plate is removed and allowed to dry. The separated components are then visualized by spraying of a number of reagents. The most widely used reagents are; (i) Vanillin in Ethanol containing a small amount of concentrated sulphuric acid (ii) Anisaldehyde treated similarly (iii) Dipping in Iodine vapour Among the other reagents , 2,4 Dinitrophenyl hydrazine in diluted hydrochloric acid will detect ketone and aldehydes, whi!e diazotized, sulphanillic acid and nitro anillin will detect phenolic compounds Faruq, et.al. in their study divided the lemongrass oil into different fractions and was subjected to tlc studies separately. 9.2 SPECTROSCOPY 1nfri.a red Spectrometry One of the most characteristic properties of organic molecules is its infra red (IR) spectrum, which originates from the absorption of W radiation by the molecule. When IR radiation strikes the bonds of molec.ules, the bond energy will be absorbed, when the correct energy for excitation of some bond in the molecule is present. The IR spectrometer will thus record each such absorption and intensity of which this occurs. Samples can be analysed as pure films, dilute solutions or made into transparent discs after dispersing in potassium bromide or as a paste made in Nujol (white oil). IR spectra are so characteristic for cornpounds that the fine structure in the spectrum is a fingerprint of each s~ich compound. Even f a complex mixtures such as essential oils an IR spectrum would be useful for checking authenticity quickly. The spectrum which is recorded can then be compared with a similar spectrum from a genuine sample of oil. 9.3 DETERMINATION OF TOTAL GERANIBL All'acetylizable constituents calculated as geraniol. Acetylation method This method involves heating the oil gently, with 95% acetic anhydride and anhydrous sodium acetate for 2 hours, decomposing the excess acetic anhydride by heating with water, washing with 10% sodium chloride, drying overnight over anhydrous sodium sulphate and determination of the saponification numberof the resulting acetylated oil. Saponification is carried out with ethanolic 0.5N potash and the excess ROH titrated against 0 5N sulphuric acid. An oil bath, sand bath or electric hot plate is used for heating the acetylation flask, not an open gas flame. The presence of traces of water and sulphuric acid in the reaction is said to cause enolisation of citronellal and formation of citronellal diacetate, which gives a high total alcohol value. Low results for total alcohols are obtained when the purity of acetic anhydride used is less than 95% and when the period of acetylation is less than 2 hours. Oximation method The oil is oximated using aqueous solutions of hydroxylamine hydrochloride and potassium carbonate and the nitrogen content determined by the Kjeldahl method. From this, the % citronellal can be calculated. The geraniol content is then determined by acetylation of the oximated oil, the total alcohols being the sum of the 2 values thus obtained. Phthalic anhydride reaction Geraniol reacts with phthalic anhydride, forming acid esters, while citronellal does not react with this reagent. Thus, by heating the oil with phthalic anhydride and benzene for 2 hours, conversion of the geraniol ester formed, to its potassium salt, with aqueous potassium hydroxide and titration of the excess alkali against sulphuric acid, the amount of geraniol in the oil can be calculated. Method of Petrova and Novikova In this method, the citronella oil is refluxed with toluene and p-toluene sulphonic acid and the settled out water titrated with Fisher's reagent, to determine the geraniol content. Citronella1 is said to interfere with the dehydration reaction. Colorimetric method Picric acid gives a red colour with geraniol in glacial acetic acid on heating. 9.4 DETERMINATION OF CITRONEELAL Hydroxylamine method (i). Total geraniol is determined by acetylation method, the citronellal removed by addition of hydroxylamine hydrochloride (neutralised with sodium carbonate) and heating at 20 - 25 OC for 2 hours and the geraniol content of the supernatent oil again determined. From the difference in the 2 values the approximate citronellal content is calculated (ii) The oil is reacted at -2 OC with a 5% alcoholic solution of hydroxylamine hydrochloride then titrated with 0.58 alcoholic potash using bromophenol blue as indicator, and a slight excess of KQH added. The excess KQH is titrated with 0.5N alcoholic hydrochloric acid. Adding the excess alcoholic KOH before adding the hydroxylamine hydrochloride reagent has modified this method. Phenyl hydrazine method In this method the oil is allowed to stand with a alcoholic solution of phenyl hydrazine for about 1 hour, then shaken with hydrochloric acid and the excess acid titsated against sodium hydroxide or potassium hydroxide, using ethyl orange as indicator. 10. CHEMICALS FROM THE OIL "552 Geranisl: Geraniol is a colourless liquid, with a flowery - rose like odour. Waterman et. al. separated geraniol from citronellal in Java citronella oil, by fractional distillation of the oil in vacuo (1-2 mm) and re-fractionation in a cathode vacuum. In the conventional method, the oil is shaken with an equal volume of saturated sodium bisulphite solution, a little neutral sulphite and 1-2 ml ether, extracted with water and citronellal precipitated with barium chloride. The remaining oil is hydrolysed by alcoholic potash and the geraniol separated through its crystalline double compound with calcium chloride. This compound is decomposed with water and steam-distilled to give geraniol. Commercially geraniol is prepared by fractional distillation from Java or Ceylon citronella oil, and freed from traces of citronellal, by boiling with dilute caustic soda solution. The citronellal is converted into high boiling products, which are eliminated by distillation. Pure geraniol is obtained through its calcium chloride compound The geraniol can also be purified through the hydrogen phthalate. According to British Patent 547,420 citronellal can be separated from the geraniol in Java citronella oil by converting the citronellal into a high boiling condensation product with a suitable amine and removing the geraniol by distillation. Citronellal: Pure citronellal is a colourless liquid with a refkeshing ordour. Crude citronellal (10 kg) obtained by fractionation of citronella oil and concentrated sodium bisulphite solution (9 kg) are run into an enamel vessel fitted with a cooling jacket and stirrer and caustic soda solution (1.25 kg, 39" Beaume) added, keeping the temperature below 0 OC AAer an hour when the mixture sets to a pasty mass, benzene ( 5 kg) is added and stirring continued for 5 hours. The product is pressed in a hydraulic press; the press cake is kneaded with benzene (5 kg) and pressed again. The pure citronellal is liberated from this bisulphite compound by steam distillation in the presence of soda ash. CitroneIlol: Citronellol is a colourless liquid with a sweet rose like odour. Citronellal is obtained by distillation of Java citronella oil and is hydrogenated to citronellol in the presence of a catalyst like Raney nickel. Also it can be done electrolytically using lead electrodes and dilute alkali as a electrolyte. Hydroxycitronellall: Java citronella oil is distilled under reduced pressure (4mm) and the fraction with a boiling range 70-1 14°C is hydrogenated with Raney - Cobalt catalyst at 30-48 "C for 2 hrs at 100 kg Isq. cm of hydrogen pressure. Distillation gives citronella1 (bp 80 - 85 "C/3 mm Hg). Hydrogenation of citronellaI gave hydrocitronellal. Dehydrogenation in the vapour phase under reduced pressure with a copper - zinc catalyst gave hydroxycitronellal Menthol: (-) - Menthol has a characteristic peppermint odour and also exerts a cooling effect. The process uses the readily occurring cyclization of citronellal to isopulegol (+) - citronellal can be isolated with an optical purity of about 80% from citronella oil. Alternatively, it can be synthesized with a purity of 98% from dialkyl - geranylamine by enantioselective isomerization to (+) - citronellal diaikylenamine followed by hydrolytic cleavage to (+> - citronellal Isomerization is effected in the presence of chiral rhodiumm-phosphine complex as a catalyst. (+)- Citronella1 is cyclized in the presence of acidic catalysts (eg silica gei) to give a mixture of optically active isopulegol isomers containing ca 20% of the corresponding racemates. (-) - Isopulegol can be isolated from this mixture and hydrogenated to (-) menthol. The remaining isopulegol stereoisomers can be partly reconverted into (+) - citronellal by pyrolytic cleavage and reused in the cyclization procedure. 11.0 STANDARDS AND SPlECIFICATIONS 11.1 STANDARDS Three grades of Ceylon citronella oil, differentiated according to the total acetylisable constituents are specified in the Sri Lanka Standard (SLS 170) Table7 and Table 8 gives the requirements for the 2 types of citronella oil as specified in various standards. Grade Abbreviations for Table 7 and Table 8 SLS = Sri Lanka standards BS = British Standards BPC = British Pharmaceutical Codex IS = Indian Standards I S 0 = International Standards EOA = Essential Oil Association Standard. n.s. = not specified. hinir;?um Total acetylisable Constituents (as geraniol) Ester value after Acetylation min. Table 7 : Citronella oil : Requirements for Cymbopogon nardus - - Table 8 : Citronella oil : Requirements for Cymhopogon winterianus Specific gravity Optical rotdion Refractive index Solazbility Total aldehydes (as citronella]) Carbonyl value Total alcohols (as geraniol) Ester value Steam distillation residue present by mass. Max. SLS 170 0.9 10 -22 to -12" 1.465 - 1.487 1 vol. in 2 vol of 80% alcohol Specific gravity Optical rot B t' lon Refractive index Solubility Total alcohols SLS 170 11,s. n.s. n.s. 1 vol. in EQA 12 - 0.898 - 0.910 -9 to -18" 1.4790 - 1.4850 1 vol. in 2 vol of alcohol BS 2999118 0.893 - 0.910 -9 to -18" 1.479 - 1.485 1 vol. in 2 vol of 80% alcohol 7 - 15% 25 - 55 59 - 65% 185- 201 BS 2999119 0.880 - 0.892 0 to -5" 1.466 - 1.473 f vol. in IS03849 0.894 - 0.910 -22 to 12" 1.479 - 1.487 1 vol. in 2 vol of 80% alcohol 18 - 55 85% 157- 200 BPC 1973 0.895 - 0.905 -9 to -18" 1.408 - 1.485 1 vol. in 4 vol of IS 512 0.587 - 0.908 -9 to -18" 1.4745 - 1.4805 1 voi. in 2 vol of BPC 1973 0.880 - 0.895 -5 to +2 1.468 - 1.473 1 I . in I S 0 3848 0.880 - , 0.895 -5 to 0" 1.4660 - 1.4730 1 vol. in IS 512-1988 0.8743 - 0.8893 -0.5 to 5" 1.4624 - 1.4730 1 vol, in alcohol alcohol I / 7 - 15% EOA 14 0.883 - 0.900 -0.30 to -6" 1.4660 - 1.4745 1 vol. in not less than 175 not greater than 4 11.2 ADULTERANTS 52 The following are among the adulterants which have been detected in citronella oil : kerosene, camphor oil, coconut oil, petroleum or mineral oil fractions, rosin spirits, lemon oil, alcohol, terpineol, wood oil from Dipteraca~pus species. Sometimes the oil has been found to contain fractions left after removal of the geraniol and/or citronella1 from citronella oil. Adulterated oil also results when weeds or root material are mixed with the grass that is distilled. 11.2.1 DETECTION OF ADULTERANTS: Fixed oil Saponification of the essential oil with alcoholic potash and precipitation of the fat can determine the amount of fixed oil. When the amount of fat present is about 0. I%, after saponification with methenolic caustic potash the resulting glycerol is oxidised with acidified potassium periodate to formaldehyde and formic acid. The excess periodate is removed using phenyl hydrazine and ferric ammmium sulphate and sulphuric acid added successively. A red product results. The % transmittance or optical density is determined at a wave length of 5200 A0 using an absorptiometer or spectrophotometer. Viscosity measurements have been used for detection of 10% or more coconut oil in citronella oil, since the viscosity of the adulterated citronella oil is much higher than that of the pure oil. Adulteration with wood oils of the Llipterocarpus species results in a higher fraction boiling between 215-225 OC and a higher saponification value (48-54 as against 35-40 for the pure oil) Kerosene, Petroleum or Mineral oil fractions Citronella oil with a flash point below 75 OC is suspected to be adulterated with benzene or gasoline. The presence of kerosene cannot be detected through flash point determinations. Kerosene has to be fractionated out and detected by its odour. Wijesekara et. al. have described a gas chromatographic method for detection of kgrosene ir. citronella oil. Ethyl alcohol When the oil is shaken up with a crystal of hchsin, the oil should remain colourless if ethyl aicohol is present. Oils with low specific gravity may be adulterated with alcohol. Solubility tests Schimmel's test or old Schimmel's test Schimmel & Zo introduced this test in 1898 as a simple quick field test for detection of adulterants before purchase of oil. To ass this test, 1 vol. of the citronella oil must be I soluble in 1-2 vol. 80% alcohol at 20 C and the solution must remain clear or be only slightly opalescent when further alcohol is added upto 10 vols. alcohol. This test permits 10% adulteration of the oil and far from being a deterrent, permitted adulteration to the limits of the test. New Schimmel's test In this test, 1 vol. of the oil is first dissolved in 1-2 vols 80% alcohol at 20 O C . Then, further alcohol is adGed dropwise, carefidly, till the point of maximum cloudiness or turbidity is reached. Not more than 10 vol. alcohol are added. If the oil separates out on prolonged standing the oil has failed to pass this test. This test allows up to 4% kerosene. Raised Schimmel's test The oil is mixed with 5% petroleum and the old Schimmel test applied, adding up to 10 vol. alcohol, disregarding any cloudiness during addition. An oily separation oz standing indicates adulteration. The Schimmel's tests however, were not satisfactory, as certain freshly distilled oils did not pass the tests. London Solubility test This test was put forward by Essential Oils Sub Committee of the Analytical Methods Committee of the Society for Analytical Chemistry. To pass this test, 1 volume of the oil should be soluble in 2 vols. 80% v/v alcohol and should be not more than faintly opalescent with no separation of oily drops when a further 4 vols. 80% v/v alcohol are added and the sample kept overnight in a stoppered cylinder at 20 O C . Bamber's test M.K. Bamber suggested this test to determine the amount of adulterant insoluble in alcohol. His test involves the shaking up of 2ml 83% wlv alcohol followed by centrifuging for % - 1 rnin. This test however was found to be qualitative only and did not gain wide acceptance. 12.0 PRODUCTION AND TRADE j2 Sri Lanka continues to be the main producer of Ceylon citronella oil. In 1892, the total area under citronella in Sri Lanka was 25,000 acres and there were 450 stills. This had increased to 40,000 acres in 191 1 and fallen to 30,000 acres in 1940 and fallen hrther to 16,800 acres in 1969 and at present it is around 15,627 acres. It is mainly cultivated in the Hambantota district with small areas under cultivation in Matara and Matale districts. Although production of Citronella oil in Sri Lanka is nowadays at a much lower level than once it was, it appears currently to be stable and is likely to remain so, particularly as demand for it is declining only slowly, although periodic shortages in supplies of citronella oil from other sources may also help to maintain the level of demand for Sri Lanka7s product Details sf exports are given in table 9. Indonesia was the first supplier of commercial quantities of Java-type citronella oil and it has been one of the world's most important suppliers of citronella oil, although China has challenged it. In recent years, Citronella oil, which typically sees price hikes prior to the summer, has not budged. The situation has got so bad that sellers are now lowering prices to entice buyers back to market. Sri Lanka distillers note that current prices are below the cost of production. Market Price for Ceylon Citronella in US market: 1 Price for 1 lb 1 $ 3.30 -3.50 1 3.30 1 4.00 - 4.25 1 The USA is the world's largest innporter of Citronella oil. Details of imports are given in Table PI & 111. Although no published figures are available, it would appear that a small proportion of imports is re-exported. Imports of the Ceylon-type oil from Sri 'Uanka have held up fairly well, which is to be expected, since consumption of citrcnella oil as a perhmery oil per se has declined far less sharply than has been the case where isolate extraction is concerned. However, of ~ava-type oils, :>ere has been a sharp fall in imports from Indonesia although, a rather higher proportion of Indonesian oil is now purchased via Taiwan Chinese oil is marginally favoured over Indonesian oil as it is less likely to be adulterated. The basic uses for the de~-ivatives of citronella oil and the comparable derivatives of turpentine apply in the USA. Some US users still prefer natural, rather than synthetic, geraniol and hydroxycitronellal, but for the latter, Eucalyptus citridora oil is often the preferred source. Sri Lanka oil appears to be favoured for the inarofacture of mosquito-repellent citronella candles. The other major import of citronella oil is United Kingdom. The United Kingdom purchases its supplies of citronella oil from many sources. The Sri Lankan oil continues to be imported in fair, although in the long-term gradually declining, quantities for per se applications in low-cost products, while for the Java-type oils China Nr. Indonesia predominate as suppliers, other significant, if irregular suppliers having included Taiwan, Vietnam, Brazil and Guatemala. Table 9 : Export Performances of Ceylon Citronella oil: Year r- vo~./kg. 7- Value/Rs. External Trade Statistics Table 10 : Citronella oil imports to USA I Year ~ Vol./kg. 1 Chem. Market Reporter Table 11 : Imports to USA (Kg.) Vietnam I 80,000 1 72,000 1 130,000 ! China 7,71,000 2,20,000 !1,73,0001 I I Russia ~ 1 , 1 5 , 0 0 0 -7 I I I I - I Cherdicccl Market Reporter - Fe b. 6998 13.1 Perfumery In applications where the oil is used as such, Ceylon oil is preferred especially in USA, because its olfactory properties are finer than Java oil. Citronella oil is said to enhance the floral and woody notes of perhmes. As early as 1893, oil of citronella had been described by Schimmel & Co. as a pe f ime with no rival. It has been used as an odour- masking agent in a wide range of products: soaps, detergents, polishes, floor waxes, disinfectants, ointments, anointing oils, animal feeds etc. Ceylon citronella oil is not popular in detergents, since it is not considered as sufficiently stable. Ceylon citronella oil is used as a masking agent s f foul smelling chemicals in deodorisers and bleaches, insect repellents and cleaning products. Opdyke gives the following values for the concentration of citronella oil is products, when used as a perfume: Soap p ~ e t e r g e n t Perfiimes 1 Maximum 0.60% 1 0.03% 1 0.30% ( 0.80% - 1 Lotions Usual 0.03% 0.03% Although geraniol and citronella1 are the main constituents of oil oC citronella, it has been suggested that camphene-borneol-methyl eugenoI complex, characterised the odour The most popular use of oil of citronella is as z soap pefime, for which purpose, it is expected tc contain rlot less than 85% geraniol. The Java oil is used for higher quality soaps, while the Ceylon oil is used as a cheap perfume for soaps, of a lower grade. By fractionation of the oil, a mixture of Geraniol.citronella1 65 35 comprising a mixture of alcohols, partly free and partly as esters is obta;ned and sold as crude geranioi or geraniol C, for use n scenting soaps, detergents, aerosols, etc 0.2% Formulary of Perfumes: I . Citronella for soap. Benzaldehyde 25g Bergamot 200g Caraway oil 2258 Citronella oil 275g Geranium palmarose oil 225g Musk xylene 25g Terpineol 25g l ooog 2. Eau de Cs!ogne for soap: Cidanvood oil, Cinnamyl Butyrate Citronella oil Clove oil Diphenyl oxide Lavender oil Linalyl acetate Musk xylene Rosewood oil Stynax, Resinoid Teqineol Thyme oil 1 oog 3% l oog 5og 1 oog 1 0og 5% 3% 200g 2% 200g 2% 1 ooog 3. Imitation Geranium for soap Cedanvood oil Citronella oil Clove oil Diphenyl oxide Linalyl acetate Musk xylene Rose wood oil Spike lavender oil Stynax, Resinoid Terpineol Thyme - 1 ooog 4. Almond, Bitter for soap Benzaldehyde 300g Caraway oil 2% Cedarwood oil 2% Citronella oil 5og Geranium Palmarosa oil 150g Phenyl ethyl alcohol 15Og Terpineol 300g ------ -- l ooog 5. Cheap soap pehrne : Lemon grass oil 400 parts Citronella oil I50 parts Bois de Rose oil 100 parts Bergamot oil 100 parts Lemon oil 200 parts Musk ambrette residue 50 parts I000 parts 6. P e h m e for Tallow soap Spike lavender oil 50 parts Java citronella oil 12 parts Geranium bourbon oil 25 parts Mace oil 13 parts 100 parts 7. P e h m e for Transparent soap Bergamot oil Cananga oil Citronella oil Eugenol Lavender oil h a l a Hair oil Perhme: Citronella oil Lemon oil Neroli oil Lavender oil Bergamot oil 5 parts 10 parts 10 parts 10 parts 25 parts 4 dram 8 dram 2 aram 20 drops 20 drops In the following patent by Tabekoff, Citronella oil is a constituent of a cleaning composition for sanitary equipment: N&So3H 50 ?arts Bu2Wd 300 parts Ammonium stearate 100 parts H3po3 30 parts Diethylene glycol Ethyl ether 505 parts Oil of citronella 7 5 parts The volatility index and odour intensities of oil of citronella after various time periods, are quoted by Appell in the following Evaporation charts Oil of citronella, Ceylon Volatility lndex 150 Odour intensity 5 1 hour 150 mg 2 hours 8 0 1 day 3 20 (odour intensity 3) 1 week 350 Residue 199 (odour intensity 2) ail of Citronella, Java Volatility lndex 100 Odour intensity 6 1 hour 100 mg 6 kours 300 mg 2 days 550 mg Xesidue 50 mg (odour intensity 2) Chicopharna in a Netherland patent describes a method for retaining the odour of oil of citronella for several months by incorporation of 1 .5 g. oil of citronella, under 3.5 atm. Pressure, in 30 g of a polyetheylene wax and then casting in 2.5 g moldings. Java oil is used for the preparation of many aroma chemicals which are used in synthetic perfkmes. Some of these isolates include: Geraniol, citronellol and their esters (e.g. formates, acetates, butyrates, iso-butyrates, valerates, benzoates), citronellal, hydroxy-citronellal, menthol, geranyl anthranilate, geranyl methyl ether, citrai, citronellyl cinnamate, citroi~ellal dimethylacetal, isogulegone, pulegone. Young claims that d-citronellal can be removed from oil of citronella by fractional distillation under reduced pressure and replaced by synthetic dl-citronella1 without loss of odour value. 13.2 PESTICIDE Insect repellent action: Citronella oil has been widely used as an insect repellent. Mixed with cedarwood oil, 'Virginia' , it has been a popular remedy against mosquito attacks for many years prior to the appearance of DDT and other modern insecticides. It is a constituent of many mosquito creams and insect repellent candles. Formulations of some insect repellents are given below: Anti-mosquito cream: Citronella oil 18.25% Camphor 1% Cedar wood oil 1% Hard paraff~n 17.25% White soft paraffin 45% Stearic acid 3% Janet Citronella milk Citronella Neem Maduruthala (Holy Basil) Lavender Vegetable oil. These can be applied to hands, face, neck, ears. It keeps off mosquitoes to have a protective action against sand flies as well. Mosquito repellent Candle Stick Wax 530g Vaselene colour 120g Eucalptus oil 5% Citronella oil 3% Stearic acid 3% Camphor 2% Melt wax and stearic acid in a pan and mix other ingredients. Jt is reported Dicophane application. (DDT application for external used on the skin.) Dicophane 2% Emulsifying wax 4% Citronella oil 5 rnl Xyiene 150ml. water to make 1,000ml. in the following preparation by show, the citronella oil is said to assist in retarding the evaporation of the preparation: Castor oil 25% Bear oil 25% Citronella oil 10% Pennyroyal oil 10% aimethyl phthalate 3 0% Steiner reports that Ceylon citronella oil is an effective repellent against the Oriental fruit fly. A report from "kistan states that the maximum protective time when using citronella oil as a repelent is 1 houi 18 min and % repellency against mosquitoes: 100% immediately after application. 45% 30 mins. after application 43% 1 hour aRer application 0 1 1/2 hours aRer application % repellency aRer washing with soap and water 67% after 30 mics. 23% after 1 hour Travis et a1 report tnat the repellent time against buffaloe gnats was 400-600 rnin. for Prosirnulium hirtipes and Simuliz~rn venustuma repellent time was 240 min. Gouck et. al. tested the efficacy of citronella oil against water leeches, while Saxene et. al. studied the efficacy of the oil agzinst lana leeches. The histopathological effects of the oil or? the riervous system of insects was studied by kchards and Cutcomp. In Marclu's patent for an insect - repellent, candle, citronella oil has been dispersed in a hydrocarbon wax and held in a windproof plastic starid. Citronella oil is a constituent of pyrethrum-based insecticides An example of such a formulation is Pyrethmm (35% extract) 2-50% by weight Pine needle oil 10-75% Bucaiyptus oil. 20-7 5% Citronella oil '-10% Peppermint oil 0.5-5% Prasad and Jamwal patented the following formula for insecticidal coils and incense sticks: P y r e t h x marc 45.3% Sawdust 10.6% Lztsea sebgeva bark 39.9% Eyrenthrum oleoresin 2% Benzoic acid 0.2% Citronella oil 2% Oil of Citronella has been recommended for use as a preservative for books and natural history specimens. Dog - repellent Citronella oil is one of the constituents of the following formulation which is a dog repellent: Oil of Citronella 8 5 parts Cil of Anise 1 Part Oil of Eucaliptus 0. 5part The weather-resistance of this mixture is said to be increased by the addition of polyacrylic acid or polymethacrylic acid (3 parts) dissolved in alcohol or acetone (95 parts) 13.3 FOOD The recommended usage level of oil of citronella, as a flavour in foods is as follows: Non-alcoholic beverages 17 ppm Ice creams, ices, etc. 26 ppm Candy 25 PPm Baked goods 31 PPm 13.4 MISCELLANEOUS USES Flotatioi~ - Oil of citronella treated with M2S has been recommended for ore flotation. In another Patent, 300g of oil of citronella, is treated with 400ml of 5% &.So4, the H2S04 layer separated, washed with water, neutralised with NaHC03 and separated from the aqueous layer to give a light yellow viscous liquid, which is said to be an excellent fiother for flotation. Electrolysis - In the electrolysis of silver fluoride solutions, smooth matty deposits of silver are said to be obtained, when boric acid and citronella oil are added. Oil of citronella is a constituent of printing inks for polythene and of stiffening and sizing agents for the textile industry. Grass : Although fresh grass is not caten by cattle, spent grass is used as a cattle feed. Spent grass is also used f ~ r thatching roofs, for growing mushrooms, as a mulch for tea bushes, and for making paper. It is usually used as a fuel for the steam boiler in distilleries. Guhu et. al. obtained the following proximate analysis for Java citronella grass dust, passing through 60 mesh and retained in 80 mesh sieve: Ash content 5.5% Alcohol-benzene solubility 15.5% Ether solubility 9.2% Cold water solubility 6.2% Hot water solubility 15.5% 1% NaOH solubility 39.0% Pentosans 15.5% Lignin 20.8% Cellulose 50.6% Fiberlength : 0.56-1.68mm Fibre diameter : 0.007 - 0.028 rnm The best pulping conditions for the grass, based on the soda process, were found to be: 3 hour cooking at 142 O C , with 17% chemicals, yielding 37.1% unbleached pulp and 32.2% bleached pulp. Permafiganate number 1 1.5 Burst factor 47 9 Folding end (double folds) 168 Brightness (MgO - 100) 65 Breaking strength 8490 rnm Tear factor 85 6 It was found that extracted grass could also be used for pulping Ash has a h g h silica contznt, used as a fertilizer for sugarcane. 1. Alam, M., Chourasia, H.K., Sattar, A. and Janardhanan, K.K. Collar rot and wilt: a new disease of Java citronella (Cymbopogon winterian~s) caused by FusurPum monilIforme Sheldon. Plant-Pathology 4336)~. 1057-6 1 (1 994) 2. Alarn, M. Khan, A.M. and Husain, A. Leaf blight a ~ d leaf spot diseases of Java citronella caused by Curvularia andropogonis. Indian Phytopathology 36(3 jp. 480-48 3 (1 986) 3. Alam, M., Sattar, A. and Janardhanam, K.K. Changes in phenols and peroxidase in the leaves of Java citronella infected with Cuwularia andropogonis.Bio1. Plant 33(3)p. 2 1 1 - 15 (1 99 1) 4. Alam, M., Sattar, A.Z., Janasdhanan, K.K. and Husain, A. Lethal yellowing of Java citronella (Cymbopogon winterianus) caused by Pythium aphunderu;~atum. Plant Disease 76(10)p. 1074-76 (1 992) 5. Alwi, N., Ginting, S. and Manurung, A. Estimation of optimum plot size for field experiments with citronella (Cymbopogon nardus). bulletin Balai Pe~zelitian Perkebunan M e h n Pl(4)p. 169-176 (1980) 6. Atal, C.K. (Ed.) Kapur, B.M. (Ed.) Cultivation & utilization of aromatic plants. CSIR, India 1982 7. Auzay, Hamid, Djisbar, A. and Hamid, A. Current work on essential oils and spices in Indonesia. Industrial Crops Research J. 2(l)p. 16-21 (1989) 8. Banerjee, S., Bhattacharya, I. and Mukherjee, N. Sensitivity of tree sclerotial rice pathogens to plant oils. Inter. Rice Res. Newsletter 14(6)p.23 (1989) 9. Barthakur, M. and Bordoloi, D.1V. In vitro regeneration of Java citronella (C,j/mbopog.on winterinnus Jowitt). Herha Hungarzca 28(3)p.21-26 (1989) 10. Bsmmegowda, A., Krishnamurthi, K. and Narayana, M.R. Row spacing and population studies in Java citronella. Indiarz J. Agronomy 25(4)p.677-68 1 (1 980) I 1. Bauer, Kurt, Garbe, Dorotfiea and Surburg, Horst Common fragrance and flavour materials, V C H Verlagsgesellscafi, Germany 1990 12. Bommegowda, A,, Krishnamurthy, K., Narayana, M.R. Rao, R.S.G., Chandrashekhar, G , and Puttanna, K. Nutrient content and uptake studies in Java citronella (Cymbopogon winterianus Jowitt). -Myysore J. Agriczcltztral Sci. 17(2)p. 109- 1 14 (1 983) 13. Bommegowda, A., Krishnarnurthy, K. and Narayana, M.R. Agronomic investigations of Java citronella micronutrient studies. Indian J Agronomy 28(2)p. 1 15-1 1'1 (1 983) 14. Carlin, James T., Kramer, Steven, Chi-Tang Ho and Lipton, T.S. Flavours and Fragrances, A World Perspective (Eds. Lawrrence, B.M., Mookerjee, B.D. and Willis, B.J.), Elsevier Sci. Publ. B. V., Amsterdam. 1988 15. Chatterjee, S.K., Nandi, R.P. and Sarkar, D.P. Effect of mineral nutrients on growth and essential oil formation in Cymbopogon winterianus. Sci. Cult. SO(1)p. 26-9 (1984; 16. Chattopadhyay, A. and Subrahmanyam, K. Changes in yield, chemical composition and rhizosphere soil properties of citronella Java suffering from iron chlorosis. J Indim Soc. Soil Sci. 4,l(l)p. 166- 67 (1993) 17 Datta, S.C. Cultivation and utilization of aromatic plants (Eds. Atal, C.K. and Kapur, B.M.), CSIR, India. 1982 18. De Silva, Tuley K. A manila1 on the essential oil industry UNDO, Austria. 1995 19. Djatmiko, B. and Jusuij J. Influence of several treatments before distillation of citronella leaves on the yield and physico-chemical quality of the oil. Bulletin Benelitian Teknologi Hasil' Pertanian 7p. 17 (1 977) 20. Dube, Gita, Rao, T i Siva Sankar, Nigam, S.S. mtifbngal efficacy of some Indian essential oils. Indian Perhmer 27(1)p.5-8 (1995) 21. Gour, T.B., Singh, T.V.K., Sathe, A. and Pasha, S.N. Stemmatophora fusciFu.ralis Snellen a new record as a pest of citroneila. Indian J. Plant Protection 119(2)p.220