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Pesticides in Essential Oils Database





This  part of the Cropwatch website is devoted to building a database on pesticides in essential oils and in the same fashion as other Cropwatch Files sections,  material will be added on an on-going basis.

As usual, we welcome contributions to any of the files as our main aim is to assemble as thorough and accurate a record as possible.


 Barrek S. & Paisse O. “Analysis of pesticide residues in essential oils of citrus fruit by GC-MS & HPLC-MS after solid-phase extraction.” Analytical & Bioanalytical Chemistry 376(2), 157-161.

Abstract: A robust reliable method for the analysis of residues of pesticides in citrus groves was developed. Residues of twelve pesticides were extracted from citrus essential oils by SPE, separated by liquid chromatography and analysed by GC-MS. In addition, ten pesticides were extracted by SPE, separated & analysed by electrospray HPLC-MS. In the case of lemon essential oils, all twenty residues were separated by liquid/solid extraction on a mixed Florasil –C18 cartridge. The method enable the analysis of twenty pesticide residues at levels of 2-30ppm with limits of detection ranging from 0.02 to 50 mg/L. 


Czerwinski J., Zygmunt B. & Snik J.N. (1996) “Headspace solid-phase micro-extraction for the GC-MS analysis of terpenoids in herb based formulations”. Fresenius J. of Analytical Chem. 356(1), 80.

Abstract: Head-Space Solid Phase Microextraction (HS-SPME) has been employed for sampling of volatile components and their volatile decomposition products occurring in herbal medicines and herb extracts with subsequent injection into a gas chromatographic column. The identification and quantification was performed by coupled gas chromatography – mass spectrometry (GC-MS) with classical splitless injection, electron impact ionization and a quadrupole mass analyzer. As fast and inexpensive technique for the isolation of organic analytes HS-SPME with GC-MS can be successfully employed for the quality control of herbal medicines and other formulations containing herb extracts. Analytical results with satisfying accuracy & precision are given.


Dellacassa E., Lorenzo D., Di Bella G. & Dugo G. (1999) “Pesticide residues in Uraguayan lemon oils.” JOER 11(4), 465-469.


Di Bella G., Saitta M., La Pera L., Alfa A. & Dugo G. (2004) “Pesticide & plasticizer Residues in bergamot oils from Calabria (Italy).” Chemosphere 56(8), 777-782.

Abstract: Organophosphorus and organochlorine pesticides, phosphorated plasticizers, chloroparaffins and phthalate esters contamination in bergamot essential oils produced in Calabria in the crop years 1999–2000 was studied by HRGC in connection with detectors FPD, ECD, MS. Residues of dicofol and tetradifon were found in oils from both crop years. The mean dicofol concentration was 0.26 mg/l in samples from 1999 and 0.20 mg/l in those from 2000; the mean tetradifon content was 0.06 mg/l for both the crop years. Among plasticizers, residues of diisobutyl phthalate, di-n-butyl phthalate, and bis(2-ethylhexyl) phthalate were found in samples from crop years 1999 and 2000, the mean content were 1.22 and 1.23 mg/l, 1.51 and 1.65 mg/l, 1.38 and 1.42 mg/l respectively.


Garland S.M., Menary R.C. & Davies N.W. (1999) “Dissipation of Propiconazole & Tebucanazole in peppermint crops (Mentha piperita (Labiatae) & their residues in distilled oils.” J. Agric. Food Chem. 47(1), 294-298. 

Abstract: The broad-spectrum, systemic fungicides propiconazole (1) and tebuconazole (2) are used to control rust in peppermint (Mentha piperita L.). An analytical method, using gas chromatography combined with detection by high-resolution mass spectrometry, was developed to allow for the simultaneous monitoring of both pesticides in peppermint leaves and oil. Field trials were established to determine the rate of dissipation of tebuconazole and propiconazole in peppermint crops. Three applications of each fungicide were trialed at two rates (125 and 250 g of active ingredient (ai)/ha). At harvest, 64 days after the final application, propiconazole was detected at levels of 0.06 mg/kg and 0.09 mg/kg of dry weight, and tebuconazole was detected at 0.26 and 0.80 mg/kg dry weight, in identical trials. Rates of dissipation of propiconazole and tebuconazole were lower at a second trial site, where three applications of 125 g/ha ai for each fungicide resulted in residue levels of 0.21 mg/kg for both pesticides, detected 89 days after the last application. Propiconazole and tebuconazole were detected in the distilled oil at levels between 0.02 and 0.05 mg/kg and between 0.011 and 0.041 mg/kg, respectively. Propiconazole had a higher tendency to co-distill with the peppermint oil, with 0.7% of that present in the vegetative material ending up in the oil, compared to 0.09% of tebuconazole.

Garland S.M., Menary R.C., Davies N.W. & Oliver G.S. (2004) Practical Approaches to the Analysis of Pesticide Residues in Essential Oils RIRDC Publicn No. 04/109 available at

Groenewoud K.M., Davies N., & Menary R.C. (1995) “Determination of propiconazole residue in Boronia extract (Concrete)” J. Agric. Food. Chem. 43, 1230-1232.

Abstract: A method for detecting residues of the fungicide propiconazole in the petroleum ether extract (concrete) of Boronia megastigma Nees was developed. Gas chromatography/mass spectrometry (GC/MS) using low-resolution selected ion monitoring (LR SIM) had a 1 ppm detection limit in samples that had some preliminary cleanup. The use of GC/MS with high-resolution selected ion monitoring (HR SIM) had a minimum detection limit of 50 ppb for crude spiked samples of boronia concrete. This method was utilized to provide an automated assay for propiconazole residues in the concrete from boronia flowers and in extracts of vegetative material.

Iwata Y., Westlake W.E, Barclay J.H., Carman G.E. & Gunther F.A. (1977) “Aldicarb residues in oranges, citrus by-products, orange leaves, & soil after an Aldicarb ssoil-application in an orange grove.” J. Agric. Food Chem 25(4), 933.

Abstract: A 15% granular formulation of aldicarb (Temik 15G) was soil applied to field plots of Valencia and navel oranges at 2.5,5.0,10, and 20 lb of active ingredient per acre. Total carbamate residues (aldicarb, its sulfoxide and sulfone) remaining in the soil and translocated to the leaves and fruit are reported. Residues were found in both rind and pulp. Total carbamate residues in molasses and dried citrus pulp, both used to supplement animal feed, orange juice, and orange oil resulting from processing residue-bearing fruit for by-products are also reported.


Kiigemagi U. & Deinzer L. (1974) “Dislogable and total residues of methomyl on mint foliage” Bulletin of Environmental Contamination and Toxicology


Kiigemagi U., Durand L., Becerra M.A. & Deinzer M.L. (1990) “Residues of the nematicide Ethoprop in Mint Hay & Oil” J. Agric. Food Chem. 38, 736-739.

Abstract: An analytical method developed for the determination of ethoprop in fresh and spent mint hay included initial extraction with hexane in the presence of anhydrous sodium sulfate, cleanup using charcoal and deactivated Florisil, and quantitation by phosphorus-specific flame photometric gas chromatography. Mint oil samples were introduced directly onto the deactivated Florisil columns, and the ethoprop concentration in the eluate was again determined by gas chromatography. The method is sensitive to 0.002 ppm in mint hay and to 0.05 ppm in mint oil. Recoveries averaged 90% for samples fortified immediately before analysis and 89% for samples stored 4-58 weeks. Residue data from nine locations collected over three seasons showed traces of ethoprop in almost all fresh and spent hay samples ranging from C0.002 to 3.36 ppm. Ethoprop residues in mint oil ranged from <0.05 to 114 ppm, the highest residue being in spearmint oil treated at 13.2 kg of AI/ha 90 days before harvest.

Kiigemagi U. & Deinzer L. (1979) “Dislogeable & total residues of methomyl on mint foliage” Bulletin of Environmental Contamination & Toxicology 22(1), 517-521.

Muraldihara; Harapanahalli S. (Cargill, Incorporated Minneapolis, MN) (1995) Removal of pesticides from citrus peel oil US Patent applicn. 411345.

Abstract: A process is disclosed for the preparation of citrus oils which are essentially pesticide free. The essentially pesticide-free citrus oil is prepared by gently distilling raw citrus oil in a short-path distillation column whereby the essentially pesticide-free citrus peel oil is collected as the distillant. Suitable citrus oils include citrus peel oils and citrus stripper oils with citrus peel oils being preferred. The essentially pesticide-free citrus peel oil generally contains less than about 1.6 ppm total pesticides, preferably less than about 0.5 ppm total pesticides, more preferably less than 0.1 ppm total pesticides, and most preferably less than 0.05 ppm total pesticides. The distillation residue contains essentially all the pesticides contained in the raw citrus peel oil. The essentially pesticide-free citrus oil, especially the essentially pesticide-free orange peel oil, can be used as a food additive (especially as an additive in orange juice) to enhance aroma and flavor characteristics and as a non-food additive in perfumes, soaps, cosmetics, lotions, and the like.


Moye H.A., Brooks R.F. & Sherer S.J. (1983) “Residues of Phenthoate (Cidial) & its oxon on grapefruit, lemon, oranges & their fractionated products & soil.” J. Agric. Food Chem. 31, 122-127.

Abstract: An analytical procedure for the analysis of phenthoate insecticide [O,O-dimethyl S-(a-carbthoxybenzyl) phosphorodithioate, Cidial] and its oxon is described for fresh grapefruit, lemons, and oranges as well as for 15 fractionated products and soil. The phenthoate, in the form of an emulsifiable concentrate (Cidial), was applied to the citrus trees at 4 and 8 oz of active ingredient/100 gal. Fresh fruit and soil exhibited typical first-order decay for phenthoate, with levels after 7 days in peel below 1 ppm; pulp levels never exceeded 0.04 ppm (orange, 7 days). Maximum phenthoate soil levels occurred at the tree drip line near the surface (0.55 ppm) but decayed to 0.12 ppm after 28 days; maximum oxon occurred at 14 days for these samples (0.04 ppm). Lemon peel oil, resulting from the 8 oz/100 gal treatment, incurred the highest phenthoate residues (16 ppm) as well as oxon (2.2 ppm). Wash water (after-water rinse) contained negligible residues of phenthoate and oxon.


Starr H., Kiigemagi U. & Terriere L.C. (1963) “Insecticide residues in peppermint & their distillation with peppermint oil” J. Agric. Food Chem. ? 481-482.

Abstract: Analyses of peppermint hay and peppermint oil after treatment of the crop with DDT, aldrin, dieldrin, or Dibrom indicate that each of these pesticides will persist through the processing of the hay. Both field and laboratory distillation experience indicate that the amount of residue found in peppermint oil depends in part on the severity of the distillation,-i.e., the amount of steam used. Up to 60 ppm of dieldrin was found in peppermint oil recovered in a small still when excessive amounts of steam were used. Oil recovered with conventional distillation procedures contained less than 1 ppm dieldrin. Peppermint grown in aldrin-treated soil contains more dieldrin than aldrin. Maximum oil residues using commercial stills were: DDT, 10.6 ppm; dieldrin, 1.9 ppm; and Dibrom, 36.4 ppm. Microcoulometric gas chromatography has been successfully applied to all samples with sensitivities as low as 0.01 ppm. attainable with fresh and spent hay. Special sample preparation methods are described.

Tang F., Yue Y., Hua R., Ge S. & Tang J. (2005) “Development of methods for determination of the residues of fifteen pesticides in medicinal herbs Isatis indigotica by capillary GC with electron-capture or flame photometric detection.” AOAC Intl. 88(3), 720-728.

Wojeck G.A., Nigg H.N., Braman R.S., Stamper J.H. & Rouseff R.L. (1982) “Worker exposed to arsenic in Florida grapefruit spray operations” Archives of Environmental Contamination & Toxicology, 11(6), 661-667.

Van Dyk L.P. (1976) “Parathion persistence on South African citrus.” Archives of Environmental Contamination & Toxicology 4(1), 289-311.

Verzera A., Trozzi A., Dugo G., Di Bella G. & Cotroneo A. “Biological lemon & sweet orange essential oil composition” Flav. & Frag. J. 19, 544-548.

Abstract: The volatile fraction composition of sweet orange and lemon oils obtained using biological and traditional cultivation is reported. The oils came from Sicily and were industrially obtained. The aim of the research was to establish whether the use of pesticides in citrus cultivation could influence the essential oil composition. The volatile fraction was analysed by HRGC and HRGC-MS. The content of organophosphorus and organochlorine pesticides was determined by HRGC-FPD and HRGC-ECD. Differences in the oil composition resulted, especially in the content of carbonyl compounds; the results obtained, altogether, show that the biological oils are of higher quality in terms of their composition than traditional ones.

See table

Yoon H.R., Lee E.J. Park M.K & Park J.H. (1998) “Sulphuric acid pre-treatment for the simultaneous GC screening of organochlorine & organophosphorus pesticides in herbal essential oils.” Chromatographia 47(9/10), 587-592.

Zuin V. G. & Vilegas J.H.Y. (1999) “Pesticide residues in medicinal plants & phytomedicines” Phytotherapy Research 14(2), 73-88. 

Abstract: Pesticides, which are mainly applied on crops for the protection of plants against a range of pests, have been found in crude medicinal plants as well as in infusions, decoctions, tinctures and essential oils. This fact has caused concern in various segments of society and scientific investigation has been demanded to assess the health hazards more accurately. The present review covers more than 30 years (1963-1998) of published methods of analysing pesticide residues in medicinal plants, with special emphasis on the relevance of these matrices, the legislation, the risks involved in using material containing uncontrolled amounts of residues and the possible effects of technological factors on the proportion of pesticides transferred from the raw material to the end-product.


Zuin V.G., Yariwake J.H. & Lancas F.M. (2003) “Analysis of pesticide residues in Brazilian medicinal plants: matrix solid phase disperaion vs. conventional (European Pharmacopoeia) methods.” J. Braz. Chem. Soc. 14(2) available at

Abstract: This paper proposes a method based on matrix solid phase dispersion (MSPD) to determine the presence of organochlorine (OC) and organophosphorus (OP) pesticide residues in species of Passiflora L. (passion fruit) leaves by gas chromatography, using an electron capture detector (HRGC-ECD). A comparison with conventional methods, mainly the European Pharmacopoeia method (EP), showed MSPD to be efficient, fast, simple and easy to perform. To date, there are no official methods or limits that take into account Brazil's "real life" conditions in the analysis of pesticides in medicinal plants and phytomedicines, and the MSPD method described herein has proved to be a feasible one for the analysis of Passiflora L-based phytomedicines.

Zuin V.G., Yariwake J.H. & Bicci C. (2003) “Fast supercritical fluid extraction & high-resolution GG with electron-capture & flame photometric detection for multi-residue screening of organochlorine and organophosphorus pesticides in Brazil’s medicinal plants.” J. of Chromatography A. 985(1), 159-166.