Journal of AnalyticalToxicology,Vol. 28, November/December2004
Negative Ion Chemical IonizationGas Chromatographic-MassSpectrometric Determination of Residuesof Different Pyrethroid Insecticides in Whole Blood and Serum Atmakuru Ramesh* and Perumal Elumalai Ravi Department of Analytical Chemistry, MassSpectrometryDivision, International Institute of Biotechnology and Toxicology-IIBAT, Padappai, Chennai-601 301, Tamil Nadu, India
Abstract A new rapid and sensitive analytical method using negative ion
chemical ionization-gas chromatography-mass spectrometry in selective ion monitoring mode has been developed for the determination of residues of different synthetic pyrethroid insecticides, allethrin, bifenthrin, cypermethrin, cyphonothrin, cyfluthrin, ~.-cyhalothrin, deltamethrin, fenvalerate, fenpropathrin, permethrin, prallethrin, and trans-fluthrin, in whole blood. The residues of pyrethrold molecules were extracted from the whole blood using a hexane and acetone (8:2, v/v) solvent mixture without separating the serum. The method was found sensitive to detect the residues of pyrethroids up to the level 0.2 pg/mL. Experiments conducted with the whole blood samples at the fortification level 1-100 pg/mL showed 91-103% recovery, whereas blood serum samples collected after the fortification of pyretbroids in whole blood showed 36-54% recovery. Recovery experiments conducted by direct fortification of pyrethroids in blood serum samples showed 96-108%. The applications of the analytical method was tested by analyzing 73 human blood samples collected from the population exposed continuously to different pyrethroid-based formulations. None of the blood samples showed residues of pyrethroids. The results were also confirmed by the detection of the appropriate amounts in a number of these samples, which had subsequently been spiked with known quantity of pyrethroids.
Introduction The study on structural modification of natural pyrethrins has lasted for more than half a century. Especially, the discovery of allethrin prompted the chemists to make structural * Author tl, whom correspondence should be, acldrc,,,',[,d. E-mail: raamt,~h
[email protected] ore.
660
modifications of the pyrethroids at an alcohol and acid moiety. As a result, number of synthetic pyrethroids has been identified and investigated for different properties. These compounds are found extensively useful in the agricultural and household insect control and to eradicate the vectors of endemic diseases like malaria. Pyrethroid insecticides display a broad spectrum of insecticidal activity and low mammalian toxicity. The enhanced insecticidal activity, greater photo stability, and relatively low toxicity (1-5) make the pyrethroids more useful when compared with other organochlorine and organophosphoric insecticides. The environmental fate and effect of the synthetic pyrethroid insecticides, mode of action, metabolism, photo stability, and mammalian toxicity have been described in detail by various authors (6-18). Some of these products may cause transient itching and/or a burning sensation on exposed human skin. The World Health Organization (WHO) (19) report states that synthetic pyrethroids are neuro-poisons acting on the axons in the peripheral and central nervous systems by the interaction with the channels in mammals/insects. The presence of residual concentrations of the pyrethroids in the environment due to the use of different formulations may possibly contribute to human exposure either by inhalation or skin resorption (20). Studies on the distribution of pyrethroids in environmental and tissue samples are complex. In general, the numbers of body tissue samples submitted to a toxicological evaluation are scarce and at insufficient quantities, causing difficulties in perfect analytical evaluations. Apart from this, residues of pesticides are likely to bind to erythrocytes. Hence, the evaluation of residues in whole blood only projects the exact indication of extent of exposure. However, literature clearly shows that most of the monitoring studies are conducted using plasma/serum instead of whole blood. The reason may be due to difficulty in the elimination of lipids associated with whole blood samples and, subsequently, the ease in the
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Journal of Analytical Toxicology,
Vol.28,
November/December
2004
separation of plasma from a blood sample by simple laboratory technique. Further, to evaluate the residues in serum, a large volume of blood has to be collected. The problem is more complex in cases of birds and small animals. Hence, wherever it is possible, nonlethal sampling approaches are preferred. In view of the greater demand for the miniaturized techniques in monitoring human health and environment and in continuation of our investigations on occupational exposure (21-26), the present studies are aimed at developing a rapid and highly sensitive analytical technique for the sequential determination of residues of different pyrethroid molecules in whole blood. The applications of the method were investigated in a human population exposed to a variety of pyrethroid-based formulations.
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Apparatus A gas chromatograph-mass spectrometer (GC-MS) attached to an AOC 20i autoinjector (Shimadzu Corporation, Tokyo, Japan) model GC-MS QP-5050A interfaced with a computer supported by Class-5000 software was used for data acquisition. Negative ion chemical ionization mode (NCI) was used in the study. A Shimadzu GC-17A GC with a DB-1 capillary column (30 m • 0.25-ram i.d., 0.25-1Jm film thickness, J&W Scientific, Folsom, CA) was used for quantitation. Helium was used as carrier gas at constant column flow rate of 1.0 mL/min. Methane gas (2.5 mL/min) was used as the reagent gas for soft ionization. The temperature conditions were as follows: column oven, initial 60~ for 3 rain, then programmed 10~ to 200~ held for 5 rain, ramp 5~ to 240~ and held for 45 min and the injector and interface temperatures were kept at 290~ and 300~ respectively. The split ratio was 1:3. The total ion chromatogram (TIC) of GC-MS-NCI spectra (Figure 1) showed the following retention times: trans-fluthrin, 22.08 min; cis- and trans-isomers of allethrin, 26.03 and 26.29 min; prallethrin,
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Figure 1. GC-MS-NCI TIC of different pyrethroids. Peak identification: 1, lindane (IS); 2, lrans-fluthrin; 3 and 4, cis- and trans-isomers of allethrin; 5, praiiethrin; 6, bifenthrin/fenpropathrin; 7 and 8, c/s-isomers of k-cyhalothrin; 9, cyphenothrin; 10 and 11, cis- and trans-isomers of permethrin; 12-15, cis- and trans-isomers of cyfluthrin; 16-19, c/s- and trans-isomers of cypermethrin; 20 and 21, cis- and trans-isomers of fenvalerate; and 22, deltamethrin.
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661
Journal of Analytical Toxicology, Vol. 28, November/December2004
26.60 min; bifethrin, 35.78 min; fenpropathrin, 35.79 min; cL~isomers of k-cyhalothrin, 39.10 and 40.12 min; cyphonothrin, 42.67 min; cis- and trans-isomers of permethrin, 43.95 and 44.87 min; cis- and trans-isomers of cyfluthrin, 48.39 and 49.25 rain and 49.90 and 50.37 min; cis- and trans-isomers of cypermethrin, 50.91 and 51.88 rain and 52.56 and 53.01 min; cisand transoisomers of fenvalerate, 60.11 and 62.98; and deltamethrin, 70.88 min. Lindane (y-benzene hexachloride) (19.06 rain) was used as internal standard (IS). Selective ion monitoring (SIM) method was used for quantitation of pyrethmid residues. From the mass spectra (Figure 2), the specific fragment ions selected were m/z 255 for lindane (IS); rn/z 207, 209 for trans-fluthrin; m/z 167 for allethrin; m/z 132, 167 for prallethrin; ra/z 205, 241 for bifenthrin; m/z 141, 205 for fenpropathrin; ra/z 205, 241 for k-cyhalothrin; m/z 167 for cyphonothin; ra/z 207, 209 for permethrin; m/z 171,207, 209 for cyfluthrin; m/z 171, 207, 209 for cypermethrin; ra/z 211, 213 for fenvalerate; and ra/z 137 for deltamethrin. Reagents All the chemicals and reagents used in the study were organic trace analysis grade, unless stated otherwise. They were purchased from E. Merck (Darmstadt, Germany). Some of the reference analytical standards of different pyrethroid insecticides were lindane (99.9%) (PESTANAL, Riedel de-Haen, Seelze, Germany); allethrin (99.0%), cyphonothrin (100.0%), fenpropathrin (99.9%), prallethrin (100.00%), and imiprothrin (94.50%) (Sumitomo Chemical Co., Ltd., Osaka, Japan); bifenthrin (93.5%) (FMCIndia Private, Ltd., Banglore, India); cypermethrin (94.50%) and fenvalerate (94.3%) (Sharda International, Mumbai, India); cyfluthrin (95.5%) and 2~-cyhalothrin (98.5%) (PESTANAL,Riedel deHaen); deltamethrin (99%) [Isagro (Asia)Agrochemicals, Ltd., Gujarat, India]; and trans-fluthrin (95.3%) (Bayer India Ltd., Mumbai, India). Preparation of stock solutions Stock solutions (100 rag/L) of all the individualpyrethroid insecticides were prepared in different volumetric flasks using trace-analytical-grade acetone. Different working standard solutions were prepared by taking the aliquots of the standard solutions, following their mixing, and suitably diluting with hexane. An Artic 380 deep freezer supplied by Froilabo (Meyzieue, France) with an automatic temperature recorder and display facility was used for storing the stock solutions and samples at -45~ Collection of blood samples In order to remove the contamination, if any, due to the foreign impurities, all the test tubes used in the study were kept in a hot air oven at 150~ for 24 h and used for collection of blood. About 5 rnL blood was collected from each donor for the experiment. Informed consent was obtained from the subject or his/her parent or legal guardian. All the samples were coded and transported in a dry ice pack to the laboratory with the details of the donors. All of the heparinized blood samples were stored at --45~ until analysis. 662
Recovery study Control blood samples were spiked with the stock solutions containing a mixture of pyrethroids, allethrin, imiprothrin, bifenthrin, cypermethrin, cyphonothin, cyfluthrin, ~-cyhalothrin, deltamethrin, fenvalerate, fenpropathrin, permethrin, prallethrin, and trans-fluthrin. Studies were conducted at eight concentration levels: 1, 5, 10, 20, 40, 60, 80, and 100 pg/mL. Three different experiments were conducted for this purpose. In the first experiment, blood samples were collected using heparinized syringes and transferred a 1.0-mL aliquot into a dry 25-mL volumetric flask using a microliter pipette spiked 20 pL of known concentration of analytes and the IS. With occasional shakings, the samples were allowed to equilibrate for 30 rain at room temperature, and then ultrasonic vibrations are applied for 20 rain to hemolyzethe blood. Extraction of residues from the whole blood To the hemolyzed blood sample, 5 mL hexane/acetone (8:2, v/v) mixture was added. A Teflon-coated magnetic bar was placed inside the flask and, with the help of a magnetic stirrer, extracted the residues by vigorous stirring for 2 rain. The contents were allowedto settle for 10 min and then the supernatant was collected into a graduated tube. The extraction process was repeated twice, and the sample was finallyrinsed with 2 mL extraction solvent. The extracts were pooledand concentrated to 1 mL under a gentle stream of nitrogen. The samples were then capped and transferred to GCautoinjector vials for quantitation. The second experiment was conducted using a nonheparinized blood sample. In this experiment, immediately after the blood collection, homogeneity of a spiked, known quantity of pyrethroids was ensured by gentle mixing and allowedseparation of the serum. The serum, thus collected,was extracted, processed, and tested for residues. In the third experiment, the blood samples collected were allowed to settle and the serum separated. The serum samples were spiked with a known amount of pyrethroids, extracted, processed, and tested for residues.
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Journal of Analytical Toxicology, Vol. 28, November/December 2004
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Figure4. GC-MS-NCI TIC of human blood sample spiked with different pyrethroids in SIM mode at 5 pg/mL concentration. Peak identification: 1, lindane (IS); 2, trans-fluthrin; 3 and 4, cis- and trans-isomers of allethrin; 5, prallethrin; 6, bifenthrin/fenpropathrin; 7 and 8, c/s-isomersof ~,-cyhalothrin; 9, cyphenothrin; 10 and 11, cis- and trans-isomers of permethrin; 12-15, cis- and trans-isomers of cyfluthrin; 16-19, cis- and trans-isomers of cypermethrin; 20 and 21, cis- and trans-isomers of fenvalerate; and 22, deltamethrin. Table I. tODs, tOQs, and Calibration Results tODs tOQs (pg/mr) (pg/mr)
Compound Allethrin Prallethrin Bifenthrin Fenpropathrin k-Cyhalothrin Cyphenothrin Permethrin Cyfluthrin Cypermethrin Fenvalerate Deltamethrin trans-Fluthrin
0.5 0.5 1 1 1 2 5 5 5 5 5 0.2
1 1 5 5 5 5 20 20 20 20 20 1
Equation y = 1.9837x- 0.2337 y = 1.3772x + 0.1596 y = 1.0774x + 0.0111 y = 1.0736x + 0.198 y = 1.6603x + 0.027 y = 0.8718x- 0.1995 y = 0.5095x- 0.0238 y = 1.5223x + 0.0108 y = 14.463x- 5.1475 y = 2.6189x- 0.6687 y = 0.3582x- 0.0249 y = 7303.4x + 898.79
Table II. Recovery of Pyrethroids in Human Whole Blood Samples* Pyrelhroid Name
Spiked Concentration Recovery (pg/mL) Range
Allethrin Prallethrin Bifenthrin Fenpropathrin k-Cyhatothrin Cyphenothrin Permethrin Cyfl uthrin Cypermethrin Fenvalerate Deltamethrin trans-Fluthrin * Average of six replications.
(1-100) (1-100) (5-100) (5-100) (5-100) (5-100) (20-100) (20-100) (20-100) (20-100) (20-100) (1-100)
96-102 95-98 92-96 94-96 94-100 96-103 95-99 91-96 94-98 97-103 94-99 95-98
Relative Standard Deviation 1.83-3.25 1.19-2.58 1.53-2.74 2.08-2.61 1.45-3.03 1.22-3.63 2.02-3.50 1.59-2.74 1.55-3.32 1.46-2.60 2.38-3.69 1.44-2.59
Method validation After the identification of the respective pyrethroids in NCI scan mode (Figures 1 and 2), two to three characteristic fragments of individual analytes and one fragment of the internal standard were monitored in SIM mode. Quantitation was performed by the ratio of the peak area of the active substance relative to that of the IS (Figures 3 and 4). For each analyte, the detector linearity over the concentration range 1-100 pg/mL was established by using a linear regression analysis. The linearity of the method was investigated by calculation of the regression line by the method of least squares and expressed by the correlation coefficient (r2). After r 2 had been achieved (0.98-1.00), linear regression equations were used to quantitate the analytes in samples. The linearity of each compound was measured at six levels. The sensitivity of the method was evaluated by determining the limit of detection (LOD) and quantitation (LOQ). The percent recovery was calculated for each analyte at different fortification levels. The lowest LOD was calculated as the quantity of analyte required to give a response of three times higher than the baseline noise at the expected retention time of the analyte in the chromatogram of a nonfortified blood extract. The LOQ was calculated as the lowest LinearDynamic standard with a signal-to-noise ratio of at least Range(pg/mt) 5. The results of the method validation experiments are presented in Table ! as a mean of six 1-500 replicate analyses. 1-500 5-500 5-500 5-500 5-500 20-500 20-500 20-500 20-500 20-500 1-200
Resultsand Discussion
Simultaneous determination of pyrethroid insecticides is more difficult when compared with the organophosphate and carbamate insecticides because the majority of the compounds structurally contain a cyclopropane ring that is similar in function to a double bond. These rings may cause the formation of stereoisomers. Thus, in the present study, pyrethroid residues were quantitated as a mixture of their stereoisomers. The analysis of the wholeblood samples produced no additional chromatographic peaks when compared with the serum samples in the region of interest. The method of extraction had a greater influence on the recoveries. When the extraction was conducted by vigorous hand shaking in a separatory funnel for a period of 10 min, it showed lower recoveries. The procedure established in the present method using a magnetic shaker for extraction worked satisfactorily and yielded good recovery. The results clearly show that the analysis of whole blood samples (Table II) and the directly spiked serum samples (Table III) produced excellent recoveries, whereas the serum collected from the spiked blood samples (Table IV) showed significantly lower recovery (36-54%). This can be attributed to the probable binding of pyrethroids molecules at erythrocytes. This was confirmed by positive detection of residues in the remaining blood samples. Thus, the data clearly prove the analysis of residues in the whole blood samples represents the actual data. 663
Journal of Analytical Toxicology, Vol. 28, November/December 2004
The residues in blood, unless immediately after spray or exposure, are likely to be small, as most of the pyrethroids get metabolized, excreted, or stored in fat, and the evaluation of such a low quantity of residues, if any, present in the samples poses particular analytical problems (27). The validity of the results depends on the suitability of the analytical methods used for the task. Thus, a major responsibility falls on the analysts to develop suitable methods and explain the reasons for the absence of residues in the samples. Only the advanced analytical technical techniques may to some extent solve the problem. Thus, the present method shows the determination of a different pyrethroid in a single chromatographic injection. Apart from the human blood samples, the applicability of the method was tested to the blood samples collected from the animal origin. Chicken blood samples were also tested for this
Table III. Recovery of PyrethroidsSpiked Directly in Human Serum Samples* Pyrethroid Name
Spiked Concentration Recovery (pg/mt) Range
Allethrin Prallethrin Bifenthrin Fenpropathrin k-Cyhalothrin Cyphenothrin Permethrin CyfJuthrin Cypermethrin Fenvalerate Deltamethrin trans-Fluthrin
(1-100) (1-100) (5-100) (5-100) (5-100) (5-100) (20-100) (20-100) (20-100) (20 100) (20 100) {1-100)
98-108 102-106 97-102 96-99 98-101 96 106 101-106 98-104 96-97 97-105 96-102 101-104
Relative Standard Deviation 1.29-3.61 1.02-3.36 0.77-3.03 1.70-3.22 1.44-3.43 1.413 2.78 1.06-2.22 1.13-2.25 1.54-2.29 0.87-2.06 1.81-5.06 I.'~8 {.l:~
9 Average ~f ,ix rupli( ,ilion,.
Table IV. Recovery of Pyrethroids in Serum Samples Collected from the Human Blood Samples Spiked with Pyrethroids* Pyrethroid
Spiked Concentration Recovery
Name
(pg/mL)
purpose. The data clearly show that the deviations in the measurements are within 2%. The method developed was studied to determine the residues of pyrethroid molecules in 73 blood samples (44 male and 29 female) collected from different age groups by constant exposure to different pyrethroid-based formulations during the night. All the blood samples showed the residues below the quantifiable level. The results were also confirmed suitably by spiking a few exposed samples subsequent to their positive detection. Thus, the method is found suitable for the analysis of residues in human blood samples and also applicable to the blood samples of animal origin. From these studies, it can be concluded that the present method, which involves the GC-MS-NICI mode, has many advantages over the previously reported methods (14,28-47) in terms of high recovery and very low detection limits, and it fills the gap with respect to the need of an analytical method for the determination of residues of pyrethroids in blood samples.
Conclusions In an exposure study, the blood and excreta are the preferred matrices. From the investigations, it is observed that the serum samples collected from the spiked blood samples show very low recovery, and, on the contrary, direct spiking of pyrethroid into the serum samples showed good recovery. Even though the analysis of serum represents the presence of pyrethroids, the real value depends on the partition coefficient of the chemical in blood to serum. The high recovery of pyrethroids after hemolysis and subsequent extraction clearly shows the binding of the molecules at erythrocytes. As such, no data is available on these lines. Thus. the method developed in the present study clearly shows that the acceptable way is to quantitate the residues in whole blood instead of serum. The method is simple, rapid, and can be adopted without any matrix interferences. The method is applicable for the detection of selected pyrethroids either in blood or plasma of human or animal origin and provides the detection sensitivity up to 0.2 pg/mL.
Relative
Standard
Range
Deviation
47-50 46-51 36-43 {8-43 37-42 41-45 39-45 40-44 41-45 43-47 39~,3 46-54
2. ~3-4.65 2.99-5.73 2.80-7.88 3~10-4.88 4.13-5.00 3.71-5.31 3.01-4.87 2.44-4.84 3.24 5.12 3.44-5.82 1.96-4.44 3.16--4.84
Acknowledgments Allethrin Prallethrin Biienthrin Eenpropathrin ~.-Cyhalothrin Cyphenothrin Permethrin Cyfluthrin Cypermethrin Fenvalerate Deltamethrin
trans-Fluthrin
(1-100) (1-100) (5 100) (5-100) (5-100) (5-100) (20 100) (20-100) (20-100) (20-100) (20-100) (1-100)
* Averageof six replications.
664
The authors are thankful to Dr. P. Balakrishnamurthy, Director, and the Management, [IBAT, India for their immense support in conducting this study.
References 1. J.P. Demoute. A brief review of the environmental fate and metabolism of pyrethroids. Pest. Sci. 27:375-385 (1989). 2. M. Elliot, N.F. Janes, EC. Kimmel, and J.E. Casida. Metabolic fate of pyrethrin I, pyrethrin II and allethrin administered orally to rats. J. A~qri. Food. Chem. 20:3005 (1972).
Journal of Analytical Toxicology,Vol. 28, November/December2004 3. Pyrethrum Flower~Production, Chemistry, Toxicology, and Uses, J.E. Casida and G.B. Quistad, Eds. Oxford University Press, New York, NY, (1995). 4. I.R. Hill. The Pyrethroid Insecticides, J.P. Leahey, Ed. Taylor and Francis, London, England, 1985, pp 151-262. 5. The Pyrethroid Insecticides, J.P. Leahey, Ed. Taylor and Francis, London, England, 1985, pp 263-342. 6. T.R. Roberts. Progress in Pesticide Biochemistry, vol. 1, D.H. Hutson and T.R.Roberts, Eds.John Wiley and Sons, New York, NY, 1981, chapter 3. 7. A.J. Gray and D.M. Soderlund. Progress in Pesticide Biochemistry and Toxicology, vol. 5, D.H. Hutson and T.R. Roberts, Eds. John Wiley and Sons, New York, NY, 1985, chapter 5. 8. J.P. Leahey, Ed. The Pyrethroid Insecticides. Taylor and Francis, London, England, 1985, chapter 5. 9. G. Leng, A./eng, K.H. Kuhn, J. Lewalter, and J. Pauluhn. Human dose-excretion studies with pyrethroid insecticides cyfluthrin: urinary metabolite profile following inhalation. Xenobiotica 27(12): 1273-1283 (1997). 10. G. Leng, K.H. Kuhn, and H. Idel. Biologial monitering of pyrethroids in blood and pyrethroid metabolites in urine: application and limitations. Sci. Total Environ. 199(1-2): 173-181 (1997). 11. J. Pauluhn. Risk assessment of pyrethroids following indoor use. Toxicol. Lett. 88(1-3): 339-348 (1996). 12. T.K. Mandal, A.K. Chakraborty, A. Bhattacharyya, R.K. Ghosh, and S. Majumder. The disposition kinetics and residues of fenvalerate in tissues following a single dermal application to black Bengal goats. Vet. Res. Commun. 20(3): 265-272 (1996). 13. J. Liu and C. Fan. Solid phase extraction method for rapid isolation and clean up of some synthetic pyrethroids in human urine and plasma. Forensic Sci. Int. 51: 89-93 (1991). 14. T.J. Class and J. Kintrup. Pyrethroids as household insecticides: analysis, indoor exposure and persistence. J. Anal. Chem. 340(7): 446-453 (1991). 15. P. Eriksson and A. Fredriksson. Neurotoxic effects of two different pyrethroids, bioallethrin and deltamethrin, on immature and adult mice, changes in behavioral and muscainic receptor variables. Toxicol. Appl. Pharmacol. 108:78-85 (1991). 16. IARC. tARC Monographs on the Evaluation of Carcinogenic Risks to Humans. International Agency for Research on Cancer, Lyon, France, 1991, pp 241-266. 17. M. Zaim, A. Aitio, and N. Nakashima. Safetyon pyrethroid treated mosquito nets. Med. Vet. Entomol. 14:1-5 (2000). 18. Z. Zhang, J. Sun, S. Chen, Y. Wu, and F. He. Levelsof exposure and biological monitoring of pyrethroids in spraymen. Br. J. Industrial Med. 48:82-86 (1991 ). 19. IPCS.International Programme on Chemical Safety, Environmental Health Criteria 87, Allethrins-Allethrin, d-Allethrin, Bioallethrin, S-Bioallethrin. World Health Organization, Geneva, Switzerland, 1989. 20. T.J. Class. Determination of pyrethroids and their degradation products in indoor and on surface by HRGC-ECD and HRGC-MS (NCl). J. High Resot. Chromatogr. 14:446-450 (1991 ). 21. A. Ramesh and M. Balasubramanian. Rapid preconcentration method for the determination of pyrethroid insecticides in vegetable oils and butter fat and simultaneous determination by gas chromatography-electron capture detection and gas chromatography-mass spectrometry. Analyst 123:1799-1802 (1998). 22. A. Ramesh and M. Balasubramanian. Impact of household preparations on the residues of pesticides in selected agricultural food commodities available in India. J. AOAC Int. 3:725-737 (1999). 23. A. Ramesh and A. Vijayalakshmi. Monitering of allethrin, deltamethrin, esbiothrin, prallethrin and transfluthrin in air during the use of household mosquito repellants. J. Environ. Monit. 3: 191-193 (2001). 24. A. Ramesh and A. Vijayalakshmi. Envirnmental exposure to residues after aerial spraying of endosulfan-residues in cow milk, fish, water, soil and cashew leaf in Kasargode, Kerala, India. Pest
Manag. Sci. 58:1048-1054 (2002). 25. A. Ramesh and A. Vijayalakshmi. Impact of long-term exposure to mosquito coils: residual deposition and dissipation of D-trans allethrin in a room. J. Environ. Monit. 4:202-204 (2002). 26. A. Ramesh and P.E.Ravi. Determination of residues of endosulfan in human blood by negative ion chemical ionization gas chromatographic/mass spectrometric method: impact of long-term aerial spray exposure. Pest. Manag. Sci. 59:252-258 (2003). 27. L. Elflein, E. Berger-Preiss, A. Preiss, M. Elend, K. Levsen, and G. Wunsch. Human biomonitoring of pyrethrum and pyrethroid insecticides used indoors: determination of the metabolites E-cis/trans-chrysanthemum dicarboxylic acid in human urine by gas chromatography-mass spectrometry with negative chemical ionization. J. Chromatogr. B 795(2): ] 95-207 (2003). 28. H.E. Braun, R. Frank, and L.A. Miller. Residuesof cypermethrin in milk from cows wearing impregnated ear tags. Bull. Environ. Contam. Toxicol. 35:61-64 (1985). 29. L.O. Ruzo, V.V. Krishnamurthy, J.E. Casida, and K. Gohre. Pyrethroid photochemistry: influence of the chloro(trifluromethyl)vinyl substituent in cyhalothrin. J. Agric. Food Chem. 35:879-883 (1987). 30. L. Junting and F. Chuichang. Solid phase extraction method rapid isolation of some synthetic pyrethroid insecticides from human urine and plasma. Forensic Sci. Int. 51:89-93 (1991). 31. R.V. Prabhakara Raju and R. Raghava Naidu. Spectrophotometric determination of decamethrin and its residues in insecticidal formulations and in water. J. AOAC Int. 77(3): 748 751 (1994). 32. G.-F. Pang, C.-L. Fan, and Y.-Z. Cho. Packed column gas chromatographic method for the simultaneous determination of 10 pyrethroid insecticides residues in fruits vegetables and grains. J. AOAC Int. 77(3): 738-747 (1994). 33. G.-F. Pang, Y.-Z. Cho, X.-S. Liu, and C.-L. Fan. Multiresidue liquid chromatographic method for simultaneous determination of pyrethroid insecticides in fruits and vegetables. J. AOAC Int. 78(6): 1474-1480 (1995). 34. G.-F. Pang, Y.-Z. Cao, C.-L. Fan, J.-J. Zhang, and X.-M. Li. Modification of AOAC mulltiresidue method for the determining synthetic pyrethroid residues in fruits, vegetables and grains. Part II1: studies of analyte stability and method ruggedness. J. AOAC Int. 80(1): 63-73 (1997). 35. D.7. Bissacot and I. Vassilieff. HPLC determination of flumethrin, deltamethrin, cypermethrin, and cyhalothrin residues in the milk and blood of lactating dairy cows. J. Anal. Toxicol. 21:397-402 (1997). 36. D.Z. Bissacot and I. Vassilieff. Pyrethroid residues in milk and blood of dairy cows following single topical applications. Vet. Hum. Toxicol. 39(1): 6-8 (1997). 37. L. Junting and S. Osamu. Conditions of solid phase extraction for the mixture of organophosphates and synthetic pyrethroids in human body fluids. Forensic Sci. Int. 99:159-161 (1999). 38. T. Frenzel, H. Sochor, K. Speer, and M. Uihlein. Rapid multimethod for verification and determination of toxic pesticides in whole blood by means of capillary GC-MS. J. Anal. Toxicol. 24: 365-371 (2000). 39. B.D. Ripley, G.M. Ritcey, C.R. Harris, M.A. Denomme, and P.D. Brown. Pyrethroid insecticide residues on vegetable crops. Pest. Manag. Sci. 57:683-687 (2001). 40. R.A. Chapman and H.S. Simmons. Gas liquid chromatography of pictogram quantities of pyrethroid insecticides. J. Assoc. Off. Anal. Chem. 60:977-978 (1977). 41. H.E. Braun and J. Stanek. Application of multi-residue method to determination of syntetic pyrethroid residues in celery and animal products. J. Assoc. Off. Anal. Chem. 65:685-689 (1982). 42. G. Leng, K.H. Kuhn, and H. Idel. Biologial monitering of pyrethroid metabolites in urine of pest control operaters. Toxicol. Lett. 88(13): 215-220 (1996). 43. X. Cao and Y. Wang. Determination of synthetic pyrethroid insecticides in biological materiaPsby GC-ECD. Chin. J. Forensic Meal. 4:156-161 (1989).
665
Journal of Analytical Toxicology,Vol. 28, November/December2004 44. B.D. Ripley, G.M. Ritcey, C.R. Harris, M.A. Denomme, and P.D. Brown. Quantitative metyhod for the determination of organochlorine persticides in serum. J. Anal. Toxicol. 20:23-26 (1996). 45. G.F. Pang, Y.Z. Cao, C.L. Fan, J.J. Zhang, and X.M. Li. Multiresidue gas chromatographic method for determination of syntetic pyrethroid pesticides in agricultural products. Collaborative study. J. AOAC Int. 82(1): 186-212 (1999). 46. S. Nemoto, Y. Tyuda, A. Nagao, K. Sasaki, and M. loyoda. Studies on the simultaneous determination of 17 organo chlorine and 9 pyrethroids pesticides in agricultural products. S Kokuritsu lyakuhin shokuhin eisei kenkyusho honkoku. 117:155-162 (1999).
666
47. G.F. Pang, Y.Z. Can, C.L. Fan, J.J. Zhang, X.M. Li, J. Mu, D.N. Wang, S.M. Liu,W.B. Song, H.P. Li, S.S. Wong, R. Kubinec, J. 1-ekel, and S. Tahotna. A laboratory study of identification and quantification of multiresidue pyrethroids in agricultural products by gas chromatography-mass spectrometry. J. Chromatogr. A 882(1-2): 231-238 (2000).
Manuscript received September 10, 2003; revision received December 31,2003.
