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A high-performance thin-layer chromatographic method has been developed for determination of four carbamate residues in vegetables. The method uses two mobile phases on silica gel 60 F 254 GLP HPTLC layers, and detection at λ = 243 nm and 207 nm, the average wavelengths of maximum adsorption of pirimicarb and methomyl, and carbaryl and carbofuran, respectively. Recovery of 1.0–5.0 mg kg −1 of the four mixed carbamates from wax gourd and potatoes was 70.05–103.7%. The accuracy and precision of the method were confirmed by means of fortification experiments.

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Residues of three pyrethroids in spiked vegetables have been analyzed by HPTLC with two mobile phases in a twin-trough chamber and in horizontal chambers. The spots were detected at λ = 203 nm and the greatest detection sensitivity for the three pyrethroids was 10 ng. Recovery after fortification at 0.5–5.0 mg kg −1 was from 70.20 to 108.5%. The relative standard deviation was 1.59–27.94%.

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A simple, rapid, and sensitive high-performance thin layer chromatographic method for analysis of the residues of tricyclazole, thiram, and folpet in tomatoes has been established and validated. The sample was extracted by mechanical vibration at room temperature with acetone-dichloromethane 1:1 ( v/v ) and the extract was directly applied as bands to glass-backed silica gel 60F 254 HPTLC plates. The plates were developed with hexane-acetone 6+4 ( v/v ) in an unsaturated glass twin-trough chamber. Evaluation of the developed HPTLC plates was performed densitometrically. The results indicated that the detection limits of tricyclazole ( R F = 0.26), thiram ( R F = 0.65), and folpet ( R F = 0.77) were 1.2 × 10 −8 , 3.0 × 10 −8 , 4.0 × 10 −8 g, respectively. Recoveries of the pesticides from tomatoes with this analytical method were 67.66–98.02%, and RSD were 0.13–22.06%. The precision and accuracy of this method were generally fit for analysis of pesticide residues in tomatoes.

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A high-performance thin-layer chromatographic (HPTLC) method for simultaneous analysis of temephos and fenitrothion in green tea has been established and validated. The sample was extracted with ethyl acetate by mechanical vibration at room temperature and the extract was cleaned by use of an SPE tandem column, before elution with dichloromethane. The extract was applied as bands to glassbacked silica gel 60F254 HPTLC plates. The plates were developed with acetone-hexane 3+7 (v/v), in an unsaturated glass twin-trough chamber. The developed HPTLC plates were evaluated densitometrically. The detection limits of temephos (R F 0.55) and fenitrothion (R F 0.69) were 20 and 10 ng, respectively. Recovery from green tea of the two pesticides at levels of 0.2 to 4 mg kg−1 was 80–107% with relative standard deviations of 4.4–20.2%. The precision and accuracy of the method were generally fit for analysis of temephos and fenitrothion residues in green tea.

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A simple, rapid, and sensitive high-performance thin-layer chromatographic method has been developed and validated for analysis of residues of imidacloprid, fenitrothion, and parathion in Chinese cabbage. The sample was extracted by sonication in an ultrasonic water bath with acetone-petroleum ether, 5:3 ( v / v ), and the extract was directly applied, as bands, to glass-backed silica gel 60F 254 HPTLC plates. The plates were developed with hexane-acetone, 7 + 3 ( v / v ), in an unsaturated glass twin-trough Camag chamber. Evaluation of the developed HPTLC plates was performed densitometrically with a Camag TLC Scanner 3 controlled by an external PC running Wincats software (Version 1.1.2). The results indicated that the detection limits of imidacloprid ( R F = 0.10), fenitrothion ( R F = 0.59), and parathion ( R F = 0.70) were 5.0 × 10 −9 g, 2.0 × 10 −8 g, 1.0 × 10 −8 g, respectively. Recoveries of the pesticides from Chinese cabbage by use of this analytical method were 80.04–85.22%, and RSD were 4.18–13.15%. The precision and accuracy of the method were generally fit for analysis of pesticide residues in Chinese cabbage.

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References [1] L.M.L. Nollet and H.S. Rathore , Handbook of Pesticides, Methods of Pesticides Residues Analysis , CRC Press, Taylor

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Acta Alimentaria
Authors: B. Šimundić, G. Krešić, A. Živkovićb, and B. Medugorac

Pesticides are used with the aim to control insects, diseases, fungi and other pests.  Along with the benefits, there are potential effects from trace amounts of residues remaining on fruits and vegetables. The objective of this study was to check for compliance with the maximum residue levels in fruits and vegetables from Kvarner region of Croatia. 14 Fourteen sorts of  vegetables and 6 sorts of fruits (n = 263), randomly selected from market,  were analysed for organochlorine, organophosphorus and fungicide residues. Multi residue analysis using GC/NPD, GC/ECD  and spectrophotometric methods were performedapplied. The results of this study indicated that though all the commodities were contaminated with pesticides, the levels were low and residues above MRL were found only in 1.52% of  samples. All other levels were below the criteria for maximum residue limits established by Croatia and the EU.

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Abstract

High-performance liquid chromatography with a hydrophilic-interaction liquid chromatographic (HILIC) column has been successfully used to retain and separate the polar phosphonic herbicides glyphosate and glufosinate. Online electrospray tandem ion-trap mass spectrometric and DAD detection were used. The effects on the separation of mobile phase acetonitrile content, buffer concentration, and flow rate, and of column temperature, were investigated. With UV-visible detection at 195 nm, LOQ were <850 mg kg−1, showing the method is suitable for product quality control of these herbicides alone or in combination. Tandem mass spectrometric conditions were optimized for ion-trap detection. Quantification was by use of selected reaction monitoring transitions m/z 168 → 150 in negative-ion mode for glyphosate and m/z 182 → 136 in positive-ion mode for glufosinate. Limits of detection (LOD; S/N > 3) were 0.20 and 0.16 ng for glyphosate and glufosinate, respectively, and the respective limits of quantification (LOQ; S/N = 10) were 0.02 and 0.05 mg kg−1. Sample derivatization was not necessary to achieve low detection limits in residue analysis in this study. Recovery from watermelon, spinach, potato, tomato, radish-root, and water fortified with the herbicides ranged from 63.6 to 107.3% and relative standard deviations were <15.3%.

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.) Methods of Pesticide Residues Analysis, CRC Press, Boca Raton-New York, 2010. Tuzimski T. Methods of Pesticide Residues Analysis

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Forschungsgemeinschaft), Manual of Pesticide Residue Analysis, Vol. II, VCH, Weinheim, 1992, pp 3–17. Manual of Pesticide Residue Analysis, Vol. II 1992

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