Risk assessment of pesticides used in the eastern Avocado Belt of Michoacan, Mexico: A survey and water monitoring approach

Pesticides use raises concerns regarding environmental sustainability, as pesticides are closely linked to the decline of biodiversity and adverse human health outcomes. This study proposed a holistic approach for assessing the potential risks posed by pesticides for human health and the environment in the eastern region of Michoacan, where extensive agricultural lands, especially corn and avocado fields, surround the Monarch Butterfly Biosphere Reserve. We used a combination of qualitative (semi-structured interviews) and quantitative (chemical analysis) data. Fifty-five interviews with smallholder farmers allowed us to identify pesticide types, quantities, frequencies, and application methods. A robust and precise analytical method based on solid-phase extraction and LC-MS/MS was developed and validated to quantify 21 different pesticides in 16 water samples (rivers, wells, runoff areas). We assessed environmental and human health risks based on the pesticides detected in the water samples and reported in the interviews. The interviews revealed the use of 28 active ingredients, including glyphosate (29 % of respondents), imidacloprid (27 %), and benomyl (24 %). The pesticide analysis showed the presence of 13 different pesticides and degradation products in the water samples. The highest concentrations were found for imidacloprid (1195 ngL-1) and carbendazim (a degradation product of benomyl; 932 ngL-1), along with the metabolite of pyrethroid insecticides, 3-PBA (494 ngL-1). The risk assessment indicates that among the most used pesticides, the fungicide benomyl and carbendazim pose the highest risk to human health and aquatic ecosystems, respectively. This study unveils novel insights on agricultural practices for the avocado, a globally consumed crop that is undergoing rapid production expansion. It calls for the harmonisation of crop protection with environmental responsibility, safeguarding the health of the people involved and the surrounding ecosystems.

Molecularly imprinted polymers for the detection of benomyl residues in water and soil samples

Benomyl is a benzimidazol fungicide used against various crop pathogens. Although banned in many countries, it is still widely used worldwide and is listed in different monitoring programs among the substances to be monitored to assess human exposure to pesticide residues. The assessment of benomyl is mainly based on the analysis of the residues of its most important metabolite, carbendazim. Existing methods often lack of selectivity and display a limited performance because of the presence of co-extracted compounds. Molecularly imprinted polymers (MIPs) offer an alternative methodology, adsorbing preferentially those target molecules for which the polymers are specifically prepared. In this study, we optimized the synthesis of a polymer imprinted with benomyl. Tests of specificity recognition showed a good performance for carbendazim compared with other similar pesticides. The mean recovery of benomyl (measured as carbendazim) from water samples was estimated to be 90% for MIPs while with real soil samples collected in Morocco the recovery efficiency was 62%. Preliminary tests also suggest that this MIP can implement traditional SPE techniques for assessing benomyl residual concentrations in environmental samples.

One-Step Fabrication of a Multifunctional Magnetic Nickel Ferrite/Multi-walled Carbon Nanotubes Nanohybrid-Modified Electrode for the Determination of Benomyl in Food

Benomyl, as one kind of agricultural pesticide, has adverse impact on human health and the environment. It is urgent to develop effective and rapid methods for quantitative determination of benomyl. A simple and sensitive electroanalytical method for determination of benomyl using a magnetic nickel ferrite (NiFe2O4)/multi-walled carbon nanotubes (MWCNTs) nanohybrid-modified glassy carbon electrode (GCE) was presented. The electrocatalytic properties and electroanalysis of benomyl on the modified electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the phosphate-buffered saline (PBS) of pH 6.0, this constructed biosensor exhibited two linear relationships with the benomyl concentration range from 1.00 × 10(-7) to 5.00 × 10(-7) mol/L and from 5.00 × 10(-7) to 1.00 × 10(-5) mol/L, respectively. The detection limit was 2.51 × 10(-8) mol/L (S/N = 3). Moreover, the proposed method was successfully applied to determine benomyl in real samples with satisfactory results. The NiFe2O4/MWCNTs/GCE showed good reproducibility and stability, excellent catalytic activity, and anti-interference.

[Determination of benomyl, carbendazim and thiabendazole in apple juice concentrate using solid-phase extraction coupled with ion exchange chromatography]

A method was developed for the determination of benomyl, carbendazim and thiabendazole in apple juice concentrate by solid-phase extraction coupled with ion exchange chromatography (IEC). The sample was diluted with water, and then benomyl was degradated completely to carbendazim at 80 degrees C, and purified by an SCX solid-phase extraction column. Liquid chromatographic analysis was performed on the instrument of Agilent 1200 series equipped with a diode-array detector and autosampler. The column was LC-SCX (25 cm x 4.6 mm, 5 microm). The mobile phase was 0.1 mol/L KH2PO4 (pH 2.5)-acetonitrile (70:30, v/v) with a flow rate of 1.0 mL/min. The presented method showed good linear relationship with good precision and accuracy at the range of 0.02 - 2.0 mg/L for carbendazim and thiabendazole. The detection limits were 0. 004 mg/kg for carbendazim and thiabendazole. The method was characterized with acceptable sensitivity to meet the requirements for monitoring these pesticides in apple juice concentrate.

Nitrile glove permeation of benomyl

The aim of this study was to investigate permeation of the fungicide benomyl at its highest field application concentration (0.70 mg/mL) in Benlate 50 WP aqueous solution (1.4 mg/mL) through two types of unsupported and unlined nitrile gloves--a disposable latex glove (Safeskin) and an industrial chemical-resistant glove (Solvex)--using an American Society for Testing and Materials (ATSM)-type permeation cell with isopropanol collection medium. The permeation cell was contained in a moving-tray water bath at 30.0 degrees C +/- 0.5 degrees C. The collection medium was evaporated and the residue derivatized with an optimized method (2,3,4,5,6-pentafluoro)benzyl bromide to form the disubstituted derivative of carbendazim (CARB), CARB.2PFB. The latter in isooctane was then quantified by gas chromatography- 63Ni-electron capture detection (GC-ECD) by the internal standard method. GC-ECD, GC-mass spectrometry (GC-MS), and reflectance infrared investigations showed that little degradation of benomyl occurred in the challenge solution of aqueous Benlate during an 8-hour exposure period. Benomyl was collected as a mixture of CARB and benomyl as shown by the presence of a diagnostic chromatographic peak identified by GC-MS. The amounts permeated during the same time period were always higher for Safeskin than for Solvex gloves, with the latter being approximately 18 times more protective than the former after 8 hours of continuous exposure. Although the Solvex gloves were safe to wear at least for 4 hours and for almost 8 hours, the ASTM breakthrough threshold was used as reference and thus ignored carcinogenic effects. Reflectance infrared investigations detected benomyl and CARB on the glove challenge surface after drying and confirmed that the cleaned glove surfaces after permeation experiments did not differ in infrared reflectance spectra from the corresponding surfaces just before the permeation experiments.

Terrestrial avoidance behaviour tests as screening tool to assess soil contamination

To assess soil quality and risk assessment, bioassays can be useful tools to gauge the potential toxicity of contaminants focusing on their bioavailable fraction. A rapid and sublethal avoidance behaviour test was used as a screening tool with the earthworm Eisenia andrei and the isopod Porcellionides pruinosus, where organisms were exposed during 48 h to several chemicals (lindane, dimethoate and copper sulphate, for isopods and carbendazim, benomyl, dimethoate and copper sulphate for earthworms). Both species were also exposed to soils from an abandoned mine. For all bioassays a statistical approach was used to derive EC50 values. Isopods and earthworms were able to perceive the presence of toxic compounds and escaping from contaminated to clean soil. Furthermore the behaviour parameter was equally or more sensitive then other sublethal parameters (e.g. reproduction or growth), expressing the advantages of Avoidance Behaviour Tests as screening tools in ERA.

Flow-through fluorescence-based optosensor with on-line solid-phase separation for the simultaneous determination of a ternary pesticide mixture

A rapid and selective method was developed for the simultaneous determination of 3 widely used pesticides, carbendazim (CBZ), carbofuran (CF), and benomyl (BNM). The method utilized a single continuous-flow, solid surface fluorometric multioptosensor implemented with a previous separation of the analytes on a minicolumn, placed just before the sensor, that was packed with the same solid support (C18 silica gel) as the flow-through cell. The separation was achieved because of the different kinetics of retention/elution of the pesticides on the solid support in the minicolumn, enabling the sequential arrival of the analytes at the sensing zone. With a single injection of the mixture, 2 of them were more strongly retained in the minicolumn (CF and BNM) while the other (CBZ) passed through the system towards the sensing material where it developed its fluorescence transitory signal. Then, CF and BNM were successively eluted from the solid support using 2 different eluting solutions, and they sequentially reached the sensing zone and developed their respective signals. A multiwavelength fluorescence detection mode was used, recording the signals of each pesticide at its maximum excitation/emission wavelength; therefore, the sensitivity was increased. The system was calibrated using a sample volume of 2000 microL. The linear dynamic range was 80-1400, 250-2400, and 150-2000 ng/mL with detection limits of 15, 68, and 35 ng/mL and relative standard deviation values of 3.5, 3.2, and 2.4% for CBZ, CF, and BNM, respectively. A recovery study was applied to spiked environmental water samples, and recoveries ranged from 96 to 104%.

Development of a single fluorescence-based optosensor for rapid simultaneous determination of fungicides benomyl and thiabendazole in waters and commercial formulations

A novel, sensitive, and straightforward spectrofluorimetric flow injection method is proposed in this work for the resolution of a binary mixture of two widely used fungicides (thiabendazole and benomyl). The continuous flow methodology is based on the implementation of on-line solid phase extraction (SPE), preconcentration, and separation of both analytes on a surface of C(18) silica gel beads placed just in the flow cell, with solid surface fluorescence detection. A 45- and 25-fold sensitivity enhancement was obtained for benomyl and thiabendazole, respectively (in relation to the liquid phase measurements in the absence of solid support). The separation of the pesticides was performed because of the different retention-desorption kinetics in their interaction with the solid support, in the zone where the stream impinges the solid material. No previous separation of the analytes before they reach the flow cell is needed, simplifying extraordinarily both the procedure and the manifold. Using a sample volume of 3200 microL, the system was calibrated in the range of 0.4-20 and 20-400 ng x mL(-)(1) with detection limits of 0.06 and 3.6 ng x mL(-)(1) for thiabendazole and benomyl, respectively, and RSD values (n = 10) smaller than 0.8% for both analytes. The RSD values obtained replacing the solid support in each measurement were lower than 3%, and the day-to-day reproducibility RSD value was also lower than 5%. Sampling frequencies of 10 and 18 h(-)(1) were obtained with 600 and 3200 microL of sample volume. Recovery studies carried out on natural water samples spiked with known amounts of both analytes at concentration levels in the range of 1-10 and 25-200 ng x mL(-)(1) provided mean recovery percentages ranging from 98.8 to 102% and from 98 to 103% for thiabendazole and benomyl, respectively. The proposed methodology was also applied to pesticide formulations.

Comparison of solid-phase extraction and micro-solid-phase extraction for liquid chromatography/mass spectrometry analysis of pesticides in water samples

Our recent on-line solid-phase extraction (SPE) device for micro-liquid chromatography, known as micro-solid-phase extraction (microSPE), was compared with traditional SPE for the analysis, from aqueous samples, of 4 pesticides belonging to different classes. Two different kinds of adsorbents, C18 and graphitized carbon black, were tested. A 2-stage ion trap mass spectrometer, equipped with homemade microflow electrospray ion (ESI) source, was used. Detection limits with a signal-to-noise ratio of 3:1 for both extraction methods were in the range of 0.1 microg/L for all compounds. However, better recoveries were obtained when microSPE traps were used.

Pesticide residues in products of plant origin in the European Union. Sampling strategy and results from the co-ordinated EU monitoring programmes in 1996 and 1997

The results of a co-ordinated monitoring programme for pesticide residues in the European Union and Norway carried out in 1996 and 1997 are presented. The aim of this programme is to work towards a system, which makes it possible to estimate actual dietary pesticide intake for the population of the European Union. Based on a statistically dérived sampling plan and within the limited number of pesticides/commodities analysed, the most critical pesticides (benomyl group and dithiocarbamates) and commodities (mandarine and lettuce) were identified. In case of detected non-compliances, repeated sampling and, if necessary, enforcement actions are to be taken by national authorities. The programme will be continued in the next years.

Evaluation of residual levels of benomyl, methyl parathion, diuron, and vamidothion in pineapple pulp and bagasse (Smooth cayenne)

The objective of this research was to study the residual levels of benomyl, methyl parathion, diuron, and vamidothion in pineapple bagasse and pulp. Benomyl (benlate), methyl parathion (Folidol 600), diuron (Krovar), and Vamidothion (Kilval 300) were applied pre-harvest to pineapples (smooth cayenne). After harvesting, the fruits were washed (100 ppm sodium hypochlorite) and the pulp was separated from the sub-products (peel, core, tops, and tails). The pulp was not submitted to any heat treatment. The sub-products and the juice expressed from them, were submitted to a blanching process (95 degrees C for 1 min). After separating the juice, the bagasse and pulp were analyzed for residues of diuron and benomyl by high performance liquid chromatography, and for residues of vamidothion and methyl parathion by gas chromatography using a TSD detector. No residues of benomyl, diuron, vamidothion, or methyl parathion were detected in the pulp within the quantification limits of the methods (0.1 mg/kg, 0.1 mg/kg, 0.005 mg/kg, and 0.005 mg/kg, respectively). Only methyl parathion (0.052 mg/kg) and vamidothion (0.021 mg/kg) were detected in the bagasse. The presence of these residues in the bagasse was probably due to the action of the wax found in the peel, which prevented the methyl parathion and vamidothion from dissolving in the juice. According to these results, the pulp was fit for human consumption, as far as pesticide residues were concerned, and the bagasse was fit for animal feed and similar applications, because the residual levels found were below the limits established for these compounds.

Determination of benomyl, diphenyl, o-phenylphenol, thiabendazole, chlorpyrifos, methidathion, and methyl parathion in oranges by solid-phase extraction, liquid chromatography, and gas chromatography

A simple and rapid method was developed for determination of benomyl, diphenyl (DP), o-phenylphenol (OPP), thiabendazole (TBZ), chlorpyrifos, methidathion, and methyl parathion in whole oranges. These compounds were extracted from a mixture of samples and anhydrous sodium acetate with ethyl acetate. The ethyl acetate extract was concentrated and cleaned up by passing through tandem solid-phase extraction columns consisting of anion-exchange and primary/secondary amine bonded silica. The eluate was concentrated and volume was adjusted with methanol for subsequent liquid chromatography (LC) and gas chromatography (GC). Benomyl (as methyl-2-benzimidazole carbamate, MBC), DP, OPP, and TBZ residues were determined by LC with fluorescence detection. Recoveries at 3 fortified levels (0.1, 1, and 10 micrograms/g) ranged from 63.9 to 97.4%, with coefficients of variation (CVs) of 1.6 to 15.5%. Limits of detection (LODs) were 0.01 microgram/g for DP, OPP, TBZ and 0.05 microgram/g for benomyl. Chlorpyrifos, methidathion, and methyl parathion residues were determined by GC with flame photometric detection. Recoveries ranged from 90.4 to 97.0%, with CVs of 2.1 to 5.9%. LODs were 0.005 microgram/g for chlorpyrifos and methyl parathion, and 0.01 microgram/g for methidathion.

Automated method for cleanup and determination of benomyl and thiabendazole in table-ready foods

An automated solid-phase extraction (SPE) cleanup with on-line liquid chromatographic (LC) analysis was developed to determine residues of benomyl (as carbendazim) and thiabendazole in table-ready food items from the U.S. Food and Drug Administration Total Diet Study (TDS). A strong-cation-exchange cleanup of an acetone extract replaces the methylene chloride solvent partitioning steps in the procedure described in the Pesticide Analytical Manual (PAM). LC analysis is accomplished with a C8 analytical column and tandem fluorescence and UV detection. Recoveries of both analytes from 32 representative TDS foods fortified at 0.05 and 0.5 microgram/g were determined. Method precision was evaluated with triplicate recovery assays on 11 foods fortified at both levels. Accuracy was tested further by assaying 47 foods for incurred residues in parallel with the validated PAM procedure for comparison, and good agreement was found. The automated SPE method reduces solvent consumption, analysis time, and labor.

Analysis of carbendazim, benomyl, thiophanate methyl and 2,4-dichlorophenoxyacetic acid in fruits and vegetables after supercritical fluid extraction

Simple methods for the analysis of carbendazim, benomyl and thiophanate methyl in fruits and vegetables and of 2,4-D in citrus fruits are presented. Sample preparation involves supercritical fluid extraction with carbon dioxide and further analysis is performed without any additional clean-up by GC-MS after derivatisation or directly by HPLC-diode array detection. The SFE methods presented are clearly faster and more cost effective than traditional solvent based approaches. The recoveries, detection limits and repeatabilities achieved, meet the needs of tolerance level monitoring of these compounds in fruits and vegetables.

High-performance liquid chromatographic determination of benomyl and carbendazim residues in apiarian samples

Simple procedures for the extraction and chromatographic determination of benomyl and carbendazim in honey, bees wax, larvae, bees and pollen are proposed. The fungicides were extracted from honey, larvae and bees using ethyl acetate, while methanol was more suitable for wax and pollen samples. Pollen extracts need a further clean-up step with n-hexane. The determination is carried out by reversed-phase high-performance liquid chromatography (HPLC) with fluorescence detection. The procedures have been applied to the analysis of benomyl on honey and larvae samples from hives whose bees were nourished with artificial food mixed with benomyl.

Monitoring of domestic and imported apples and rice by the U.S. Food and Drug Administration pesticide program

In 1993-94, the U.S. Food and Drug Administration (FDA) conducted a statistically based study of pesticide residues in domestic and imported fresh apples and processed rice. For apples, 769 domestic and 1062 imported samples were collected and analyzed; 85% of the domestic and 86% of the imported samples had detectable residues. Benomyl, a widely used fungicide, was found with greatest frequency in domestic apples, while diphenylamine was found most often in imported apples. One domestic and 4 imported samples contained violative residues of pesticides for which there are no U.S. tolerances on apples. The statistically weighted (by domestic packer throughput or import shipment size) violation rates for domestic and imported apples were 0.30% (0.13 unweighted) and 0.41% (0.38 unweighted), respectively. For rice, 598 domestic and 612 imported samples were collected and analyzed; 56% of the domestic and 12% of the imported samples had detectable residues. Malathion had the greatest frequency of occurrence in both groups of rice. Eight domestic and 9 imported samples were violative, all as a result of use of pesticides for which there are no U.S. tolerances on rice. The statistically weighted violation rates for domestic and imported rice were 0.43% (1.3 unweighted) and 1.1% (1.5 unweighted), respectively. Results of the statistically based study show that, as in FDA's regulatory monitoring, the levels of most pesticide residues found in these 2 commodities are generally well below U.S. tolerances, and few violative residues are found.

Monitoring of exposure to benomyl in nursery workers

We compared urinary levels of the metabolite methyl-5-hydroxy-2-benzimidazole carbamate (5-HBC) among nursery workers exposed to the fungicide benomyl (specifically Benlate 50 DF [DuPont, Wilmington, DE]) and workers not exposed to benomyl. Environmental exposures were quantitated from gloves, body patches, and air samples collected with area and personal monitors. The median concentration of 5-HBC in the urine of benomyl-exposed workers was 23.8 mumol of 5-HBC per mole of creatinine. No 5-HBC was detected in the reference group. Industrial hygiene results and biological monitoring findings indicate that use of Benlate 50 DF in the ornamental industry can lead to absorption of the active ingredient, benomyl. Weighing, mixing, and application activities involved the highest exposures. Dermal contact appeared to be the primary route of exposure.

Comparison of HPTLC and HPLC procedures for the determination of certain xenobiotic residues in apples and pears

HPTLC was used to check for residues of benomyl, carbendazim, ethoxyquin and thiabendazole in apples and pears. The method used showed good precision with a percentage coefficient of variation of less than 5%; recoveries were always greater than 90%. The limits of determination using HPTLC were always at least four times lower than Italian statutory limits. Selectivity with respect to other matrix components was excellent for all fruit varieties tested. Comparison with HPLC confirmed the validity of the results.

Rapid on-line precolumn high-performance liquid chromatographic method for the determination of benomyl, carbendazim and aldicarb species in drinking water

A reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of trace concentrations of benomyl, carbendazim, aldicarb, aldicarb sulphoxide and aldicarb sulphone in drinking water. A 10-ml sample of water is passed through a 3-cm precolumn, packed with 5-microns C8 sorbent, at a flow-rate of 5 ml/min. The HPLC system is then switched to an acetonitrile-water gradient elution program. The preconcentrated analytes are eluted from, and separated by, the 3-cm C8 precolumn and determined by UV absorption. The total analytical time is 25 min. The lowest detectable concentrations are in the range of 2.5 x 10(-9)-11.0 x 10(-9) g/ml for the five analytes investigated with 10 ml of sample.

Enzyme-linked immunosorbent assay of benomyl and thiabendazole in some foods

Enzyme-linked immunosorbent assays were developed for benomyl as its decomposition product, methyl 2-benzimidazole carbamate, and thiabendazole in foods. Immunogens consisting of human serum albumin coupled to 2-succinamidobenzimidazole or 2-(2'-succinamido-4'-thiazolyl)benzimidazole were used in rabbits to raise antisera that were specific for the respective fungicides. Lower limits of quantitation of 0.35 ppm for benomyl and 0.03 ppm for thiabendazole were established without cleanup of the ethyl acetate extract. Recoveries of benomyl from 3 crops spiked at 0.5 to 10 ppm averaged 89% (range 73-109%) and of thiabendazole from 5 crops spiked at 0.1 to 2.0 ppm were 93% (range 81-105%).

High performance liquid chromatographic method for simultaneous determination of residual benomyl and methyl 2-benzimidazole carbamate on apple foliage without cleanup

A simple HPLC method has been developed to individually determine residues of benomyl and MBC on apple leaves without cleanup. Sample leaves in a Mason jar are freeze-dried and tumbled for extraction in CHCl3 containing 5000 microgram n-propyl isocyanate/mL at 1 degree C. n-Butyl isocyanate is added to the extract of 5000 microgram/mL, and 20 microL of the mixture is injected into the HPLC system. A brownlee LiChrosorb silica gel column with a guard column is operated with a mixed mobile phase of chloroform--hexane (4 + 1) saturated with water. MBC, present as a degradation compound of benomyl, is identified as methyl 1 - (n - propylcarbamoyl) - 2 - benzimidazole carbamate (MBC-n-PIC derivative). At 280 nm, both benomyl and MBC-n-PIC can be detected with a UV detector at a level of 0.2 ppm in apple leaves.

Determination of benomyl, carbendazim and 2-aminobenzimidazole (2-ab) in plant materials. Part I: Apples, red-currants, grapes, kale and sugar beets

Benomyl and Carbendazim are widely used fungicides with systemic activity. In the Federal Republic of Germany the legal limits of Benomyl and Carbendazim lie between 0.1 and 7 ppm dependent on the substrate. A method for the determination of Benomyl and Carbendazim in apples, red-currants, grapes, kale, and sugar beets was developed. Benomyl and Carbendazim are extracted with ethyl acetate, saponified and determined as 2-aminobenzimidazole by thin-layer chromatography. The detection limits lie between 0.02--0.08 ppm, recoveries amount to 87% at 0.5-ppm levels.

[Radiometric determination of 11 carbamate pesticides in the nanogram and subnanongram ranges by means of cholinesterase inhibition]

This method for determining carbamates is based on the inhibiting action of these substances on acetylcholinesterase activity. The use of radioactively labelled acetylcholine as a substrate, the ensuing extractive separation of the radioactive acetic acid (formed by hydrolysis) and its radiometric determination permit to detect very small amounts of carbamates. The limit of detection for aldicarb, baygon, benomyl, bux, carbaryl, CIPC, matacil, phenmedipham and promecarb lies in the picogram range; that for barban and methomyl, in the nanogram range. The lower, linear parts of the curves for the different carbamates fall within the range 0.001-10 ng. The sensitivity (expressed as delta% inhibition/delta lg ng carbamate) ranges from 1.0 to 9.7.

Determination of benomyl and 2-(4-thiazolyl) benzimidazole in plant tissues by high-performance liquid chromatography using fluorimetric detection

Methods for determining benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazole carbamate] residues in plant tissues involve isolation of the residue by extraction with ethyl acetate, hydrolysis of the extracted residue to 2-aminobenzimidazole and final determination by high-performance liquid chromatography using a fluorimeter. 2-(4-Thiazolyl) benzimidazole is also determined by a similar procedure without hydrolysis. The sensitivities of these methods are 0.02 ppm for benomyl and 0.001 ppm for 2-(4-thiazolyl) benzimidazole. Recoveries of these compounds from various plant tissues were 90.5-102.9%. No interference with these methods from the plant tissues tested was found.

High speed liquid chromatography of pesticides

High speed liquid chromatography has just begun to be explored as an analytical technique for pesticides, particularly residues. It is the intent of this article to provide a comprehensive review of pesticide related applications, point out possibilities for better utilization of existing columns, describe some of the more promising experimental detectors and suggest approaches which could lead to the development of practical analytical methods.