Simple analytical method for determination of pesticide residues in human serum by liquid chromatography tandem mass spectrometry

The aim of this study was to develop an analytical method for the determination of residues of organophosphorus and carbamate pesticides which are widely used in Tunisia. This method involves a liquid-liquid extraction procedure followed by liquid chromatography tandem mass spectrometry (LC/MS/MS) for the identification and quantification of compounds. Ionization of molecules was performed by the electrospray mode. Multiple reactions monitoring (MRM) was the acquisition mode used for the monitoring of two MS/MS transitions for each compound. The average recoveries obtained, at three different fortification levels, ranged between 65% and 106% for most of the pesticides studied, except for methamidophos (lower than 25%).The linearity of the method was in the range of 5 to 50 μ g/L with a correlation coefficient from 0.995 to 0.999, depending on the analyte. The estimated limit of detection and limit of quantification were 2 μ g/L and 5 μ g/L, respectively. The precision of the analytical procedure was satisfactory and the coefficients of variation, evaluated at three concentration levels were lower than 15% for most pesticides studied. The application of the method was investigated in a population of agricultural workers chronically exposed to various pesticides some of which, such as carbofuran, carbendazim, methomyl and pirimicarb, were detected in some serum samples.     

Determination of 28 pesticides applied on two tomato cultivars with a different surface/weight ratio of the berries,using a multiresidue GC-MS/MS method

The behavior of 28 pesticides on two tomato cultivars with a different surface/weight (S/W) ratio of the berries (S/W, Birikino vs. Tombola) was studied, in order to provide appropriate indications about their persistence on crops reaching the pre-harvest interval (PHI). Quantitative analysis was performed using a GC MS/MS method. Birikino cv. (BIR) was a “cherry type tomato” with a double S/W ratio compared with Tombola cv. (TOM). The results showed a different pesticide behavior. Azoxystrobin, Boscalid, Bupirimate, Difenoconazole, Etofenprox, Iprodione, Mepanipyrim, Myclobutanil, Tebuconazole, Zoxamide, Metalaxyl M, Pyrimethanil, Tetraconazole, Benalaxyl, Cyprodinil, Fenamidone, Famoxadone and Fludioxonil immediately after treatments showed residues on BIR higher than TOM, and this behavior is consistent with its greater exposed surface. BIR showed higher decay rates of these pesticides during the whole trial, nevertheless residue averages remained higher than TOM reaching the time of harvest. Residues at the PHI were all below their Maximum Residue Levels (MRLs), but data indicated that they could exceed their legal limits especially if the above-mentioned active ingredients were employed more than once per crop cycle on cherry type tomatoes. As regards to Chlorpyrifos, Chlorpyrifos methyl, Triadimenol, Pyridaben and Tebufenpyrad, no different residual behavior related to S/W ratio of the cultivars was observed. Even in this case, residues at the PHI were all below MRLs. As for Cyfluthrin, Deltamethrin, Lambda cyhalothrin, Etoxazole and Cyproconazole, residues were lower than the limit of quantitation (LOQ) of the analytical method just after the treatment, according to their low doses of employment.     

The degradation of anilazine and dihydroxy‐anilazine at various soil depths of an orthic luvisol

Abstract

In conformity with Guideline 4.1 of the Federal German Biological Agency, degradation experiments with the fungicide active ingredient [benzene ring‐U‐¹⁴C]anilazine and its major metabolite [triazine ring‐U‐¹⁴C]dihydroxy‐anilazine were carried out in an orthic luvisol. Mineralization of the benzene ring carbon of anilazine amounted to less than 2 % in 110 days and that of the triazine ring carbon of dihydroxy‐anilazine to less than 8 %. Increasing the incubation temperature from 22 °C to 30 °C and adding organic substance influenced the mineralization slightly. In soils which received two or three applications in succeeding years with subsequent ageing in the open‐air lysimeter no stimulation of the mineralization was observed. Extractions after incubation showed that only 10.2 to 18.6 % of the ¹⁴C‐activity applied with anilazine was extractable with acetone/CaCl₂. The major proportion was bound in the fractions of the soil organic matter, namely 45.0 to 59.6 % of the radiocarbon applied was accounted for by the humin fraction, 12.0 to 27.4 % by the fulvic acids, and 9.4 to 15.0 % by the humic acids. In the case of dihydroxy‐anilazine, 28.9 to 89.7 % of the applied ¹⁴C‐activity was extractable with acetone/CaCl₂. Of tJhe radiocarbon bound in the soil, the greatest proportion, i.e. 18.5 to 35.5 % of the radiocarbon applied, was accounted for by the fulvic acids.     

Chemical and biological release of 14C‐bound residues from soil treated with 14C‐p,p'‐DDT

Abstract

¹⁴C‐p,p'‐DDT‐bound residues in soil can be released by treatment with concentrated sulphuric acid at ambient temperatures. Within 6 days, about 70% of the bound residues was released. Bound residues released after 9 months incubation with ¹⁴C‐DDT showed the presence of DDT and DDE only while bound residues released after 18 months, contained in addition 13% DDD.

Release of bound ¹⁴C‐residues also occurs readily following inoculation of the soil‐bound residues with fresh soil or with individual microorganisms. Almost complete release of bound residues was observed after incubation for 45 days. The rate of release was rapid during the first two weeks and decreased thereafter. TLC and HPLC analysis showed that the released residues contained DDE (about 80%) and a smaller amount of DDD. The disappearance of DDT from the released residues may be attributed to its microbiological degradation to DDE and DDD, shortly after its release.     

Persistence of herbicide fenoxaprop ethyl and its acid metabolite in soil and wheat crop under Indian tropical conditions

The persistence of fenoxaprop ethyl {Ethyl (RS)-2-[4-(6-chloro-1,3-benzoxazol-2-yloxy) phenoxy] propionate} herbicide and its active metabolite fenoxaprop acid was investigated in soil and wheat crop. Fenoxaprop acid was prepared by alkaline hydrolysis of fenoxaprop ethyl. A HPLC method was developed in which fenoxaprop ethyl herbicide and its acid metabolite showed sharp single peak at 6.44 and 2.61 min respectively. The sensitivity of the method for ester and acid was 2 and 1 ng respectively with limit of detection of 0.1 and 0.05 μg mL^?1. The recovery of fenoxaprop ethyl and fenoxaprop acid from soil, wheat straw and grain ranged between 73.8–80.2%. In a field experiment fenoxaprop ethyl (Puma super® 10 EC) when applied to wheat crop at the rate of 120 g and 240 g a.i. ha^-1 as post emergence spray, fenoxaprop ethyl converted to fenoxaprop acid. Residues of fenoxaprop ethyl and acid dissipated in soil with a half-life of 0.5 and 7.3 days, respectively. At harvest no detectable residues of fenoxaprop ethyl or acid were observed in soil, wheat grain and straw samples.     

Detection and occurrence of pentachlorophenol residues in chicken liver and fat

Abstract

A method for the detection of pentachlorophenol (PCP) residues in chicken liver and fat is presented. A detection limit of 0.002 mg/kg was achieved. Recoveries from liver and fat were in the range 82–88% and 95–97%, respectively.

Low level residues of PCP were found in all 1072 liver and 723 fat samples. These levels were <0.010 mg/kg in 92.7% of the fat and 75.6% of the livers. Only 0.75% of the liver samples had PCP levels>0.1 mg/kg. None of the more toxic impurities of PCP were detected in the chicken tissues.     

Evaluation of the field dissipation of fungicides and insecticides used on fruit bearing trees in northern Italy

The dissipation of the fungicides captan, cyprodinil, fludioxonil, dithianon, and tebuconazole and of the insecticides chlorpyrifos, fenitrothion, and malathion was studied, following a single treatment of different cultivars of pears, apples, and peaches. The study was conducted in northern Italy, over two successive growing seasons (2004 and 2005). The treatments were performed by the farmers involved, in line with their usual practice. At various time intervals from treatment to harvest, representative samples of fruit were collected and analyzed for pesticide residues. In some cases, concentrations lower than the maximum residue levels (MRLs) were found immediately after treatment. In all trials a rapid decline in pesticide concentrations was observed leading to residues at harvest greatly below the MRLs.     

Role of dissolved humic acids in the biodegradation of a single isomer of nonylphenol by Sphingomonas sp

This study shows the important role of humic acids in the degradation of ¹⁴C and ¹³C labeled isomer of NP by Sphingomonas sp. strain TTNP3 and the detoxification of the resulting metabolites. Due to the association of NP with humic acids, its solubility in the medium was enhanced and the extent of mineralization of nonylphenol increased from 20% to above 35%. This was accompanied by the formation of significant amounts of NP residues bound to the humic acids, which also occurred via abiotic reactions of the major NP metabolite hydroquinone with the humic acids. Gel permeation chromatography showed a non-homogenous distribution of NP residues with humic acids molecules, with preference towards molecules with high-molecular-weight. Solid state ¹³C nuclear magnetic resonance spectroscopy indicated that the nonextractable residues resulted exclusively from the metabolites. The chemical shifts of the labeled carbon indicated the possible covalent binding of hydroquinone to the humic acids via ester and possibly ether bonds, and the incorporation of degradation products of hydroquinone into the humic acids. This study provided evidences for the mediatory role of humic acids in the fate of NP as a sink for bacterial degradation intermediates of this compound.     

农药施用对兴凯湖水中农药残留的影响及其风险评价

主要研究了中国东北兴凯湖周围水稻种植区域农药残留以及对湖水水质的影响.分别于水稻抽穗期和水稻成熟期在兴凯湖地区对稻田、排干和大小兴凯湖地表水进行采集并对27种农药及其降解产物进行分析.结果表明,在水稻抽穗期所分析的27种农药及其降解产物全部检出,总浓度范围为247.97~6 094.49 ng·L^-1;水稻成熟期检出25种,总浓度范围为485.36~796.23 ng·L^-1,两时期对比,抽穗期的农药及其降解产物检出数量更多且总浓度更高;在水稻抽穗期阿特拉津、西草净和多效唑为主要检出农药,在水稻成熟期阿特拉津和稻瘟灵为主要检出农药;大小兴凯湖水中农药的分布特征与排干水相似,表明大小兴凯湖水中农药及其降解产物很可能来源于稻田排干的输入;在排干和大小兴凯湖水中,阿特拉津、西草净、扑草净、丁草胺、稻瘟灵和草酮RQ均值大于0.1,对水生生物存在潜在生态风险.     

我国典型秸秆露天燃烧黑碳的高时间分辨率排放特征及其排放清单

农作物秸秆燃烧是大气中黑碳(black carbon,BC)气溶胶的主要来源之一。目前农作物秸秆燃烧排放黑碳的研究主要集中在通过离线样品分析获得的BC排放特征,缺少实时在线排放特征的研究。本研究收集了我国具有代表性的4种农作物秸秆(小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆),通过在实验室燃烧平台模拟农作物秸秆露天燃烧的过程,利用黑碳仪获得农作物秸秆燃烧过程中BC的实时浓度排放变化;利用质量重建,获得BC在线排放因子。结果表明:农作物秸秆在明燃过程中BC的排放因子较为稳定。通过平均排放因子的计算,获得小麦秸秆、水稻秸秆、玉米秸秆和大豆秸秆的BC排放因子分别为(0.32±0.05) g?kg~(-1)、(0.31±0.13) g?kg~(-1)、(0.31±0.09) g?kg~(-1)和(0.44±0.01) g?kg~(-1)。在排放因子的基础上,结合我国农作物秸秆露天燃烧量,最终建立了2015年我国省级(不含港澳台地区)典型农作物秸秆燃烧的BC排放清单。