Recoveries Of Organochlorine Pesticides Research Articles

Comparison of gas chromatography techniques for the analysis of organochlorine pesticides in sediments

ABSTRACTThe response of two chromatography techniques (GC) for electron capture (GC-ECD) and GC-coupled to a mass spectrometer with negative chemical ionization (GC-MS/NCI) was compared to validate the quantification of organochlorine pesticides (OCPs) in certified sedimentary material. Curves linearity, limits of detection, limits of quantification, accuracy, efficiency and precision were used to validate the analytical techniquesAs result, both GC methods displayed high values of validation parameters, demonstrating an optimal analytical response; however, comparative ANOVA analysis and Fisher test showed significative differences between ECD and MS/NCI. A high linearity (r) and sensitivity were observed in GC-MS/NCI and ECD; MS/NCI showed around r=0.998-0.99 for the 14 standard OCPs, whereas GC-ECD displayed a range between r=0.983-0.998. Limits of detection and quantification from MS/NCI showed also a high detection of low concentration (0.03 ng/mL) of OCPs compared to ECD (1.2 ng/mL).Accuracy of analysis of OCPs by ECD exhibited a positive bias for the specific analyte’s alpha-HCH, aldrin and heptachlor epoxide and in low concentration (1-10 ng/mL); however, MS/NCI showed only positive bias in the analysis of endosulfan I (1-2 ng/mL).Recoveries of OCPs by GC-MS/NCI were higher than those obtained by GC-ECD (82-117%); demonstrating a high precision within the acceptance criterion stipulated ≤20%.

Optimization of in-cell accelerated solvent extraction technique for the determination of organochlorine pesticides in river sediments

Organochlorine pesticides (OCPs) are ubiquitous environmental contaminants with adverse impacts on aquatic biota, wildlife and human health even at low concentrations. However, conventional methods for their determination in river sediments are resource intensive. This paper presents an approach that is rapid and also reliable for the detection of OCPs. Accelerated Solvent Extraction (ASE) with in-cell silica gel clean-up followed by Triple Quadrupole Gas Chromatograph Mass Spectrometry (GCMS/MS) was used to recover OCPs from sediment samples. Variables such as temperature, solvent ratio, adsorbent mass and extraction cycle were evaluated and optimized for the extraction. With the exception of Aldrin, which was unaffected by any of the variables evaluated, the recovery of OCPs from sediment samples was largely influenced by solvent ratio and adsorbent mass and, to some extent, the number of cycles and temperature. The optimized conditions for OCPs extraction in sediment with good recoveries were determined to be 4 cycles, 4.5g of silica gel, 105°C, and 4:3 v/v DCM: hexane mixture. With the exception of two compounds (α-BHC and Aldrin) whose recoveries were low (59.73 and 47.66% respectively), the recovery of the other pesticides were in the range 85.35–117.97% with precision <10% RSD. The method developed significantly reduces sample preparation time, the amount of solvent used, matrix interference, and is highly sensitive and selective.

Development of a GC-MS/MS method for determination of organochlorine pesticide residues in wild Ligusticum chuanxiong and chestnut

A gas chromatographic-tandem mass spectrometric method (GC-MS/MS) has been developed for sensitive and reliable detection of 8 organochlorine pesticide residues in wild L. chuanxiong and chestnut. The target compounds were extracted from both samples and simultaneously rudely cleaned up by water-acetone and dichloromethane. Then, the obtained dichloromethane phase was evaporated to dry, treated with H2SO4, centrifuged, evaporated and redissolved in 0.5 mL of benzene for GC-MS/MS detection. When spiked from 5 to 500 μg/kg, the average recoveries of organochlorine pesticides in two kinds of sample ranged from 74.2 to 110.9% with the intra-day RSD of 0.1 to 10.1% and the inter-day RSD of 0.7 to 10.5%. The limit of detection of eight compounds varied from 0.13 to 1.2 μg/kg in two kinds of samples.

Simultaneous Determination of Organochlorine, Organophosphorus, and Pyrethroid Pesticides in Bee Pollens by Solid-Phase Extraction Cleanup Followed by Gas Chromatography Using Electron-Capture Detector

A method for routine determination of the residues of nine organochlorine pesticides (OCPs), ten organophosphorus pesticides (OPPs), and seven pyrethroid pesticides (PPs) in bee pollens was developed. Bee pollen samples were extracted by petroleum ether followed by solid-phase extraction cleaning and detected by gas chromatography–micro electron capture detection. Range of detection limits are 0.3–3.3 μg/kg for OCPs, 1.0–19.1 μg/kg for PPs and 1.1–19.7 μg/kg for OPPs. Recoveries of OCPs, OPPs, and PPs were in the range of 88.9–122.7 %, 86.8–123.1 %, and 90.8–118.7 %, respectively. The method was applied successfully to analyze real bee pollen samples. The results show a low level of contamination caused by pesticide residues indicating safe supply of bee pollen for consumers.

Comparison of two sample preparation methods for analysis of organochlorine pesticides residues in fish muscle

The aim of this study was to compare recoveries of organochlorine pesticides (heptachlor, α-HCH, β-HCH, γ-HCH, op′-DDD, pp′-DDD, pp′-DDE, op′-DDT, pp′-DDT) from fish muscle dried by two alternative methods: (i) grinding with anhydrous sodium sulphate and (ii) freeze drying. Pesticide residues content was determined by gas chromatography-mass spectrometry (GS-MS) method. For four pesticides (γ-HCH, α-HCH, heptachlor and pp;-DDD) in four of five fish species, higher recoveries were obtained from the freeze-dried samples. For five remaining pesticides, correlations between fish species and drying method were not found. The results of this study do not clearly indicate which drying method caused lower losses of analytes. Recoveries from the freeze-dried samples ranged from 69.9 to 117.6 %, while recoveries from the samples ground with sodium sulphate varied from 64.4 to 126.7 %. Either of the methods gave satisfactory recoveries and they both can be used interchangeably.

Extraction of organochlorine pesticides in sediments using soxhlet, ultrasonic and accelerated solvent extraction techniques

The application of soxhlet, ultrasonic and accelerated solvent extraction techniques to the analysis of six organochlorine pesticides (α-HCH, β-HCH, γ-HCH, o, p′-DDT, p, p′-DDT and p, p′-DDE) in Taihu Lake sediment samples is described. It was found that the limits of quantification ranged from 0.002 µgg−1 to 0.004 µgg−1, and the recoveries of organochlorine pesticides with the three extraction techniques were acceptable (>80.7%). With a mass selective detector, better results were obtained by accelerated solvent extraction using hexane-acetone (1:1) as compared with soxhlet and ultrasonic extraction. It was shown that the accelerated solvent extraction was the optimum technique for the analysis of organochlorine pesticides in sediments. The general features of the three extraction techniques are also presented.

Persistent chlorinated pesticides and polychlorinated biphenyls in selected fish species from Lake Tanganyika, Burundi, Africa

Concentrations of selected organochlorine pesticides and PCBs in seven fish species (cichlids) from the north end of the Lake Tanganyika, Burundi, Africa were determined. Results were compared to previous work on the Lake Tanganyika and other water bodies and to the European Community maximum residue levels (MRLs) in edible fat. The analytical method included a hot Soxhlet extraction with a mixture of acetone: hexane (1:3, v/v), gravimetrically lipid determination, and a single step clean-up. For PCBs and stable pesticides, the clean-up was done on activated silica gel impregnated with concentrated sulfuric acid, while for non acid-stable pesticides superposed layers of alumina, silica and florisil impregnated with 15% methanolic solution of KOH were successively used. Recoveries of organochlorine pesticides from certified reference material (CRM 430) were ranging from 86% for p,p′-DDT to 107% for endrin, while recoveries from blank fat spiked fortified at three different levels were between 65% for alachlor at the lowest fortification level and 107% for mirex at the highest fortification level. The limits of detection for each analyte were ranging from 0.1 ng/g to 0.5 ng/g fat. All chlorinated pesticides were found in the analyzed species but at low concentrations. Boulengerochromis microlepis contained the highest concentrations of HCHs (288.2±15.5 ng/g fat) and DDTs (909.1±42.5 ng/g fat), while the highest PCB levels (166.7±37.4 ng/g fat for the sum of 12 congeners) were found in Oreochromis niloticus. However, there is no evidence that Lake Tanganyika is more contaminated with pesticides than other African water bodies.

Extraction and recovery of organochlorine pesticides from fungal mycelia

An extraction method was developed to recover organochlorine pesticides (OCPs) associated with live and mercuric chloride-treated fungal mycelia. A Cladosporium sp. was inoculated into potato dextrose broth, DDT (90 mg/l) added and incubated for seven days. The combination of a microextraction procedure for aqueous-phase-associated DDT and a sonication extraction for mycelia-bound DDT, using dichloromethane as the extracting solvent, resulted in the recovery of 31–51% of added DDT. DDT recovery was increased to 62–65% by grinding the fungal mycelia before sonication. Alkali and nitric acid pretreatments were tested to increase the recovery of DDT associated with fungal mycelia, however, these treatments resulted in the production of unidentified DDT transformation products. Pretreating mycelia containing DDT in concentrated hydrochloric acid at 60°C for 2, 4 and 6 h resulted in DDT recoveries of 90–91%, 99% and 101–102% respectively without the production of transformation products. When an OCP mixture (DDT, DDD and DDE) was added to fungal mycelia, between 89% and 96% of DDT, DDD and DDE were recovered from live cultures compared to 85–91% in mercuric chloride-treated cultures using the microextraction/hydrochloric acid pretreatment (60°C/6 h) sonication extraction method.

Supercritical Fluid Extraction of Polychlorinated Biphenyls and Organochlorine Pesticides from Freeze-Dried Tissue of Marine Mussel, Mytilus eduli

Abstract Supercritical fluid extractions (SFEs) of 21 polychlorinated biphenyls (PCBs) and 8 organochlorine pesticides (OCPs) from freeze-dried mussel tissue are compared with traditional Soxhlet extractions. The aim was to determine the efficacy of supercritical CO2 to extract these 2 classes of lipophilic compounds. A spike study to determine the feasibility of on-line cleanup by inclusion of an inert matrix (activated alumina) in the extraction vessel showed that the chemical integrity of the PCBs was not compromised, whereas some DDTs were decomposed to their respective metabolites. Relatively long static extraction time, higher density, and lower temperature yielded quantitative recoveries of PCBs from freeze-dried mussel tissue with good reproducibilities. Recoveries of OCPs were nonquantitative and highly variable. Finally, the efficacy of fluoroform (CHF3) as an alternative supercritical fluid to selectively extract PCBs and OCPs was studied. Fluoroform yielded nonquantitative and variable recoveries of PCBs and OCPs, but its use eliminated the need for in situ alumina to retain coextracted lipids from the matrix.

Multiresidue Method for Determination of Organochlorine Insecticides and Polychlorinated Biphenyl Congeners in Fatty Processed Foods

A previously published gel permeation chromatographic (GPC) procedure for determination of organophosphorus insecticides is used to determine 24 organochlorine (OC) pesticide and 9 polychlorinated biphenyl (PCB) residues in 8 fatty preserved foods of vegetable and animal origin. Samples are extracted with methylene chloride and cleaned up by automated GPC with a Biobeads SX3 column and a methylene chloride-cyclohexane (15 + 85) eluant. Compounds are quantitated by gas chromatography/ mass spectrometry (GC/MS) with selected ion monitoring using a DB-5 column. Average recoveries of OC pesticides from samples fortified at 0.010-0.080 mg/kg ranged from 73 to 98%. Average recoveries of 9 PCB congeners spiked at 2 levels (0.0025 and 0.020 mg/kg) were between 85 and 104%. Quantitation limits were between 0.002 and 0.025 mg/kg, depending on the compound. The purified extracts were analyzed further by GC with electron capture detection (ECD), and the results were compared with those obtained by MS. Determination of some OC pesticides and PCB congeners was not possible by ECD because of matrix interference.

Influence of pesticide–soil interactions on the recovery of pesticides using supercritical fluid extraction

The role of soil organic matter on the recovery of two classes of pesticides and two classes of herbicides using supercritical carbon dioxide has been investigated. Initial studies from spiked Celite indicated that the more polar herbicides required the addition of 10% methanol modified supercritical carbon dioxide to affect extraction. Whereas the relatively non-polar organochlorine pesticides (OCPs) could be extracted using supercritical carbon dioxide only, the moderately polar organophosphorus pesticides (OPPs) required 5% methanol-modified supercritical carbon dioxide to affect quantitative recovery. When using these supercritical conditions each class of pesticide or herbicide was extracted from a slurry-spiked soil. The effects on the recovery from soils with a range of organic matter were noticeable for both classes of pesticides, particularly when the organic matter was at its highest (35%). The role of the modifier was found to be critical in affecting recovery of the polar OPPs and herbicides. The soil-pesticide interaction from these slurry spiked soils could be negated if excess modifier (10%) was added to the supercritical carbon dioxide. Matrix interactions were most severe when no modifier was added (recoveries of OCPs from soil were approximately 50%).

Organochlorine contaminants in double-crested cormorants from Green Bay, WI: I. Large-scale extraction and isolation from eggs using semi-permeable membrane dialysis.

A 41.3-kg sample of double-crested cormorant (Phalacrocorax auritus) egg contents was extracted, yielding over 2 L of egg lipid. The double-crested cormorant (DCC) egg extract, after clean-up and concentration, was intended for use in egg injection studies to determine the embryotoxicity of the organic contaminants found within the eggs. Large-scale dialysis was used as a preliminary treatment to separate the extracted contaminants from the co-extracted sample lipids. The lipid was dialyzed in 80x5 cm semi-permeable membrane devices (SPMDs) in 50-ml aliquants. After the removal of 87 g of cholesterol by freeze-fractionation, the remaining lipid carryover (56 g) was removed by 100 routine gel permeation chromatography (GPC) operations. A 41,293-g sample was thus extracted and purified to the extent that it could easily be placed at a volume of 5 ml, the volume calculated to be necessary for the egg injection study. Analyses were performed comparing contaminant concentrations in the final purified extract to those present in the original egg material, in the extract after dialysis and cholesterol removal, and in the excluded materials. Recoveries of organochlorine pesticides through dialysis and cholesterol ranged from 96% to 135%. Total polychlorinated biphenyls in the final extract were 96% of those measured in the original egg material. Analysis of excluded lipid and cholesterol indicated that 92% of the polychlorinated dibenzo-dioxins and -furans were separated into the final extract.