Organochlorine pesticides, extraction

The results presented in Table VI for the 42 organochlorine pesticides extracted from spiked sand indicate that SFE with carbon dioxide worked reasonably well for 35 of the 42 compounds (recovery > 50 percent) from those 35 compounds, 30 compound had recoveries > 70 percent. Among the seven compounds with recoveries < 50 percent, two are very volatile (DBCP and hexachlorocyclopentadiene). Three of the remaining five compounds (chlorthalonil, captan, and endosulfan sulfate) gave very poor recoveries with carbon dioxide alone, probably because of their polarity however, in other experiments we have recovered them quantitatively from spiked sand with carbon dioxide modified with 10 percent methanol (1). Chlorobenzilate recoveries were poor, even when we used carbon dioxide with 10 percent methanol, and captafol was not tested with the carbon dioxide/methanol combination. 

Demeter J, Heyndrickx A. 1979. Selection of a high-performance liquid chromatographic cleanup procedure for the determination of organochlorine pesticides in fatty biological extracts. Vet Hum Toxicol 21 151-155. 

Gaido K, Dohme L, Wang F, et al. 1998. Comparative estrogenic activity of wine extracts and organochlorine pesticide residues in food. Environ Health Perspect 106(6) 1347-1351. 

One example, a candidate matrix material of organotin species in marine water, had stability determined by storage for 120 days at 4°C in the dark, at ambient temperature, and exposed to daylight (Quevauviller and Donard 1991). Frequently storage at different temperatures over at least a i-year period are reported. Examples include organochlorine pesticides (OCPs) in BCR CRM 430, where pork fat was stored at -2o°C, -i-20°C, and -r37°C (van der Paauw et al. 1992). Storage at -20°C, -i-20°C, and -i-4o°C was performed for total and methyl Hg in BCR CRMs 463 and 464, tuna fish (Quevauviller et al. 1994), and metals in BCR CRM 600, EDTA and DTPA-extractable trace metal contents in calcareous soil (Quevauviller et al. 1998m). 

Weichbrodt et reported on the use of focused open-vessel microwave-assisted extraction (EOV-MAE) for the determination of organochlorine pesticides in high-moisture samples such as fish. The results were comparable to those with closed-vessel microwave-assisted extraction (CV-MAE) and ASE. The main advantage of FOV-MAE is that the use of Hydromatrix is unnecessary as the solvent mixture of ethyl acetate and cyclohexane allows the removal of water from the sample matrix via azeotropic distillation. 

The use of SPE with porous materials such as alumina, diatomaceous earth, Horisil and silica for the cleanup of fat-soluble organochlorine pesticides in fatty foods such as meat, flsh, shellfish, milk and vegetable oils has been well documented. The choice of elution solvents is critical because relatively small amounts of lipid in the final extract can cause rapid deterioration of GC capillary columns and also contaminate the gas chromatograph. A number of workers have used a porous material in tandem with Cig to effect an improved cleanup.Di Mucchio employed a multicartridge system comprising Extrelut, silica and Cig to extract organophosphorus pesticides from oils and fatty extracts. Relatively few literature applications include the pyrethroids, but Ramesh and Balasubramanian reported a simple carbon-based SPE method for the analysis of pyrethroids in vegetable oil. 

SFE. SFE has been established as the extraction method of choice for solid samples. The usefulness of SFE for soil samples has been demonstrated for carbamate,organophosphorus and organochlorine pesticides. However, SFE is more effective in extracting nonpolar than polar residues. In order to obtain a greater extraction efficiency for the polar residues of imidacloprid, the addition of 20% methanol as modifier is required. Extraction at 276 bar and 80 °C with a solvent consisting of supercritical carbon dioxide modified with methanol (5%) for 40 min gives a recovery of 97% (RSD = 3.6%, n = 10). It is possible to use process-scale SFE to decontaminate pesticide residues from dust waste. ... 

Millar et al. [371] carried out experiments to study a method for the recovery of 18 organochlorine pesticides and seven PCBs from water. Extractions with dichloromethane, and 15% dichloromethane in hexane, at pH 2,7, and 10, and liquid-solid column chromatography using columns of Florasil or alumina, produced excellent results. An investigation was also made into the effects of... 

Accelerated solvent extraction is a new technique for the extraction of a range of organic pollutants from soils and related material. The technique is based on the use of a solvent or combination of solvents to extract organic pollutants at elevated pressure and temperature from a solid matrix. The range of organic pollutants for which the technique is proposed includes semivolatile compounds, organochlorine pesticides, organophosphorus pesticides, chlorinated herbicides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons [53-56],... 

Tomkins BA, Merriweather R, Jenkins RA. 1992. Determination of eight organochlorine pesticides at low nanogram/liter concentrations in groundwater using filter disk extraction and gas chromatography. J AOAC International 75 1091-1099. 

Seidel V, Lindner W. 1993. Universal sample enrichment technique for organochlorine pesticides in environmental and biological samples using a redesigned simultaneous steam distillation-solvent extraction apparatus. Anal Cem 65 3677-3683. 

SPMD sample extracts, e.g., certain organochlorine pesticides (OCPs), are known to inhibit cholinesterase activity. Therefore, these results were not unexpected. However, it was surprising that a similar response was not observed with brain cholinesterase activity. It is possible that brain cells can more readily metabolize the chemicals, that the chemicals did not pass the brain blood barrier or that the effects occurred earlier in the exposure period, effectively allowing the activity to recover. Considering the numerous neurotoxic chemicals potentially entering aquatic ecosystems or present as airborne vapor phase chemicals, the neurotoxic mode of action related to exposure to contaminants is of increasing interest. Evidence presented in this work demonstrate that SPMDs concentrate members of this class of toxicants. 

Supercritical fluid extraction of polynuclear aromatic hydrocarbons Supercritical fluid extraction of PCB and organochlorine pesticides (update IVB)... 

Di Muccio A, Rizzica M, Ausili A, et al. 1988. Selective, on-column extraction of organochlorine pesticide residues from milk. J Chromatogr 456(1) 143-148. 

The efficacy of supercritical fluid extraction (SFE) for the recovery of 16 common organochlorine pesticides (OCPs) from liquid whole eggs was investigated by employing supercritical carbon dioxide (SC-C02) without the use of a solvent modifier to minimize interfering coextractives (Fiddler et al., 1999). 

K. Gaido et al., Comparative Estrogenic Activity of Wine Extracts and Organochlorine Pesticide Residues in Food, Environ. Health Perspect. 106 (Suppl. 6,1998) 1547-51. 

The determination of OCP residues in milk has always presented problems, because the most common approach has required the total extraction of fat, together with lipophilic compounds, including organochlorine pesticide residues. Only one procedure for the extraction and separation of OCPs directly into an HPLC system has been described (11). The direct procedure injects the samples into an internal-surface reversed-phase C18 column connected online with the analytical column. 

Y Pico, E Viana, G Font, J Manes. Determination of organochlorine pesticide content in human milk and infant formulas using solid phase extraction and capillary gas chromatography. J Agric Food Chem 43 1610-1615, 1995. 

Samples of sand spiked with 36 nitroaromatic compounds, 19 haloethers, and 42 organochlorine pesticides, and a standard reference soil (certified for 13 polynuclear aromatic hydrocarbons, dibenzofuran, and pentachlorophenol) were extracted with supercritical carbon dioxide in a two- or four-vessel supercritical fluid extractor to establish the efficiency of the extraction and the degree of agreement of the parallel extraction recoveries. Furthermore, the many variables that influence the extraction process (e.g., flowrate, pressure, temperature, moisture content, cell volume, sample size, extraction time, modifier type, modifier volume, static versus dynamic extraction, volume of solvent in the collection vessel, and the use of glass beads to fill the void volume) were investigated. 

The extraction of 42 organochlorine pesticides from the four spiked sand samples (3 g each, spiked at the levels indicated in Table VI) was begun at 150 atm/50°C/10 min (static), continued at 200 atm/60/10 min (dynamic), and completed at 250 atm/70°C/30 min (dynamic) using 2.5-g samples. 

Procedure. The field-portable system was taken to a grassy field where pesticides were extracted from a soil sample spiked with 100 /tg each of 18 organochlorine pesticides. The extraction from the 2.5 ml cartridge was performed at 55°C, 5000 psi, with 30 ml of CQ in 15 minutes. The collection solvent was hexane. 

As indicated in Table VII, 13 of the 18 OCPs were retrieved in excess of 90% recovery during the first extraction. The remaining four OCPs, endrin, endosulfan n, endosulfan sulfate, and methoxychlor were recovered at levels between 10-57%. Since no significant amount of any OCP was recovered during the follow-up extraction, breakdown of some organochlorine pesticides endrin in the injection port of the GC was suspected. 

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