Supercritical fluid extraction pesticides

Supercritical fluid extraction (SFE) has been widely used to the extraction processes in pharmaceutical industries. Besides application of SFE in phannaceuticals, it has been applied on a wide spectmm of natural products and food industries such as natural pesticides, antioxidants, vegetable oil, flavors, perfumes and etc [1-2]. 

B. Mumgaverl and K. J. Voorhees, On-line supercritical fluid extraction/chromatography system for trace analysis of pesticides in soybean oil and rendered fats , ]. Microcolumn Sep. 3 11-16(1991). 

Camel V. 1997. The determination of pesticide residues and metabolites using supercritical fluid extraction. TrAC Trends Anal Chem (PersEd) 16(6) 351. 

Extraction of residues from soil samples is much more difficult than their extraction from plant or water samples. The pesticide residues in the soil exist often in several forms as bound residue , which may affect the extraction efficiency of pesticides from the soil. Then, various extraction methods such as organic solvent extraction, Soxhlet extraction, sonication extraction, microwave dissolution and supercritical fluid extraction (SEE) are used. Some extraction methods are described in the following. 

V. Lopez-Avila, C. Charan, and J. van Emon, Supercritical fluid extraction-enzyme-linked immunosorbent assay applications for determination of pesticides in soil and food, in Immunoassays for Residue Analysis Food Safety (R.C. Beier and L.H. Stanker eds), ACS Symposium Series 621, American Chemical Society, Washington (1996). 

Snyder JL, Grob RL, McNally ME, OostdykTS.The effect of instrumental parameters and soil matrix on the recovery of organochlorine and organophosphate pesticides from soils using supercritical fluid extraction. J. Chromatogr. Sci. 1993 31 183-191. 

Snyder et al. [20] have compared supercritical fluid extraction with classical sonication and Soxhlet extraction for the extraction of selected pesticides from soils. Samples extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave a =85% recovery of organochlorine insecticides including Dichlorvos, Endrin, Endrin aldehyde, p,p -DDT mirex and decachlorobiphenyl (and organophosphorus insecticides). 

Djordjevic MV, Hofmann D, Fan J. 1994. Assessment of chlorinated pesticides and polychlorinated biphenyls in adipose breast tissue using a supercritical fluid extraction method. Carcinogenesis 15(11) 2581-2585. 

Snyder JL, Grab RL, McNally ME, et al. 1992. Comparison of supercritical fluid extraction with classical sonication and soxhlet extractions for selected pesticides. Anal Chem 64 1940-1946. 

L. Sun and H.K. Lee, Optimization of microwave-assisted extraction and supercritical fluid extraction of carbamate pesticides in soil by experimental design methodology. J. ChromatogrA 1014 (2003) 165-177. 

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

Aguilera, A. Brotons, M. Rodriguez, M. Valverde, A. Supercritical Fluid Extraction of Pesticides from a Table-Ready Food Composite of Plant Origin (Gazpacho). J. Agric. Food Chem. 2003, 51, 5616-5621. 

An automated supercritical fluid extraction and in-line clean-up system has been developed for organochlorine and organophosphate pesticide residues contained in fats (Hopper, 1999). 

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). 

A method for the determination of diazinon in human serum has recently been published by researchers at the Centers for Disease Control and Prevention (Liu et al. 1994) in which 2-dimensional chromatography was used to determine 15 pesticides in 4 minutes. Supercritical fluid extraction (SFE) was used to recover pesticides into methylene chloride and this extract was analyzed using two 2-meter columns connected by an on-column thermal desorption modulator. Sensitivity for diazinon was reported to be 1.8 pg on-column no details about overall recoveries were provided. 

Solid-phase extractions can reduce solvent consumption in analytical chemistry. For example, a standard procedure approved by the U.S. Environmental Protection Agency for the analysis of pesticides in wastewater requires 200 mL of dichloromethane for the liquid-liquid extraction of 1 L of water. The same analytes can be isolated by solid-phase extraction on C g-silica disks. The pesticides are recovered from the disks by supercritical fluid extraction with C02 that is finally vented into a small volume of hexane. This one kind of analysis can save 10s kg of CH2C12 per year.24... 

AL Howard, C Braue, LT Taylor. Feasibility of thiocarbamate pesticide analysis in apples by supercritical fluid extraction and high-performance liquid chromatography. J Chromatogr Sci 31 323-329, 1993. 

A Izquierdo, MT Tena, MD Luque de Castro, M Valcarcel. Supercritical fluid extraction of carbamate pesticides from soils and cereals. Chromatographia42 206-212, 1996. 

In this paper, the supercritical fluid extraction (SFE) of organic compounds from sand spiked with 36 nitroaromatic compounds, 19 haloethers, and 42 organochlorine pesticides, and from a standard reference material certified for 13 polynuclear aromatic hydrocarbons (PAH), dibenzofuran, and pentachlorophenol was examined using a two- and a four-vessel extractor. Although the results achieved by SFE for the sand and the standard reference soil samples were very encouraging, previous data obtained in our laboratory on the standard reference soil and a few other standard reference marine sediments were less favorable. It was therefore decided that an investigation of seven variables for their influence on the analyte recoveries from the standard soil sample would be useful. Two tests were conducted in which these variables were investigated. In Test 1, the seven variables selected were pressure, temperature, moisture content, cell volume, sample size, extraction time, and modifier volume. In Test 2, the seven variables were pressure, temperature, volume of toluene added to the matrix, volume of solvent in the collection vessel,... 

Figure 15.13 Comprehensive two-dimensional GC chromatogram of a supercritical fluid extract of spiked human serum. Peak identification is as follows 1, dicamba 2, trifluralin 3, dichloran 4, phorate 5, pentachlorophenol 6, atrazine 7, fonofos 8, diazinon 9, chlorothalonil 10, terbufos 11, alachlor 12, matalaxyl 13, malathion 14, metalochlor 15, DCPA 16, captan 17, folpet 18, heptadecanoic acid. Adapted from Analytical Chemistry, 66, Z. Liu et al., Comprehensive two-dimensional gas chromatography for the fast separation and determination of pesticides extracted from human serum , pp. 3086-3092, copyright 1994, with permission from the American Chemical Society.

Applications of supercritical fluid extraction and headspace analysis are, however, now creeping in. Thus supercritical fluid extraction with carbon dioxide-methanol has been used to extract 2,4-chlorophenol from crops [231 ], sulfonylurea herbicides from plants [161], and organophosphorus pesticides from fruit and vegetables [226]. 

Alzaga, R., G. Durand, D. Barcelo, and J.M. Bayona (1994). Comparison of supercritical fluid extraction and liquid-liquid extraction for isolation of selected pesticides stored in freeze-dried water samples. Chromatographia, 38(7-8) 502-508. 

Bengtsson, S., T. Berglof, S. Granat, and G. Jonsall (1994). Solid-phase extraction of pesticides from surface water using discs, bulk sorbents and supercritical fluid extraction (SFE). Pestic. Sci., 41 55-60. 

Lopez-Avila, V., C. Charan, and W.F. Beckert (1994). Using supercritical fluid extraction and enzyme immunoassays to determine pesticides in soils. Trends Anal. Chem., 13(3) 118-125. 

Nam, K.S. and J.W. King (1994). Supercritical fluid extraction and enzyme immunoassay for pesticide detection in meat products. J. Agric. Food Chem., 42(7) 1469-1474. 

Koskinen, W.C., H.H. Cheng, L.J. Jarvis, and B.A. Sorenson (1995). Characterization of mechanisms of pesticide retention in soils using the supercritical fluid extraction technique. Intern. J. Environ. Anal. Chem., 58 379-385. 

Many detectors have been used to detect pesticides and herbicides in SFC. Among these detectors, the flame ionization detector (FID) is most commonly used for detection of a wide range of pesticides and herbicides, with a detection limit ranging from 1 ppm (for carbonfuran) to 80 ppm (for Karmex, Harmony, Glean, and Oust herbicides). The UV detector has frequently been used for the detection of compounds with chromophores. The detection limit was as low as 10 ppt when solid-phase extraction (SPE) was on-line coupled to SFC. The mass spectrometric detector (MSD) has also been used in many applications as a universal detector. The MSD detection limit reached 10 ppb with on-line SFE (supercritical fluid extraction)-SFC. Selective detection of chlorinated pesticides and herbicides has been achieved by an electron-capture detector (ECD). The limit of detection for triazole fungicide metabolite was reported to be 35 ppb. Other detectors used for detection of pesticides and herbicides include thermoionic, infrared, photometric, and atomic emission detectors. 

Fig.l Schematic diagram of the main steps of the solid-liquid extraction (SLE) and supercritical fluid extraction (SEE) methodologies for pesticide residue analysis. 

Ling, Y. C., H. C. Teng, and C. Castwright, Supercritical fluid extraction and cleanup of organochlorine pesticides in Chinese herbal medicine, /. Chromatogr. A 835 (1-2), 145-157 (1999). 

Berset, J.D. Holzer, R. Quantitative determination of polycyclic aromatic hydrocarbons, polychlorinated biphenyls and organochlorine pesticides in sewage sludges using supercritical fluid extraction and mass spectrometric detection. J. Chromatogr., A 1999, 852, 545-558. 

Barnabas, 1. J., Dean, J. R., Hitchen, S. M., and Owen, S. P. 1994. Selective extraction of organochlorine and organophosphorus pesticides using a combined solid phase extraction-supercritical fluid extraction approach. Anal. Chim. Acta, 291 261-267. 

Yoo WJ, Taylor LT. Supercritical fluid extraction of polychlorinated biphenyl and organochlorine pesticides from freeze-dried tissue of marine mussel, Mytilus edulis. J AOAC Int 1997 80 1336-1345. 

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