Organophosphorus extractants

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. 

Other methods for extracting organophosphorus compounds from soil, waste, and sediment samples have been described in recently published articles. They include supercritical fluid (such as carbon dioxide) extraction (SEE) with cosolvents such as methanol, SPE after extraction by methanol, and SPME in headspace or immersion mode after extraction by methanol. The recoveries obtained with these techniques for OPP extraction in soil samples are given in Table 23.7. 

In 1994, Nam and King (68) developed a SFE/SFC/GC instrumentation system for the quantitative analysis of organochlorine and organophosphorus pesticide residues in fatty food samples (chicken fat, ground beef and lard). In this way, SFC was used as an on-line clean-up step to remove extracted material. The fraction containing pesticide residues is then diverted and analysed by GC. 

Recently there has been a renewed interest in the extraction of actinides with various neutral bifunctional organophosphorus extractants (1-9). An excellent review on this subject has been published recently by Schulz and Navratil (9). Interest in neutral bifunctional organophosphorus extractants stems largely from the fact that these compounds have the ability to extract tri-... 

The reagent sequence is specific for endosulfan and phosphamidon. Other insecticides, e.g. organochlorine insecticides, such as endrin, aldrin, dieldrin, DDT and BHC, organophosphorus insecticides, such as malathion, parathion, dimethoate, quinalphos, phorate and fenitrothion, or carbamate insecticides, such as baygon, car-baryl and carbofuran do not react. Neither is there interference from amino acids, peptides or proteins which might be extracted from the biological material together with the pesticides. 

Methyl parathion was determined in dog and human serum using a benzene extraction procedure followed by GC/FID detection (Braeckman et al. 1980, 1983 DePotter et al. 1978). An alkali flame FID (nitrogen-phosphorus) detector increased the specificity of FID for the organophosphorus pesticides. The detection limit was in the low ppb (pg/L). In a comparison of rat blood and brain tissue samples analyzed by both GC/FPD and GC/FID, Gabica et al. (1971) found that GC/FPD provided better specificity. The minimum detectable level for both techniques was 3.0 ppb, but GC/FPD was more selective. The EPA-recommended method for analysis of low levels (<0.1 ppm) of methyl parathion in tissue, blood, and urine is GC/FPD for phosphorus (EPA 1980d). Methyl parathion is not thermally stable above 120 °C (Keith and Walters 1985). 

Kadoum AM. 1968. Cleanup procedure for water, soil, animal, and plant extracts for the use of electron-capture detector in the gas chromatographic analysis of organophosphorus insecticide residues. Bull Environ Contam Toxicol 3 247-253. 

Lores EM, Bradway DE. 1977. Extraction and recovery of organophosphorus metabolites from urine using an anion exchange resin. J Agric Food Chem 25 75-79. 

A fluxional amido-salt (24), in which the y-nitrogen atom acts as an internal nucleophile, has been identified by variable-temperature n.m.r. spectroscopy. At — 63 °C two methyl signals are observed, one a singlet, one a doublet (J = 11 Hz) whereas at + 60 °C there is only one signal, a doublet with J = 5.5 Hz (the average of the low-temperature coupling constants). The solvent extraction of organophosphorus compounds has also been studied by and H n.m.r, ... 

Although the improved extraction kinetics also increase the concentration of coextractives in the final extract, some degree of selectivity can be achieved by careful selection of the solvent or solvents used. Matrix co-extractives may be removed, or at least partially removed, by placing a suitable sorbent, such as alumina, at the exit of the extraction cell to remove lipid co-extractives. Excellent recoveries of both polar and nonpolar pesticides from a wide range of foodstuffs have been reported. Specific applications include organophosphorus and A-methylcarbamate pesticides. 

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. ... 

Garcia-Valcarcel AI, Tadeo JL (2009) A combination of ultrasonic assisted extraction with LC-MS/MS for the determination of organophosphorus pesticides in sludge. Anal Chim Acta 641 (1—2) 117—123... 

Preston, J. S. duPreez, A. C. Solvent extraction of nickel from acidic solutions using synergistic mixtures containing pyridinecarboxylate esters. 1. Systems based on organophosphorus acids. J. Chem. Technol. Biotechnol. 1996, 66, 86-94. 

Zhu, T. Structure of organophosphorus acid extractants and their steric effect. Chin. J. Inorg. Chem. 2000, 16, 305-309. 

Preston, J. S. Solvent extraction of cobalt and nickel by organophosphorus acids. I. Comparison of phosphoric, phosphonic, and phosphinic acid systems. Hydrometallurgy 1982, 9, 115-133. 

In spite of their toxicity, alkyl phosphites have been used extensively as lubricant additives, corrosion inhibitors, and antioxidants. In addition to their use as intermediates in synthesis, organophosphorus compounds are useful for separating heavy metals by solvent extraction. Several insecticides that were formerly in widespread use are derivatives of organic phosphates. Two such compounds are malathion and parathion. 

The plutonium concentration in marine samples is principally due to environmental pollution caused by fallout from nuclear explosions and is generally at very low levels [75]. Environmental samples also contain microtraces of natural a emitters (uranium, thorium, and their decay products) which complicate the plutonium determinations [76]. Methods for the determination of plutonium in marine samples must therefore be very sensitive and selective. The methods reported for the chemical separation of plutonium are based on ion exchange resins [76-80] or liquid-liquid extraction with tertiary amines [81], organophosphorus compounds [82,83], and ketones [84,85]. 

Ahnoff and Josefsson [18] built a solvent extraction apparatus for river work which was later modified into their in situ extractor [ 17]. The unit as described in the earlier work could easily be adapted for seawater analysis. A unit based on a Teflon helix liquid-liquid extractor, some 332 feet (101.5 metres) in length, was constructed by Wu and Suffet [19]. The extractor was optimized for the removal of organophosphorus compounds, specifically pesticides, with an efficiency of around 80%. For some compounds, these continuous extraction methods should be the methods of choice and should be explored. 

Lacorte S. and Barceld D., 1995. Determination of organophosphorus pesticides and their transformation products in river waters by automated online solid-phase extraction followed by thermospray liquid chromatography. J Chromatogr A 712 103. 

Organophosphorus derivatives, with P-C bonds, 19 23-24t Organophosphorus extractants,... 

Phosphorus (P), 19 1-19. See also GaAsP system Gallium phosphide (GaP) semiconductor InGaAsP alloy Organophosphorus extractants Phosphate fertilizers atomized, 18 820... 

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],... 

David and Seilier [1] compared the efficiencies of various extraction techniques including supercritical fluid [2], high pressure solvent and Soxhlet extraction for the removal of organophosphorus hydraulic fluids from soil. High pressure solvent extraction was at temperatures up to 200°C and pressures up to 170 bar was the favoured technique. Extraction efficiencies were similar in all three methods, but the favoured method was more rapid and cheaper to operate. 

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). 

Novikova [21] has reviewed the literature (209 references) covering the extraction, clean-up and analysis of organochlorine (and organophosphorus) insecticides in soil. Johnson and Starr [22] and Chiba and Morley [4] have studied factors affecting the extraction of Dieldrin and Aldrin from different soil types ultrasonic extraction was recommended by these workers. Lopez-Avila et al. [23] used microwave assisted extraction to extract chlorinated insecticides from soils. 

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