Pesticides comparison

Klopman G, Contreras R, Rosenkranz HS, et al. 1985. Stmcture-genotoxic activity relationships of pesticides Comparison of the results from several short-term assays. Mutat Res 147 343-356. 

International Food Safety Comparison of U.S. and Codex Pesticide Standards, GAO/PEMD-91-22, U.S. General Accounting Office, Washington, D.C., Aug. 1991. 

Other Chlorobenzenes. The market for the higher chlorobenzenes (higher than di) is small in comparison to the combined mono- and dichlorobenzenes. Trichlorobenzenes are used in some pesticides, as a dye carrier, in dielectric fluids, as an organic intermediate and a chemical manufacturing solvent, in lubricants, and as a heat-transfer medium. These are small and decreasing markets. 

N. Masque, R. M. Marce and R Bonnll, Comparison of different sorbents for on-line solid-phase exti action of pesticides and phenolic compounds from natural water followed by liquid chromatography , J. Chromatogr. 793 257-263 (1998). 

A subsequent comparison of these ionization techniques for the study of another eight pesticides, this time including three of the five of interest [28], i.e. carbendazim, thiabendazole and thiophanate methyl, showed that ESI gave enough sensitivity to allow reliable determination of the pesticides at concentrations below their respective maximum residue levels. 

Table 1 Comparison of the reaction of pesticides (amounts applied 0.8 ng, without chromatographic development) with N,N-DPDD (Wurster s Red) and TPDD (Wurster s Blue) reagents [4] - = negative, (+) = weakly positive and + + + = positive reaction.

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). 

Campbell JL, Smith MA, Eiteman MA, et al. 2000. Comparison of solvents for removing pesticides form skin using an in vitro porcine model. Am Ind Hyg Assoc J 61 82-88. 

NIST has also used results obtained from inter-laboratory studies as an additional set of results in the two or more methods approach (mode 2 in Table 3.13). For example for the recent value assignment for PCBs and pesticides in SRM 1944, the mean of results from 19 laboratories participating in an inter-laboratory comparison exercise was used as an additional set of data in the determination of the certified values. Similar inter-laboratory study results were also included in the value assignment of PAHs, PCBs, and pesticides for two recently issued mussel tissue materials, SRM 2977 and SRM 2978. 

Several methods have been discussed for the determination of method limitations when evaluating procedures for the determination of pesticides in food. A brief comparison of the methods discussed for the determination of the detection and quantification limits of methods used for the analysis of food products can be found in Table 2. 

Until 1991, manufacturers seeking authorizations for pesticides had to fulfil country-specific requirements of validation of enforcement methods. The term enforcement method means analytical methods which are developed for post-registration control and monitoring purposes. The harmonization of these requirements was initiated with the European Economic Community (EEC) Council Directive 91/414/EEC and temporarily finalized with the Guidance Document on Residue Analytical Methods SANCO/825/00 rev. 6, dated 20 June 2000 [Santd et Protection des Consommateurs (SANCO)]. The evaluation of validation studies by the competent authority is conducted by comparison of these European Union (EU) requirements with the study results and most often without any practical experience of the method. Some details of this evaluation are discussed below. 

However, there is no general requirement that enforcement methods need to monitor all metabolites of an active ingredient. The primary purpose of enforcement methods is to detect violations of good agricultural practice. For this purpose, residue levels found in samples from the market (so-called Market Basket Surveys) have to be compared with MRLs, which are derived from residue concentrations found in supervised trials. It is not necessary for this comparison to be based on the total pesticide residue. Most often the choice of a single compound (e.g., parent or primary metabolite) as a marker of the total pesticide residue is more feasible. Method development and the later method application are much easier in that case. Only for intake calculation purposes, e.g., when the daily intake of pesticide residues (calculated from the results... 

Validation of true extraction efficiency normally requires the identification and quantitation of field-applied radiolabeled analyte(s), including resulting metabolites and all other degradation products. The manufacturer of a new pesticide has to perform such experiments and is able to determine the extraction efficiency of aged residues. Without any identification of residue components the calculation of the ratio between extracted radioactivity and total radioactivity inside the sample before extraction gives a first impression of the extraction efficiency of solvents. At best, this ratio is nearly 1 (i.e., a traceability of about 100%) and no further information is required. Such an efficient extraction solvent may serve as a reference solvent for any comparison with other extraction procedures. 

This validation typically requires samples with radiolabeled analytes. However, alternative approaches are proposed which involve (i) comparison with extraction of samples using a procedure which has been previously validated rigorously, (ii) comparison with extraction of samples by a very different technique or (iii) analysis of a certified reference material. Generally, this validation should be performed with samples containing analyte incurred by the route by which residues would normally be expected to arise. The simplest option (i) requires fully validated and documented enforcement methods provided by the manufacturer of a pesticide. 

Comparison of at least one blank sample and a sample to which a known amount of pesticide has been added additional determinations in the presence of pesticides suspected of interfering with the analyte... 

The principal limitation in the use of electrophoretic techniques is the lack of availability of suitable detection systems for quantitative analysis and unequivocal identification of pesticide analytes. Traditionally, either ultraviolet/visible (UVA IS) or fluorescence detection techniques have been used. However, as with chromatographic techniques, MS should be the detection system of choice. A brief comparison of the numbers of recent papers on the application of GC/MS and LC/MS with capillary elec-trophoresis/mass spectrometery (CE/MS) demonstrates that interfaces between CE... 

Leonas, K.K. (1991) Effect of pesticide formulation on transmission a comparison of three formulations, Bull. Environ. Contam. Toxicol., 46 697-704. 

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