Determination Of Methyl Parathion Research Articles

Electroanalytical procedure for the determination of methylparathion in soil suspensions and its application for sorption studies with Brazilian soils

The differential pulse polarography technique was used to establish an electroanalytical procedure for the determination of the organophosphorous insecticide methyl parathion (O,O-dimethyl O-(4-nitrophenyl) phosphorothioate) in soil samples. Three reduction peaks were observed in mercury electrodes as a function of the solution pH. The more cathodic peak (Ep= -0.55V), only observed for pH values higher than 5.0, was chosen for the analytical determinations. The limit of detection was 1.93x10-8 mol L-1 for pure water and about 8x10-8 mol L-1 for soil suspensions with a scan rate of 2 mV s-1 and a pH of 6.75. The electroanalytical procedure developed was applied for the determination of sorption isotherms of methylparathion on 3 soils from Sao Paulo State, Brazil, at different pH and diverse amounts of clay and organic matter. The experimental data were fitted using the Freundlich isotherm model and the Freundlich coefficients (KF) obtained for each soil varied from 7 to 29 L kg-1, representing a low to medium sorption capacity, according to the IBAMA (Brazilian Environmental Protection Agency) standards. The amounts of organic matter and clay were the most important soil parameters controling the sorption of methylparathion by these soils.

A modified extraction and clean-up procedure for the detection and determination of parathion-methyl and chlorpyrifos residues in tea.

Recent advances in methodology and instrumentation have made possible the detection and determination of pesticides at microgram kg-1 (ppb) levels. The sensitivity of a method of analysis depends greatly on the efficient extraction of the pesticide and the subsequent clean-up of the extract. The extract from green tea leaves is a mixture of aroma components, polyphenols and caffeine. The preparation of made tea from green tea leaves adds to this complexity by concentrating these coextractives. Conventional clean-up techniques provide poor recoveries for parathion-methyl and chlorpyrifos from both green tea leaves and made tea. This arises from interference by caffeine during gas chromatography, as it has a similar retention time to the two pesticides and peaks overlap. A modification to the protocol based on a solvent partitioning process using dichloromethane and subsequent washing of the extracts with warm water removed the caffeine, and pigments were removed by column chromatography. Recoveries ranging from 80 to 90% were then obtained for both pesticides.

Univariate and Multivariate Calibration for the Quantitative Determination of Methyl-Parathion in Pesticide Formulations by FT-Raman Spectroscopy

A Fourier transform (FT)-Raman method for the quantitative determination of methyl-parathion in pesticide formulations is described. The proposed method was applied to the analysis of formulations of methyl-parathion. Univariate and multivariate calibration were used and compared for quantitative analysis. Bands observed at 634, 661, 1113, 1348, and 1527 cm−1 were used for univariate calibration. Calibration curves were linear (correlation coefficients: 0.996–0.998 and 0.994–0.999 for band intensity and band area measurements, respectively) in the concentration range of 0.6–3.75 M for the 634, 661, and 1527 cm−1 bands; 0.05–3.75 M for the 1113 cm−1 band; and 0.1–3.75 M for the 1348 cm−1 band. Precision ranged from 0.5 to 5.2% and 0.1 to 6.8% relative standard deviation (RSD) ( n = 4) for band intensity and band area measurements, respectively. Spectra normalization against the 802 cm−1 cyclohexane band improved the long-term stability of calibration, allowing the use of calibration data acquired 30 days prior to analysis. The application of the method was extended through multivariate calibration by multiple linear regression using the 858 and 2952 cm−1 bands. Results obtained compare well with those obtained by the high-performance liquid chromatography (HPLC) reference method. The FT-Raman method developed is rapid, simple, and safe, as toxic samples are analyzed “as received” without sample pretreatment.

Degradation of Some Organophosphorous Pesticides under Different Field Conditions

HPLC procedure for the determination of methylparathion and malathion in radish, carrot and the soil has been developed to measure the decay pattern of the pesticides in three different seasons winter, summer and post-monsoon. The pesticide was extracted and chromatographed on a μ bondapak RP-C18 column using a mixture of acetonitrile and water and detected using an ultraviolet detector. The decay in winter and post-monsoon is linear while in summer two distinct profiles are observed. The degadation is faster in summer than the other two seasons. There are no significant differences in the degradation pattern of the pesticides on the two plants. The rate is faster in soil than on the plants. These results present a data base depicting the effect of temperature and humidity on the degeneration of pesticides on plants and in soil.

Rapid Determination of Methyl Parathion and Methyl Paraoxon in Milk by Gas Chromatography with Solid-Phase Extraction and Flame Photometric Detection

Methyl parathion (MPT; O,O-dimethyl-O-4-nitrophenyl phosphorothioate) and its active metabolite, methyl paraoxon (MPO; O,O-dimethyl-O-4-nitrophenyl phosphate), were isolated from raw milk by solid-phase extraction (SPE) and determined by gas chromatography with flame photometric detection. The SPE method was compared with a traditional liquid-liquid extraction (LLE) procedure to determine whether SPE had suitable sensitivity and better efficiency in extracting MPT and MPO from milk of cows and goats. Method detection limits were higher for SPE, but the differences were not significant (t-test). Recoveries of MPT and MPO from raw milk samples spiked at 0.05, 0.5, and 5.0 micrograms/mL ranged from 80.0 to 118%, and the coefficients of variation were usually less than 10% for both methods. LLE required more organic solvents and was more time consuming compared with SPE.

Voltammetric determination of methyl parathion, ortho, meta and para nitrophenol with a carbon paste electrode modified with C18

The determination of methyl-parathion (MPT), ortho (ONP), meta (MNP) and para nitrophenol (PNP) has been studied by differential pulse voltammetry with a carbon-paste electrode modified with 50% (w/w) of C18. A study of the influence of the pH in the preconcentration cell and the measurement cell was carried out for an electrode with 50% modifier and an accumulation time of 5 min. The voltammograms were recorded with a sweep rate of 40 mV s−1 and a pulse amplitude of 50 mV. With the optimum conditions of pH for both of the steps, various other variables were studied. The variables for each compound were optimized and the possibility of application to the determination of a mixture of the four compounds was investigated. The determination limits found for all the compounds are: 2 ng ml−1 for ONP, 5 ng ml−1 for MNP, 4.3 ng ml−1 for PNP and 7.9 ng ml−1 for MPT. The method was applied to samples of a small lake which gathers rain water and water filtered from land on which cereals are grown.

Thin Layer Chromatographic Determination of Methyl Parathion as Paraoxon by Cholinesterase Inhibition

A simple, sensitive, and rapid method is described for the quantitative estimation of nanogram amounts of methyl parathion (O, O-dimethyl O-p-nitrophenyl phosphorothioate) as methyl paraoxon (O,O-dimethyl O-p-nitrophenyl phosphate) on thin layer chromatograms. Methyl paraoxon is detected by pig liver acetone powder cholinesterase inhibition, using p-nitrobenzenediazoniumfluoroborate as the chromogenic reagent. Commercial pig liver acetone powder is more advantageous than raw liver sources because it is readily available and can be preserved indefinitely. About 0.1 ng methyl parathion can be detected, and amounts from 5 to 50 ng can be quantitatively estimated.

Colorimetric Determination of Methyl Parathion and Oxygen Analog

A simple, sensitive, and rapid colorimetric method is described for determining methyl parathion (O,O-dimethyl-O-p-nitrophenyl phosphorothioate) and methyl paraoxon (O,O-dimethyl-O-p-nitrophenyl phosphate), using p-nitrobenzene diazonium fluoroborate as the chromogenic salt. This colorimetric method is more sensitive than are other colorimetric methods based on non-enzymatic reactions. Pig liver acetone powder cholinesterase was found to be sensitive to methyl parathion. Inhibition can be detected at picogram levels, and 50-80 ng methyl paraoxon and 1-9 micrograms methyl parathion can be estimated.

High Pressure and Gas-Liquid Chromatographic Methods for the Determination of Parathion in Formulations: Collaborative Study

Abstract The official first action high pressure (HPLC) and gas-liquid (GLC) chromatographic methods for the determination of methyl parathion were adapted to analyze technical parathion, and 25 and 50% parathion emulsifiable concentrates. A technical parathion sample was analyzed and then used to prepare 5 of the 6 collaborative samples. At a 95% confidence level, only 1 of the 10 means was significantly different from the theoretical value. There was no significant difference in the CLC and HPLC means for each sample. The average of the coefficients of variation for the 6 CLC determinations (15 collaborators) was 0.86%. For the HPLC determinations (8 collaborators), the average was 0.81%.

Collaborative Study of Gas-Liquid Chromatographic Method for Analysis of Microencapsulated Methyl Parathion Insecticide

Abstract Eleven laboratories collaboratively studied the assay of methyl parathion in 2 formulations of Penncap-M insecticide. The procedure includes a grinding and extraction step, followed by the determination of methyl parathion by flame ionization gas-liquid chromatography. At the 15% level, the variance within laboratories was 0.0905, and among laboratories, 0.0755. At the 20% level, the figures were 0.0556 and 0.0205, respectively. The method has been adopted as official first action.

Gas-liquid chromatographic determination of methyl parathion and metabolites.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGas-liquid chromatographic determination of methyl parathion and metabolitesPrem S. Jaglan, Ralph B. March, T. Roy. Fukuto, and Francis A. GuntherCite this: J. Agric. Food Chem. 1970, 18, 5, 809–813Publication Date (Print):May 1, 1970Publication History Published online1 May 2002Published inissue 1 May 1970https://doi.org/10.1021/jf60171a011RIGHTS & PERMISSIONSArticle Views78Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (570 KB) Get e-Alerts Get e-Alerts