Pesticides plant materials

El Zorgani GA, Omer IS, Abdullah AM. 1986. Bound residues of endosulfan and carbofuran in soil and plant material. Proceedings of the Final Research Co-ordination Meeting on Isotopic Tracer-aided Studies of Unextractable or Bound Pesticide Residues in Soil, Plants, and Food. Vienna, Austria International Atomic Energy Agency, 51-56. 

The multi-residue method DFG was intended to be used in state enforcement laboratories or in private contract or food industry laboratories. It was aimed initially only at plant materials and water and included a relatively large number of pesticides which are amenable to GC. 

Sample preparation techniques vary depending on the analyte and the matrix. An advantage of immunoassays is that less sample preparation is often needed prior to analysis. Because the ELISA is conducted in an aqueous system, aqueous samples such as groundwater may be analyzed directly in the immunoassay or following dilution in a buffer solution. For soil, plant material or complex water samples (e.g., sewage effluent), the analyte must be extracted from the matrix. The extraction method must meet performance criteria such as recovery, reproducibility and ruggedness, and ultimately the analyte must be in a solution that is aqueous or in a water-miscible solvent. For chemical analytes such as pesticides, a simple extraction with methanol may be suitable. At the other extreme, multiple extractions, column cleanup and finally solvent exchange may be necessary to extract the analyte into a solution that is free of matrix interference. 

E.V. Gogol, G.A. Evtyugin, E.V. Suprun, G.K. Budnikov, and V.G. Vinter, Determination of residual pesticide in plant materials using planar cholinesterase sensors modified with nation. J. Anal. Chem. 56, 963-970 (2001). 

Consider the analysis of plant material for a pesticide residue by GC. Two grams of the material is chopped up and placed in a Soxhlet extractor (Chapter 11) and the pesticide quantitatively extracted into an appropriate solvent. Following this, the solvent is evaporated to near dryness and the residue is diluted to volume in a 25-mL flask. Then 2.5 pL of this solution and standards is injected in a GC with the following results ... 

What is the parts per million of pesticide in the original plant material ... 

On December 3, 1984, a toxic gas release from a pesticide plant in India killed nearly 3000 people and injured at least 100,000 others. The chemical that leaked was methyl isocyanate, a chemical intermediate that was supposed to be stored in a cooled bunker near the plant s outer boundary. The vapor is highly toxic and causes cellular asphyxiation and rapid death. Despite engineering and procedural provisions to prevent its release, a total system breakdown resulted in the release of 40 tons of the deadly material into the densely populated community of Bhopal. Because of this incident, the plant was dismantled and ultimately the parent corporation. Union Carbide, was forced to make a number of organizational changes. The occurrence is considered by many to have been the most tragic chemical accident in history. 

The determination of diazinon in foods is important because this chemical is used as a pesticide on plant crops and, at least in some cases, in pesticide dips for the control of parasitic infestations in animals (Brown et al. 1987 Miyahara et al. 1992). Because animals are exposed to this compound, both via pesticide dips and by ingestion of crops to which diazinon has been applied, some methods have been reported for animal products. The majority of methods, however, deal with the determination of residues in plant products. Most of the analytical methods found that describe the extraction from, and determination of, diazinon residues in various crops (plant materials) were developed as part of multiresidue methods. They are based on homogenization of the sample with an organic solvent (polar or non-polar) the isolation of the residues from this initial extract and, usually, some additional cleanup prior to the analysis of the extract by GC. The most common non-MS modes of detection exploit the... 

The extraction of vegetable plant-material requires careful selection of raw materials, in connection with chemical analysis, because the content of the vegetables to be extracted can vary substantially. Also the possibility of high concentrations of undesired substances - either contained within them, or contaminations such as pesticides - can influence the product quality enormously. Exhaustive extraction is not always possible with acceptable effort, owing to the vegetable structure, and the extraction efficiency using low-quality raw materials may be too poor to allow economic processing. 

J Tekel, S Hatrik. Pesticide residue analyses in plant material by chromatographic methods clean-up procedures and selective detectors. J Chromatogr A 754 397-410, 1996. 

WP Cochrane, D Chaput, J Singh. Analysis of pesticides and PCB residues in water, soil and plant material. In Stevenson D, Wilson ID, eds. Sample Preparation for Biomedical and Environmental Analysis. New York Plenum Press, 1994, pp 191-201. 

Some examples of the types of procedures used to determine insecticides and pesticides in plant materials are given below. 

Table 8.2. Determination of insecticides and pesticides in plant materials (from author s own files)... 

TMN. 1987. Survey finds little dioxin at control sites Industry finds trace amounts in paper products and highest levels at pesticide plants. Toxic Materials News. September 30, 301. 

Wainerdi, R. E., and M. P. Menon Comparison of Nuclear Activation Methods for Bromine. Instrumental Analysis of Pesticides in Plant Materials Close to the Limit of Sensitivity. Proceedings of the 1967 Symposium, Nuclear Activation Techniques in the Life Sciences, Amsterdam, May 8—12, 1967, pp. 33—50. Vienna International Atomic Energy Agency 1967. 

Zrostlikova J, Hajslova J, Poustka J, Begany P (2002) Alternative calibration approaches to compensate the effect of co-extracted matrix components in liquid chromatography-electrospray ionization tandem mass spectrometry analysis of pesticide residues in plant materials. J Chromatogr A 973 13-26... 

A method applicable to the analysis of several pesticide residues on plant material was developed by Thier (1972), by previous bnomination of the chemieals (among which PBO). followed by gas chromatography with an electron capture detector, This very sensitive technique allows the detection of residues at the nanogram level. 

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