Pesticide with coupling effects

The full extent of the toxicity of pesticides to aquatic life is not known. Although chronic toxicity testing is required for new substances, little is known about the long-term effects of older pesticides. Also, very little is known about the toxicity and occurrence of the products formed when pesticides break down (metabolites) or the many non-pesticidal additives (co-formulants and adjuvants) used in pesticide formulations. However, the future is looking brighter. New modelling techniques, EQS development, and the involvement of the NRA in the pesticide registration process, coupled with the development of newer, less persistent pesticides with lower dose rates, all should help to reduce the risk of pesticide pollution. 

Figure 13.7 Selectivity effected by employing different step gradients in the coupled-column RPLC analysis of a surface water containing 0.40 p-g 1 bentazone, by using direct sample injection (2.00 ml). Clean-up volumes, (a), (c) and (d) 4.65 ml of M-1, and (b) 3.75 ml of M-1 transfer volumes, (a), (c) and (d), 0.50 ml of M-1, and (b), 0.40 ml of M-1. The displayed cliromatograms start after clean-up on the first column. Reprinted from Journal of Chromatography, A 644, E. A. Hogendoom et al, Coupled-column reversed-phase liquid chromatography-UV analyser for the determination of polar pesticides in water , pp. 307-314, copyright 1993, with permission from Elsevier Science.

Pentachlorophenol. Pentachlorophenol, a component of many wood preservatives, is also encountered in the pulp and paper and in other industries, and is sometimes used as a pesticide. Exposure to pentachlorophenol may result in serious toxic effects. Reverse phase HPLC coupled with a special technique referred to... 

Thermospray is a gentle mode of ionization. The spectrum contains mostly the intact molecular ion and its adduct with buffer components. Because fragmentation of the molecular ion species is relatively sparse, stmctural information is usually absent. Several classes of compounds, snch as peptides, dinucleotides, prostaglandins, diquatemary ammonium salts, pesticides, drugs, dyes, and environmental pollutants, are accessible to thermospray analysis. Also, it is an effective interface for LC/MS applications. Conventional colnmns with flow rates up to 2 mLmin can be coupled to this interface. 

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