Organophosphorus pesticides analytical techniques

As well as these major application fields, biosensors and analytical techniques should also benefit from the technology. Some examples have already been described. The detection of formaldehyde by a formaldehyde dehydrogenase coated onto a piezoelectric crystal has been performed at the ppm level. Detection of pesticides and organophosphorus compounds at the ppb level has been rendered... 

The HPLC/MS technique used in EPA Method 8321 is best suited for analysis of thermally unstable compounds that are hard to analyze with conventional GC methods, such as organophosphorus pesticides, chlorinated herbicides, and carbamates. In this technique, the detection with mass spectrometry provides the ultimate selectivity. The sensitivity for each individual compound depends on the interferences in a given environmental matrix and on the chemical nature of the analyte. 

SPME was hrst used by Pawliszyn et al. in 1990. It is a two-step process conductive to the simultaneous extraction and preconcentration of analytes form sample matrices. In the first step, a fused-silica fiber coated with a polymeric stationary phase is exposed to the sample matrix where the analyte partitions between the matrix and the polymeric stationary phase. In the second step, the fiber/analyte is transferred to the analytical instrument for desorption, separation, and quantification. SPME has a number of advantages over traditional extraction techniques for pesticides. In fact, it is fast, simple, solvent-free, and easily automated for both GC and HPLC instruments. It exhibits good linearity and sensitivity. Thus, carbamate and organophosphorus pesticides in golf course samples were successfully extracted by SPME and analyzed by HPLC by Jinno et al. ... 

Organophosphorus compounds are significant major environmental pollutants due to their intensive use as pesticides. The modem techniques based on inhibition of cholinesterase enzyme activity are discussed. Potentiometric electrodes based on detection of cholinesterase inhibition by analytes have been developed. The detection of cholinesterase activity is based on the novel pindple of molecular transduction. Immobilized peroxidase acting as the molecular transducer, catalyzes the electroreduction of hydrogen peroxide by direct (mediatorless) electron transfer. The sensing element consists of a carbon based electrode containing an assembly of co-immobilized enzymes cholinesterase, choline oxidase and peroxidase. 

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