Methyl pirimiphos

FIGU RE 2.10 Plasma A-esterase activities of birds and mammals. Activities were originally measured as nanomoles product per milliliter of serum per minute, but they have been converted to relative activities (male rat = 1) and plotted on a log scale. Each point represents a mean value for a single species. Substrates , paraoxon , pirimiphos-methyl oxon. Vertical hues indicate limits of detection, and all points plotted to the left of them are for species in which no activity was detected. (Activities in the male rat were 61 4 and 2020 130 for paraoxon and pirimiphos-methyl oxon, respectively.) (From Walker 1994a in Hodgson and Levi 1994.)... 

The organophosphorons insecticides dimethoate and diazinon are mnch more toxic to insects (e.g., housefly) than they are to the rat or other mammals. A major factor responsible for this is rapid detoxication of the active oxon forms of these insecticides by A-esterases of mammals. Insects in general appear to have no A-esterase activity or, at best, low A-esterase activity (some earlier stndies confnsed A-esterase activity with B-esterase activity) (Walker 1994b). Diazinon also shows marked selectivity between birds and mammals, which has been explained on the gronnds of rapid detoxication by A-esterase in mammals, an activity that is absent from the blood of most species of birds (see Section 23.23). The related OP insecticides pirimiphos methyl and pirimiphos ethyl show similar selectivity between birds and mammals. Pyrethroid insecticides are highly selective between insects and mammals, and this has been attributed to faster metabolic detoxication by mammals and greater sensitivity of target (Na+ channel) in insects. 

Brealey, C.J. (1980). Comparative Metabolism of Pirimiphos-methyl in Rat and Japanese Quail. Ph.D. Thesis, University of Reading, UK. 

Brealey, C.J., Walker, C.H., and Baldwin, B.C. (1980). A Esterase activities in relation to differential toxicity of pirimiphos-methyl. Pesticide Science 11, 546-554. 

Picket fence configuration, 157 Pigments, 29S Pilocarpine, 297 Piprozoiin, 283 Pirimiphos methyl, 297 Plate height, 167 accuracy of measurements, 12 dependence on flow velocity, 10 minimum, 9,13,18 reduced, 10... 

Forensic analysis of street drugs include that of cocaine together with excipients frequently encountered (579), amphetamines 080), and dyes found in heroin samples 081). An on-line photochemical derivitization of cannabinoids has been described 082). Other pharmaceutical agents studied in formation include nortriptyline in tablets. 083), glycyrrhizic acid from licorice extract 084, 585), pirimiphos methyl 086), digitalis glycosides 0S7), pilocarpine 088), and its antagonist atropine 009). 

Extraordinary selectivity has been accomplished with the parathion-type of insecticide by incorporating Q or CH3 groups in the meta position of the aryl ring. These groups interact sterically with acetylcholinesterase (AChE), increasing the affinity for the insect enzyme and decreasing it with the mammalian enzyme. Selectivity also is enhanced by differences in the rates of microsomal oxidation of P=S to P=0 and in hydrolytic detoxication between insects and mammals. The compounds, fenitrothion, fenthion, ronnel, bromophos, iodofenfos, chlorpyrifos—methyl, and pirimiphos —methyl, and dicapthon are used widely in public health, household, and agricultural pest control. 

M. Del Carlo, A. Pepe, M. Mascini, M. De Gregorio, A. Visconti and D. Compagnone, Determining pirimiphos-methyl in durum wheat samples using an acetylcholinesterase inhibition assay, Anal. Bioanal. Chem., 381 (2005) 1367-1372. 

Among organophosphates dichlorvos (2,2-dichlorovinyl dimethyl phosphate) and pirimiphos methyl (0-[2-(diethylamino)-6-methyl-4-pyr-imidinyl]0,0-dimethylphosphorothioate) are important contaminants for the durum wheat industry. Dichlorvos is one of the most widely used pesticides worldwide in the storage of many products, such as com, rice, and durum wheat, finding widespread use in most European countries... 

The possibility of detecting a phosphotionate pesticide in durum wheat has been also investigated. The determination was accomplished via chemical oxidation of the phosphothionate molecule both in buffer and in matrix extract solution optimizing the experimental parameters (reagents concentration and reaction time). The procedure was then applied to standardize the pirimiphos methyl detection obtaining the calibration curves under different conditions. The LOD with matrix extract was 50 or 100 ng/mL, depending on the extract % addition, which allowed the detection of samples contaminated at the MRL — 5 mg/kg. The samples mean recovery was 70.3% and no false positive samples were detected [49]. 

Screen-printed electrochemical sensors for the detection of dichlorvos and pirimiphos-methyl... 

Pirimiphos-methyl determination in durum wheat samples The electrochemical assay for the detection of AChE inhibitors outlined above has been optimized for the detection of pirimiphos methyl-pirimiphos-methyl in durum wheat. Pirimiphos methyl is a phosphot-ionate insecticide and therefore it requires to be transformed in the corresponding oxo-form to act as an effective AChE inhibitor, in fact it did not show inhibition of AChE in a concentration range 50-5000 ng/ mL (data not shown). 

The applications described above, coupled with the realization of a dedicated portable instrumentation and software, represent a user-friendly analytical tool dedicated to durum wheat safety. Moreover, all the applications are based on the use of one single type of thick-film SPE facilitating the overall procedure for the final user that has to store and handle one single type of transducer. The developed device, which consists of the hand-held potentiostat, the multiplexer for eight-channel control and a dedicated software, can be used to detect OPs pesticides, such as dichlorvos and pirimiphos methyl at contamination level below the MRL settled by the European Union, OTA, and also amplified DNA of F. culmorum. 

Phospholipid-bilayer membrane 96, 102 Photo-induced charge carriers 97 Photocrosslinking 805 Photocurable polymeric 107 ac Photocurrent 89 Photocurrent-voltage curve 91 Photolithographic 828 Physical adsorption 808 Pipecolic acid 64, 67 Pirimiphos-methyl 531, 687, e299 Plasma e5 water 6... 

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