title: TLC-spectrophometric separation and trace determination of monocrotophos and dichlorvos in enviromental and biological samples.
abstract: Organophosphorus insecticides, monocrotophos and dichlrovos are increasingly being used in agriculture to control insects on a wide range of crops. Their ready access has resulted in misuse in many instances of homicidal and suicidal poisoning cases. This paper describes about a chromogenic spray reagent for the detection/determination of monocrophos and dichlrovos in environmental and biological samples by TLC and spectrophotometric method. Monocrotophos and dichlorvos on alkaline hydrolysis yield N-methyl acetoacetamide and dichlroacetaldehyde respectively, which in turn react with diazotized p-amino acetophenone to give red-violet and red coloured compounds. Other organophosphorus insecticides do not give this reaction. Moreover, organochlorine and synthetic pyrethroid insecticides and constituents of viscera (amino acids, peptides, proteins etc), which are generally coextracted with the insecticides, do not interfere. However, phenolic compounds and hydrolysed product of carbamate insecticides may interfere and differentiate from monocrotophos and dichlrovos by Rf values. The lower limit of detection is 0.2 mg for monocrotophos and 0.1 mg for dichlorovos. The absorption maxima of the reddish-violet and red colour formed by monocrotophos and dichlrovos, are measured at 560 nm and 540 nm respectively. Beer's Law is obeyed over the concentration range of 1.2 to 6.8 mg and 6.2 to 35 mg in the final solution volume of 25 mL. The molar absorptivity and Sandell's sensitivity of monocrotophos and dichlrovos were found to be 7.1 x 10(5) (+100) 1 mole(-1) cm(-1) and 0.008 mg cm(-2), 1.2 x 10(5) 1 mole(-1) cm(-1) and 0.003 mg cm(-2) respectively. The standard deviation and relative standard deviation were found be +/- 0.005 and 2.05% +/- 0.007 and 2.02% respectively. The developed method has been successfully applied to the detection and determination of monocrotophos and dichlrovos in environmental and biological samples.
authors.affiliation: Chhattisgarh Council of Science & Technology, Pt. Ravishankar Shukla University Campus Raipur, Chhattisgarh, India.
authors.forename: Etesh K
authors.initials: EK
authors.lastname: Janghel
authors.forename: J K
authors.initials: JK
authors.lastname: Rai
authors.forename: S
authors.initials: S
authors.lastname: Khan
authors.forename: M K
authors.initials: MK
authors.lastname: Rai
authors.forename: V K
authors.initials: VK
authors.lastname: Gupta
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods; D002855:Chromatography, Thin Layer / Q000379:methods*; D004006:Dichlorvos / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents / Q000494:pharmacology; D008999:Monocrotophos / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis; D015203:Reproducibility of Results; D012997:Solvents / Q000032:analysis; D013053:Spectrophotometry / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D007202:Indicators and Reagents; D010573:Pesticide Residues; D012997:Solvents; D014874:Water Pollutants, Chemical; D008999:Monocrotophos; D004006:Dichlorvos