TLC-spectrophometric separation and trace determination of monocrotophos and dichlorvos in enviromental and biological samples.

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.

Aerial and tidal transport of mosquito control pesticides into the Florida Keys National Marine Sanctuary

This project was undertaken as the initial monitoring program to determine if mosquito adulticides applied along the Florida Keys cause adverse ecological effects in the Florida Keys National Marine Sanctuary (FKNMS). The study monitored the distribution and persistence of two mosquito adulticides, permethrin and dibrom (naled), during three separate routine applications by the Florida Keys Mosquito Control District. The approach was to determine if toxic concentrations of the pesticides entered the FKNMS by aerial drift or tidal transport. The amount of pesticide entering the FKNMS by way of aerial drift was monitored by collection on glass fiber filter pads, set on floats in a grid pattern on either side of the FKNMS. Permethrin was recovered from filter pads on the leeward side for each of the three applications, ranging from 0.5 to 50.1 microg/m(2) throughout the study. Tidal current transport was monitored by collection of surface and subsurface water samples at each grid site. Tidal transport of naled and dichlorvos (naled degradation product) was apparent in the adjacent waters of the FKNMS. These compounds were detected in subsurface, offshore water at 0.1 to 0.6 microg/1, 14 hr after application. Permethrin was not detected in offshore water samples; however, concentrations ranging from 5.1 to 9.4 microg/l were found in surface water from the canal system adjacent to the application route. Comparison of the observed environmental concentrations with toxicity data (permethrin LC-50, 96 hr for Mysidopsis bahia = 0.02 microg/l) indicated a potential hazard to marine invertebrates in the canals with possible tidal transport to other areas

An indirect evaluation of liquid inseticide concentrations in atmospheres for mutagenicity experiments

A method for the generation of a dichlorvos atmosphere to be used in mutagenicity experiments is proposed, based on a simple device which allows indirect estimation of insecticide concentration. The system can also be applied to other kinds of liquid insecticides, since it is simply based on the weight losses of the flask during vaporization