Extractive spectrophotometric method for the determination of carbaryl in environmental samples

Abstract

In the view of the potential hazards associated with the widespread use of carbaryl insecticide, a new simple extractive spectrophotometric method has been developed for its determination in environmental samples viz. soil, water and foodstuffs for its safer and more effective use. The proposed method is based on the microwave assisted alkaline hydrolysis of the insecticide to methylamine. The later is measured as methyl isobutyl ketone (MIBK) extractable yellow nickel(II)-methyldithiocarbamate complex at 380 nm through the reaction with carbon disulfide and nickel(II) acetate. The insecticide can be determined in the linearity range from 2.01 to 60.3 µg mL^-1 with a correlation coefficient of 0.996. The method has been applied to the analysis of carbaryl in its commercial formulation and its recovery from vegetable and water samples for monitoring health hazards. Recoveries of the insecticide from vegetables and spiked water samples were good, ranging from 87.6-92.8%, with RSDs ranging from 0.54-1.02%. The method has also been validated for investigating the sorption of carbaryl on five soils with different characteristics to evaluate its leaching behaviour which is a measure of ground and surface water contamination. The leaching potential of the insecticide in terms of groundwater ubiquity score (GUS) has values in the range 1.8-2.2 classifying it as transition leacher hence it has potential to contaminate groundwater.

KEY WORDS: Carbaryl, Spectrophotometry, Environmental toxicity, Soil-sorption study, Leaching/GUS

Bull. Chem. Soc. Ethiop. 2015, 29(2), 173-186

DOI: http://dx.doi.org/10.4314/bcse.v29i2.2