Determination of fenitrothion in water samples by spectrometry using new reagents iminodibenzyl and 4-amino-5-hydroxy-2,7-naphthalene disulfonic acid

Simple and sensitive spectrophotometric methods for the determination of fenitrothion in either pure form or in its formulations are described. The methods are based on the diazotization of reduced fenitrothion followed by coupling with alcoholic iminodibenzyl (IDB) in acidic medium to give a purple coloured product having a gamma(max) of 575 nm (first method) or coupling with 4-amino-5-hydroxy-2,7-naphthalene disulfonic acid monosodium salt (AHND) to produce red color product with gamma(max) of 523 nm (second method) at pH 11.5. Both the methods are highly reproducible and have been applied formulations and in water samples. The proposed methods have been applied successfully for the determination of fenitrothion residues in water samples upto the ppb level with the preconcentration oil Amberlite XAD-4.