A rapid spectrophotometric assay of some organophosphorus pesticide residues in vegetable samples.

A rapid and sensitive spectrophotometric method for the determination of some organophosphorus insecticides, i.e. malathion, dimethoate and phorate is described. It is based on the oxidation of organophosphorus pesticide with slight excess of N-bromosuccinimide (NBS) and the unconsumed NBS is determined with rhodamine B (lambda max: 550 nm). Beer's law is obeyed in the concentration range 0.108-1.08, 0.056-0.56 and 0.028-0.28 microg mL(-1) for malathion, phorate and dimethoate, respectively. The method has been successfully applied for the determination of organophosphorus pesticide residues in various vegetable samples.

Direct and selective spectrophotometric method for the determination of vanadium in steel, environmental and biological samples.

A simple, direct and selective spectrophotometric method for determination of vanadium is described. The present methodology is based on the strong oxidizing power of vanadium (V). Vanadium (V) selectively oxidizes leucocrystal violet (LCV) to crystal violet in the presence of phosphoric acid. The violet colored dye obtained shows maximum absorbance at 590 nm. Beer's law is obeyed in the concentration range 0.06-0.6 µg ml(-1). The molar absorptivity and Sandell's sensitivity are found to be 6.78×10(4) l mol(-1) cm(-1) and 0.0044 µg cm(-2), respectively. The proposed method is simple, direct, and sensitive. It has been successfully applied for the determination of vanadium in various environmental, biological and steel samples.