Simple and sensitive spectrophotometric method for the determination of benzene in environmental samples

Abstract

Chemistry Department, Government Arts and Science College, Durg, India School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur-492 010, India Manuscript received 3 May 2001, revised 24 September 2001, accepted 28 December 2001 A sensitive spectrophotometric method has been developed for the determination of benzene based on nitration of benzene to 1,3-dinitrobenzene and its subsequent reduction to 1,3-phenylenediamine. The 1,3-phenylenediamine so formed is determined by diazotization-coupling reaction using 1,3,5-trihydroxybenzene as coupling agent. The yellow orange azo dye formed in alkaline medium is measured spectrophotometrically at 415 nm. Beer's law is obeyed at 0.2-2.0 ppm benzene. The molar absorptivity is 3.07 x 104 dm3 mo-1 cm-1• The standard deviation and relative standard deviation are ±0.01 and 1.62%, respectively, for 40 µg of benzene per 25 ml analyzed over 7 days. The method may be used to determine benzene in petrol vapour, coke oven effluent and cigarette smoke.