Spectrophotometric and direct-reading methods for the analysis of gas phase peroxyacetic acid

A new method for the determination of peroxyacetic acid (PAA) in gas phase samples is described. It is based on the oxidation of ABTS (2,2'-azino-bis( 3-ethylbenzothiazoline)-6-sulfonate) by PAA with formation of a radical cat ion which is characterized by four strong absorption maxima between 405 nm and 810 nm. These allow for sensitive spectrophotometric determination of t he peracid. The selectivity of the method towards hydrogen peroxide is stro ngly dependent on the sampling method used. Impinger sampling and sampling based on the use of coated solid sorbents (test tubes) was performed. Limit s of detection are 10(-8) mel, limits of quantification are 5 x 10(-8) mel, the linear range consists of 1.5 concentration decades in both cases. Usin g ABTS-coated test tubes above 1 x 10(-7) mel, direct reading of the result s is possible and may be used as rapid screening method for the PAA concent ration.