RING TEST FOR THE DETERMINATION OF N-TERMINAL VALINE ADDUCTS OF STYRENE 7,8-OXIDE WITH HEMOGLOBIN BY THE MODIFIED EDMAN DEGRADATION TECHNIQUE

A ring-test was organised between three laboratories using different v ersions of the modified Edman degradation technique for the gas chroma tographic-mass spectrometric determination of N-terminal valine adduct s of styrene 7,8-oxide. The analyses were performed on a sample of hum an haemoglobin reacted in vitro with styrene 7,8-oxide and on a set of five haemoglobin samples from mice dosed by i.p. injection of styrene . Strong correlations between the haemoglobin adduct determinations of the different laboratories were observed. However, covariance analysi s revealed different slopes for the dose-response curves, indicating d ifferences for the calibration of the reference globin or reference pe ptide. (C) 1997 Elsevier Science B.V.