SIMULTANEOUS VOLTAMMETRIC DETERMINATION OF TOXIC METALS IN SEDIMENTS

Voltammetric methods are very suitable, versatile and rapid techniques for the simultaneous metal determination in complex matrices. The wor k, regarding the determination of As(III), Se(IV) and Mn(II), is a ver y interesting example of the possibility for simultaneously determinin g each single element in real samples in a wide range of concentration ratios. The differential pulse (DPV) measurements were carried out us ing a conventional three-electrode cell, while ammonia-ammonium chlori de buffer (pH 9.6) was employed as the supporting electrolyte. The ana lytical procedure was verified by the analyses of standard reference m aterials: estuarine sediment BCR-CRM 277 and river sediment BCR-CRM 32 0. Precision and accuracy, expressed as relative S.D. and relative err or, respectively, were in all cases of the order of 3-5%. while the de tection limit for each element was around 10(-8) M. The standard addit ion technique improved the resolution of the voltammetric method, even in the case of very high element concentration ratios. (C) 1998 Elsev ier Science B.V. All rights reserved.