Analytica Chimica Acta, 135 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (1982) 263-276 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands zyxwvutsrqponmlkjihgfedcb ANODIC STRIPPING VOLTAMMETRJC DETERMINATION OF THE CONTAMINATION OF SEAWATER SAMPLES BY CADMIUM, LEAD AND COPPER DURING FILTRATION AND STORAGE GIUSEPPE SCARPONI*, GABRIELE CAPODAGLKO and PAOLO CESCON Cattedm di Chimica Analitica Strumentale. Zstituto di Chimica Generale ed Znorganica. Universitii di Venezia, 30123 Venezia (Italy) BIANCA COSMA and ROBERTO FRACHE Zstituto di Chimica Generale ed Znorganica, Universitc di Genova, I6132 Genova (Italy) (Received 7th August 1981) SUMMARY Anodic stripping voltammetry is employed to investigate the contamination of sea- water by cadmium, lead and copper during filtration and storage of samples. Seawater leaches metals from uncleaned membrane filters but, after 1 1 of water has passed through, the contamination becomes negligible_ Samples stored in conventional polyethylene con- tainers (properly cleaned and conditioned with prefiltered sea water) at 4°C and natural pH remain uncontaminated for 3 months (5 months for cadmium); losses of lead and copper occur after 5 months storage. Reproducibility (95% confidence interval) was 8- 10%, 3-8%, and 5-6%, at concentration levels of about 0.06, 2.5, and 6.0 pg I-‘, for cadmium, lead, and copper, respectively_ The samples were collected near the coast of an industrial area. The determination of traces of heavy metals in natural waters can be greatly affected by contamination (positive or negative) during filtration and storage of samples [l-6]. This problem, especially as regards filtration, has not been studied adequately and systematically with respect to the deter- mination of cadmium, lead, and copper in seawater. Frequently, in order to make the determination easier, synthetic matrix samples [6, ‘71 and/or high metal concentrations [S-9] have been used; otherwise, in order to demon- strate possible filter contamination, washed and unwashed filters have been analysed after ashing [ lO-16]_ The same filter can release or adsorb trace metals depending on the metal concentration level and the main constituents of the sample [S, 171, therefore claimed results must be considered with caution in working with natural samples. To avoid contamination, the follow- ing procedures have often been used. Filters have been cleaned by soaking them in acids [2-4, 13, 16-261 or complexing agents [l, 2, 141, and/or conditioned either by soaking in seawater or a simulated seawater solution [lS, 27, 21.1 or by passing a 0.2-2-l sample before aliquots are taken for analysis [ 2, 4, 16, 18, 22, 231. Sometimes, however, the washing procedure