Direct determination of cadmium in sea-water by electrothermal atomic absorption spectrometry with sodium hydroxide as a chemical modifier

• Published in: Analyst (London) Vol. 118; no. 2; pp. 189 - 192
• Main Author: Lan, Chi-Ren
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 1993
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Spectrometric and optical methods; Trace analysis; Cadmium; Chemical modification; Chemical analysis; Sodium Hydroxides; Thermoelectric atomization; Matrix effect; Coprecipitation; Seawater; Chemical enrichment; Atomic absorption spectrometry
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/AN9931800189

In an effort to reduce severe background absorbance problems associated with the direct analysis of seawater, sodium hydroxide was used as a chemical modifier in the determination of trace amounts of cadmium by electrothermal atomic absorption spectrometry (ETAAS). Sodium hydroxide permitted a selected ashing temperature up to 1400C and markedly reduced the background signal while the ashing time was prolonged to 100 seconds. Addition of sodium hydroxide resulted in the formation of colloidal magnesium hydroxide precipitates with which trace amounts of cadmium were thought to be coprecipitated. This method was applied to open ocean seawater samples. The validity of the procedure was checked with 2 certified reference seawaters (CASS-1 and CASS-2), the results being in good agreement with certified values. A detection limit of 0.015 ng per ml was obtained for 80 ul injections.