Extraction-spectrometric determination of lead in high-purity aluminium salts

Trace amounts of lead were determined in high purity aluminium salts (especially in ammonium aluminium sulfate) using inductively coupled plasma–optical emission spectrometry (ICP-OES) after extractive pre-concentration and matrix separation. Metals were extracted from the aluminium matrix in the form of chelates with ammonium pyrolidine dithoocarbamate into methyl isobutyketone. The organic extract was digested with nitric acid and hydrogen peroxide. The limit of detection for the determination of lead in crystalline ammonium aluminium sulfate was ca. 0.044 μg g−1. The relative expanded uncertainty of the lead determination was ca. 23% at the level of 0.2 μg g−1 and ca. 16% at the level of 1.0 μg g−1. The main uncertainty contribution was associated with repeatability of the whole analytical procedure.