Application of rapid furnace programmes in atomic absorption spectrometry to the determination of lead, chromium and copper in digests of plant materials
Following pressure digestion with nitric acid and pre-treatment with hydrofluoric acid for chromium in silica-containing materials, lead, chromium and copper are determined in plant materials by graphite furnace atomic absorption spectrometry with furnace programmes designed to keep the analysis time to a minimum, consistent with good accuracy and reproducibility. Lead is determined on a L'vov platform with 2%m/V diammonium hydrogen phosphate as a matrix modifier, chromium using a pyrolytic tube and copper on a platform in an uncoated tube, the last two after dilution of samples 1 + 10 with distilled water. An ashing stage was found to be unnecessary for the determination of copper and chromium in the materials studied. No cooling stage was used for determinations with the platform. Cycle times of 72, 56 and 58 s were achieved for lead, chromium and copper, respectively.