Development of an automated sequential injection on-line solvent extraction-back extraction procedure as demonstrated for the determination of cadmium with detection by electrothermal atomic absorption spectrometry

摘要: Abstract An automated sequential injection (SI) on-line solvent extraction-back extraction separation/preconcentration procedure is described. Demonstrated for the assay of cadmium by electrothermal atomic absorption spectrometry (ETAAS), analyte initially complexed with ammonium pyrrolidinedithiocarbamate (APDC) in citrate buffer and chelate extracted into isobutyl methyl ketone (IBMK), which separated from aqueous phase means a newly designed dual-conical gravitational separator. A metered amount organic eluate aspirated stored PTFE holding coil (HC) SI-system. Afterwards, it dispensed mixed an back extractant dilute nitric acid containing Hg(II) ions as stripping agent, thereby facilitating rapid metal-exchange reaction APDC ligand transfer Cd phase. The second separator, 30 μl entrapped sample loop (SL) subsequently introduced via air segmentation graphite tube quantification. ETAAS determination performed parallel process ensuing sample. enrichment factor 21.4, detection limit 2.7 ng l −1 , along sampling frequency 13 h were obtained at flow rate 6.0 ml min . precision (R.S.D.) 0.4 μg l level was 1.8% compared to 3.2% when quantifying directly. applicability demonstrated trace levels three certified reference materials.