Flow injection online solid phase extraction system using Oasis-HLB™ micro-cartridge for chromium(VI) and copper determination by flame atomic absorption spectrometry

[摘要] An online flow injection sorption preconcentration method for automatic trace chromium(VI) and copper determination in environmental water samples was developed, using flame atomic absorption spectrometry (FAAS). The use of hydrophobic reversed-phase co-polymeric sorbent material Oasis-HLB in readily exchangeable micro-cartridge format was estimated. Effective online formation and retention of sodium diethyldithiocarbamate (DDTC) chelate complexes of analytes were achieved at pH 2.0, while highest elution effectiveness was observed with methanol. The sorbent and the micro-cartridge exhibited high long term chemical and mechanical stability with fast kinetics for both metals. Several analytical parameters like sample acidity, DDTC concentration, loading/elution flow rate and preconcentration time governing the efficiency of the method were evaluated. For 90 s preconcentration time (10.0 mL of sample volume) and sampling frequency 24 h−1, the enhancement factor was 70 and 195, the detection limit (3s) found to be 0.8 μg L−1 and 0.1 μg L−1 with relative standard deviations 3.5% (at 10.0 μg L−1) and 2.7% (at 5.0 μg L−1) for chromium(VI) and copper respectively. The presented method was evaluated by analyzing certified reference materials and spiked natural water samples...

[学科分类] 分析化学