Speciation Determination of Chromium Using Cloud Point Extraction with Double-slotted Quartz Tube Atom Trap-Flame Atomic Absorption Spectrometry

Cloud point extraction(CPE) for speciation determination of chromium in environmental water samples with double-slotted quartz tube atom trap-flame atomic Absorption spectrometry(STAT-FAAS) was developed.Preconcentration of chromium(Ⅵ) and total chromium in different pH solutions was achieved by CPE,with nitrosophenyl hydroxylamine(cupferron) as the chelating agent and Triton X-114 as the cloud point extractant.The effect of pH,concentration of cupferron,Triton X-114,centrifugalization time,equilibration temperature and time on CPE were studied.The results showed that the enrichment factor was 50 for chromium(Ⅵ) or total chromium from the initial 100 mL sample solution to the final 2 mL determined solution,when the system solution buffered at pH 3.0 or 6.0,was kept in the thermostatic bath maintained at 40 ℃ for 15 min,then centrifuged for 5 min.Compared with the FAAS method,the sensitivity was improved 5-fold for chromium by STAT-FAAS method.The linear concentration range was 0.005-0.5 mg/L for chromium(Ⅵ) and 0.01-1.2 mg/L for total chromium.The detection limits of chromium(Ⅵ) and total chromium were 0.66 μg/L and 0.81 μg/L,respectively.