Determination of ultra-trace amounts of inorganic selenium species in natural water by ion chromatography-inductively coupled plasma-mass spectrometry coupled with nano-Al2O3 solid phase extraction

This work presents a nano-Al2O3 solid phase extraction technique for the determination of ultra-trace amounts of inorganic selenium species in aqueous systems using ion chromatography inductively coupled plasma-mass spectrometry (IC-ICP-MS). In this experiment, the inorganic selenium species were successfully extracted on a nano-Al2O3 solid phase column and then quantitative eluted with a 100 mmol L-1 NaOH solution. Extraction conditions such as solvent identity, solvent concentration, solvent volume, solvent pH and salt addition were optimized. Under the optimum extraction conditions (elute solvent: 100 mmol L-1 NaOH, solvent volume: 4 mL, pH: 7.0), low detection limits (Se (IV): 6 ng L-1, Se (VI): 11 ng L-1; RSD< 5.0%) and good linear range (0.5-100 ng mL(-1), R-2 > 0.999) were obtained for all of the analytes. Good spiked recoveries over the range of 80-98% were obtained by applying the proposed method on real environmental water samples. These results indicated that this method is very sensitive and reliable when monitoring trace levels of inorganic selenium species in aqueous samples.