Abstract:

An analytical method using ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS) for the determination of hexavalent chromium (Cr(Ⅵ)) in atmospheric particles PM_2.5 and PM₁₀ was established. The Cr(Ⅵ) in the atmospheric particles was extracted ultrasonically with sodium bicarbonate solution. An anion exchange column (AG7, 50 mm×4 mm) with 75 mmol/L ammonium nitrate solution (containing 0.22 g/L Na₂EDTA, pH 7.0) as mobile phase was used for the separation. ICP-MS was used as a detector for the determination of hexavalent chromium. The calibration curve was linear in the range of 0.05-5 μg/L and the correlation coefficient was 0.9999 for Cr(Ⅵ). The cellulose filter was fit for sampling. With the alkaline cellulose filter, the recovery of Cr(Ⅵ) increased from 75% to 102%. The recovery was complete and stable when the samples were sonicated in 20 mmol/L sodium bicarbonate solution for 30 min. The limit of quantification (LOQ) of Cr(Ⅵ) was 0.0004 ng/m³ when the sampling volume was 20 m³. The average recoveries of Cr(Ⅵ) in the spiked PM_2.5 and PM₁₀ samples ranged from 91.6% to 102% with the relative standard deviations not more than 7.6%. The method is efficient and reliable. It can meet the requirement for the determination of Cr(Ⅵ) in atmospheric particles.

Key words: atmospheric particles, hexavalent chromium, ion chromatography with inductively coupled plasma mass spectrometry (IC-ICP-MS), PM₁₀, PM_2.5