Simultaneous Determination of Cr(Ⅲ) and Cr(Ⅵ) in Cigarette Tipping Paper by HPLC-ICP-MS

Sample of cigarette tipping paper 1.000 g was extracted with 15 mL of 50 mmol·L^-1 NaOH solution by vortical oscillation for 2 h and then filtered. The extract (0.5 mL) was separated and neutralized with 0.1 mol·L^-1 HCl solution to pH 7.0. After addition of 5 mL of 0.1 mol·L^-1 Na₂-EDTA solution, the extract was kept at 80℃ for 20 min, and the solution was separated chromatographically by using Dionex AS19 column as the stationary phase, and 0.15 mol·L^-1 NH₄NO₃ solution (pH 7.0) as the mobile phase. In ICP-MS analysis, helium was used as the collision gas so as to reduce the MS interference of ³⁵Cl¹⁶O¹H⁺ and ⁴⁰Ar¹²C⁺ to ⁵²Cr⁺. Linearity ranges were found 20.0-1 000 μg·L^-1 for Cr(Ⅲ) and 0.20-10.0 μg·L^-1 for Cr(Ⅵ) with values of detection limits (3s) of 4.81, 0.63 μg·kg^-1 respectively. Test for recovery was made by standard addition method at 3 concentration levels, giving results in the range of 95.2%-104% for Cr(Ⅲ), and 80.0%-116% for Cr(Ⅵ), with RSDs (n=7) in the range of 2.5%-3.1% for Cr(Ⅲ), 2.6%-3.6% for Cr(Ⅵ).