Determination of trace Cr, Mo, Pd, Cd, Pt and Pb in drug tablets by ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry

Abstract

Ultrasonic slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry (USS-ETV-ICP-MS) has been applied to determine Cr, Mo, Pd, Cd, Pt and Pb in drug tablets. The influences of instrument operating conditions and slurry preparation on the ion signals were reported. A mixture of ammonium pyrrolidine dithiocarbamate (APDC) and 8-hydroxyquinoline (8-HQ) was used as the modifier to enhance the ion signals. The background ions at the Cr masses m/z 52 and 53 were significantly reduced in intensity by using NH₃ as reaction cell gas in the dynamic reaction cell (DRC). The introduction of dry aerosol with ETV sampling device and DRC effectively alleviated the spectral interferences. This procedure has been applied to determine Cr, Mo, Pd, Cd, Pt and Pb in antihypertensive tablets purchased locally. The values obtained by ETV-ICP-MS were in good agreement with reference values obtained by pneumatic nebulization ICP-MS of completely dissolved samples. The precision between sample replicates was better than 5% (25% for Pt) for all determinations. The method detection limits estimated from standard addition curves were in the range 0.1–0.5, 0.5–0.9, 0.2–0.3, 0.1–0.3, 0.1 and 0.2–0.3 ng g⁻¹ for Cr, Mo, Pd, Cd, Pt and Pb, respectively, in original tablets.