Determination of Cr(VI) in welding fumes by anion-exchange fast protein liquid chromatography with electrothermal atomic absorption spectrometric detection

Abstract.

The applicability of an anion-exchange fast protein liquid chromatographic-electrothermal atomic absorption spectrometric procedure (FPLC-ETAAS) was investigated for the determination of Cr(VI) in welding fumes after alkaline extraction of aerosols loaded on filters. Gas tungsten arc welding (GTAW) of stainless steel was applied. Samples of welding fumes were collected during regular welding on polycarbonate membrane filters of 8 µm and 0.4 µm pore size (inhalable and respirable aerosols). Alkaline extraction (2% NaOH-3% Na₂CO₃) of filters in a heated ultrasonic bath was applied to leach Cr from the airborne particulate matter. 0.5 cm³ of sample extract was then injected onto an anion-exchange FPLC column. Tris-HCl buffer (0.005 mol dm^–3, pH 8.0) and the same buffer with NaCl (0.5 mol dm^–3) were employed in gradient elution (15 min, flow rate 1 cm³ min^–1). The separated Cr species were determined "off line" by ETAAS in 0.5 cm³ fractions. Cr(VI) was reproducibly and quantitatively eluted from 12.0 to 13.0 min with a maximum peak at 12.5 min. Good repeatability of measurement (±3.0%) of alkaline extracts was obtained for Cr(VI). The LOD (3s) was found to be 0.035 µg m^–3 Cr(VI), when 2 m³ of aerosols were collected on the filter. Validation of the procedure was performed by spiking alkaline extracts and by the analysis of standard reference material CRM 545, Cr(VI) in welding dust loaded on a filter. The technique was successfully applied for the determination of Cr(VI) in welding fumes.