Simultaneous determination of As, Bi, Sb, Se and Sn by microwave induced plasma spectrometry using a quadruple-mode microflow ultrasonic nebulizer for in situ hydride generation with internal standardization

A method based on continuous-microflow ultrasonic nebulizer quadruple-mode micro-capillary system (μ-USN/QCS-HG) has been used for the efficient generation of As, Bi, Ge, Sb, Se and Sn hydrides directly formed at vibrating quartz plate before detection by microwave induced plasma-optical emission spectrometry (MIP-OES). The ultrasonic nebulizer incorporates four solution capillaries with independent liquid feeding and a common gas inlet. The μ-USN/QCS-HG allowed the hydride generation directly into the cyclonic spray chamber without using any additional device either for solution and gas control or for gas phase separation. The μ-USN/QCS-HG-MIP OES makes feasible the implementation of an on-line internal standard (IS) calibration strategy and Ge was suggested as internal standard. A univariate approach and the simplex optimization procedure were used to achieve optimized conditions and derive analytical figures of merit. Analytical performance of the ultrasonic nebulization system was characterized by determination of the limits of detection (LODs) and precision (RSDs) with the μ-USN/QCS-HG-MIP OES observed at a 50 μL min− 1 flow rate. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σblank criterion, peak height) were 1, 5, 2, 3 and 2 ng mL− 1 for As, Bi, Sb, Se and Sn, respectively. The method offers good precision (RSD ranged from 2% to 3%) for micro-sampling analysis. The potential application of this system was demonstrated by successfully analyzing several certified reference environmental samples (CRM DOLT-2, SRM 2710 and SRM 1643e) with satisfactory results. The measured of contents of elements in certified reference materials were in good agreement with the certified values, according to the t-test, for a confidence level of 95%.