Method development for simultaneous multi-element determination of hydride forming elements (As, Bi, Ge, Sb, Se, Sn) and Hg by microwave induced plasma-optical emission spectrometry using integrated continuous-microflow ultrasonic nebulizer-hydride generator sample introduction system

The analytical potential of a coupled continuous-microflow ultrasonic nebulizer dual capillary system (µ-USN/DCS)–Ar/He mixed gas microwave induced plasma-optical emission spectrometry (MIP-OES) has been evaluated for the purpose of determination of hydride forming elements (As, Bi, Ge, Sb, Se, Sn) and a vapor element (Hg). 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/DCS observed at a 15 µL min^{− 1} flow rate. At flows of ≤ 15 µL min^{− 1}, solvent loading in the plasma is sufficiently low to make desolvation unnecessary. 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, 3σ_blank criterion, peak height) were 1.2, 5.4, 6.3, 1.8, 3.3, 2.4 and 3.0 ng mL^{− 1} for As, Bi, Ge, Sb, Se, Sn and Hg, respectively. The method offers relatively good precision (RSD ranged from 8 to 11%) for liquid analysis and microsampling capability. Interference effects by transition metals have been shown to be corrected by the addition of thiourea, as a pre-reducing agent and masking agent. The accuracy of the method was verified using certified reference materials (DOLT-2, GBW 07302, SRM 2710, and SRM 1643e) and by the aqueous standard calibration technique. The measured contents of elements in reference materials were in satisfactory agreement with the certified values.