Ultrasonic Nebulization/UV Photolysis Vapor Generation Sample Introduction System for the Determination of Conventional Hydride (As, Bi, Sb, Se, Sn) and Cold Vapor (Hg, Cd) Generation Elements in Reference Materials in the Presence of Acetic Acid by Microwave-Induced Plasma Spectrometry

Abstract

ABSTRACT A novel synergic effect of ultrasonic nebulization (USN) and ultraviolet (UV) radiation (photolysis) when used in combination has been exploited for efficient generation of conventional hydride elements (As, Bi, Sb, Se, Sn), Hg vapor, and volatile molecular Cd species. Several UV-based systems were studied, the most advantageous design being an ultrasonic nebulizer fitted with a 6 W mercury pen lamp supplying a microliter sample to a quartz oscillator, converting liquid into aerosol at the entrance of the UV spray chamber. Optimal conditions utilized a 40% v/v solution of acetic acid as the generation medium. The volatile species are detected by microwave-induced plasma optical emission spectrometry (MIP-OES). The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times the standard deviation of the blank (LOD, 3σblank criterion, peak height), were 11, 22, 16, 19, 20, 11, and 15 µg L−1 for As, Bi, Sb, Se, Sn, Cd, and Hg, respectively. The method offers relatively good precision (RSD ranged from 3% to 5%) for liquid analysis and microsampling capability. The methodology was validated through determination of elements in two Certified Reference Materials (NRCC DOLT-2, NIST 1643e) and by the aqueous standard calibration technique.