Photochemical vapor generation of carbonyl for ultrasensitive atomic fluorescence spectrometric determination of cobalt

UV photochemical vapor generation (photo-CVG) as sample introduction was first adapted for determination of ultratrace cobalt by atomic fluorescence spectrometry (AFS). Cobalt volatile species can be generated when the buffer system of formic acid and formate containing Co (II) is exposed to UV radiation. The generated gaseous products were separated from liquid phase within a gas-liquid separator and then transported to AFS for determination of cobalt. Factors affecting the efficiency of photo-CVG were investigated in detail, including type and concentration of low molecular weight (LMW) organic acid, buffer system. UV irradiation time, reaction temperature, carrier gas flow rate and hydrogen flow rate. With 4% (v/v) HCOOH and 0.4 mol L-1 HCOONa buffer solution, 150s irradiation time and 15 W low pressure mercury lamp, a generation efficiency of 23-25% was achieved. A limit of detection (LOD) of 0.08 ng mL(-1) without any pre-concentration procedure and a precision of 2.2% (RSD, n = 11) at 20 ng mL(-1) were obtained under the optimized conditions. The proposed method was successfully applied in the analysis of several simple matrix real water samples. (C) 2010 Elsevier B.V. All rights reserved.