Issue 8, 2016

System optimization for determination of cobalt in biological samples by ICP-OES using photochemical vapor generation

Abstract

An optimized photochemical vapor generation (PVG) approach for efficient synthesis of volatile cobalt species is described. Solutions containing Co(II) in a pH 3.3 medium of 50% formic acid were exposed to a source of deep UV (254 and 185 nm) radiation generated within a 19 W flow-through low pressure mercury discharge lamp. Following efficient phase separation, the analyte was transported to an ICP-OES system for detection at the 238.892 nm emission line of Co I. Several variables were investigated, including the type of UV lamp and gas–liquid separator, identity and concentration of the low molecular weight organic acid, solution pH, sample flow rate and exposure time to the UV irradiation as well as transport gas flow and mode of introduction of sample (continuous or segmented) to the ICP. In continuous mode, an optimum generation efficiency of 42 ± 2% was achieved with an irradiation time of 10 s, providing a 27-fold improvement in sensitivity compared to pneumatic nebulization and a limit of detection of 0.4 μg L−1 with a precision of 3% at 100 μg L−1. Direct analysis of acid digested biological tissues (NRC TORT-2 and TORT-3) was hampered by strong matrix interferences from the presence of nitrate and other ions which could be circumvented by longer irradiation time and sufficient dilution such that accurate analysis of real samples by the method of additions could be achieved while maintaining high generation efficiency.

Graphical abstract: System optimization for determination of cobalt in biological samples by ICP-OES using photochemical vapor generation

Article information

Article type
Paper
Submitted
25 Febr. 2016
Accepted
31 Maijs 2016
First published
31 Maijs 2016

J. Anal. At. Spectrom., 2016,31, 1590-1604

System optimization for determination of cobalt in biological samples by ICP-OES using photochemical vapor generation

H. Coutinho de Jesus, P. Grinberg and R. E. Sturgeon, J. Anal. At. Spectrom., 2016, 31, 1590 DOI: 10.1039/C6JA00069J

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