Nickel and Strontium Nitrates as Modifier for the Determination of Selenium in Urine by Zeeman Platform Graphite-Furnace Atomic Absorption Spectrometry

Abstract

A mixture of nickel and strontium nitrates has been proved to be suitable and feasible for the determination of selenium in urine by graphite-furnace atomic absorption spectrometry with respect to the thermal stabilization and minimization of urine matrix interferences. Thermal pretreatment temperature of 1400 degrees C and 900 degrees C can be utilized in aqueous standard solution and 1:3 diluted urine with the proposed modifier, respectively. The results demonstrate that nickel and strontium nitrate mixed modifier can significantly remove or depress troublesome interference caused by sulfate, phosphate and concomitant metal ions. The graphite furnace temperature program and modifier mass have been optimized. The amount of mixed modifier required for stabilizing selenium and suppressing the effect of urine matrix is markedly lower than those documented in the literature, which reduces the risk of graphite furnace contamination. The effects of different atomizer surfaces on the selenium sensitivity were compared in this work. Better recoveries were obtained for different urine samples in the presence of nickel and strontium nitrates.