OPTIMIZATION OF SAMPLE PREPARATION OF CARROT-FRUIT JUICE FOR DETERMINATION OF ANTIMONY, ARSENIC, AND SELENIUM BY HYDRIDE GENERATION-INDUCTIVELY COUPLED PLASMA OPTICAL EMISSION SPECTROMETRY

摘要

Sample preparation procedures for the determination of As, Sb, and Se in carrot-fruit juice by hydride generation inductively coupled plasma optical emission spectrometry (HG-ICP OES) were examined. The applicability of a partial decomposition using aqua regia and simple dilution with a 2% (v/v) HNO_3 solution were tested and compared to a traditional treatment based on the wet digestion with a HNO_3/H_2O_2 mixture. The pre-reduction and hydride generation reaction conditions were evaluated. Under the optimal conditions, the hydrides were produced in the reaction of an acidified sample with NaBH4 after pre-reduction with ascorbic acid [0.5% (m/v)] and KI [0.5% (m/v)] in 3 molL~(-1) HCl for total As and Sb, and boiling with HCl (6 molL~(-1)) for total Se. The best results were obtained for the aqua regia procedure, resulting in limits of detection (LODs) between 1.2-2.4 ng g~(-1) in the samples and recoveries from 90.9% to 109.1%. The method was successfully applied (without matrix effects) for the determination of As in dense mousse and pulp juice samples and for Sb in pulp juices. Standard solutions, processed in the same way as samples, were used for the calibration. Undecomposed matrix constituents strongly influenced Se; hence this element was determined using the method of standard addition. Concentrations of studied elements in analyzed products were at the trace level, that is, 6-32 ng g~(-1), 4-10 ng g~(-1), and 4-13 ng g~(-1) for Se, As, and Sb, respectively.