Journal
INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY
Volume 99, Issue 2, Pages 157-171Publisher
TAYLOR & FRANCIS LTD
DOI: 10.1080/03067319.2019.1581884
Keywords
Chromium; speciation; solid phase extraction; direct ultrasonic slurry sampling-ETAAS; nanometer-sized zirconium dioxide
Categories
Funding
- Slovak Research and Development Agency APVV [SK-KR-18-0009]
- Scientific Grant Agency of the Ministry of Education of the Slovak Republic, VEGA [1/0899/16]
- Comenius University [UK/36/2018]
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A new analytical procedure for the determination of chromium Cr(III) and Cr(VI) species in different water samples was developed. The method involves solid-phase extraction (SPE), direct ultrasonic slurry sampling (DUSSS), and subsequent electrothermal atomic absorption spectrometry (ETAAS). The nanometer-sized zirconium dioxide (ZrO2) was used as the sorbent material. The optimal conditions for the proposed solid phase extraction were: 50 mg ZrO2, 20 min extraction time, pH 2.5 for Cr(VI) and pH 8.0 for Cr(III) and for the ETAAS measurement: 1500 degrees C pyrolysis and 2300 degrees C atomisation temperatures, 1.5 g L-1 Mg(NO3)(2) as matrix modifier. The samples were sonicated directly in the autosampler cup, using an ultrasonic probe at 20% power setting for 10 seconds prior to injection into the graphite tube with & vov platform. In this way, all drawbacks due to the elution procedure were eliminated. The limit of detection and limit of quantification for Cr(III) obtained under optimised conditions were 0.48 mu g L-1, and 1.61 mu g L-1, respectively, and for Cr(VI) 0.27 mu g L-1 and 0.90 mu g L-1. The pre-concentration factors attained for both the species were 25. The effects of alkaline, alkaline earth and some metal ions and some anions were also examined. The relative standard deviation estimated from six replicate measurements at a concentration of 0.4 mu g L-1 for both Cr(III) and Cr(VI) with a pre-concentration factor of 25 was 2.96% and 4.06%, respectively. The accuracy of the method was confirmed by analysis of the standard reference material SRM 1643e Trace Elements in Water &. The proposed technique is simple, sensitive, environmentally friendly, and the risk of contamination is low. Hence, it was successfully applied to spiked synthetic and real water samples with recoveries ranging from 91.3% to 109.2%
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