Micelle mediated extraction of cadmium from water and tobacco samples with glyoxal-bis(2-hydroxyanil) and determination by electrothermal atomic absorption spectrometry

Abstract

The purpose of this article is to combine cloud point extraction (CPE) with electrothermal atomic absorption spectrometry (ETAAS) for determining cadmium in water and tobacco samples. This developed method is based on the colour reaction of cadmium with glyoxal-bis (2-hydroxyanil) (GBHA) in sodium hydroxide-sodium tetraborate buffer media and mixed micelle-mediated extraction of complex. The cadmium was extracted as Cd-GBHA complex, at pH 12.4 +/- 0.2 mediated by micelles of the non-ionic surfactant Triton X-114 and anionic SDS. The incubation step is not necessary for the separation of the phases. The phase separation was observed at room temperature using TX-114/SDS/NaCl system. The optimal micellar extraction and reaction conditions (e.g., surfactant concentration, reagent concentration, effect of time) were studied and the analytical characteristics of the method (e. g., limit of detection, linear range and preconcentration factor) were obtained. Linearity was obeyed in the range of 0.02 to 0.4 mu g L(-1) of cadmium ion and the detection limit of Cd with ETAAS was 7 ng L(-1). After optimising extraction conditions, a preconcentration factor of 22 was obtained for a sample of only 10 mL and the relative standard deviation (n = 5; C = 0.2 mu g L(-1)) was 2.3%. The interference effect of some anions and cations was also tested. The method was applied to the determination of Cd in tap (after standard addition), lake, seawater and tobacco samples, and validated by analysis of a geological sample.