Combination of Ultrasonic-Assisted Cloud Point Extraction with Flame AAS for Preconcentration and Determination of Trace Amounts of Silver and Cadmium in Dried Nut and Vegetable Samples

摘要

In this article, ultrasonic-assisted cloud point extraction (UA-CPE) was used to the preconcentration of trace Ag(I) and Cd(II) in dried nut and vegetable samples. After ion association of Ag(I) and Cd(II) ions with 3,7-diamino-2,8-dimethyl-5-phenyl-phenaziniumchlorid (Safranin T) in the presence of excess potassium iodide (KI) at pH 6.0, the ternary complexes formed were quantitatively extracted into a micellar phase of poly(ethyleneglycol-mono-p-nonylphenylether) (PONPE 7.5) and then determined by flame atomic absorption spectrometry (FAAS). The matrix effects of possible some interfering ions on the method recovery and tolerance limits were also investigated. Under the optimized reagent conditions, the method was linearly dependent on the analyte concentrations in the range of 0.08-90 and 3-250 mu g L-1 with limits of detection of 0.02 and 0.9 mu g L-1 for Ag(I) and Cd(II), respectively. The reproducibility as the percent relative standard deviations (RSDs %) (0.5, 5.0, and 25 mu g L-1 for Ag(I) and 15, 30, and 100 mu g L-1 for Cd(II), n = 6) was lower than 3.6 % for both analytes. The accuracy of the method was controlled by analysis of two certified samples (SRM 1573a Tomato leaves and SRM 1643e Trace elements in waters) as well as recovery studies from spiked samples. It has been observed that the results obtained are in a good agreement with the certified values at confidence interval of 95 %. The method was successfully applied to determination of Ag(I) and Cd(II) in several dried nut and vegetable samples by FAAS after separation/preconcentration with UA-CPE.