Catanionic mixed micellar cloud point extraction of metal ions in coal fly ash samples and their determination by CS-ETAAS

Abstract

The catanionic mixed micellar cloud point extraction for the simultaneous pre-concentration and determination of different analytes in coal fly samples with Cetyltrimethylammonium bromide (CTAB) and Sodium dodecyl sulfate (SDS) mixed micelles using continuum source electro thermal atomic absorption spectrometry (CS-ETAAS) has been demonstrated. The negative complexes formed by analytes with both chloride ions and negative surfactant SDS are converted into ion pair complexes with positive surfactant and then extracted. This method is rather simple and efficient for the simultaneous extraction and determination of various analytes in a coal fly ash sample using catanionic mixed micelles, which also avoids the microwave digestion of the samples prior to their determination by CS-ETAAS and uses only HCl as well as ultrasonication. The limits of detections (LODs) calculated based on three times the standard deviation of the ten measurements of the procedural blanks of Cd, Bi, Tl, Pt, Au and Ag were found to be 0.001588, 0.02646, 0.01446, 0.18807, 0.07832 and 0.08529 ng mL–1, respectively. The pre-concentration factor and phase volume ratio of the method were found to be 14.3 and 0.075 respectively. The recoveries were found to be in between 100 and 104% with relative standard deviation range of 2–5%. The accuracy of the proposed procedure was validated by analyzing the certified reference materials such as constituent elements of coal fly ash NIST 1633b and this method has been successfully applied for the determination of analytes in real coal fly ash samples.