Analytical Sciences

Abstract − Analytical Sciences, 27(4), 439 (2011).

Inorganic Arsenic Speciation in Groundwater Samples Using Electrothermal Atomic Spectrometry Following Selective Separation and Cloud Point Extraction
Jameel A. Baig, Tasneem G. KAZI, Mohammad B. ARAIN, Abdul Q. SHAH, Ghulam A. KANDHRO, Hassan I. AFRIDI, Sumaira KHAN, Nida F. KOLACHI, and Sham K. WADHWA
Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080, Pakistan
A method has been developed for speciation of total, total inorganic and organic arsenic (As) species in groundwater samples. The inorganic species of As(III,V) were separated from organic forms by adsorbing on alumina (Al2O3) whereas the organic As was eluted out. The retained inorganic As species was eluted by 0.2 M HCl. Then eluent AsIII and AsV were formed as complexes with ammonium pyrrolidinedithiocarbamate (APDC) and molybdate, respectively. Then AsIII-PDC and AsV-molybdate complexes were quantitatively extracted into a non-ionic surfactant Triton X-114. The total As was determined by conventional preconcentration procedures. The resulting solutions of each method were determined by ETAAS with modifier. The main factors affecting the separation and cloud point extraction (CPE) were investigated in detail. The limits of detection values were found as 0.04 and 0.20 μg L−1 for AsIII and AsV, respectively, whereas limits of quantification were observed as 0.13 and 0.33 μg L−1 for AsIII and AsV, respectively. Standard addition method confirmed the accuracy. The recoveries of AsIII and AsV were found in the range of 98 – 99%. The proposed method was applied to groundwater samples collected from different areas of Sukkur district.