Methodology for preconcentration and determination of silver in aqueous samples using cloud point extraction

Abstract

For the selective extraction of silver, a cloud point extraction (CPE) procedure was developed. After synthesizing the solvation species through the reaction of silver ions with 2, 4-dimethyl pentane-3-one (2,4 DMP), the salting-out agent (0.4 mol L-1 NaNO3) was added at 35 °C and, after 10 min, Triton X-114 was used to separate silver ions from aqueous solution. The type and quantity of salting-out agent, silver ion, temperature, heating time, and surfactant volume were all examined as important factors determining the CPE. The analytical curve in the 0.1-100 μg L-1 Ag range was straight at optimal conditions. The detection limit (LOD), quantification limit (LOQ), and enrichment factor (E) were 0.05 μg L-1, 0.15 μg L-1, and 200, respectively. The relative standard deviation (RSD) was estimated as 0.2-3.9% (n = 5) in relation to 1, 40, and 80 μg L-1 Ag. Flame atomic absorption spectrometry and spectrophotometry exploiting dithizone were used to assess the CPE accuracy. The proposed approach was then applied to river water, rain water and sand samples.