Application of Ultrasound-assisted Cloud-point Extraction and Spectrophotometry for Preconcentration and Determination of Trace Amounts of Copper(II) in Beverages

Resumo

A new method for preconcentration of trace Cu(II) in beverages before determination by spectrophotometry is presented. The method is based on the ternary complex formation of Cu(II) with Safranin T in presence of pyrogallol at pH 5.5 followed by its extraction into the micellar phase of Triton X-114. The ternary complex was monitored by spectrophotometry at 532 nm. Variables affecting extraction efficiency were evaluated and optimized. Under the optimal conditions, the detection limit was 0.6 µg/L in the range of 2–300 µg/L with sensitivity enhancement of 55 after preconcentration from 15 mL of the sample, and precision was in the range of 2.5–3.9%. The accuracy was verified by the analysis of two certified samples and recovery studies of the spiked samples. The intra- and inter-day precision varied in the ranges of 3.7–4.6 and 3.9–5.2%, respectively. The method was successfully applied to determination of trace Cu(II) in beverages.