Determination of Trace Copper in Food and Beverage by Flame Absorption Spectrometry-Cloud Point Extraction

A new method for determination of trace copper in food and beverage samples by flame atomic absorption spectrometry combined with cloud point extraction was developed.The cloud point extraction system was based on Triton X-114 as surfactant and sodium diethyldithiocarbamate (DDTC) as chelating agent.The parameters affecting cloud point extraction,including pH,dosage of Trion X-114,concentration of DDTC,extraction temperature and time were investigated and optimized.It was found that under optimized test conditions,a detection limit (3σ) of 1.55 μg/L,relative standard deviation of 3.4% (n = 7,c = 100 μg/L),and linear scope of 0～250 μg/L were reached.The proposed method was successfully applied to determine trace copper in tea certified reference sample (GBW07605),milk powder and mineral water,with recovery being 96.7%～113.5%.