Off-line determination of trace silver in water samples and standard reference materials by cloud point extraction-atomic absorption spectrometry

An off-line method for the determination of trace silver in water samples and certified reference materials by cloud point extraction (CPE) followed by flame atomic absorption spectrometry (FAAS) has been worked out. Preconcentration of CPE was based on complex formation of silver with dithizone in the presence of non-ionic micelles of octylphenoxy polyethoxy ethanol (Triton X-114) at pH 4.0. Optimization was performed on the variables influencing complexation and phase separation. The detection limit of silver in certified samples was 1.42 ng mL(-1), the quantification limit was 4.72 ng mL(-1), and precision expressed as relative standard deviation was 2.2% (n = 3, for silver concentration of 50 ng mL(-1)). The method was applied for the determination of trace silver in certified reference materials with satisfactory results.