A highly sensitive procedure for determination of ultra trace amounts of molybdenum by graphite furnace atomic absorption spectrometry after dispersive liquid-liquid microextraction

A simple, rapid and sensitive method is developed for selective determination of ultra trace amounts of molybdenum(VI) from different water samples. The method is based on highly efficient separation and pre-concentration of molybdenum(VI) by dispersive liquid-liquid microextraction followed by its determination with graphite furnace atomic absorption spectrometry. Ultra traces of the target ion were extracted and pre-concentrated from acidic water samples by using sodium diethyldithiocarbamate as a suitable chelating agent, and carbon tetrachloride and acetone as extraction and disperser solvents, respectively. After optimizing different parameters, including type and volume of extraction and disperser solvents, pH of test solution, extraction time, volume and concentration of the chelating agent and sample volume, an enrichment factor of 362 was obtained. The linear concentration range, limit of detection and relative standard deviation of the method were evaluated as 0.04-0.8 ng mL(-1), 0.007 ng mL(-1) and 4.5%, respectively. This method was applied successfully to the determination of molybdenum in tap water and wastewater samples.