Dispersive liquid–liquid microextraction combined with graphite furnace atomic absorption spectrometry: Ultra trace determination of cadmium in water samples Original Research Article

Dispersive liquid–liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 μL methanol (disperser solvent) containing 34 μL carbon tetrachloride (extraction solvent) and 0.00010 g ammonium pyrrolidine dithiocarbamate (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with ammonium pyrrolidine dithiocarbamate, and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25 ± 1 μL). Then a 20 μL of sedimented phase containing enriched analyte was determined by GF AAS.