SOLVENT-EXTRACTION OF CADMIUM AS A PREVIOUS STEP FOR ITS DETERMINATION IN BIOLOGICAL SAMPLES BY ELECTROTHERMAL ATOMIZATION ATOMIC-ABSORPTION SPECTROMETRY

A method is proposed for the solvent extraction of cadmium using 1,5-b is(di-2-pyridyl-methylene)thiocarbohydrazide (DPTH) as extractant. The optimum extraction conditions were evaluated from a critical study of the effect of pH, concentration of extractant, shaking time and ionic strength. The maximum volume ratio of the aqueous to organic phase wa s 30:1 for a single-stage extraction of 99-100% of the metal ion. The detection limit is 0.01 ng/ml cadmium, and the calibration is linear f rom 0.1 to 5 ng/nil. The relative standard deviation for 10 replicate measurements is 1.8% for 2 ng/ml cadmium. The extraction method was ap plied to the determination of cadmium in some biological materials usi ng graphite furnace atomic absorption spectrometry.