Effectiveness of Palladium–Sodium Azide Modifier for the Direct Determination of Urinary Cadmium by Graphite-Furnace Atomic Absorption Spectrometry

A combination of palladium and sodium azide is proposed as a mixed modifier for cadmium determination in urine by graphite-furnace atomic absorption spectrometry using calibration against matrix-free standard solutions. It permits the use of a pretreatment temperature of 900–1000°C and markedly reduces the background absorption caused by inorganic salt matrices. The urine was simply diluted 1+1 with the addition of 1% HCl, Pd and NaN3. The recovery of cadmium obtained from urine was higher than 95%. The relative standard deviation at a cadmium level of 2.10–4.56 µg l-1 was smaller than 4%. The detection limit (3 s, n=20) is 0.16 µg l−1 of cadmium.