Hydride generation atomic absorption spectrometry using a flow injection system by merging zones has been used successfully to determine selenium at the ultra trace level. The detection limit was 0.3 ng mL-1, corresponding to 30 pg of selenium and sample throughput of 140 samples per hour was obtained. The precision (r.s.d.) for determination of 1.0 ng mL-1 of selenium is 2.0%. Reagent consumption (0.5 mg of NaBH4 per determination) and waste generation is low. The application of the developed methodology to the analysis of urine samples evidenced the presence of 4.0 ng mL-1 of selenium for patients without administration of drugs containing selenium. For patients with administration of drugs containing selenium, the selenium concentration in the analyzed urine samples was 5.0 ng mL-1 until 16.0 ng mL-1 level. Recovery of selenium from two samples ranged from 90.0 to 103.0%. The method was validated by analyzing with the standard reference material SRM 2670 urine (certified value: 30.0±8.0 ng mL-1 and obtained value: 27.0±2.0 ng mL-1).
selenium; ultra trace; flow injection; hydride generation; urine
