title: Multielement determination of cadmium and lead in urine by simultaneous electrothermal atomic absorption spectrometry with an end-capped graphite tube.
abstract: A method for the multielement determination of cadmium and lead in urine is proposed by simultaneous electrothermal atomic absorption spectrometry (SIMAAS) with an end-capped transversely heated graphite atomizer (EC-THGA). The best conditions for cadmium and lead determination were obtained in the presence of NH4H2PO4 as a chemical modifier, using 500 degrees C and 1800 degrees C as the pyrolysis and atomization temperatures, respectively. Urine samples were diluted 1 + 4 directly in autosampler cups with a mixture of 0.125% (w/v) Triton X-100 + 2.5% (v/v) HNO3 + 0.31% (w/v) NH4H2PO4. The optimized heating program was carried out in 57 s, and the instrument calibration was done with aqueous reference solutions. The use of EC-THGA increased the sensitivity of cadmium and lead by 14% and 25%, respectively. The detection limits (n = 20, 3delta) were 0.03 microg L(-1) (0.36 pg) for cadmium and 0.57 microg L(-1) (6.8 pg) for lead. The performance of EC-THGA was acceptable up to 500 heating cycles. The reliability of the entire procedure was checked with the analysis of a lyophilized urine certified reference material. The found concentrations were in agreement with the recommended values (95% confidence level).
authors.affiliation: Instituto de Química, Universidade de São Paulo, C. P. 26077, CEP 05513-970, São Paulo, SP, Brasil.
authors.forename: Paulo R M
authors.initials: PR
authors.lastname: Correia
authors.forename: Cassiana S
authors.initials: CS
authors.lastname: Nomura
authors.forename: Pedro V
authors.initials: PV
authors.lastname: Oliveira
mesh_terms: D002104:Cadmium / Q000592:standards / Q000652:urine*; D006358:Hot Temperature; D006801:Humans; D007854:Lead / Q000592:standards / Q000652:urine*; D008274:Magnesium / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D015203:Reproducibility of Results; D013054:Spectrophotometry, Atomic / Q000295:instrumentation / Q000379:methods
chemical_list: D010710:Phosphates; C024788:ammonium phosphate; D002104:Cadmium; D007854:Lead; D008274:Magnesium