Direct determination of bismuth in urine samples by electrothermal atomic absorption spectrometry: study of chemical modifiers

Abstract

In this work the performance of some chemical modifiers (no modifier, Pd 1 Mg, Ir in solution, Ru, Ir or Zr independently as permanent modifier and Ir 1 Rh permanent) was investigated for the direct determination of Bi in human urine by electrothermal atomic absorption spectrometry (ETAAS). The urine samples were diluted directly in the autosampler cups with one-fold dilution with nitric acid 1% v/v. The obtaining of the permanent modifiers (500 mg of iridium, ruthenium and zirconium independently and 250 mg of Ir plus 250 mg of rhodium) was described elsewhere. Without modifier at all temperatures the signal was negative with a high background. Using Pd 1 Mg the best temperatures were of 1000 and 2500 uC, respectively, for pyrolysis and atomization, but the sensitivity was half that when using Ir 1 Rh. Using ruthenium, iridium or zirconium independently no peak was obtained but a plateau that did not return to baseline even in 15 s of atomization. With iridium applied in solution together with the sample the best pyrolysis and atomization temperatures were of 900 and 2500 uC, respectively, but the sensitivity was analogous with that obtained using Pd 1 Mg. Using Ir 1 Rh, the optimum pyrolysis and atomization temperatures were lower (900 and 1400 uC), but in this case the best sensitivity was obtained with a characteristic mass of 29.2 pg (recommended of 30 pg for the manufacturer for the metal in aqueous solutions). With this modifier, the obtained peak was very symmetrical, returning to the baseline in 3 s with very low background. The use of low temperatures and a low time of atomization coupled to the use of permanent modifer will certainly extend the lifetime of the graphite tube. Aqueous calibration curves and standard addition were parallel with slopes of 0.042 and 0.044 for aqueous and standard addition, respectively. For this reason, the calibration was carried out with aqueous solutions. The r values of calibration curves were higher than 0.99. Spiked urine samples with 5.0, 10.0, 15.0, 20.0, 25.0 and 30.0 mg l 21 , analysed on different days, presented a recovery between 80.0 and 100.0%. The limit of detection was 50 pg. The lifetime of the tube was more than 500 cycles of atomization.

Comparative efficacy of platinum group metal modifiers in electrothermal atomic absorption spectrometry

“…For the determination of bismuth in urine [51], the performance differences amongst chemical modifiers studied were much more pronounced. With the use of regular modifiers (Ir, Pd+Mg), pyrolysis and atomization temperatures for bismuth were 900-1000 and 2500 8C, respectively.…”

“…Elimination of matrix interferences (pyrolysis temperature for bismuth was 900 8C) allowed determination of bismuth in 1+1 diluted urine samples with calibration using aqueous standard solutions. A very low optimum atomization temperature (1400 8C) resulted in a rather long graphite tube lifetime (more than 500 determinations) [51].…”

Pre-concentration procedure using dispersive liquid–liquid microextraction for the determination of bismuth by flame atomic absorption spectrometry

“…The use of bismuth and its compounds is increasing, even though this element is known to be toxic for humans, animals and plants. [3][4][5] Although intestinal absorption of bismuth is limited in humans, because of its low solubility and its propensity to form insoluble oxychloride salts, absorption is certain to occur, and this produces measurable concentrations in body fluids and tissues. 6 As the use of bismuth in medicine increases, it has spread in the environment and the chance of exposure of organisms to bismuth has increased and a number of toxic effects in humans have been attributed to bismuth compounds.…”

Development and validation of methods for the determination of copper and iron in serum of dogs with canine visceral Leishmaniasis using multivariate optimization and GF AAS

“…The diluent was selected as described by Pinto et al 24 in human serum and based on the results obtained for Bi, Cr and Al determinations in human serum samples. [27][28][29] Multivariate optimization…”