Flow injection determination of bismuth in urine by successive retention of Bi(III) and tetrahydroborate(III) on an anion-exchange resin and hydride generation atomic absorption spectrometry.
Bismuth as BiCl(4)(-) and BH(4)(-) ware successively retained in a column (150mm x 4mm, length x i.d.) packed with Amberlite IRA-410 (strong anion-exchange resin). This was followed by passage of an injected slug of hydrochloric acid resulting in bismuthine generation (BiH(3)). BiH(3) was stripped from the eluent solution by the addition of a nitrogen flow and the bulk phases were separated in a gas-liquid separator. Finally, bismutine was atomized in a quartz tube for the subsequent detection of bismuth by atomic absorption spectrometry. Different halide complexes of bismuth (namely, BiBr(4)(-), BiI(4)(-) and BiCl(4)(-)) were tested for its pre-concentration, being the chloride complexes which produced the best results. Therefore, a concentration of 0.3moll(-1) of HCl was added to the samples and calibration solutions. A linear response was obtained between the detection limit (3sigma) of 0.225 and 80mugl(-1). The R.S.D.% (n = 10) for a solution containing 50mugl(-1) of Bi was 0.85%. The tolerance of the system to interferences was evaluated by investigating the effect of the following ions: Cu(2+), Co(2+), Ni(2+), Fe(3+), Cd(2+), Pb(2+), Hg(2+), Zn(2+), and Mg(2+). The most severe depression was caused by Hg(2+), which at 60mgl(-1) caused a 5% depression on the signal. For the other cations, concentrations between 1000 and 10,000mgl(-1) could be tolerated. The system was applied to the determination of Bi in urine of patients under therapy with bismuth subcitrate. The recovery of spikes of 5 and 50mugl(-1) of Bi added to the samples prior to digestion with HNO(3) and H(2)O(2) was in satisfactory ranges from 95.0 to 101.0%. The concentrations of bismuth found in six selected samples using this procedure were in good agreement with those obtained by an alternative technique (ETAAS). Finally, the concentration of Bi determined in urine before and after 3 days of treatment were 1.94 +/- 1.26 and 9.02 +/- 5.82mugl(-1), respectively.
Carrero
Pablo
P
Faculty of Sciences, University of Los Andes, IPOSTEL La Hechicera, P.O. Box 68, Mérida 5101-A, Venezuela.
Gutiérrez
Luis
L
Rondón
Carlos
C
Burguera
José Luis
JL
Burguera
Marcela
M
de Peña
Yaneira Petit
YP