Determination of Cr(VI) and Cr(III) species in parenteral solutions using a nanostructured material packed-microcolumn and electrothermal atomic absorption spectrometry

MONASTERIO, R.P.; LASCALEA, G. E.; MARTÍNEZ, L. D.; WUILLOUD, R. G.

JOURNAL OF TRACE ELEMENTS IN MEDICINE AND BIOLOGY

Elsevier

Año: 2009 vol. 23 p. 157 - 166

0946-672X

In the present work, a sequential preconcentration and speciation on line of Chromium was performed. For this purpose, a micro column packed with a nanocrystalline a-alumina powder coupled with a graphite furnace Atomic Absorption Spectrometer for analysis water samples was used. This method involves the selective elution of Cr(VI) with ammonium and of Cr(III) with nitric acid. By using this device, diverse advantages are attained: (a) Speciation and preconcentration in one step, (b) Low use of reactive and low waste generation, and (c) Increase of the sensitivity by preconcentration. The procedure was optimized for some analytical parameters including pH, eluent type, flow rates of sample and eluent, interfering effects, etc. The preconcentration factors for Cr(VI) and Cr(III) were found as 41 and 13 respectively. The limit of detection (LOD, 3s), was 1.9 ng L-1 for Cr(VI) and 6.1 ng L-1 for Cr(III). The calibration graph was linear with a correlation coefficient of 0.999 at levels near the detection limit and up to at least 26.0 g L-1 and 36.7 g L-1 for Cr(VI) and Cr(III) respectively. The relative standard deviation (RSD) was 8.6% (c= 10 g L-1, n= 10, sample volume= 25 mL). Verification of the accuracy was carried out by analysis of a standard reference material (NIST SRM 1643e ?Trace elements in natural water?). The method was successfully applied to the determination of Cr(VI) and Cr(III) species in drinking water samples.