Keywords
azide
spectrophotometry
complexes
How to Cite
Abstract
A sensitive and alternative method for the spectrophotometric determination ofchromium(III) based on the formation of chromium(III)/azide complexes was established by
investigating a new band in the ultraviolet region. The best experimental conditions for the analytical
determination of this metallic ion were: ligand and perchloric acid analytical concentration = 493 and
12.0 mmol L -1 , respectively; aqueous medium; T = 25.0 oC; contact time = 1 hour. The maximum
molar absorptivity coefficient occurred at 287 nm (average 1.481 ± 0.008 × 10 4 L mol -1 cm -1 ), leading
to the determination of metal ion concentrations one hundred times lower than the ones formerly
determined in the visible region. The system obeys Beer’s Law and is suitable for chromium
determination in the 0.702-2.81 mg L -1 concentration range (15-65% T, 1.00 cm-width quartz cells).
Analytical applications of the current method were tested with a nutritional supplement containing
chromium. Results were compared with those obtained with atomic absorption spectrometry.
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