Comparison of a Biosensor and a Commercial UV-Visible Method for Measuring Hexavalent Chromium in Liquid Medium

Abstract

The objective of the research was to contrast two methods for the quantification of hexavalent chromium. The first method is the biosensor that from the gene transformation of the cells of Escherichia coli, was incorporated by electroporation the plasmid pTOP Blunt V2, synthesized with luxA genes that provides luminescence through the catalytic activity of the luciferase top and chr genes that give the bacteria resistance to chromium. The second method is the application of the UV-visible colorimetric technique. Chromium was analysed at different concentrations, from 0.05 mg l−1 (maximum allowable limit for human consumption); 0.1 mg l−1; 0.2 mg l−1; 0.4 mg l−1; 0.8 mg l−1 and 1 mg l−1 with 5 replicates, subsequent to this, the two methods of chromium analysis were applied in river samples, thus obtaining that the biosensor in concentrations of 2x106 CFU of E. coli, has a margin of error of 1.4%, a result derived from the coefficient of determination of the absorbance of chromium, unlike the UV-visible method with the colorimetric equipment, which presented a reading error of 3.9%.