Determination of mercury(ii) by invertase enzyme inhibition coupled with batch injection analysis

Abstract

The determination of mercury(II) ions at the trace level by inhibition of the invertase enzyme-catalysed hydrolysis of sucrose into glucose and fructose coupled to electrochemical batch injection analysis was investigated using two approaches. In the first, the glucose produced was detected by injection of 100 microliters samples into the batch injection cell containing a platinum electrode modified by immobilised glucose oxidase. In the second, the glucose and fructose present in injected samples were oxidised directly at a copper-modified glassy carbon electrode. The experimental parameters were optimised and the degree of enzyme inhibition by mercury(II) ions under both conditions was measured. Mercury concentrations in the ng ml-1 range were determined by these two techniques with low sample and reagent consumption. Comparison is made between the two methods and perspectives as a screening test for field application are indicated.

Enzyme inhibition-based biosensors for food safety and environmental monitoring

“…These results confirm those obtained with the free enzyme, i.e. that a higher percentage of inhibition is often observed with lower enzyme concentration (Evtugyn et al, 1998;Mohammadi et al, 2002 and thus a low enzyme concentration should in general enhance sensitivity to the inhibitor.…”

Batch Injection Analysis: An Almost Unexplored Powerful Tool

“…Thinfilm gold electrodes were utilized for hydrogen peroxide quantification [27] and subsequently the same magnetron sputtered gold films were used for the construction of a biosensor for glucose, coupled with batch injection analysis [28]. An invertase biosensor was utilized for the indirect amperometric quantification of mercury, based on the enzyme inhibition [29]. Carbon paste electrodes modified with zeolites and methyl viologen were used for indirect determination of mono and divalent cations [30] and the use of enzymes, tissues and cells incorporated in carbon paste was discussed by Gorton [31].…”

A Fast and Direct Amperometric Determination of Hg2+ by a Bienzyme Electrode Based on the Competitive Activities of Glucose Oxidase and Laccase

“…7.4 10 À6 M) [16] but remained inferior to those of conventional biosensors based on mercury inhibition [5,20,21], especially the high value of I 50 . However, it should be noted that the I 50 obtained with the bienzyme electrode is an apparent value due to the combination of mass transport, enzyme kinetics, matrix and immobilization effects [22].…”