Development of a Disposable Screen Printed Amperometric Biosensor Based on Glutamate Dehydrogenase, for the Determination of Glutamate in Clinical and Food Applications

A screen printed carbon electrode (spce) containing the electrocatalyst meldola’sblue (mb) has been investigated as the base transducer for a glutamate biosensor. thesandwich biosensor was fabricated by firstly depositing a chitosan (chit) layer onto thesurface of the transducer (mb-spce), followed by glutamate dehydrogenase (gldh): thisdevice is designated gldh-chit-mb-spce. nad+ was added to buffer solutions prior tothe measurement of glutamate. this biosensor was used in conjunction with amperometry instirred solution at an applied potential of +0.1 v (vs. ag/agcl). optimum conditions for theanalysis of glutamate were found to be as follows: temperature, 35 °c; buffer, ph 7; ionicstrength, 75 mm; nad+, 4 mm; chit 0.05% in 0.05 m hcl; gldh, 30 u. the linear rangeof the biosensor was found to be 12.5 ?m to 150 ?m, the calculated limit of detection (basedon three times signal to noise) was 1.5 ?m and the sensitivity was 0.44 na/?m. the proposedbiosensor was used to measure glutamate in serum before and after fortification withglutamate. the endogenous concentration of glutamate was found to be 1.68 mm and thecoefficient of variation (cv) was 4.1%. the serum was then fortified with 2 mm ofglutamate, and the resulting mean recovery was 96% with a cv of 3.3% (n=6). an unfilteredbeef oxo cube was analysed for monosodium glutamate (msg) content. the endogenouscontent of msg was 125.43 mg/g with a cv of 8.98%. the oxo cube solution was fortifiedwith 0.935 g (100 mm) of glutamate, the resulting mean recovery was 91% with a cv of6.39%.