Amperometric glutathione sensors based on hydrogen peroxide or Clark-type oxygen electrodes, coupled with a novel enzyme glutathione oxidase, have been assembled and analytically evaluated. Calibration curves were linear in the range 5 x 10(-6) to 10(-3) m for the H2O2-based probe and 10(-5) to 2 x 10(-4) M for the oxygen probe. When the glutathione analysis was carried out using the O2-based probe, a flow-through system was used to maintain better control over the oxygen content of the sample. Temperature, pH and selectivity studies were carried out and optimized. Stability studies of the enzyme electrode showed an enzyme lifetime of one month, with more than 200 analyses performed. The precision of both sensors was tested by making 20 measurements of glutathione in phosphate buffer, pH 6.5. Results showed relative standard deviations of 4-6% and 4.1%, respectively. The response time for both electrodes was one or two minutes, depending on the blocking membrane used. The analysis of glutathione in human erythrocytes has been carried out using the 02-based probe and the flow-through system. Results were in agreement with those reported in the literature.[...]
AMPEROMETRIC GLUTATHIONE ELECTRODES
COMPAGNONE, DARIO;
1993-01-01
Abstract
Amperometric glutathione sensors based on hydrogen peroxide or Clark-type oxygen electrodes, coupled with a novel enzyme glutathione oxidase, have been assembled and analytically evaluated. Calibration curves were linear in the range 5 x 10(-6) to 10(-3) m for the H2O2-based probe and 10(-5) to 2 x 10(-4) M for the oxygen probe. When the glutathione analysis was carried out using the O2-based probe, a flow-through system was used to maintain better control over the oxygen content of the sample. Temperature, pH and selectivity studies were carried out and optimized. Stability studies of the enzyme electrode showed an enzyme lifetime of one month, with more than 200 analyses performed. The precision of both sensors was tested by making 20 measurements of glutathione in phosphate buffer, pH 6.5. Results showed relative standard deviations of 4-6% and 4.1%, respectively. The response time for both electrodes was one or two minutes, depending on the blocking membrane used. The analysis of glutathione in human erythrocytes has been carried out using the 02-based probe and the flow-through system. Results were in agreement with those reported in the literature.[...]I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
