OpenLB
Open Library of Bioscience

In acetate buffer solution and in the presence of glucose oxidase (GOD), glucose reduced the dissolved oxygen to form H2O2 that oxidized catalytically the excess KI to from I3- by horseradish peroxidase (HRP). The I3- combines respectively with rhodamine S (RhS), rhodamine 6G(Rh6G), butyl-rhodamine B(b-RhB) and rhodamine B(RhB) to form RhS-I3, Rh6G-I3, b-RhB-I3 and RhB-I3 associated particles that result in fluorescence quenching at 556, 556, 584 and 584 nm, respectively. Under the optimal conditions, the concentration of glucose in the range of 0.083-9.99, 0.17-8.33, 0.33-8.33 and 0.33-9.99 micromol x L(-1) is linear with their fluorescence quenching at 556, 556, 584 and 584 nm, with detection limits of 0.059, 0.17, 0.21 and 0.16 micromol x L(-1) glucose. And the regression equation was deltaF = 40.0c + 3.0, deltaF = 23.9c + 8.1, deltaF = 25.6c + 4.2, and deltaAF = 18.4c + 0.8, respectively. The RhS system was the most sensitive and stable, and was chosen for use. Influence of some foreign substances on the RhS fluorescence quenching determination of 6.67 micromol x L(-1) glucose was examined, with a relative error of +/- 10%. Results showed that 1000-fold Mg2+ and Cu2+, 300-fold Mn2+, 100-fold Zn2+, Al3+ and Co2+, 60-fold L-tyrosine, urea and nicotinic acid, 50-fold Fe3+, HSA and BSA, 10-fold sucrose, vitamin B2, L-lysine, L-glutamic acid and L-cystine did not interfere with the determination. This RhS fluorescence quenching assay was applied to the determination of glucose in the serum samples with satisfactory results.