Flow-injection system with glucose oxidase immobilized on a tubular reactor for determination of glucose in blood samples

A spectrophotometric method for the determination of glucose in blood sample is proposed. This method is based on selective oxidation of β-d-glucose to d-gluconate and hydrogen peroxide using an on-line tubular reactor containing glucose oxidase immobilized on Amberlite IRA-743 resin. The hydrogen peroxide, in the presence of phenol, 4-aminoantipyrine and peroxidase, produces a red compound (λmax = 505 nm). Beer's law is obeyed in a concentration range of 10-100 μmol/L glucose with an excellent correlation coefficient (r = 0.9991), at pH 6.5, with a relative standard deviation (R.S.D) < 3%. The flow rate of 2.0 mL/min and injecting 200 μl sample volumes was adopted. The detection limit of the method is 5.7 μmol/l. Rectors prepared, presented high stability for at last 1 week under intense use in flowing solutions. The results show a simple, accurate, selective and readily applied method to the determination of glucose in blood sample. The analytical results obtained for these products by the proposed method are in agreement with those of obtained by the classical the spectrophotometric method with enzyme, free in solution.