[Spectrophotometric study on the interaction of acridine orange and heparin]

The interaction of acridine orange (AO) and heparin was studied by spectrophotometry. In the pH 2. 0 Britton-Robinson (B-R) buffer solution, AO had a maximum absorption at 478 nm and 492 nm. After the addition of heparin, the absorbance value at 492 nm decreased greatly and a new absorption peak at 453 nm appeared, indicating a strong interaction taking place in the reaction solution. Under the optimal condition, the decrease in absorbance at 492 nm was linear with the concentration of heparin in the range of 3. 0-15.0 mg m L(-1). The m olar absorptivity w as calculated to be E=l. 599X 10(5) L mol(-1) x cm(-1) and the detection limit was 0. 236 mg x L(-1) (3sigma). The method was furthur applied to the detection of heparin sodium injection samples with satisfactory results. The binding number was calculated to be 1 : 3 with molar ratio method.