[Determination of vitamin B12 concentration by fluorescence quenching with acridine orange-rhodamine 6G energy transfer system].

An energy transfer technique between acridine orange (AO) and rhodamine 6G (R6G) was studied, and the optimum experimental conditions of energy transfer were defined. It was found that the effective energy transfer could occur between AO and R6G in the dodecylbenzene sodium sulfonate solution with Na2 HPO4-citric acid buffer solution at pH 5.0. The fluorescence intensity of AO-R6G system was diminished by vitamin B12 in an alkalescence medium. Based on the AO-R6G energy transfer system anovel fluorescence quenching method for the determination of vitamin B12 has been developed. Under optimal conditious, the linear range of calibration curves for the determination of vitamin B12 was 0-3.0 x 10(-5) mol x L(-1). The detection limits were 4.8 x 10(-7) mol x L(-1) for Vitamin B12. Among six times of determination, the relative standard deviation was 0.51%-0.64%, and the recovery was 98.40% -103.62%. The method features good recurrence, rapidity of reaction, good stability, and few interfering substances. It can be satisfactorily used in the determination of the injection content of vitamin B12.