Analytical Sciences

Determination of Menadione Sodium Bisulfite in Pharmaceutical Preparations by Flow-Injection On-line Photochemical Spectrofluorometry

Qiaohong HE, Zhixin WANG, Xiaoxia CAO, Hengwu CHEN,  and Yinfen KE

Department of Chemistry, Zhejiang University, Xixi Campus, Hangzhou 310028, P. R. China

A flow-injection on-line photochemical spectrofluorometry (FI-PF) was developed for the determination of menadione sodium bisulfite (MSB) using acetone and sodium sulfite as sensitizing reagents. An injected sample band carried by a water stream was on-line merged with a mixed NaOH, Na₂SO₃ and acetone solution in a "T" connector. It was then driven to pass a knotted PTFE photochemical reactor (0.5 mm i.d. x 200 cm, KR) that was freely coiled around a 6-W low-pressure mercury lamp. While passing the KR, MSB was derived into an intensively fluorescent compound that was on-line delivered into a flow-through cell and detected therein at an emission wavelength of 459 nm and an excitation wavelength of 336 nm. Under optimized conditions a detection limit of 0.38 ug l^-1 was achieved at a sampling rate of 90 h^-1. Eleven determinations of 0.5 mg l^-1 and 0.05 mg l^-1 MSB standard solution gave RSDs of 0.75% and 1.3%, respectively. The calibration curve was linear in the MSB concentration range 0.005 - 1.5 mg l^-1. The proposed method was successfully applied to assay the MSB content in MSB injection.

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