Determination of menadione sodium bisulfite in pharmaceutical preparationsby flow-injection on-line photochemical spectrofluorometry

A flow-injection on-line photochemical spectrofluorometry (FI-PF) was devel oped for the determination of menadione sodium bisulfite (MSB) using aceton e and sodium sulfite as sensitizing reagents. An injected sample band carri ed by a water stream was on-line merged with a mixed NaOH, Na2SO3 and aceto ne solution in a "T" connector. It was then driven to pass a knotted PTFE p hotochemical reactor (0.5 mm i.d. x 200 cm, KR) that was freely coiled arou nd a 6-W low-pressure mercury lamp. While passing the KR, MSB was derived i nto an intensively fluorescent compound that was on-line delivered into a f low-through cell and detected therein at an emission wavelength of 459 nm a nd an excitation wavelength of 336 nm. Under optimized conditions a detecti on limit of 0.38 mug l(-1) was achieved at a sampling rate of 90 h(-1). Ele ven 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 w as successfully applied to assay the MSB content in MSB injection.