Spectrofluorimetric Determination of Vitamin K3 by a Solid-phase Zinc Reactor Immobilized in a Flow Injection Assembly

Abstract

The spectrofluorimetric determination of vitamin K3 (menadione) using a flow injection (FI) assembly provided with a solid-phase reactor with immobilized zinc is described. The naphthohydroquinone was produced by means of two coupled steps in the FI system: hydrolysis of the sodium sulfite derivative of the menadione in a basic medium and reduction of the generated menadione in the zinc reactor in an acidic medium. The fluorescent product was monitored spectrofluorimetrically (lambda ex 325 nm; lambda em 425 nm). The calibration graph was linear over the range 0.1-18 micrograms ml-1 with a reproducibility of 1.6%; the limit of detection was 0.005 microgram ml-1 and the sample throughput was 70 h-1. The influence of foreign compounds was studied and the procedure was applied to the determination of vitamin K3 in three different pharmaceutical formulations.

Spectrofluorimetric determination of vitamin K3

“…Recently, Martínez Calatayud et al 16 reported a spectrofluorimetric determination of vitamin K 3 by using a flow injection assembly provided with a solid-phase reactor with immobilized zinc, where MSH was hydrolysed in alkaline medium and reduced by zinc in HCl medium. The limit of detection was 0.005 mg ml 21 .…”

Flow injection determination of vitamin K3 by a photoinduced chemiluminescent reaction

“…17 The second method uses a flow injection assembly provided with a solid-phase reactor with immobilized zinc, where MSB is hydrolysed in alkaline medium and reduced by zinc in an acidic medium. 18 The reported detection limits were 4.4 3 10 29 and 2.9 3 10 28 mol l 21 , respectively. Both procedures were applied to the determination of menadione in pharmaceutical formulations.…”

Microplate analytical method for quinones by pulse photo-irradiation and chemiluminescence detection

“…Although the high sensitivity achieved by the fluorescence detection, quinones lack native fluorescence and have to be reduced to their hydroquinone form prior to fluorescence detection. Different procedures are used for quinone reduction, either chemically, [13][14][15] electrochemically 16 or photochemically 17,18 . Although the fluorescence detection may accomplish the required sensitivity, the methods lacked simplicity and rapidity because the reduction processes required many additional systems component such as reducing column, electric reactor or photoreactor.…”