A Quantitative Photochemical-Fluorimetric Method for Measurement of Nonfluorescent Vitamin K₁

Abstract

Vitamin K1 (2-methyl-3-phytyl-1,4-naphthoquinone) is not naturally fluorescent, but yields a fluorescent photochemical product upon ultraviolet irradiation. Among several solvents, dioxane was found to be the most suitable for the determination of vitamin K1. A photochemical-fluorimetric method is proposed for measurement of original vitamin K1 concentration using two different readout methods: (1) digital integration of the fluorescence increase due to the photoproduct at 431 nm; and (2) analog recording of photoproduct fluorescence as a function of irradiation time. The two methods gave limits of detection of 5 ppb, with a better precision for the digital procedure. Limits of detection and speed of analysis are shown to be more satisfactory for the determination of vitamin K1 than in previously reported analytical methods. The specific data obtained depends greatly on the quality of the solvent and excitation-photolysis source used.

Spectrofluorimetric determination of vitamin K3

“…We also prepared vitamin K 3 samples in the presence and absence of sodium hydrogensulfite and these samples were irradiated for at least 30 min in accordance with the procedure proposed by Aaron et al 17 However, no effect of irradiation on obtaining the fluorescent derivative was observed.…”

Rapid fluorimetric determination of phenothiazines employing in situ photochemical oxidation

“…Photochemical decomposition of the sample may be regarded as a hindrance in fluorimetric analysis, but recently, both digital and analog readout methods have been applied so as to overcome photochemical complications (16)(17)(18). Linear calibration curves, measuring either native fluorescence (16) or fluorescent photoproducts (17,18) can be obtained over several orders of magnitude at ppb concentrations. In the case of phenothiazines, in situ photochemical oxidation and simultaneous fluorimetry appeared promising for a rapid, sensitive, and convenient quantitation.…”