Xq. Guo et al., STUDY ON SENSITIZED PHOTOCHEMICAL FLUORESCENCE OF MENADIONE SODIUM BISULFITE AND ITS APPLICATION IN PHARMACEUTICS ANALYSIS, Analytica chimica acta, 343(1-2), 1997, pp. 109-116
Menadione sodium bisulfite (MSB), vitamin K-3, a non-fluorescent compo
und, was converted into an intensive fluorescent compound (lambda(ex)/
lambda(em)=340 nm/465 nm) on irradiation with ultraviolet radiation in
an anaerobic alkaline medium, and acetone showed a strong sensitizing
effect on this photochemical reaction when the radiation used was abs
orbed by acetone. The reaction rate increased as the concentration of
acetone increased, the maxima of the fluorescence spectra, however, re
mained unchanged. The sensitized photochemical reaction was assumed to
begin with the absorption of photons by acetone and a triplet-triplet
energy transfer process was proposed for the sensitizing mechanism, i
n which acetone acted as an energy donor, and MSB as an energy accepto
r. A new in situ photochemical fluorimetric method was consequently pr
oposed for the determination of MSB. The solutions were pumped through
a PTFE mixing-tube and then stopped and kept in an 18 mu l flow cell
where the photochemical reaction took place in situ on irradiation for
120 s (with an excitation wavelength, lambda(ex), 280 nm, excitation
slit, EX, 7 nm), and then lambda(ex) was changed from 280 to 340 nm pr
omptly to measure the fluorescence intensity of the photochemical prod
uct at 465 nm. Na2SO3 was used as the deoxygenation reagent. The calib
ration graph was linear up to 1.1 mu g ml(-1) MSB (r=0.999), and the l
imit of detection (LOD) was 0.76 ng ml(-1). The coefficients of variat
ion were 1.0% (n=6) and 0.99% (n=6) for 0.44 and 1.1 mu g ml(-1) MSB,
respectively. Its application to the analyses of vitamin injections an
d urine samples was satisfactory, and the recovery of vitamin K-3 in u
rine was 92-94%. The kinetic behavior of this reaction and the effects
of some experimental conditions as well as the mechanism for the sens
itization by acetone were investigated and discussed in detail.