E. Bramanti et al., Selective determination of thiolic proteins by hydrophobic interaction chromatography coupled with on-line cold vapour atomic fluorescence spectrometry, J ANAL ATOM, 16(2), 2001, pp. 166-171
A new analytical method is proposed for the determination and characterizat
ion of thiolic proteins, based on hydrophobic interaction chromatography (H
IC) coupled on-line with cold vapour atomic fluorescence spectrometry (CVAF
S). Thiolic groups are derivatized pre-column by p-hydroxymercurybenzoate (
PHMB) and the derivatized proteins are separated on a TSKgel Ether-5PW colu
mn. Post-column on-line reaction of derivatized proteins with bromine, gene
rated in situ by KBr/KBrO3 in HCl medium, allowed the fast conversion of pr
otein-bound PHMB to inorganic mercury, Hg(ii), which is selectively detecte
d by AFS after sodium borohydride reduction to Hg-0. Under optimized condit
ions, on-line bromine treatment gives a 85 +/- 2% recovery of both free and
protein-complexed PHMB in less than 2.5 s and at room temperature. Glycera
ldehyde-3-phosphate dehydrogenase, aldolase, pyruvate kinase, trioso phosph
ate isomerase and phospho-glucose isomerase have been examined. Sensitivity
and limit of detection of proteins depends on the number of -SH groups rea
cting with PHMB and are in the range of 10(-8)-10(-9) mol dm(-3) with calib
ration curves spanning over four decades of concentration.