Published: Journal of Chromatographic Science, Volume 35, Number 11, November 1997, pp. 545–548.
Chromatographic Problems Related to
Mobile Phase Degassing and Fluorescence Detection
A.S. van Brakel, A.R.
Matheson, and A.K. Hewavitharana
Two problems are encountered in degassing hexane-based mobile phases. First, when fluorescence is used for the detection of vitamins A and E, the peak responses observed for consecutive injections of the same sample decrease over time due to quenching by oxygen dissolved in the mobile phase. Second, a rapid increase in retention time is observed with consecutive injections due to the preferential evaporation of the modifier, isopropanol (0.5%) in hexane. The rapid evaporation is due to the formation of an azeotrope between isopropanol and hexane with a boiling point of 63°C. A discussion of possible solutions to the two problems is given.
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