High-performance liquid chromatography of xanthines. Effects of N-methyl and C-8 hydroxyl substitution on the retention times.
The capacity factors of 26 xanthine derivatives were measured by reversed-phase high-performance liquid chromatography. N-Methyl substitution increased the capacity factor and the related lipid solubility. The descending order of the increase in capacity factor by the N-methyl group is: N-1 methyl greater than N-3 methyl greater than N-7 methyl greater than N-9 methyl. C-8 hydroxylation reduces the capacity factor in the xanthines. The reduction factor is 3.34 in xanthines with N-3 methyl substitution, 2.41 in xanthines with N-1 and/or N-7 methyl substitution and 1.68 in xanthines with N-9 methyl substitution.
Vree
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Department of Clinical Pharmacy, Saint Radboud Hospital, University of Nijmegen, The Netherlands.
Riemens
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Koopman-Kimenai
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D055598:Chemical Phenomena; D002621:Chemistry; D002851:Chromatography, High Pressure Liquid; D006900:Hydroxylation; D008745:Methylation; D012995:Solubility; D014970:Xanthines / Q000032:analysis*
D014970:Xanthines