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Reversed‐polarity capillary zone electrophoretic analysis of usnic acid
Author(s) -
Kreft Samo,
Štrukelj Borut
Publication year - 2001
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200108)22:13<2755::aid-elps2755>3.0.co;2-6
Subject(s) - usnic acid , methanol , capillary electrophoresis , electrophoresis , chromatography , chemistry , acetic acid , capillary action , detection limit , analytical chemistry (journal) , materials science , biochemistry , organic chemistry , lichen , botany , composite material , biology
A capillary zone electrophoretic (CZE) method for the determination of usnic acid is described for the first time. Usnic acid is an antibiotic substance from lichens. Due to its low solubility in water, a high content of methanol in CZE buffer is required. Because of the methanol in the buffer, the electroosmotic flow velocity was lower than the electrophoretic mobility of usnic acid. Accordingly, the use of reversed‐polarity (with the anode on the detector side of the capillary) was necessary. The optimal buffer composition was 50 m M NaOH, 20 m M acetic acid and 5% water in methanol. The detection limit of UV detector at 290 nm for usnic acid in the injected extract was 3.5 mg/L and the relative standard deviation of the normalized peak area was 3.3% at 250 mg/L.