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Simple Determination of Deoxycholic and Ursodeoxycholic Acids by Phenolphthalein‐β‐Cyclodextrin Inclusion Complex
Author(s) -
Cadena Pabyton G.,
Oliveira Eric C.,
Araújo Alberto N.,
Montenegro Maria C. B. S. M.,
Pimentel Maria C. B.,
Lima Filho José L.,
Silva Valdinete L.
Publication year - 2009
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-009-3353-z
Subject(s) - phenolphthalein , chemistry , ursodeoxycholic acid , deoxycholic acid , cyclodextrin , chromatography , detection limit , inclusion compound , nuclear chemistry , bile acid , organic chemistry , biochemistry
An expeditious colorimetric methodology for the determination of the deoxycholic acid (DCA) and of the ursodeoxycholic acid (UDCA) in pharmaceutical formulations is reported. The method is based on their competitive complexation reaction with a color indicator to form β‐cyclodextrin‐inclusion complexes. Several pH color indicators were tested, but phenolphthalein (PHP) showed the best interaction with the β‐cyclodextrin (β‐CD) with an inclusion yield higher than 95%. The best concentrations of β‐cyclodextrin to form inclusion complexes were 1.24 × 10 −3 and 6.2 × 10 −4 M at pH 9.5 and 10.5. Statistical analysis of the results showed that the pH had a significant effect on the DCA determination and that high β‐CD‐PHP inclusion complex concentrations had a significant negative effect on the UDCA determination ( p < 0.05). The limit of detection and limit of quantification were 3.94 × 10 −5 and 1.31 × 10 −4 M for DCA (range: 6.1 × 10 −6 –3.13 × 10 −3 M), 4.08 × 10 −5 and 1.36 × 10 −4 M for UDCA (range: 6.05 × 10 −6 –3.88 × 10 −4 M). This simple and cheap method showed high stability and feasible instrumentation.