Retention behaviour and fluorimetric detection of procaine hydrochloride using carboxymethyl-beta-cyclodextrin as an...

The retention behaviour of procaine hydrochloride on an Alltima octadecyl silica (C18) column, with a mobile phase containing negatively charged carboxymethyl-beta-cyclodextrin (CM-beta-CD), influenced by a combination of hydrophobic and electrostatic interactions was systematically investigated. Various factors affecting the retention of procaine on the C18 column such as the concentration of CM-beta-CD, pH and the methanol percentage in the mobile phase, were studied. An equation was applied to estimate the apparent binding constant of the CM-beta-CD-procaine inclusion complex as an aid for understanding the retention mechanism. The first analytical application of CM-beta-CD as a mobile phase additive for the determination of procaine was developed. The calibration curve was linear in the range 22-1360 ng ml(-1) with an RSD of 2.1%. The detection limit based on 3sigma was 1 ng ml(-1) with fluorimetric detection at the excitation and emission wavelengths of 305 nm and 350 nm, respectively. The limit of quantitation based on 10sigma was 22 ng ml(-1). The proposed method has been successfully applied to real sample analysis.