Optimisation of mobile phase pH in liquid chromatography. Application to fluorimetric detection of series of quinolones

Abstract

SummaryThe dissociation constants of several quinolones in a 7 % acetonitrite-water mixture are determined. A model describing the effect of pH on the retention of quinolones by an octadecylsilica stationary phase with a 7 % acetonitrile-water mobile phase is proposed. The model uses pH values in the mobile phase instead of pH values in water and takes into account the effect of activity coefficients. Fluorescence of quinolones in the mobile phase is studied, and a chromatographic separation with fluorimetric detection is established. Detection limits for the proposed method range from 3 to 12 gg.L q.

Optimization of the composition and pH of the mobile phase used for separation and determination of a series of quinolone antibacterials regulated by the European Union

“…In previous work [18,38,45,46] Cls and polymeric columns have been used but in this work the best results were obtained by use of a Cs column. Although acetonitrile-water mixtures are suitable for chromatography of quinolones [9,18,45], good peak symmetry is obtained only if an organic competing base or an ammonium salt is added [9]. The most widely used phosphate buffers [9,18,45] are not compatible with mass spectrometric detection which was the objective of our subsequent work.…”

“…Although acetonitrile-water mixtures are suitable for chromatography of quinolones [9,18,45], good peak symmetry is obtained only if an organic competing base or an ammonium salt is added [9]. The most widely used phosphate buffers [9,18,45] are not compatible with mass spectrometric detection which was the objective of our subsequent work. For these reasons in our study we initially chose a Cs stationary phase and a mobile phase containing acetonitrile and 0.020 mol L 1 ammonium acetate solution, the pH of which was adjusted by use of formic acid.…”

Determination of fluoroquinolones in human urine by liquid chromatography coupled to pneumatically assisted electrospray ionization mass spectrometry1

“…The best results were obtained with a C 8 column [18]. Acetonitrile-water mixtures are suitable for chromatography of quinolones but good peak symmetry is only obtained if an organic competing base or an ammonium salt is added [12,16,26]. Moreover, the widely used phosphate buffers [12] are not compatible with mass spectrometric detection.…”

Application of principal component regression to luminescence data for the screening of ciprofloxacin and enrofloxacin in animal tissues

“…Current methods of analysis of quinolones are based on liquid chromatography (LC), mainly with fluorimetric detection. [2][3][4][5] However, luminescence spectroscopy offers other possibilities for sensitive and selective detection, such as the use of lanthanide-sensitised luminescence. 6,7 The main advantages of this technique include long wavelength emission and long luminescence lifetimes, thus resulting in the elimination of light scattering interference and a significant decrease in background fluorescence.…”