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Evaluation of Some Empirical Retention Models for High Submicellar Liquid Chromatographic Separation of Aromatic Diamines

Hadjmohammadi M. R., Nazari S. S. S. J.

Acta Chromatographica

2015

Vol. 27, no. 3

399--411

Description of the retention of five aromatic diamines in high submicellar liquid chromatography was carried out through several hyperbolic and logarithmic retention models using the retention data of mobile phases consisting of sodium dodecyl sulfate (SDS) (0.09–0.15 M) and methanol (50–70% v/v) at pH 3. Among the investigated models, the logarithmic retention model 0.5 log k = c0 + c1ϕ + c2[M]+ c12(ϕ[M])0.5 showed the best prediction capability and used to predict the solutes retention factors. The mean relative error of the prediction of retention factors of five aromatic diamines in the selected variables space was lower than 0.5%. Based on the best retention model, a grid search program was used to predict the retention times of each solute for all combinations of SDS and methanol concentrations in the factor space. In order to find optimal separation condition, two different chromatographic goals, analysis time and retention differences between adjacent peaks, were evaluated simultaneously using Derringer's desirability function for each mobile phase composition. At the optimal conditions (0.143 M SDS, 53% v/v methanol), a good agreement was observed between predicted and experimental values of the retention times (R2 = 0.9999 and mean relative error of 0.96%).

Computer-assisted optimization of liquid-liquid extraction for HPLC analysis of domperidone and pantoprazole in human plasma

Sivakumar T., Manavalan R., Valliappan K.

Acta Chromatographica

2008

Vol. 20, no. 4

549-562

This paper deals with optimization of a liquid-liquid extraction procedure for simultaneous HPLC analysis of domperidone and pantoprazole in human plasma. Central composite design and Derringer’s desirability function were used to optimize the concentration of KOH and the volume of ethyl acetate as the main factors affecting the liquid-liquid extraction procedure. After extraction, the analytes were separated quantitatively on a C 18 column with 10 mM pH 7.0 phosphate buffer-methanol-acetonitrile 48.46:20:31.54 ( υ / υ ) as mobile phase at a flow rate of 1.20 mL min -1 and with UV detection at 285 nm. It was concluded that extraction recovery of both the analytes was affected by KOH concentration and that recovery of pantoprazole was affected by ethyl acetate (extraction solvent) volume. Extraction recovery under optimum extraction conditions was 93.52% for domperidone and 92.72% for pantoprazole. The optimized extraction method was validated. Linearity was established for six levels in the ranges 10–1000 ng mL -1 for pantoprazole and 15–1000 ng mL -1 for domperidone. The lower limit of quantitation (LLOQ) and detection (LOD) were estimated as 9.84 and 5.91 ng mL -1 , respectively, for pantoprazole and 14.56 and 8.79 ng mL -1 for domperidone. The optimized method was linear, specific, accurate, and precise; the high recovery (>92%) and low relative standard deviation (<2.5%) enable reliable quantification of these analytes in spiked human plasma.