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Micellar liquid chromatography (MLC) is a useful technique for the determination of compounds in biological samples. Here, a sensitive procedure has been developed for the determination of carbaryl, a phenyl-N-methylcarbamate, and its main metabolite, 1-naphthol, using a C18 column (150 mm × 4.6 mm) and fluorescence detection. After performing optimization studies with an interpretative strategy, the selected mobile phase was sodium dodecyl sulfate (SDS) 0.15 M – 6% (v/v) pentanol - NaH2PO4 0.01 M buffered at pH 3. The validation studies include linearity (r2 > 0.9999), limits of detection and quantification, (0.0325 and 0.1 µM for carbaryl; 0.125 and 0.350 µM for 1-naphthol, respectively), intra- and inter-day precisions below 4%, and robustness parameters below 5%, all of which are adequate for the quantification of these two compounds in urine and serum samples to be directly injected into the chromatographic system. [ABSTRACT FROM AUTHOR]

Isoniazid is a drug that is widely used against tuberculosis. However, it shows high interpatient variability in metabolism kinetics and clinical effect, which complicates the prescription of the medication and jeopardizes the success of the therapy. Therefore, in a specific patient, the pharmacokinetics of the drug must be elucidated to decide the proper dosage and intake frequency to make the drug suitable for therapeutic drug monitoring. This can be performed by the quantification of the drug in urine as this process is non-invasive and allows the effects of long-time exposure to be inferred. The paper describes the development of a micellar liquid chromatographic method to quantify isoniazid in urine samples. Extraction steps were avoided, making the procedure easy to handle and reducing the waste of toxic organic solvents. Isoniazid was eluted in less than 5 min without interference from other compounds of the urine using a mobile phase containing 0.15 SDS–12.5% 1-propanol (v/v)–Na2HPO4 0.01 M buffered at pH 7, running at 1 mL/min under isocratic mode through a C18 column with the detection wavelength at 265 nm. The method was validated by following the requirements of the Guidelines on Bioanalytical Method Validation issued by the European Medicines Agency (EMA) in terms of selectivity, calibration curve (r2 = 0.9998 in the calibration range (0.03–10.0 μg/mL), limit of detection and quantification (10 and 30 ng/mL respectively), precision (<16.0%), accuracy (−0.9 to +8.5%), carry-over, matrix effect, and robustness. The developed method was applied to quantify isoniazid in urine samples of patients of an Indian hospital with good results. The method was found to be useful for routine analysis to check the amount of isoniazid in these patients and could be used in its therapeutic monitoring. [ABSTRACT FROM AUTHOR]

Abstract: A procedure was developed for the determination of caffeine and theophylline using a C18 column (5μm, 250mm×4.6mm) and micellar liquid chromatography using hybrid mobile phases containing sodium dodecyl sulfate (SDS) and propanol, butanol or pentanol as modifiers. Detection was performed with a variable wavelength UV–vis detector at 272nm. After the application of an interpretative strategy for the selection of the optimimum mobile phase, caffeine and theophylline can be resolved and determined in serum samples by direct injection, using a mobile phase made up of 50mM SDS–2.5% (v/v) propanol–10mM KH2PO4, pH 7, with an analysis time below 5min. Calibration was linear in the range 0.05 to 50μgmL−1 with r >0.999. The statistical evaluation of the method was examined by performing intra-day (n =6) and inter-day calibration (n =7) and was found to be satisfactory, with highly accurate and precise results. The proposed method was suitably validated and applied to the determination of caffeine and theophylline in serum samples of patients treated with bronchodilators. [Copyright &y& Elsevier]

Rivaroxaban is one of the most prescribed anticoagulants. The ingestion of the correct dosage is a key to the success of the therapy. A procedure to evaluate the content of active principle ingredient in rivaroxaban pharmaceutical formulations, based on micellar liquid chromatography, has been developed. Tablets were solved in the mobile phase and directly injected, thus avoiding the use of large volumes of organic solvents. Analysis was performed using a C18 column and a mobile phase containing 0.05 M sodium dodecyl sulfate—12.5% 1-propanol, buffered at pH 7 with phosphate salt, running under isocratic mode at 1 mL/min. The analyte was resolved in less than 6.0 min. Detection was by UV absorption at 250 nm. The method was successfully validated by the guidelines of the International Conference of Harmonization in terms of specificity, calibration range (0.01–1.00 mg/L), linearity, limit of detection (0.002 mg/L), limit of quantification (0.006 mg/L), trueness (99.6–99.7%), precision (< 2%), robustness, system suitability, carry-over effect and stability, thus proven the adequate quality of the analytical results. A set of incurred and quality control samples was analyzed in the same run; and adequate results were obtained. The procedure was found practical, easy-to-conduct, rapid, safe, eco-friendly, inexpensive and with a high sample throughput; and then useful for routine analysis for pharmaceutical quality control purposes. [ABSTRACT FROM AUTHOR]