Sensitivity enhancement in capillary electrophoresis and their applications for analyses of pharmaceutical and related biochemical substances.

This review aims to illustrate sensitivity enhancement methods in capillary electrophoresis (CE) and their applications for pharmaceutical and related biochemical substance analyses. The first two parts of the article describe the introduction and principle of CE. The main part focuses on strategies for sensitivity improvement in CE including detector and capillary technologies and preconcentration techniques. Applications of these techniques for pharmaceutical and biomedical substance analyses are surveyed during the years 2018-2021.

Potentially antioxidant compounds indicated from Mallotus and Phyllanthus species fingerprints.

The genera of Mallotus and Phyllanthus contain several species that are commonly used as traditional medicines in oriental countries. Some species show interesting pharmaceutical activities, such as an antioxidant activity. To produce clinically useful medicines or food supplements (nutraceuticals) from these herbs, the species should be identified and a thorough quality control should be implemented. Nowadays, the integration of chromatographic and chemometric approaches allows a high-throughput identification and activity prediction of medicinal plants. In this study, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied and compared to distinguish Mallotus and Phyllanthus species. Moreover, peaks from their chromatographic fingerprints, which were responsible for their antioxidant activity were assigned. For the latter purpose, the relevant information was extracted from the chromatographic fingerprints using linear multivariate calibration techniques, i.e., Partial Least Squares (PLS) and Orthogonal Projections to Latent Structures (O-PLS). Results reveal that exploratory analysis using PCA shows somewhat diverging clustering tendencies between Mallotus and Phyllanthus samples than HCA. However, both approaches mainly confirm each other. Concerning the multivariate calibration techniques, both PLS and O-PLS models demonstrate good predictive abilities. By comparing the regression coefficients of the models with the chromatographic fingerprints, the peaks that are potentially responsible for the antioxidant activity of the extracts could be confirmed.

A micellar electrokinetic capillary chromatography method for monitoring mycophenolic acid in serum of transplant recipients.

Mycophenolic acid (MPA), the active metabolite of the immunosuppressive agent mycophenolate mofetil (MMF), was for the first time quantified in the serum of transplant recipients using micellar electrokinetic capillary chromatography (MEKC). Sample preparation was carried out with solid phase extraction (SPE) using octadecyl-modified endcapped silica (C18 EC) as sorbent. Extremely varying recovery rates in preliminary experiments showed both the importance of pH monitoring during the single SPE steps and the necessity of an internal standard. MPA carboxy butyl ether (CBE), a specifically developed reference standard, was employed. Furthermore, optimisation of the MEKC parameters detection wavelength and injection time was of primary importance in order to enable the quantitation of therapeutic trough serum levels of MPA in the range lower than 5 microg x mL(-1). Under optimised conditions, a limit of quantitation of 1.0 microg x mL(-1) was achieved allowing the determination of MPA in the serum of patients.

Feather degradation by Bacillus sp. FK 46 in submerged cultivation.

Cultivation conditions affecting feather degradation by Bacillus sp. FK 46 were investigated. The results showed that feather was almost completely degraded under the following conditions: 1% whole chicken feather as a substrate at the initial medium pH of 9 with 5% bacterial inoculum, at a temperature of 37 degrees C and a shaking speed of 250 rev/min. Glucose, methanol, Tween 80 and Triton X-100, however, had no effect on feather degradation. After feather was degraded, its residue and fermented broth would become a protein feed for animals.

Direct determination of s-carboxymethyl-l-cysteine in syrups by reversed-phase high-performance liquid chromatography.

A simple reversed-phase high-performance liquid chromatography method was developed for the determination of s-carboxymethyl-l-cysteine in syrup preparations. The experiments were performed without specific sample pre-treatment. The LC conditions used were acetonitrile-10 mM sodium dihydrogenphosphate buffer, pH 2.0 (1:99, v/v) on a C(18) Inersil column with a flow rate of 1.5 ml/min. Ultraviolet detection was carried out at 240 nm. The method showed excellent linearity (r(2)>0.9998) over the concentration range tested (0.8-25.6 mg/ml) with good precision and accuracy (%R.S.D. 0.7%). Recoveries were good (>99%) with a limit of detection and limit of quantitation of 0.1 and 0.8 mg/ml. Other compositions in the syrup vehicle did not interfere the analysis of s-carboxymethyl-l-cysteine.

Separation of cold medicine ingredients by capillary electrophoresis.

This study demonstrates the separation of cold medicine ingredients (e.g., phenylpropanolamine, dextromethorphan, chlorpheniramine maleate, and paracetamol) by capillary zone electrophoresis and micellar electrokinetic chromatography. Factors affecting their separations were the buffer pH and the concentrations of buffer, surfactant and organic modifiers. Optimum results were obtained with a 10 mM sodium dihydrogen-phosphate-sodium tetraborate buffer containing 50 mM sodium dodecyl sulfate (SDS) and 5% methanol (MeOH), pH 9.0. The carrier electrolyte gave a baseline separation of phenylpropanolamine, dextromethorphan, chlorpheniramine maleate, and paracetamol with a resolution of 1.2, and the total migration time was 11.38 min.