Journal of Pharmaceutical and Biomedical Analysis Open最新文献

The main reasons for performing derivatization in capillary electrophoresis are largely the same as for liquid chromatography, however there are specific aspects in electrokinetic separations where derivatization plays specific roles. The review is focused on the articles published in the past 5 years with the aim to highlight this unicity. Derivatization is mainly applied to improve the inherent low sensitivity of capillary electrophoresis when optical detection is used and the introduction of originally developed derivatization approaches have been addressed mainly to the detection by laser-induced fluorescence. A further peculiarity concerns the development of automatized as well as in-capillary derivatization that can be performed using the commercially available instrumentation. The majority of the methods considered deal with the derivatization of amine group in small molecules (in particular, amino acids) as well as in proteins and peptides. Applications are also addressed to chiral analysis and for trapping unstable and reactive small molecules and inorganic ions. The analysis of proteins and saccharides in glycomics, have been covered in dedicated sections.

The aim of the research was to determine carbamazepine (CBZ) and its main metabolite 10,11-epoxy-10,11-dihydro-carbamazepine (CBZ-E) in human hair using the capillary electrophoresis (CE) system coupled with mass spectrometry detection (MS) and to compare the obtained results with the liquid chromatography (LC) technique, also coupled with the MS detector. Hair samples were prepared using microwave-assisted extraction (MAE) at 60 °C for 10 min in an alkaline solution (pH = 10) with ethyl acetate as the extraction solvent. In the frame of this study, the procedure for the separation of CBZ and CBZ-E using the CE-MS technique was developed. The best results were achieved using 10 mM ammonium acetate (pH=6.8) as the background electrolyte (BGE), after filling the capillary with 1% highly sulfonated β-cyclodextrin (HSβCD) in 10 mM ammonium acetate. Then, the validation parameters of the MAE/CE-MS and MAE/LC-MS methods such as: limit of detection (for CBZ are: 0.36 and 0.22 ng/mg, respectively; for CBZ-E 0.38 and 0.17 ng/mg, respectively), limit of quantification (for CBZ are: 0.86 and 0.72 ng/mg, respectively; for CBZ-E 0.94 and 0.56 ng/mg, respectively), precision (6.91–14.5% and 2.16–15.6%, respectively), recovery (87.7–102.7% and 88.9–105.5%, respectively), and matrix effect (99.5–111.0% and 98.9–115.1%, respectively) were defined and compared. Finally, the validated methods were applied to identify and quantify carbamazepine and its metabolite in hair in patients who received CBZ for medical reasons.

The analytical methods reported to evaluate 6-Thioguanine nucleotides (6-TGNs) level in red blood cells (RBC) are based on the conversion of 6-TGNs to 6-Thioguanine (6-TG) using 6-thioguanine as calibration standard.

Using the LC-DAD method previously reported by Dervieux and Boulieu in 1998 to determine 6-TGNs, we evaluated the use of 6-Thioguanine Riboside (6-TGR) as standard instead of the base 6-TG for the monitoring of 6-TGNs in RBC from patients with IBD.

Our results show that 6-TGN values measured in RBC from 30 patients were significantly (p < 0,00001) higher when 6-TGR was used as calibration standard compared to 6-TG. The difference observed may be explained by the presence of ribose in the chemical structure of 6-TGR contrary to 6-TG. This difference in 6-TGN values was also observed in external quality control assay using 6-TGR versus 6-TG calibration standard.

The use of the nucleoside 6-TGR as calibrator constitutes a better reflection of the chemical reaction which occurs in RBC compared to 6-TG. This preliminary observation suggests that the choice of calibration standard to monitor 6-TGNs may have a significant impact on the values measured in patients and laboratory should be aware of this potential pitfall.