The practical application of implementing the equimolar response principle of chemiluminescent nitrogen detection in pharmaceutical analysis

High-Performance Liquid Chromatography Methods for Determining the Purity of Drugs with Weak UV Chromophores - A Review

High-performance liquid chromatography (HPLC) is one of the most useful techniques for the separation and determination of new drugs with a complex nature. The selection of an HPLC detector depends on the chemical nature of molecules, potential impurities, matrix of the sample, sensitivity, availability, and/or cost of the detector. HPLC methods with UV/Vis detectors are the most used and simple analytical procedures in pharmaceutical applications, but it is limited to compounds that possess a chromophore. Hence, this review provides an overview on the development of analytical methods for compounds with weak chromophores. The review described selected papers about HPLC based methods in the PubMed, Scopus, Semantic Scholar and ScienceDirect databases, basically between 2006 and 2023. Of the analytical studies, the HPLC methods with UV-Vis, FLD, CAD, ELSD, RID, ECD, CLND and MS detection were found. This study is a comparison of different types of detection that are described in scientific literature and are routinely used for compounds with weak chromophores. It is expected that this review will be helpful for scientists in the analytical development fields to improve research related to the drug candidates and to ensure its quality according to regulatory levels.

Seeking universal detectors for analytical characterizations

It is highly desirable to have a universal detector that can detect all types of compounds and give a uniform response regardless of the physiochemical properties of the compounds. With such a universal detector, all components in a sample can be accurately quantified without the need for individual standards. This is especially needed for the characterization of unknowns and for non-targeted analysis, or for samples that have no isolated standards available for each component. Over the years, much effort has been put into seeking a universal detection technology. In this review, we discuss the commonly used detectors for analytical characterization, including UV, RI, ELSD, CAD, CLND, FID, VUV, MS, NMR, and hyphenated detection, with the focuses on the "universal" features of these detectors regarding the types of molecules they can detect and the uniformity of responses.

Relative response factor determination of β-artemether degradants by a dry heat stress approach

During the stability evaluation of β-artemether containing finished drug products, a consistent and disproportional increase in the UV-peak areas of β-artemether degradation products, when compared to the peak area decline of β-artemether itself, was observed. This suggested that the response factors of the formed β-artemether degradants were significantly higher than β-artemether. Dry heat stressing of β-artemether powder, as a single compound, using different temperatures (125-150 °C), times (10-90 min) and environmental conditions (neutral, KMnO(4) and zinc), resulted in the formation of 17 degradants. The vast majority of degradants seen during the long-term and accelerated ICH stability study of the drug product, were also observed here. The obtained stress results allowed the calculation of the overall average relative response factor (RRF) of β-artemether degradants, i.e. 21.2, whereas the individual RRF values of the 9 most prominent selected degradants ranged from 4.9 to 42.4. Finally, Ames tests were performed on β-artemether as well as a representative stressed sample mixture, experimentally assessing their mutagenic properties. Both were found to be negative, suggesting no mutagenicity problems of the degradants at high concentrations. Our general approach and specific results solve the developmental quality issue of mass balance during stability studies and the related genotoxicity concerns of the key antimalarial drug β-artemether and its degradants.