Supercritical fluid chromatography hyphenated to mass spectrometry: A reliable tool for pharmaceutical quality control

Quality control (QC) holds a position of utmost significance within the pharmaceutical industry. Undoubtedly, ensuring the quality of medicines stands as a fundamental imperative that ultimately contributes to safeguard public health. Analytical techniques, in this context, play a fundamental role by enabling the assessment of critical quality attributes of drug substances and products. From this perspective, the evaluation of supercritical fluid chromatography (SFC) is now well described in the literature and SFC is emerging as a promising additional tool for QC laboratories. The hyphenation of mass spectrometry (MS) to SFC to harness the combined benefits and advantages of both these techniques is now readily accessible through the availability of several instrumentation and interfaces. Nevertheless, the evaluation of SFC-MS performance for pharmaceutical QC remains underrepresented in the literature. This thesis specifically focused on the exploration of SFC-MS, with the primary objective of assessing the capabilities of this technique for pharmaceutical quality control.
The performance of this technique was first explored in a qualitative application focused on the quality control of herbal medicinal products, in the context of detection of adulterations. Synthetic cannabinoids (SCs), which are part of the category of new psychoactive substances, are illicitly manufactured and distributed in various forms, including within herbal products. This served as the focal point for this investigation. The interest of SFC-MS in detecting such adulterants in the cannabis plant was evaluated. To meet the challenges posed by the rapid emergence of these novel substances, the objective was to propose a generic method that could be applicable to a large panel of SCs. To achieve this goal, an extensive exploration of the selectivity space was essential to be able to distinguish SCs from the natural cannabinoids in the herbal matrix. In this context, a robust optimization of the separation was conducted following analytical quality-by-design (AQbD) principles.
After the demonstration of the qualitative performance of SFC-MS, the work was focused on the quantitative performance of this technique. First, the performance of SFC-MS in the determination of an active pharmaceutical ingredient (API) in drug products was considered. This study specifically focused on the determination of vitamin D3 in oily formulations. A dedicated SFC-MS method previously developed in the laboratory was first transferred to a new mass spectrometer. Subsequently, the determination of vitamin D3 was performed as a routine test for various oily forms of drug products and food supplements. To monitor the performance of the SFC-MS method, a control strategy was implemented. It was based on a three-level system suitability test that systematically assessed the quality of the separation, the adequacy of the calibration and the trueness of the method. Additionally, matrix effects were evaluated throughout the entire study. Ultimately, this work permitted to propose a generic SFC-MS methodology for this QC test of these products.
After demonstrating the quantitative performance of SFC-MS in API determination, the focus shifted towards assessing its performance in determining impurities within a drug product. This study marked a significant step in further evaluating the quantitative capabilities of SFC-MS, tackling a more complex scenario characterized by an increased number of target analytes and the demand for heightened sensitivity. Building upon the previous research, the investigation focused on the quantification of seven impurities of vitamin D3 in an oily formulation. These impurities included two esters of vitamin D3 and five non-esters, including four isobaric compounds to vitamin D3. The challenges faced were related to the characteristics of the impurities, the complexity of the sample matrix, and the required sensitivity. To address these challenges, SFC-MS method and sample preparation technique were developed and carefully optimized. Finally, two validation studies were performed to gain extensive knowledge about the quantitative performance of the method: a limit test for ester impurities, and a full quantitative validation based on the total error approach for three non-ester impurities.
To summarize, the research carried out in this thesis tackled various pertinent QC challenges using SFC-MS. The demonstration of both qualitative and quantitative performance through analytical validation and routine analysis permitted to highlight the potential of SFC-MS in pharmaceutical quality control analysis. Consequently, SFC-MS could be presented as a highly compelling and promising technique in the field of pharmaceutical quality control.