Mass spectrometry coupled to diode array detection (LCMS/DAD): a useful tool for efficient and improved stability testing
Stability testing is one of the key task supporting compounding in hospital pharmacies. As reported by stabilis.org website, more than 2000 studies have been published in this field from more than 600 research teams around the world. Unfortunately, those studies do not provide the same level of evidence as stated by the infostab team in a recent paper (1). In many past studies the degradation products are not determined, moreover some products including the active ingredients do not absorb in the light, thus making them impossible to detect in a regular UV detector. For some molecules, to allow a sensible detection, one also has to work at around 200nm, which is not specific, this is for example the case for cyclophosphamide. In order to improve sensitivity or specificity and allow an universal detection and chemical determination of roughly all molecules and their degradation products, mass spectrometry (MS) coupled to the regular diode array detector (DAD) was used after liquid chromatography separation. It allowed us to perform two full stability studies 1- on hydroxyzine formulation and 2- on cyclophosphamide interaction and stability after contact with spikes. Those studies would have been limited without the use of mass detection. The stability data on those two molecules are still being accumulated at the date of submission, but all results will be presented and will hopefully highlight the advantages of this new procedure in hospital pharmacies to enrich the stability data. Specificity, sensitivity, product identification are improved with mass detection. Hypothesis on degradation pathways are also easier to raise. Using both DAD and MS detection in the same run allows to bring a lot of information (3D Spectra, peak purity, MS Scan) on the detected molecules. In conclusion LCMS/DAD is another step beyond in the field of stability testing in hospital pharmacies.
(1) E. D’Huart, P. Lider, J. Vigneron, B. Demoré. Evolution of the Stabilis® database: creation of a level of evidence for stability Studies. Pharm Tech Hosp Pharm, 3 (1), pp 3-12 (2018)