A GC–MS Method for Determination of β-Propiolactone Residues in Inactivated Covid-19 Vaccines

β-propiolactone is a common inactivator agent used in vaccines. Due to β-propiolactone carcinogenicity, complete hydrolysis of it is necessary to prevent cytotoxicity in mammalian cells. As a result, more attention should be paid to it at the clinic, and it is important to measure its trace amounts. β-propiolactone analysis is challenging due to its instability. A simple and fast gas chromatography–mass spectrometry method was developed for quantitation of residual β-propiolactone in inactivated coronavirus disease 2019 (Covid-19) vaccines. Caprolactone was used as an internal standard in sample solutions; the analysis was performed after extraction of analyte from vaccine media by ethyl acetate. The validity of the method was studied with a linearity of r2 > 0.99 over the concentration range of 0.2–20 μg/mL with the limit of detection and the limit of quantification of 0.07 and 0.20 μg/mL, respectively. The target analyte β-propiolactone was not detected in the samples, demonstrating the test samples were qualified. The established method can be used for quality control of inactivated Covid-19 vaccines.