Detection of Local Anesthetic Ingredients Including Lidocaine, Tetracaine, and Prilocaine in Illegally Distributed Drugs Through Gas Chromatography–Time‐of‐Flight Mass Spectrometry and Gas Chromatography–Triple Quadrupole Mass Spectrometry

Local anesthetic compounds may be mixed with counterfeit products and distributed as legitimate pharmaceuticals. In this study, gas chromatography-time-of-flight mass spectrometry (GC-TOF MS) and gas chromatography-triple quadrupole mass spectrometry (GC-QQQ MS) methods are used simultaneously to determine 18 local anesthetics and identify illegal products. First, GC-TOF MS is performed to determine the fragmentation patterns and structures of the 18 compounds and qualitatively screen the samples. GC-QQQ MS is used for quantitative analysis and thoroughly validated for specificity, linearity, limit of detection, limit of quantification, accuracy, precision, and recovery. The samples are divided into liquid, cream, and other forms for testing, with 65.6% (40/61) of samples contaminated with local anesthetics. Lidocaine is frequently identified in the analyzed samples, with a detection range of 0.153-164.0 mg/g. Furthermore, linearity is observed within the concentration ranges of 0.41-1.28, 2.29-2.43, and 1.83-16.3 mg/g for prilocaine, procaine, and tetracaine, respectively. Eugenol is detected in a single sample at 3.45 mg/g. In addition, three components are detected in one sample, adversely affecting human health when used in combination. Therefore, the proposed analytical methods may contribute to the removal of illegal products containing pharmaceutical compounds.