Investigation of 8 exogenous medicines illegally added into Guangdong herbal teas by solid phase extraction and ultrahigh performance liquid chromatography-tandem mass spectrometry

Abstract

Anti-inflammatory and antipyretic analgesic western medicine chemicals such as aspirin and antibiotics have the potential to be illegally added into Guangdong herbal teas (GHT, Guangdong Liangcha) to enhance its efficacy. The present work reports firstly a ultrahigh performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method after HLB solid phase extraction (SPE) and purification for the simultaneous analysis of 8 chemical substances including aspirin, acetaminophen, chlortrimeton, diclofenac, cefradine, cefalexin, cefazolin and azithromycin illegally added into GHT. Supernatant was adjusted to pH 3–4 after high speed centrifugation of sample. It was subsequently extracted and purified in one step by HBL SPE. Eight target substances were separated on a C18 column by gradient elution with acetonitrile and 0.1% formic acid in water as mobile phase, scanned by dynamic switching of ESI positive ion mode and negative ion mode, detected with MS/MS in multiple reactions monitoring (MRM) mode and quantified by external standard method. The limit of detection, matrix effect, recovery and precision of the developed method were investigated. Results were linear in the concentration range of 1.0–200 μg/L for all analytes of interest, with R2 >0.999. Limits of detection (LOD) were in the range of 0.1–2.0 μg/kg. Matrix effects were in the range of 85–102%. Recoveries for negative samples at three spiked levels were between 80.2% and 103%, and the intra-day precision and inter-day precision were in the ranges of 3.1–9.0% and 4.7–11.8%, respectively. The method was successfully applied to analyze 8 western medicines chemicals in 36 GHT and 3 illegal chemical substances especially acetaminophen were detected in several Liangcha samples.