LC–MS/MS Method for Determination of Non-opioid Analgesics Adulterants in Herbal Medicines

The increased use of herbal medicines necessitates their quality and safety assurance. Among of other factors affecting herbal medicines is adulteration with conventional drugs that can potentially contribute to human health effects. This stimulate the high level of quality control that can be done by having strengthened analytical capacity. The present study developed a high throughput method for the determination of five (5) non-opioid analgesics namely acetaminophen, caffeine, acetylsalicylic acid, ibuprofen and diclofenac. A developed method was validated for its selectivity, sensitivity, linearity, accuracy, precision, recovery, matrix effects and stability. The results showed a good linear relationship with the concentration of the analytes over wide concentration ranges (0.001–10.00 µg/mL) with a coefficient of determination, R(2) ≥ 0.9931. The limit of detection (LOD) and limit of quantification (LOQ) for each compound were within the range of 0–3.7 µg/mL. The intra-precision of the method was expressed as relative standard deviation and was less than 9.5% with varying matrix effect from 68.56 to 138.88%. The absolute recoveries ranged from 59.63 to 107.10%. Among 132 collected samples, 21% were adulterated with caffeine and acetylsalicylic acid. The method developed met the ICH guidelines for detection and quantification of acetaminophen, caffeine, acetylsalicylic acid, diclofenac and ibuprofen in HM. Elimination of adulteration by introducing measures like setting education programmes for practitioners are recommended.