Analytical methods for the detection of undeclared synthetic drugs in traditional herbal medicines as adulterants

Traditional herbal medicines (THMs) are gaining popularity worldwide as an alternative approach to prescription drugs for many reasons including a general perception that they are safe. But recently there have been number of reported studies that reveal adulteration of THMs with undeclared synthetic drugs, which may potentially cause serious toxic adverse effects. This paper reviews the various classes of synthetic drugs that were found to be adulterated in THMs worldwide. The main focus is to highlight newer analytical tools used to detect adulteration. Due to the advancement in hyphenated techniques like liquid chromatography tandem mass spectrometry (LC-MS/MS), gas chromatography-tandem mass spectrometry (GC-MS/MS) and other conventional tools, it has become possible to detect synthetic drugs and their structural analogues as adulterants even if they are present in small quantities. This review also gives an overview of health-related risks after consuming such spurious products and challenges for future perspectives to control such type of malpractices.