Microscopic, phytochemical, HPTLC, GC-MS and NIRS methods to differentiate herbal adulterants: Pepper and papaya seeds

Objective: Herbal medicine products contribute a considerable part of the pharmaceutical market all over the world. Quality control of herbal medicines remains an obstacle in the herbal industry due to the existence of adulterants. Although some chemical methods are being employed to differentiate the herbal adulterants, they are time-consuming, costly and environmentally hazardous due to the use of dangerous chemicals. Hence, there is an urgent need to develop a rapid and reliable analytical method for the identification of herbal adulterants. Methods: In the present study, the authors have employed different techniques such as Microscopy, Phytochemical screening, high-performance thin layer chromatography (HPTLC), gas chromatography coupled with mass spectroscopy (GC-MS) and near infra-red spectroscopy (NIRS) methods to differentiate Piper nigrum (black pepper) and its adulterant papaya seeds. Results: Based on the results, microscopic method was found to be helpful to differentiate the herbal adulterants but required a lot of time and skilled human resource. Phytochemical methods are useful, but the process of extract preparation requiring the use of hazardous chemicals is not an environmentally friendly approach. The analytical techniques like HPTLC, GC-MS, and NIRS are useful methods, but require sophisticated instrumentation and skilled human resources involving time-consuming sample preparation steps. Conclusion: In addition to conventional Botanical and Chemical characterization, NIRS was also found to be a very efficient, rapid and accurate technique for differentiating black pepper and papaya seed powders without the necessity for any sample preparation step.