PHARMACEUTICAL ANALYSIS | Plant Extracts

Abstract

Plant extracts are complex mixtures of constituents and their extraction, sample cleanup, separation, and detection is typical for each extract. The extraction procedures generally used are solid–liquid extraction (SLE), solid-phase extraction (SPE), liquid–liquid extraction (LLE), but more recently, the introduction of supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE) have received a great interest to overcome the disadvantages of classical solvent extractions. Quality control starts with the unequivocal identification and authentication of active constituents or markers, and it is generally achieved using spectroscopic, spectrometric, and chromatographic techniques. The most widely used is ultraviolet (UV) spectroscopy, whilst it is increasing the interest in near infrared (NIR) and nuclear magnetic resonance (NMR) spectroscopy. Mass spectrometry (MS) provides excellent sensitivity, selectivity, and crucial structural information. The most common ion sources are atmospheric pressure chemical ionization (APCI), electrospray ionization (ESI), matrix-assisted laser aesorption/ionization (MALDI), thermospray ionization (TS). The most used chromatographic methods are thin layer chromatography (TLC and HPTLC), gas chromatography (GC), high performance liquid chromatography (HPLC and UPLC), supercritical fluid chromatography (SFC), and capillary electrophoresis (CE). The development of techniques coupled with different detectors has greatly aided the analysis of extracts. Mandatory is a systematical validation of all the procedures.