The Application of HPLC with Coulometric Electrochemical Array Detection to the Study of Natural Products and Botanicals: From Targeted Analyses to Metabolomics

Many potentially important bioactive phytochemicals are electrochemically active and can be measured using HPLC with electrochemical detection (HPLC-ECD). Such compounds, come from diverse chemical classes and include phenols, polyphenols, aromatic amines, quinones, isoquinolines, indoles, thiols and conjugated polyenes. Although HPLC-ECD with a single amperometric working electrode offers the analyst excellent sensitivity and some degree of selectivity, this approach is limited as it cannot be used routinely with gradient chromatography, relatively few analytes are measured concurrently, and qualitative information is lacking. The coulometric flow-through graphite working electrode is both sensitive (˜100% of an analyte will react) and maintenance free. When used in series, chromatographically co-eluting analytes can be resolved voltammetrically. Such behavior can be used to identify and characterize an analyte in an analogous fashion to the use of spectral data from a diode array detector. Furthermore, the CoulArray® detector, with its array of up to sixteen serially placed coulometric sensors, is fully gradient compatible and can be used for either targeted or metabolomics studies. During this presentation I will illustrate the capability of coulometric array detection for the measurement of specific analytes in plant, animals and human tissues. I will also discuss the use of metabolite profiles/metabolomics with pattern recognition and how this can be used to study product and botanical adulteration, contamination and composition.

Keywords: HPLC, electrochemical, botanicals, natural products, plasma, urine, adulteration, characterization