Novel, universal approach for the measurement of natural products in a variety of botanicals and supplements

Botanicals contain a great diversity of compounds that exhibit wide variation in their physicochemical properties. Although no single analytical method is available to measure all potentially active components, HPLC with charged aerosol detection is a nearly universal approach that nively measures any nonvolatile and many semivolatile compounds; that is, CAD does not require that analytes be ionizable (as required for mass spectrometry) or contain a chromophore (as required for UV spectrophotometry).

A number of isocratic and gradient HPLC/UHPLC methods with charged aerosol detection were developed and evaluated for the measurement of phytochemicals extracted from a variety of botanicals including: steroidal and pregnane glycosides from Hoodia gordonii; oxypregnane glycosides from Caralluma fimbriata; steroidal lactones from Withania somnifera; flavonolignans from milk thistle (Silybum marianum); triterpene glycosides from black cohosh (Cimicifuga racemosa); ginsenosides from ginseng (Panax ginseng); and diterpene glycosides from stevia (Stevia rebaudiana).

Analytes showed consistent response independent of chemical structure (typically < 10% variability between compounds corrected for gradient elution). All methods had a wide dynamic range (˜four orders of magnitude), good sensitivity (typically low ng levels of detection), and excellent reproducibility (RSDs typically < 2%) even at low detection levels. Comparative data from ELSD and UV detection will also be discussed.