Direct analysis in real time (DART) ion source is a powerful ionising
technique for the quick and easy detection of various organic
molecules without any sample preparation steps, but the lack of
quantitation capacity limits its extensive use in the field of
phytochemical analysis. Objective – To improvise a new system which
utilize DART-MS as a hyphenated detector for quantitation. Methodology
– A total extract of Schisandra chinensis fruit was analyzed on a TLC
plate and three major lignan compounds were quantitated by three
different methods of UV densitometry, TLC-DART-MS and HPLC-UV to
compare the efficiency of each method. To introduce the TLC plate into
the DART ion source at a constant velocity, a syringe pump was
employed. The DART-MS total ion current chromatogram was recorded for
the entire TLC plate. The concentration of each lignan compound was
calculated from the calibration curve established with standard
compound. Results – Gomisin A, gomisin N and schisandrin were well
separated on a silica-coated TLC plate and the specific ion current
chromatograms were successfully acquired from the TLC-DART-MS system.
The TLC-DART-MS system for the quantitation of natural products showed
better linearity and specificity than TLC densitometry, and consumed
less time and solvent than conventional HPLC method. Conclusion – A
hyphenated system for the quantitation of phytochemicals from crude
herbal drugs was successfully established. This system was shown to
have a powerful analytical capacity for the prompt and efficient
quantitation of natural products from crude drugs.
