Abstract
The quality of herbal drugs is usually controlled using several tests recommended
in a monograph. HPTLC is the method of choice for identification in many pharmacopoeias.
If combined with a suitable reference material for comparison, HPTLC can provide information
beyond identification and thus may simplify quality control. This paper describes,
as a proof of concept, how HPTLC can be applied to define specifications for an herbal
reference material and to control the quality of an herbal drug according to these
specifications. Based on multiple batches of cultivated Angelica gigas root, a specific HPTLC method for identification was optimized. This method can distinguish
27 related species. It also can detect the presence of mixtures of A. gigas with two other Angelica species traded as “Dang gui” and is suitable as well for quantitative assessment
of samples in a test for minimum content of the sum of decursin and decursinol angelate.
The new concept of “comprehensive HPTLC fingerprinting” is proposed: HPTLC fingerprints
(images), which are used for identification, are converted into peak profiles and
the intensities of selected zones are quantitatively compared to those of the corresponding
zones of the reference material. Following a collaborative trial involving three laboratories
in three countries, the method was applied to check the quality of further candidates
for establishing an appropriate reference material. In conclusion, this case demonstrates
that a single HPTLC analysis can provide information about identity, purity, and minimum
content of markers of an herbal drug.
Key words
Angelica gigas - Apiaceae - HPTLC - identity - purity - minimum content
