Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev

14 QUALITY CONTROL OF MEDICINAL AND AROMATIC PLANTS AND THEIR EXTRACTED PRODUCTS
BY HPLC AND HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHY
cence mode is optional. Data acquisition and analysis is through standard
PC-based software. Multi-wavelength scanning, recording and comparing ultraviolet
spectra, and generating and acquiring spectra libraries are among
several options available on the software provided with the TLC scanner.
The determination of analyte concentration is through a standard
plot or single or double point calibrations.
14.4.10 Improving the Efficiency of TLC
Several precautions can be taken to improve the effi ciency of
TLC analysis. These include carefully selecting the range of concentrations
for analysis; using correct instrument parameters like slit dimensions, wavelength
selection, scanning speed, base line correction; using HPTLC plates
for high sensitivity and resolution; use of appropriate sorbent from a wide
range of sorption properties to optimize selectivity; use of automated sample
application, development and detection; use of precise in situ recording
and quantitation of chromatograms; and avoiding derivatization in assay procedures
and, if necessary, using dip-in technique of derivatization.
The following example, of one of the Ayurvedic drugs, illustrates
the use of TLC in quality control of plant material. The drug was analyzed for
one of the active compounds and the TLC fi ngerprint profi le was used for the
purpose of positively identifying the plant material.
To prepare the fi ngerprint profi le, about 5 g plant material was
extracted with 50 ml methanol for 30 min at 50° C in a conical fl ask. The
extract was fi ltered and the fi ltrate was concentrated to about 5 ml under
vacuum. One of the active constituents isolated from this plant (code name
DPH-1) was used as a reference. The solution of the reference substance
was prepared by dissolving about 5 mg in 1 ml chloroform. About 10 μl of
each test and reference solution was manually applied in band form on aluminium
base, silica gel 60 F 254 , 0.2-mm thick TLC plates (Merck). The plate
was developed using mobile phase containing 95 volumes toluene and 5
volumes ethyl acetate. The plate after development was dried and visualized
under 254 nm ultraviolet light (Figure 1A). The same plate was sprayed
with anisaldehyde-sulphuric acid reagent and heated for about 10 min to
visualize the spots (Figure 1B). These profi les can be used to confi rm the
identity of the plant material and to obtain semiquantitative information on
the amount of DPH-1 present in the drug.
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