Analytical Methods
Published monographs in a pharmacopeia are the most practical approach for
quality control of herbal drugs and there are many available
When pharmacopeial monographs are unavailable, development and vali-
dation of analytical procedures have to be carried out by the manufacturer. The
best strategy is to follow closely the pharmacopeial definitions of identity, purity,
and content or assay. Valuable sources for general analytical procedures are includ-
ed in the pharmacopeias, in guidelines published by the WHO [60, 65, 76]. Addi-
tional information, especially on chromatographic and/or spectroscopic methods
can be found in the general scientific literature. The plant or plant extract can be
evaluated by various biological methods to determine pharmacological activity, po-
tency, and toxicity. A simple chromatographic technique such as TLC may provide
valuable additional information to establish the identity of the plant material. This
is especially important for those species that contain different active constituents.
2.3 Quality Control of Herbal Drugs 37
Qualitative and quantitative information can be gathered concerning the presence
or absence of metabolites or breakdown products [60].
TLC fingerprinting is of key importance for herbal drugs made up of essential
oils, resins, and gums, which are complex mixtures of constituents that no longer
have any organic structure. It is a powerful and relatively rapid solution to distin-
guish between chemical classes, where macroscopy and microscopy will fail.
Chromatograms of essential oils, for example, are widely published in the scientif-
ic literature, and can be of invaluable help in identification.
The instruments for UV-VIS determinations are easy to operate, and validation
procedures are straightforward but at the same time precise. Although measure-
ments are made rapidly, sample preparation can be time consuming and works
well only for less complex samples, and those compounds with absorbance in the
UV-VIS region.
HPLC is the preferred method for quantitative analysis of more complex mix-
tures. Though the separation of volatile components such as essential and fatty oils
can be achieved with HPLC, it is best performed by GC or GC/MS.
The quantitative determination of constituents has been made easy by recent de-
velopments in analytical instrumentation. Recent advances in the isolation, purifi-
cation, and structure elucidation of naturally occurring metabolites have made it
possible to establish appropriate strategies for the determination and analysis of
quality and the process of standardization of herbal preparations. Classification of
plants and organisms by their chemical constituents is referred to as chemotaxon-
omy. TLC, HPLC, GC, quantitative TLC (QTLC), and high-performance TLC
(HPTLC) can determine the homogeneity of a plant extract. Over-pressured layer
chromatography (OPLC), infrared and UV-VIS spectrometry, MS, GC, liquid
chromatography (LC) used alone, or in combinations such as GC/MS, LC/MS, and
MS/MS, and nuclear magnetic resonance (NMR), electrophoretic techniques, es-
pecially by hyphenated chromatographies, are powerful tools, often used for stan-
dardization and to control the quality of both the raw material and the finished
product. The results from these sophisticated techniques provide a chemical fin-
gerprint as to the nature of chemicals or impurities present in the plant or extract
[44, 77–79].
Based on the concept of photoequivalence, the chromatographic fingerprints of
herbal medicines can be used to address the issue of quality control. Methods
based on information theory, similarity estimation, chemical pattern recognition,
spectral correlative chromatograms (SCC), multivariate resolution, the combina-
tion of chromatographic fingerprints and chemometric evaluation for evaluating
fingerprints are all powerful tools for quality control of herbal products.
Published monographs in a pharmacopeia are the most practical approach for
quality control of herbal drugs and there are many available
When pharmacopeial monographs are unavailable, development and vali-
dation of analytical procedures have to be carried out by the manufacturer. The
best strategy is to follow closely the pharmacopeial definitions of identity, purity,
and content or assay. Valuable sources for general analytical procedures are includ-
ed in the pharmacopeias, in guidelines published by the WHO [60, 65, 76]. Addi-
tional information, especially on chromatographic and/or spectroscopic methods
can be found in the general scientific literature. The plant or plant extract can be
evaluated by various biological methods to determine pharmacological activity, po-
tency, and toxicity. A simple chromatographic technique such as TLC may provide
valuable additional information to establish the identity of the plant material. This
is especially important for those species that contain different active constituents.
2.3 Quality Control of Herbal Drugs 37
Qualitative and quantitative information can be gathered concerning the presence
or absence of metabolites or breakdown products [60].
TLC fingerprinting is of key importance for herbal drugs made up of essential
oils, resins, and gums, which are complex mixtures of constituents that no longer
have any organic structure. It is a powerful and relatively rapid solution to distin-
guish between chemical classes, where macroscopy and microscopy will fail.
Chromatograms of essential oils, for example, are widely published in the scientif-
ic literature, and can be of invaluable help in identification.
The instruments for UV-VIS determinations are easy to operate, and validation
procedures are straightforward but at the same time precise. Although measure-
ments are made rapidly, sample preparation can be time consuming and works
well only for less complex samples, and those compounds with absorbance in the
UV-VIS region.
HPLC is the preferred method for quantitative analysis of more complex mix-
tures. Though the separation of volatile components such as essential and fatty oils
can be achieved with HPLC, it is best performed by GC or GC/MS.
The quantitative determination of constituents has been made easy by recent de-
velopments in analytical instrumentation. Recent advances in the isolation, purifi-
cation, and structure elucidation of naturally occurring metabolites have made it
possible to establish appropriate strategies for the determination and analysis of
quality and the process of standardization of herbal preparations. Classification of
plants and organisms by their chemical constituents is referred to as chemotaxon-
omy. TLC, HPLC, GC, quantitative TLC (QTLC), and high-performance TLC
(HPTLC) can determine the homogeneity of a plant extract. Over-pressured layer
chromatography (OPLC), infrared and UV-VIS spectrometry, MS, GC, liquid
chromatography (LC) used alone, or in combinations such as GC/MS, LC/MS, and
MS/MS, and nuclear magnetic resonance (NMR), electrophoretic techniques, es-
pecially by hyphenated chromatographies, are powerful tools, often used for stan-
dardization and to control the quality of both the raw material and the finished
product. The results from these sophisticated techniques provide a chemical fin-
gerprint as to the nature of chemicals or impurities present in the plant or extract
[44, 77–79].
Based on the concept of photoequivalence, the chromatographic fingerprints of
herbal medicines can be used to address the issue of quality control. Methods
based on information theory, similarity estimation, chemical pattern recognition,
spectral correlative chromatograms (SCC), multivariate resolution, the combina-
tion of chromatographic fingerprints and chemometric evaluation for evaluating
fingerprints are all powerful tools for quality control of herbal products.
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