Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev
Extraction Technologies for Medicinal and Aromatic ... - Capacity4Dev 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 be known beforehand, the photodiode array detector is useful, especially when constructing profi les of plant extracts. The fi ngerprint profi le of plant extracts can be used for identifi cation purposes and also for obtaining semiquantitative information if the sample preparation was not done for quantitative analysis. Similarly, the profi le can be generated for the fi nished product and used to record batch to batch variations. The fi ngerprint profi le can be used to study changes in the composition of the fi nished product or, in other terms, to indicate the stability of the product. The most important use of HPLC is in estimation of markers in plant drugs. The steps in HPLC analysis are fundamentally the same as used for any other analytical technique. The response of the test sample is compared to that of a known quantity of the marker to quantify the marker in the test substance. The HPLC method is developed from knowledge of the technique and chemistry of the marker. In chemical analysis, HPLC has no parallel and can be customized to produce the most precise and accurate results. The HPLC analysis is vital in the analysis of a finished product and the expected results are superior to those from TLC, as the separations in HPLC are better. However, run time of HPLC analyses usually varies from 15 to 30 min, which restricts its use if large numbers of samples are to be analyzed. 14.6 TLC versus HPLC TLC has emerged as a major tool in standardization of plant materials. The advancement and automation of the technique has made it a fi rst choice for plant drugs. Its use has become more popular in developing countries where advancements of HPLC are not cost effi cient. TLC offers several advantages over HPLC. Sample and mobile phase preparation do not require elaborated steps of purifi cation, degassing, and fi ltration, which are essential to protect expensive columns from deterioration. Several samples (up to 18) can be accommodated on a single 20 x 20 cm 2 plate. The test samples and standards are analyzed simultaneously under the same conditions. Several analysts can work simultaneously as each step in analysis is carried out independently using separate equipment. The choice of solvent systems is unlimited, unlike for HPLC where column chemistry disallows the use of extremes of pH in mobile phase. The technique allows enormous fl exibility of derivatization with chromogenic spray reagents, making possible the detection of an analyte that is transparent to ultraviolet light. It also allows multiple evaluations of the developed chromatogram, which is not possible in HPLC. There is no leftover from the previous analysis to interfere in the next, as each time a fresh plate is employed. Lastly, it saves tremendously on the time and cost of the analysis. TLC offers many advantages but also has some disadvantages. It fails to match the sensitivity of HPLC and has not kept with the pace of developments and advancements happening in the area of HPLC. TLC is 258
EXTRACTION TECHNOLOGIES FOR MEDICINAL AND AROMATIC PLANTS an open system and hastens the degradation of compounds sensitive to light and air, which in the case of HPLC pass through an enclosed environment. Detection of the analyte in HPLC occurs in solution, permitting high sensitivity, whereas in TLC the solid phase interaction makes detection less sensitive. Finally, recent advances and effi cient fl ow kinetics of HPLC allow more complex separations than TLC. 14.7 Conclusions Both TLC and HPLC are vital in the analysis and quality control of plant material and the extracted products. Each of these techniques has its own limitations and advantages. TLC is fast, adaptable and economical, whereas HPLC is more precise and accurate. Based on the preferences and demand of the situation, one can opt to use one or the other for quality assurance of plant products. Bibliography Barwick, V. J., 1999, Sources of uncertainty in gas chromatography and high performance liquid chromatography, Journal of Chromatography A, 849: 13-33 EMEA, 2006, Guideline on Quality of Herbal Medicinal Products/Traditional Herbal Medicinal Products, EMEA/CVMP/814/00 Rev 1, European Medicines Agency, London, U.K., p. 1-11 EMEA, 2006, Guideline on Specifi cations: Test Procedures and Acceptance Criteria for Herbal Substances, Herbal Preparations, and Herbal Medicinal Products / Traditional Herbal Medicinal Products, EMEA/CVMP/815/00 Rev 1, European Medicines Agency, London, U.K., p. 1-21 European Pharmacopoeia 5.0, 2004, Vol. 2, European Directorate for the Quality of Medicines, Strasbourg, France, p. 2667-2668 ICH, 1996, ICH-Harmonised Tripartite Guideline on Validation of Analytical Procedures: Methodology, International Conference on Harmonization, p. 1-8 Poole, C. F., 1999, Planar chromatography at the turn of the century, Journal of Chromatography A, 856: 399-427 Poole, C. F., 2003, Thin-layer chromatography: challenges and opportunities, Journal of Chromatography A, 1000: 963-984 Sherma, J., 2000, Thin-layer chromatography in food and agricultural analysis, Journal of Chromatography A, 880: 129-147 WHO, 1998, Quality Control Methods for Medicinal Plant Materials, World Health Organization, Geneva, p. 1-114 259
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EXTRACTION TECHNOLOGIES FOR MEDICINAL AND AROMATIC PLANTS<br />
an open system <strong>and</strong> hastens the degradation of compounds sensitive to<br />
light <strong>and</strong> air, which in the case of HPLC pass through an enclosed environment.<br />
Detection of the analyte in HPLC occurs in solution, permitting high<br />
sensitivity, whereas in TLC the solid phase interaction makes detection less<br />
sensitive. Finally, recent advances <strong>and</strong> effi cient fl ow kinetics of HPLC allow<br />
more complex separations than TLC.<br />
14.7 Conclusions<br />
Both TLC <strong>and</strong> HPLC are vital in the analysis <strong>and</strong> quality control<br />
of plant material <strong>and</strong> the extracted products. Each of these techniques has<br />
its own limitations <strong>and</strong> advantages. TLC is fast, adaptable <strong>and</strong> economical,<br />
whereas HPLC is more precise <strong>and</strong> accurate. Based on the preferences <strong>and</strong><br />
dem<strong>and</strong> of the situation, one can opt to use one or the other <strong>for</strong> quality assurance<br />
of plant products.<br />
Bibliography<br />
Barwick, V. J., 1999, Sources of uncertainty in gas chromatography <strong>and</strong> high per<strong>for</strong>mance<br />
liquid chromatography, Journal of Chromatography A, 849: 13-33<br />
EMEA, 2006, Guideline on Quality of Herbal <strong>Medicinal</strong> Products/Traditional Herbal<br />
<strong>Medicinal</strong> Products, EMEA/CVMP/814/00 Rev 1, European Medicines Agency,<br />
London, U.K., p. 1-11<br />
EMEA, 2006, Guideline on Specifi cations: Test Procedures <strong>and</strong> Acceptance Criteria<br />
<strong>for</strong> Herbal Substances, Herbal Preparations, <strong>and</strong> Herbal <strong>Medicinal</strong> Products /<br />
Traditional Herbal <strong>Medicinal</strong> Products, EMEA/CVMP/815/00 Rev 1, European<br />
Medicines Agency, London, U.K., p. 1-21<br />
European Pharmacopoeia 5.0, 2004, Vol. 2, European Directorate <strong>for</strong> the Quality of<br />
Medicines, Strasbourg, France, p. 2667-2668<br />
ICH, 1996, ICH-Harmonised Tripartite Guideline on Validation of Analytical Procedures:<br />
Methodology, International Conference on Harmonization, p. 1-8<br />
Poole, C. F., 1999, Planar chromatography at the turn of the century, Journal of Chromatography<br />
A, 856: 399-427<br />
Poole, C. F., 2003, Thin-layer chromatography: challenges <strong>and</strong> opportunities, Journal<br />
of Chromatography A, 1000: 963-984<br />
Sherma, J., 2000, Thin-layer chromatography in food <strong>and</strong> agricultural analysis, Journal<br />
of Chromatography A, 880: 129-147<br />
WHO, 1998, Quality Control Methods <strong>for</strong> <strong>Medicinal</strong> Plant Materials, World Health<br />
Organization, Geneva, p. 1-114<br />
259
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