Herbal Medicine in India by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9789811372483
Publisher: Springer Singapore

Medium-pressure LC (5–20 bar/75–300 psi)

Low-pressure LC (<5 bar/75 psi)

Flash chromatography (ca. 2 bar/30 psi)

21.7.1.1 High-Performance Liquid Chromatography

HPLC is gaining momentum as the most widespread instrumental technique for the separation of flavonoids and preparative as well as analytical purpose. The technique is continuously improved by introducing changes in instrumentation, column technology and packing materials making it a more effective and attractive separation technique.

Analytical and preparative HPLC can be differentiated by the fact that analytical HPLC does not focus on sample recovery, while preparative chromatography emphasizes on isolation of pure material from a mixture as it is a purification method.

Columns with an internal diameter of 8–20 mm packed with 10 mm or smaller particle size particles can be used for samples of 1–100 mg in semipreparative HPLC separations while preparative installations are used for large samples.

Optimization can be achieved on analytical HPLC columns before reversal to semipreparative scale. In earlier days, preparative HPLC was not been utilized efficiently for isolation of flavonoids. But presently 80% of all flavonoid separations comprise a HPLC step. Octadecylsilyl phases with isocratic and gradient conditions are used in 95% of the reported HPLC methods.

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