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Determination of Pokeweed by HPLC with ELSD

What is vaporative light scattering detector(ELSD)?

It has been in development and production for decades, but for many chromatographers it is still a new product. The first ELSD was developed by scientists at the Union Carbide Research Laboratory in Australia, and was converted into commercial products in the early 1980s. The second generation of ELSDs using lasers as the light source was introduced in the 1980s. Since then, the operational performance of the ELSD has been improved through continuous design. ELSD is now increasingly used as a general-purpose detector in high performance liquid chromatography, supercritical chromatography (SFC) and countercurrent chromatography.

Detection Uniqueness: A general-purpose detector that can detect organic substances without UV absorption. The greatest advantage of ELSD is that it can detect compounds without chromophores, such as: carbohydrates, lipids, polymers, underivatized fatty acids and amino acids, surfactants, drugs, and in the absence of standards and compounds whose structural parameters are unknown. detection of unknown compounds.

Evaporative Light Scattering Detector

Pokeweed Content Determination-HPLC (ELSD) Method

  1. Reference basis
    Pharmacopoeia of the People's Republic of China, 2020 Edition, Part 1.
  2. Chromatographic conditions
Flow rate1.0ml/minMobile phaseMethanol: 0.4% glacial acetic acid = 70:30
Column and temperatureOctadecylsilane bonded silica column 4.6×250mm,5μm,35℃Detection room temperature50℃
Evaporation tube temperature80℃Nebulizer temperature80℃
Gas flow0.4SLMGain50

3.Instruments equipped

  • P3100B Binary High Pressure Gradient Pump
  • ELSD 3100
  • CT3100 full temperature column oven
  • AS3100 Autosampler

4.Sample Preparation
Preparation of reference substance: Take an appropriate amount of Pokeweed Saponin A reference substance, accurately weigh it, and add methanol to make a solution containing 0.5mg per 1ml.
Preparation of the test product: Take about 1g of this product powder (passed through a No. 3 sieve), accurately weigh it, put it in a conical flask with a stopper, add 25ml of dilute ethanol precisely, weigh it, and ultrasonically treat it (power 500W, frequency 40kHz) 30 minutes, let it cool, weigh the weight again, use dilute ethanol to make up the lost weight, shake well, filter, and take the filtrate.

5.Test results

Reference substance chromatogram

pokeweed chromatogram

The test product chromatogram

pokeweed chromatogram

HPLC determination result data

Sample nameCompound nameRetention timePeak areaPeak heightSeparationNumber of theoretical platesCapacity factor
Reference substancePokeweed A9.565153.50410.039--90050
The test productPokeweed A9.58746.1393.069--95300



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