HPLC sample preparation
1. Why sample pretreatment is required for high-performance liquid chromatography analysis?
(1) Sample concentration adjustment: The concentration of some components to be measured in the sample is too low or too high, making instrument detection difficult, so the sample needs to be concentrated or diluted in advance.
(2) Avoid contamination and protect the instrument: the pH, ionic strength, etc. of some samples can easily cause system contamination and shorten the service life of the instrument.
(3) Eliminate interference: interference from matrix or coexisting substances
(4) Media replacement: The sample medium is not suitable for subsequent separation and detection, and media replacement needs to be performed in advance.
2. Principles of sample pretreatment for high-performance liquid chromatography analysis
(1) Remove matrix impurities and eliminate interference factors;
(2) Keep the components to be tested intact and avoid chemical reactions or contamination of the components to be tested as much as possible during the treatment process;
(3) The method is simple, easy to implement, reproducible and low cost.
3. High performance liquid chromatography analysis sample pretreatment technology
Use the difference in solubility or distribution coefficient of each component in the sample in the solvent to achieve the purpose of separation
Mostly used in the medical field, such as the extraction of artemisinin
Solid Phase Extraction
A solid adsorbent is used to adsorb the component to be tested, and interfering substances are removed, and then the component to be tested is separated using an eluent.
Mostly used for food safety and environmental pollution analysis
Using the action of high-frequency electromagnetic waves, the components to be measured in the sample are released from the cells, dissolved in the extraction solvent at low temperature, and filtered to achieve the purpose of separation.
Extraction of natural medicines, pesticide residues, organic metal compounds and other substances
Ultrasonic assisted extraction
The mechanical effect, cavitation effect and thermal effect of ultrasonic waves are used to destroy the sample cell tissue and increase the mass transfer efficiency within the cells, thus promoting the release and extraction of the components to be measured.
Extraction of proteins, polysaccharides, nicotine and other substances
supercritical fluid extraction
Carbon dioxide is used as the fluid. Under supercritical conditions, carbon dioxide causes each component of the sample to be extracted in sequence. When normal temperature and pressure are restored, the components to be measured dissolved in carbon dioxide are immediately separated from the gaseous fluid in a liquid state.
Mostly used for the extraction of natural substances
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