Domestic food content detection is generally preferred to refer to the Chinese pharmacopoeia, or food safety national standards. If there is no pharmacopoeia standard or national standard, the enterprise standard will be recorded. The quantitative analysis methods for drug content determination in Pharmacopoeia of Traditional Chinese Medicine mainly include chromatographic analysis, spectral analysis and quantitative analysis.
First, chromatographic analysis: is a separation analysis method, according to the difference in the chromatographic behavior of each component in the mixture, the component is separated from the mixture and then selectively treated the measured component for analysis.
Chromatographic analysis is therefore the most powerful means of analyzing mixtures.
1. HPLC, also known as High performance liquid chromatography (HPLC). High performance liquid chromatography means that mobile phase is pumped into a column equipped with filler by a high-pressure infusion pump to separate and determine the test product. General area normalization method, external standard method, internal standard method, plant extracts with the first two more.Area normalization method: simple operation, no standard, relatively accurate results, but the correction factor determination cumbersome and repeatability is not good. In order to save costs, many domestic plant extract manufacturers use this detection method.
External standard method: To use standard products, the test results are accurate, but subject to the reference material and linear range. Standard products are divided into domestic and imported, sometimes customers will specify imported standard products, the price is relatively expensive. Many plant extraction plants claim to use external standard testing, but in fact, they only use standard products in the research and development stage, and only test by experience after production, without standard products. Internal standard method: The detection results are accurate but the selection of internal standard is difficult. Plant extracts are not usually used.
2. TLC: Thin layer chromatography
It is a method for the identification of drugs or the detection of impurities by comparing the chromatogram obtained by expanding and inspecting the test product solution on a thin layer plate with the chromatogram obtained by the same method with the appropriate reference.
The reproducibility and accuracy of HPLC method is superior to thin layer chromatography because of its strong separation function and fast analysis speed for complex systems containing many components. It is the preferred method for the content determination of traditional Chinese medicine and its preparations. Most Chinese pharmacopoeia uses HPLC for content determination.
3. GC: Gas chromatography is a chromatographic method in which a gas is used as a mobile phase through a column equipped with a filler to separate and determine. It is generally used to measure the content of volatile substances, such as pesticide residue 666 and DDT.
2. Spectral analysis: When a substance absorbs radiant energy or heat energy, its internal energy level transition occurs. The spectrum obtained by recording the radiation energy generated by the energy level transition with the change of wavelength is called spectrum. The method of qualitative, quantitative and structural analysis using substance spectra is called spectroscopic analysis.
1. UV, full name: Ultraviolet - visiblespectrophotometry, Ultraviolet and visiblespectrophotometry, It is a chromatographic analysis method based on the absorption characteristics of material molecules to monochromatic optical radiation in ultraviolet region (wavelength 200-400nm) and visible region (wavelength 400-760nm)
The characteristics of the method are simple and easy to operate, low cost and easy to operate, but the specificity is poor and it is easy to lack selectivity for the related materials with similar structure. Scope of application: Generally measure the sum of a class of substances, such as the measurement of marigold extract of beta Carotenoids. Such as Lutein 10%UV.
The difference between HPLC and UV: steamed buns with meat (pork, chicken, beef... Mixed fillings), for example
UV measures the total amount of meat in the meat filling
HPLC was used to measure the amount of each kind of meat, such as pork and chicken
2. AAS Atomic Absorption Spectroscopy (abbreviation for absorption spectroscopy) is a method based on the absorption intensity of atomic resonance radiation in the range of ultraviolet and visible light by electrons on the outer layer of gaseous ground state atoms to quantify the content of measured elements. Is a method of measuring the absorption of light radiation by certain gaseous atoms. AAS atomic absorption method is often used for the determination of heavy metals such as lead, arsenic, mercury and cadmium in plant extracts.
3. quantitative analysis (also known as titration method), is the known concentration of titration liquid (standard substance solution) by burette drip into the measured solution, until the titration liquid and measured substance reaction completely (through the appropriate method indicated), and then according to the concentration of titration liquid and the volume consumed, according to the stoichiometric relationship to calculate the content of measured substance.
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