What are the chemical composition analysis? Demand for samples and use methods

Date：2022-02-18 16:00:00 Views：1466

Component analysis technology is mainly used to analyze unknown substances and unknown components. Through component analysis technology, you can quickly determine the various components in the target sample, help you conduct qualitative and quantitative analysis on the sample, and identify the materials, raw materials, additives, specific components and contents, foreign matters, etc. of polymer materials such as rubber.

Chemical composition analysis

Analysis based on the chemical reaction of substances is called chemical analysis. Chemical analysis, also known as classical analysis, has a long history and is the basis of analytical chemistry. Chemical analysis is absolutely quantitative. The amount of components to be measured is calculated according to the amount of samples, reaction products or reagents consumed and the stoichiometric relationship of the reaction. Another important analytical method, instrumental analysis, is relatively quantitative, which is estimated according to the standard working curve. Chemical analysis can be divided into titration analysis and gravimetric analysis according to different operation methods.

Titration analysisAccording to the concentration and volume of the standard solution consumed by titration and the stoichiometric relationship between the measured substance and the standard solution, the content of the measured substance is calculated. This analysis is called titration analysis, also known as volumetric analysis. Four equilibria of the solution are used: acid-base (ionization) equilibrium, redox equilibrium, complexation (coordination) equilibrium and precipitation dissolution equilibrium. According to different reaction types, titration analysis can be divided into: (a) acid-base titration: measure the pH and acid-base content of various acids and bases; (b) Redox titration: measure substances with redox property; (c) Complexometric titration: measure the content of metal ions; (d) Precipitation titration: measure halogen and silver.

Gravimetric analysisAccording to the chemical properties of the substance, select the appropriate chemical reaction to convert the measured component into a precipitation or gas form with fixed composition. After a series of treatments such as passivation, drying, burning or absorption of absorbent, accurately weigh and calculate the content of the measured component. This kind of analysis is called gravimetric analysis.

Application method of component analysis

Component analysis: refers to the technical method of analyzing the components of products or samples through micro spectrum and laser femtosecond detection of molecular structure, and performing qualitative and quantitative analysis on each component. Component analysis technology is mainly used to analyze unknown substances and unknown components. Through component analysis technology, you can quickly determine the various components in the target sample, help you conduct qualitative and quantitative analysis on the sample, and identify the materials, raw materials, additives, specific components and contents, foreign matters, etc. of polymer materials such as rubber. Common methods of polymers and chemicals: FTIR (Fourier transform infrared spectrometer), PGC-MS (pyrolysis gas chromatography-mass spectrometry), TGA (thermogravimetric analysis), DSC (differential calorimetry), high temperature calcination method, chemical extraction method, XRF method, GC-MS, LC-MS, ICP-MS, nuclear magnetic resonance, IC, GPC, XRD, etc. Common methods for testing metal materials: wet analysis direct reading spectroscopy (OES), inductively coupled plasma emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), atomic absorption spectrometry (AAS), handheld XRF, laser femtosecond detection method (FMA, rapid determination of molecular vibration and electronic transition).

Demand for samples for component analysis

Special requirements for samples: whether the products can obtain accurate qualitative and quantitative results through component analysis. The requirements for samples are relatively strict. Generally, the following points need to be considered: 1. Does the sample contain natural unknown components? For example, traditional Chinese medicine ointment, seafloor sediment, extraterrestrial meteorite, etc. these samples contain natural unverified components. It is very difficult for such samples to obtain accurate qualitative and quantitative results through component analysis. 2. Is the sample quantity sufficient? In general, multiple steps and multiple analysis and separation methods will be used for component analysis. There is a large demand for samples, which requires repeated verification. If the amount is only a few milliliters, it is difficult to obtain good analysis results. 3. Is the sample stable? If the sample is extremely unstable in the air, it is also difficult to analyze its composition.

4. Is the sample bioactive? If it is a sample with biological activity, it is difficult to obtain information by conventional physical and chemical analysis.

5. Is the sample a post reaction product? For example, rubber, plastics and polymer materials are polymers obtained by reaction.