Chemical Analysis Detection Process? Detection methods commonly used in chemical analysis

Disinfection was performed by reflectometry and spectroscopy.

Determine salt and vitamin C by volumetric titration

and raw ingredients such as calcium.

The water content was determined by Karl Fischer (kF) titration.

Trace elements were analyzed by atomic absorption spectrometry (AAS).

Inductively coupled plasma (ICP) is used to determine the metal content.

Sample preparation method for planar pesticide extraction combined with Quechers solid-phase extraction.

Samples are prepared directly for instrumental analysis by solid-phase microextraction (SPME).

with high-performance liquid chromatography.

and ultra-performance liquid chromatography (mass spectrometry) to screen for toxins and pesticides.

Titration. Carbohydrates were confirmed by gas chromatography (GC) determination of fatty acid methyl esters (FAME) enzymatic analysis.

Sugars, lipids.

and raw material components of proteins.

Nutritional data for packaged foods and beverages.

Nutritional data must be presented on food packaging so that consumers can consume rationally according to dietary needs or diet-related disease control requirements. Therefore, according to the relevant labelling regulations, nutrition labels need to provide detailed information such as nutrient content, content and caloric value. Producers explain the nutritional content of carbohydrates (sugars, sugars) and dietary fiber in food.

Organic acids, sugar alcohols, fats (fatty acids, fatty acid methyl esters, glycerides), proteins (amino acids.

peptides), sodium, vitamins and minerals are additionally tested.

1. Sample collection and preservation;

2. Sample pretreatment, preparation of test samples;

3. Sample determination;

4. Data processing;

5. Prepare inspection reports.

If you're referring to quantitative analytical chemistry, there are gravimetric and titration methods of analysis.

Gravimetric method includes precipitation gravimetric method, gasification method, electrolysis method, extraction method, etc., gravimetric analysis method is suitable for constant analysis, the relative error is small, but the operation is cumbersome and time-consuming.

The titration method includes four methods: acid-base titration, combined titration, redox titration and precipitation titration. This method is simple, rapid, with sufficient accuracy and small relative error, and is mainly used for the determination of macro components, but requires specific indicators.

Photoabsorbance is sometimes included in the category of chemical analysis, mainly because absorbance measurement usually requires a process that works with color development, which is a chemical process.

The test method for identifying which elements a metal consists of is called qualitative analysis, and the test method for determining the relationship between the amounts of each component (usually expressed as a percentage) is called quantitative analysis. If chemical methods are basically used to achieve the purpose of analysis, it is called chemical analysis. If chemical and physical methods are mainly used (especially in the final determination stage, physical methods are often used), instruments are generally used to obtain analytical results, which is called instrumental analysis.

Chemical analysis uses chemical reactions to perform qualitative or qualitative analysis of metallic materials according to the unique chemical properties of various elements and their compounds. Quantitative chemical analysis can be divided into three types: gravimetric analysis, titration analysis and gas volumetric analysis according to the final determination method. Gravimetric analysis is to convert the measured element into a certain compound or element, separate it from other components in the sample, and finally determine the content of the element by the balance weighing method.

Titration analysis is a complete chemical reaction between a standard solution of known and accurate concentration with the measured element, and the content of the measured element is calculated based on the volume (measured with a burette) and concentration of the standard solution consumed. The gas volumetric method is to measure the volume of the gas to be measured (or the element to be measured) to be absorbed (or generated) with a measuring tube to calculate the content of the element to be measured. Due to its wide range of applications and ease of generalization, chemical analysis is still used by many standard analytical methods.

Instrumental analysis is based on the qualitative or quantitative analysis of metal materials based on certain physical properties or the interrelationship between physical and chemical properties of the elements in the metal composition or their compounds. Some instrumental analyses still inevitably need to be done through certain chemical pretreatment and necessary chemical reactions. There are two commonly used instrumental analysis methods for metal chemical analysis: optical analysis and electrochemical analysis.

Optical analysis is a method of analyzing substances based on their interrelationships with electromagnetic waves, including the entire spectrum from rays to radio waves, or by using the optical properties of matter. The most commonly used are absorbance (infrared, visible and ultraviolet absorption spectroscopy), atomic absorption spectroscopy, atomic fluorescence spectroscopy, emission spectrometry (spectral analysis), turbidity, flame photometry, X-ray diffraction, X-ray fluorescence analysis, and radiochemical analysis. Electrochemical analysis is a method of analysis based on the concentration of an element or its compound in a measured metal as a function of potential, current, conductance, capacitance, or electricity.

It mainly includes potentiometric method, electrolysis method, galvanic method, polarographic method, coulomb (electric amount) method, conductivity method and ion selective electrode method. Instrumental analysis is characterized by fast analysis speed, high sensitivity, easy to realize computer control and automatic operation, which can save manpower, reduce labor intensity and reduce environmental pollution. However, the test setter is usually large and complex, and some large, complex and precise instruments are only suitable for the analysis of large quantities and complex samples.

The main component of bauxite is Al2O3 and impurities.

X (dilute hydrochloric acid) was added, the residue was SiO2 (not reactive with hydrochloric acid), and the feed solution was AlCl3 and FeCl3

Excessive NaOH was added, and the feed solution was Naalo2 (alkaline, not alkaline), and the solid was Fe(OH)3

The final step is electrolytic melting of alumina.