Reagent, also known as biochemical reagent or reagents. Mainly to achieve chemical reactions, analytical tests, research experiments, teaching experiments, chemical formulations used in pure chemicals.
Generally, it is divided into general reagents, high purity reagents, analytical reagents, instrumental analysis reagents, clinical diagnostic reagents, biochemical reagents, inorganic ion chromogenic reagents, etc. according to the use.
Classification of reagents
Inorganic analysis reagent
Inorganic analytical reagents are commonly used inorganic chemicals for chemical analysis. Its purity is higher than industrial products, and its impurities are less.
Organic analysis reagent
Organic reagents for inorganic analysis are special organic compounds for the determination, separation, and enrichment of elements in inorganic analysis, such as precipitants, extractants, chelating agents and indicators, rather than general Solvents, organic acids, and organic bases.
These organic reagents must have good sensitivity and selectivity. With the development of the analytical chemistry and chemical industries, such reagents with better sensitivity and selectivity will be developed, such as those that have been completed for some metals (such as alkali metals, alkaline earth metals) and ammonium ions since 1967.
This is the case with Crown ether compounds.
Primary standards are compounds with high purity, low impurities, good stability, and constant chemical composition.
Among the reference reagents, there are classifications such as volume analysis, pH measurement, calorific value measurement, and the like.
There is a score between the first benchmark and the working benchmark in each category.
The first benchmark must be verified by the National Metrology Institute, and the production unit uses the first benchmark as the measurement standard for the work-based product.
The benchmark reagent for commercial operation mainly refers to the capacity analysis work standard in the capacity analysis category [content range is 99.96% to 100.05% (weight titration)]. Generally used to calibrate titrants.
Standard substances are chemicals used for comparison in chemical analysis, instrumental analysis, or chemicals used to calibrate instruments.
It is chemical composition, content, physical and chemical properties, and impurities contained must be known and meet the requirements or be recognized.
Micro-analytical reagents are suitable for microanalytical reagents with a permissible amount of only one percent (weight of about 1 to 15 mg, the volume of about 0.01 to 2 ml).
Organic analytical standard
Organic analytical standards are chemical reagents used for comparison when determining the composition and structure of organic compounds. Its components must be precisely known. It can also be used for microanalysis.
Pesticide analysis standard
Pesticide analytical standards are suitable for the comparison of petrochemicals for the analysis of pesticides or for the determination of pesticide residues. Its content is required to be precise.
There are solutions prepared from a small amount of a single pesticide, and a mixed solution prepared from a plurality of pesticides.
Atomic absorption spectrometry
Atomic absorption spectroscopy Standards (Atomic absorption spectroscopy standards) is in the use of atomic absorption spectroscopy analysis of a sample used as a standard reagent.
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Refractive index liquid is a high-purity stable liquid whose refractive index is known to determine the refractive index of crystalline substances and minerals. The refractive index is indicated on the outside of each package.
The normal solution is an aqueous solution containing one gram equivalent of solute in one liter of solution, that is, a solution having a concentration of 1N.
An indicator is a substance that changes its color by the influence of the presence of certain substances. Mainly used in the end point of the volumetric analysis to indicate titration.
Generally, it can be classified into an acid-base indicator, a redox indicator, an adsorption indicator, and the like. In addition to analysis, indicators can also be used to test for the presence of certain harmful toxic substances in a gas or solution.
Instrumental analysis reagent
Instrumental analytical reagents are reagents used in the analysis of samples using special instruments designed according to physical, chemical or physical-chemical principles.
For chromatography reagents are reagents and materials used in analytical methods such as gas chromatography, liquid chromatography, gas-liquid chromatography, thin layer chromatography, and column chromatography. There are fixatives, supports, and solvents.
For electron microscopy (For electron microscopy) reagents are reagents such as fixatives, embedding agents, and stains used in research work using electron microscopy in the fields of biology and medicine.
For polarography reagents are reagents required for quantitative and qualitative analysis by polarography.
Spectrography reagents generally refer to higher purity reagents that have been analyzed by emission spectroscopy.
Spectrophotometric pure reagent refers to the solution used in spectrophotometric analysis and has a certain wavelength transmittance for qualitative analysis and quantitative analysis.
Biochemical reagent refers to biological materials or organic compounds related to life science research, as well as reagents for clinical diagnosis and medical research. Due to the wide range of life sciences and rapid development, this type of reagents has a wide variety and complex nature.
Other national standard reagents
National Standard Reagents: These reagents are stipulated by China’s national standards and are applicable to inspection, identification, and detection of reagent grades (RG, red label): standard chemicals as reagents.
Teaching reagents: A class of reagents that can meet the teaching objectives of students and do not cause deviations in chemical reaction phenomena.
Designated level (ZD), which is a chemical reagent ordered for a specific user according to the quality control indicators required by the user.
High Purity Reagent (EP): Includes ultra-pure, ultra-pure, high-purity, spectrally pure, standard solution.
The quality of such reagents is concerned with the fact that during the analysis of a particular method, the deviation of the analytical results may be caused, and the impurity content of the component analysis or content analysis may be disturbed, but the main content is not required.
Indicator (ID): For the preparation of the indicator solution. The quality indicators are the range of discoloration and the sensitivity of discoloration. It can be used in place of CP and is also suitable for organic synthesis.
Biochemical reagent (BR): Preparation of biochemical test solution and biochemical synthesis. Quality indicators focus on biologically active impurities. An alternative indicator for organic synthesis
Biological stain (BS): Preparation of microbial specimen staining solution. Quality indicators focus on biologically active impurities. An alternative indicator for organic synthesis
Electronic Pure (MOS): Suitable for the production of electronic products, the content of electrical impurities is extremely low.
Electroplating grade: suitable for electroplating industry production, less harmful impurities for electroplating, purity is much higher than an industrial grade, slightly lower than chemical purity. Equivalent reagent (3N, 4N, 5N): The main component contents are 99.9%, 99.99%, and 99.999%, respectively.
Electrophoresis reagent: The quality index focuses on the control of electrical impurity content.
In addition, there are special reagents, the production is very small, and almost on-demand and the quantity and quality of such reagents are generally specified by the user.
Synthetic reagent: The so-called synthetic reagent, a kind of chemical reagent related to various physical constants of the product is strictly given under the premise of indicating the main content of the component.
Four common specifications
There are four common specifications: excellent grade pure or first grade (GR, precision analysis and scientific research work), analytical pure or secondary products (AR, important analysis and general research work), chemical pure or tertiary products (CP, Industrial and mining schools and general chemical experiments), experimental reagents (LP).
Excellent grade pure (GR, green label): High content of main components, high purity, suitable for accurate analysis and research work, and some can be used as reference materials.
Analytically pure (AR, red label): High content of main components, high purity, low interference impurities, suitable for industrial analysis and chemical experiments.
Chemically pure (CP, blue label): High content of main components, high purity, interference impurities, suitable for chemical experiments and synthetic preparation.
Experimental pure (LR, yellow label): high content of main components, poor purity, and impurity content are not selected, only for general chemical experiments and synthetic preparation.
The reference reagent content should be 99.9% to 100%. With the development of science and technology and emerging industries, the requirements for purity, clarity, and precision of chemical reagents are becoming more stringent and specialized.
It is widely used in analytical chemistry. The grade and specifications of the reagents should be selected according to the specific requirements and usage.
The basis for grading is the purity (ie, content) of the reagent, the impurity content, the ease of purification, and various physical properties.
It is also sometimes graded according to the application, such as spectrally pure reagents, chromatographically pure reagents, and pH standard reagents.
Chemicals used to achieve chemical reactions. It is widely used in analytical chemistry. The grade and specifications of the reagents should be selected according to the specific requirements and usage.
In the Chinese National Standard (GB), the general reagents are divided into three grades: the primary reagent is excellent grade, the second reagent is analytically pure, and the tertiary reagent is chemically pure.
The basis for grading is the purity (ie, content) of the reagent, the impurity content, the ease of purification, and various physical properties. It is also sometimes graded according to the application, such as spectrally pure reagents, chromatographically pure reagents, and pH standard reagents.
Necessity and method
According to the given content of the main component and the relevant physical constant, it is up to the user to judge whether the work needs are met, and if necessary, the user can perform the corresponding purification.
The quality indicators are clear and reliable. Such reagents are very suitable for synthetic preparation.
The internationally accepted method is to indicate the grade and purity of chemical reagents according to the main content of the chemical, physical constants, and the like.
It is generally believed that when the main content, boiling point, melting point, density, refraction, and even the spectrum are known, the purity and application range of a substance can be completely determined.
In actual work, it is sometimes impossible to obtain a reagent of the required purity, which needs to be purified, and a suitable purification method should be selected for different reagents.
1 distillation. For volatile reagents, such as commonly used inorganic acids, organic solvents, etc. are the most commonly used purification methods. According to the boiling point, the atmospheric pressure or vacuum distillation method is used.
2 Shenghua. For some sublimation reagents, such as iodine, naphthalene, etc., this method is the easiest.
3 recrystallization. For the purification of most solid reagents, the key is to choose the right solvent.
4 solvent extraction. Purification can be achieved regardless of the extraction of the parent or impurities into the organic solvent phase.
5 ion exchange chromatography separation. It is a new type of high-efficiency purification method, for example, adsorption of iron (FeCl4-) in hydrochloric acid by anion exchange resin.
In addition, thin layer chromatography, electrodialysis, zone melting, an ion exchange membrane special means like isolated and purified Chemicals.
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Management and storage
Most of the chemical reagents have certain toxicity and danger. Strengthening the management of chemical reagents is not only the need to ensure the quality of analytical results but also the need to ensure the safety of people’s lives and property.
The management of chemical reagents should be managed in different ways according to the different characteristics of the toxicity, flammability, corrosiveness, and deliquescence of the reagents.
Only a small amount of short-term drug should be stored in the laboratory. The flammable and explosive reagents should be placed in the iron cabinet.
The top of the cabinet should have a vent. It is strictly forbidden to store a total of 20L of flammable liquid in the laboratory.
A large number of reagents should be placed in the reagent library. For general reagents, such as Yuanji salt, it should be stored in the reagent cabinet in an orderly manner and can be stored according to the elemental cycle family or in the form of acid, alkali, salt, oxide and the like.
When storing reagents, pay attention to the storage period of chemical reagents. Some reagents will gradually deteriorate during storage and even form hazardous materials.
Such as ethers, tetrahydrofuran, dioxane, alkene, liquid paraffin, etc., under the light conditions, if exposed to air can form peroxide, the longer the time is placed, the more dangerous Some reducing reagents, such as benzenetriol, titanium trichloride, sodium tetrahydroborate, iron sulfate, vitamin C, vitamin E, and metal wire, aluminum, magnesium, zinc powder, etc., are easily oxidized by oxygen in the air.
Chemical reagents must be stored separately in isolation and cannot be mixed together. Usually, the reagents are divided into the following categories and stored separately.
(1) Flammable flammable liquids are highly volatile and become a gas. They are burned when exposed to open flame. Generally, liquids with a flashpoint below 25 °C are included in the flammable class.
Those having a flash point below -4 ° C include petroleum ether, ethyl chloride, ethyl bromide, diethyl ether, gasoline, carbon disulfide, acetal, acetone, benzene, ethyl acetate, methyl acetate and the like.
The flash point below 25 ° C is butanone, toluene, methanol, ethanol, isopropanol, xylene, butyl acetate, amyl acetate, trioxane, pyridine and the like.
These reagents are required to be stored separately in a cool, ventilated place with an ideal storage temperature of 4 to 4 °C. Reagents with a flashpoint below 25 ° C, storage room temperature should not exceed 30 ° C, especially pay attention to keep away from fire.
(2) Acute poisoning refers to an agent that causes a poisoning death by invading a small amount of the digestive tract.
Biological tests with a lethal dose below 5Omg/kg are called highly toxic substances, such as potassium cyanide, sodium cyanide, and other highly toxic cyanides, arsenic trioxide and other highly toxic arsenic compounds, mercury dichloride and other extremely toxic mercury salts. , dimethyl sulfate, certain alkaloids, and poisonous buds.
These reagents should be placed in a cool, dry place and isolated from the acid reagent. It should be locked in a special drug cabinet to establish a two-person registration and signature system.
Establish systems for use, consumption, and waste disposal. It is forbidden to operate such substances when there is a wound in the skin.
(3) Strong corrosion refers to liquids and solids (including vapors) that are highly corrosive to human skin, mucous membranes, eyes, respiratory tracts and articles, such as fuming sulfuric acid, sulfuric acid, fuming nitric acid, hydrochloric acid, hydrofluoric acid, hydrogen.
Bromic acid, chlorosulfonic acid, chlorosulfone, monochloroacetic acid, formic acid, acetic anhydride, phosphorus oxychloride, phosphorus pentoxide, anhydrous aluminum trichloride, bromine, sodium hydroxide, potassium hydroxide, sodium sulfide, Phenol, anhydrous hydrazine, hydrazine hydrate, and the like.
The storage area is required to be cool and ventilated and placed in isolation from other medicines. Corrosion-resistant materials such as acid-resistant cement or acid-resistant ceramics should be used like shelves to hold these drugs.
The rack should not be too high, and should not be placed on the elevated frame. It should be placed on the ground against the wall to ensure safe storage.
(4) In the case of such explosives, the reaction with water is very violent, and there are potassium, sodium, lithium, calcium, lithium aluminum hydride, calcium carbide, etc. Potassium and sodium should be stored in kerosene.
The reagent itself is explosive or extremely explosive, such as nitrocellulose, picric acid, trinitrotoluene, trinitrobenzene, azide or diazo compounds, and sulfate.
Substances that are in contact with air to cause strong oxidation and cause combustion, such as yellow phosphorus, should be stored in water and cut in water.
Low ignition point, substances that can be burnt or even explode by heat, impact, friction or contact with oxidants, such as phosphorus sulfide, red phosphorus, magnesium powder, zinc powder, aluminum powder, naphthalene, and camphor.
Such reagents are required to be stored in a room temperature not exceeding 30 °C and should be stored separately from combustibles and oxidants. The rack is made of brick and cement, with grooves and fire sand in the tank.
The reagents are placed in the sand and capped. In case of an accident, the situation will not be expanded.
(5) Strong oxidizing agents these kinds of agents are peroxides or oxyacids and their salts, which may explode under appropriate conditions and form explosive mixtures with flammable solids such as organic matter, magnesium, aluminum, zinc powder, and sulfur.
Some of these substances react violently with water, such as the risk of explosion of peroxide in contact with water. In this category are ammonium nitrate, potassium nitrate, sodium nitrate, perchloric acid, potassium perchlorate, sodium perchlorate, magnesium perchlorate or strontium, chromic anhydride, ammonium dichromate, potassium dichromate, and other chromates. , potassium permanganate and another permanganate, potassium chlorate, barium chlorate, ammonium persulfate and other persulfates, sodium peroxide, potassium peroxide, barium peroxide, dibenzoyl peroxide, peracetic acid and the like.
The storage area should be cool and ventilated and should not exceed 30 °C. It should be separated from acids and flammable materials such as wood chips, carbon powder, sulfides, and sugars, or combustibles or oxides (ie, reducingsubstances). Stacking should not be too high or too high, pay attention to heat dissipation.
(6) The radioactive general laboratory cannot have radioactive materials. Testing and handling such substances requires special protective equipment and knowledge to protect personal safety and prevent the contamination and spread of radioactive materials.
The above six categories are all dangerous goods.
(7) Low-temperature storage Classes of such reagents need to be stored at a low temperature so as not to cause deterioration or other accidents.
Among such are methyl methacrylate, styrene, acrylonitrile, vinyl acetylene, and other polymerizable monomers, hydrogen peroxide, ammonium hydroxide and the like.
Store at temperatures below 10 °C.
(8) Special reagents, ultrapure reagents, rare elements and their compounds which are expensive in the valuable class belong to this category.
Most of these reagents are in small packages. Such reagents should be stored separately from the general reagents to strengthen management and establish a system of use.
Common palladium black, palladium chloride, platinum chloride, platinum, iridium, platinum, asbestos, gold chloride, gold powder, rare earth elements.
(9) The indicator and the organic reagent indicator may be classified according to an acid-base indicator, a redox indicator, a complexometric titration indicator, and a fluorescent adsorption indicator. The organic reagents can be arranged in the number of carbon atoms in the molecule.
(10) General reagents are stored in a cool, ventilated, cabinet with a temperature below 30 °C.
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