Chemical reagents are the most widely used in the laboratory, and they consume the most frequently purchased and dangerous substances. Therefore, the management of chemical reagents is undoubtedly the primary task of laboratory managers. The management of reagents can be said to be the highlight of laboratory management, because reagent safety is related to laboratory safety. So this article's laboratory reagent classification knowledge, let's share it!
Classification of chemical reagents China's reagent specifications are basically divided according to purity (how much impurity content), and there are 7 kinds of high purity, pure spectrum, reference, spectroscopic pure, excellent grade pure, analytical and chemical purity.
The state and the competent authorities promulgate three main types of quality indicators: pure, graded pure and chemically pure.
(1) (GR:Guaranteed reagent), also known as primary or guaranteed reagent, 99.8%, this reagent has the highest purity and the lowest impurity content, suitable for important and precise analytical work and scientific research work, using green bottles sign.
(2) Analytical purity (AR), also known as secondary reagent, with high purity, 99.7%, slightly below the pure grade, suitable for important analysis and general research work, using red bottle label.
(3) Chemically pure (CP), also known as tertiary reagent, ≥99.5%, the purity and analytical purity are quite different, suitable for industrial and mining, general analysis of schools. Use a blue (dark blue) label.
(4) Experimental reagent (LR: Laboratory reagent), also known as a four-stage reagent. In addition to the above four levels, there are currently on the market: Benchmark Reagent (PT: Primary Reagent): used exclusively as a reference material, can directly prepare standard solutions. Spectral pure reagent (SP: Spectrum pure): indicates that the spectrum is pure. However, since the organic matter is not displayed on the spectrum, the main component may not be more than 99.9%, and care must be taken when using it, especially when it is used as a reference material. A reagent with a purity much higher than that of a pure grade is called a high purity reagent (≥99.99%).
At present, the specifications of chemical reagents produced by foreign reagent factories tend to be classified according to their uses. The common ones are as follows:
Biochemical reagent (BC: Biological chemical) Biological reagent (BS: Biological Stain) Complex for titration (FCM: For Complexometry) chromatography (FCP: For chromatography purpose) Fluorescence analysis (FIA) microorganism Infrared absorption by (F: For Microscopic purpose) (F: For Microscopic purpose) synthesis (FS: Gas synthesis) high performance liquid chromatography (HPLC: High Pressure Liquid chromatography) indicator (Ind: Indicator) (IR) liquid chromatography (LC) nuclear magnetic resonance (NMR) organic analysis standard (OS: Organic analytical standard) analysis (PA: Proanalysis) internship (Pract: Practical use) (Purepurum pure) Puriss (Purissmum special pure) synthesis (SYN) Industrial Tech: Techincal grade) Thin layer chromatography (TLC: Thin Layer chromatography) Spectroscopic pure, optically pure, pure spectrophotometric pure (UV: Ultra violetpure)
Laboratory chemical reagent management
The primary task of laboratory reagent management is to purchase, so the laboratory should first have a complete set of requisition, approval, procurement, acceptance, warehousing and requisition systems. Special attention should be paid to the purchase of reagents produced in accordance with national standards and industry standards of the Ministry of Chemical Industry at the regular reagent store with regular purchase channels. The reagent label should be marked with the name (including the common name), category, product standard, content, specification, manufacturer, factory batch number (or production date); some reagents should also indicate the shelf life. For experienced researchers, observing the reagent label is an important means of judging the authenticity of the reagent, and it can avoid the purchase of counterfeit reagents and affect the test. Acceptance and warehousing are also a serious and meticulous work. Due to the wide variety of chemical reagents, the same chemical reagents have different specifications such as excellent grade, analytical grade, pure spectrum, chemical purity, etc., making their content, price and use. They are different, so pay attention to acceptance, registration and classification.
The storage of chemical reagents is the daily work of laboratory personnel, requiring managers to have a high knowledge of chemical reagents. General chemical reagents are stored separately as simple substances, inorganic substances, organic substances, indicators, and the like.
Inorganic substances and organic substances should be stored separately according to the type and specifications of the reagents. Since there are many types and specifications, they will not be described here. For some reagents that are not commonly used, the management personnel should check regularly to ensure that the reagents are packaged intact, the labels are complete, and the writing is clear. The solid reagent should be free from moisture absorption and deliquescence; the liquid reagent should be free of sediment, otherwise the seal of the reagent should be checked. Some reagents should be carefully checked, such as the oil seal on the surface of potassium and sodium, and whether the water seal on the surface of white phosphorus or mercury meets the requirements to avoid danger. The quality of chemical reagents is one of the factors that directly affect the quality of the experiment. Managers should have certain knowledge of reagent quality judgment.
Generally, the remaining reagents after opening are more susceptible to deterioration, including: 1. Changes in the shape and state of the reagent, such as sodium hydroxide from crystal to powder. 2. The change of the volume of the reagent, including volatilization and sublimation, such as the bottle reagent containing iodine is less, and the bottle is discolored and opaque. 3. Color change, such as long-term storage of test paper discoloration, precipitation of mercury dichloride (HgCl2), silver nitrate (AgNO3) solution; white precipitate of tin dichloride (SnCl2) solution and ferrous sulfate (FeSO4) solution change Brown and so on.
When the above phenomenon occurs in the reagent, it can be judged that the reagent has volatilized or has deteriorated.
There are many reasons for the deterioration of reagents. Different reagents have different causes of deterioration and cannot be generalized. Sealing, illuminating, dampening, warming, etc. of the reagent may deteriorate the reagent. Some reagents, although well sealed, are prone to volatilization and deterioration (such as ether, carbon disulfide, tetrahydrofuran, isopropyl ether, etc.). The labels of these reagents should be marked with the date of manufacture and shelf life, and the management should check them regularly.
There are many kinds of indicators used in chemical reagents, and generally solid indicators (except test papers) are not easily deteriorated for long-term storage. In addition, the long-term storage of the solution prepared by the complex indicator may cause polymerization or oxidation reaction. The general phenomenon is that turbidity or flocculent precipitation occurs, and it is difficult to sharply indicate the end point of the titration. The indicator is used in many times, but the amount of the indicator is very small, and the total amount is also small. It should be purchased as little as possible, stored less, and less.
Classification and management of hazardous reagents
In the work of chemical laboratory, it is necessary to contact various chemical reagents, samples and gases, volatiles, smoke, etc. generated by chemical reaction processes. Some of these substances are toxic to human body, and some are highly corrosive. It is flammable and explosive. In addition to strengthening safety education for students, the experimental management personnel should have solid safety management knowledge and reagent management knowledge, which is undoubtedly one of the necessary conditions.
The hazardous reagents used in chemical laboratories mainly include three major categories of drugs, strong corrosives and flammable and explosive materials. The following sections describe the classification and management of hazardous reagents:
Drug
According to the national standard GB6944-86, the drugs used in the laboratory are: mercury salt, chromium salt, lead salt, arsenic compound, nitrite compound, polycyclic aromatic hydrocarbon and its derivatives, and chlorine-containing phosphorus organic matter. Due to the wide variety and the type of poisoning is extremely complicated, it will not be described here. Drugs (especially drugs) should be stored in separate containers according to regulations, strictly managed, regularly inventoried, and outflows are strictly prohibited. Some of these drugs, such as cyanide used in the coordination titration, should strictly implement the "five-double system" according to the regulations, that is, double-custodian, double-receiving, double-receiving, double-accounting, and double-lock management. The reagent room for releasing drugs should be well ventilated to prevent the accumulation and release of toxic gases from accumulating indoors; the reagent bottles containing drugs should be well sealed and gently handled when moving to prevent human contact with drugs.
2. Strong corrosion products
The strong corrosive products used in the laboratory mainly include concentrated sulfuric acid, hydrofluoric acid, liquid chlorine, liquid bromine and the like. This type of material should be handled gently and gently. It is strictly forbidden to impact, bump and strong vibration. It is strictly forbidden to carry the shoulder. Strongly corrosive products must be placed in a firm reagent cabinet. Do not place them in difficult locations such as the top or inner layers. As with other dangerous goods, strong corrosive products must also ensure safe management, safe access, and eliminate outflows.
3. Flammable and explosive products
There are many kinds of flammable and explosive varieties used in the laboratory. The gaseous state is hydrogen, gas, liquefied gas, oxygen, and the like. Many flammable liquids have low flash point, easy ignition, high volatility, low viscosity, low density and easy diffusion. When used as an organic solvent, when they are mixed with a certain proportion of vapor and air, they can form gaseous explosives. When exposed to open flames, static electricity or electric sparks, it can cause an explosion. Therefore, laboratories often use flammable liquids as the focus of prevention against fire and explosion.
The petroleum ether and gasoline used in the laboratory are the most flammable liquids. These substances are in contact with some strong oxidants (such as nitrate, potassium permanganate, potassium chlorate, etc.), and can be exploded in case of friction or collision. Prevent.
Solid flammable materials include white phosphorus, potassium metal, sodium, magnesium, aluminum powder, sulfur and many inorganic and organic compounds. Some of them are pyrophoric. Many substances are extremely sensitive to heat, friction and collision. Most of them are flammable. The combustion releases gases that are toxic.
Laboratory management personnel should be familiar with the nature of such reagents and knowledge of purchase, use, and storage, and be prepared for safe firefighting, constantly unremitting, and be vigilant to prevent potential accidents. Dangerous goods in the laboratory also include radioactive reagents and certain biochemical reagents. Since they are not used in general laboratories, they are not described here.
Chemical reagent management is a professional and complex discipline. The purchase, handling, storage, and requisition should be managed or on-site by personnel with professional knowledge. The reagent room for storing dangerous goods should have a clear warning sign and is strictly prohibited. Unrelated personnel enter to ensure the safety of the laboratory. There are many kinds of chemicals and reagent solutions in various chemical management laboratories. Most of the chemicals have certain toxicity and danger. Strengthening management is not only the need to ensure the quality of analytical data, but also the need to ensure safety. The laboratory should only store a small amount of medicines that are needed in the short term. Chemicals are recommended to be classified according to inorganic substances, organic substances and biological culture agents. Inorganic substances are stored in the order of acid, alkali and salt. The salts are classified according to the order of metal activity. The biological culture agents are stored according to different culture groups. The dangerous drugs in dangerous chemicals should be locked in special drug cabinets, and they should be locked and kept by special personnel, and the system of application, approval, and signature registration for two persons should be used.
What are the chemicals that are dangerous?
1. Explosive and unstable substances. Such as concentrated hydrogen peroxide, organic peroxides and the like.
2. Oxidizing substances. Such as oxidizing acids, hydrogen peroxide is also this type.
3. Flammable substances. In addition to flammable gases, liquids, and solids, substances that generate combustibles in moisture are also included. Such as alkali metal hydride, calcium carbide and substances that are self-igniting in contact with air such as white phosphorus.
4. Toxic substances.
5. Corrosive substances. Such as acid, alkali and so on.
6, radioactive materials.
Management system for the use of chemical reagents
1. Follow the principle of being both beneficial to use and ensuring safety, and manage the use of chemicals and strengthen safety education.
2, chemical drugs must be classified according to chemical properties, flammable, explosive, highly toxic, strong corrosive products should not be mixed. Chemicals should be stored in special cabinets, storage rooms for storing special cabinets; cool, ventilated, moisture-proof, and protected from light;
3. All medicines must have obvious signs. Labels that are unclear should be replaced in time, and drugs that are expired and unlabeled should not be used and should be disposed of properly.
4. The test drug container must have a label. The packaged drug should be marked with the name, specification and concentration on the container label; the unlabeled or unidentifiable reagent should be treated as a dangerous item after re-identification, and should not be handled casually. Litter, so as not to cause serious consequences. If the medicines placed in the laboratory are not used for a long time, they should be placed in the drug storage room for unified management.
5. The chemical container should be closed to prevent air leakage and deliquescence. Chemicals that are prone to change in light should be placed in dark glass containers or in dark containers. The quality of chemical packaging and drugs should be checked regularly.
6. Strengthen the management of fire sources. Fire sources are strictly prohibited around and inside the chemical storage room; the fire source of the laboratory should be kept away from flammable and explosive materials, and when there is a fire source, it cannot leave the person.
7. Storage of inflammable and explosive materials should be protected from light, fire and electricity. The flammable and explosive materials stored in the laboratory should be determined to be reasonably stored. Excessive amounts should be allowed and the packaging container should be sealed. Flammable and explosive reagents should be stored in iron cabinets (wall thickness 1mm or more), and the top of the cabinet has vents. Drugs that can decompose or burn or explode in water, potassium, sodium, phosphorus trichloride, phosphorus pentachloride, fuming sulfuric acid, sulfur, etc. are not allowed to come into contact with water, and should not be stored in a damp place.
8. The procurement and transportation of dangerous goods shall be handled in accordance with the relevant provisions of the public security department and the transportation department. Poisonous, radioactive objects and other dangerous items should be stored separately and managed by a double-double lock. The medicine cabinets for storing highly toxic substances should be sturdy and insured, and a strict and strict use registration should be obtained.
9. Always check dangerous materials to prevent spontaneous combustion and self-explosion accidents caused by deterioration and decomposition. Containers, metamaterials, waste residues and waste water of highly toxic substances should be properly disposed of.
10, do not borrow medicines, special need to borrow medicines, must be approved by the leadership to sign.
11. Vessels with chemical reagents must be separated. Each reagent should be used in one piece and should not be mixed.
12. Use organic solvents and volatile reagents in a well ventilated area or in a fume hood. Under no circumstances should the organic solvent be heated directly with an open flame.
13. When using chemical reagents such as strong acid and alkali, it should be operated and stored according to the specified requirements.
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