The use of standard products runs through our daily sample analysis work. So dear friends, how much do you know about the little knowledge of standard products?

1. Name of "Standard product"

The term "standard" is often used as a generic term. In chromatographic analysis, most of the standard substances used in physical and chemical analysis of samples belong to the "compound purity/concentration standard". At this time, the term "standard substance" covers the "standard substance" and "standard sample" often said in the non-pharmaceutical industry, as well as the "traditional Chinese medicine reference substance" and "chemical reference substance" often said in the pharmaceutical industry. Methyl methacrylate

When used as a special reference, the term "standard substance" refers specifically to the "standard substance" of the pharmacopoeia system. There is a clear definition in the general principles of 0291 National Pharmaceutical Standard Substances in Four parts of The Chinese Pharmacopoeia, which has not been revised in the 2020 edition of the Pharmacopoeia.

2. Product form of standard products

Common product forms include pure product type, standard liquid type (or called liquid standard). Standard gases are not discussed here.

The pure type standard can be divided into solid, semi-solid and liquid pure according to the state of the compound under the conventional storage condition.

The standard liquid type can be divided into single standard and mixed standard according to whether the solute is a single component compound or a multi-component compound. Take A2S standard as an example, the component difference between single standard and mixed standard products is reflected in the certificate.

3. Common containers for standard products

Common containers include different sizes of glass ampoules and glass bottles with LIDS.

Under normal circumstances, solid and semi-solid pure products usually use glass bottles with covers, but also use ampoule bottles, such as the National drug standard substances of the Chinese People's Procuratorate.

Liquid pure products or standard liquid products often use ampoule bottles, volatile substances also use capillary bottles. The container has a colorless transparent material and a brown translucent material, depending on whether it needs to be stored away from light or not.

Take A2S standard as an example, glass bottles are usually used for solid semi-solid pure products, while ampoule containers are usually used for standard liquid or liquid pure products.

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4. Expiration date of standard product

Unopened products must be kept under the recommended conditions on the certificate or label to ensure that the validity period provided on the certificate is valid. If the certificate does not indicate the expiry date of the product (such as the CPIC's drug reference substance), pay close attention to the new statement on the expiry date of the REFERENCE substance issued by the Pharmacopoeia agency Gnet. Or ask the manufacturer.

After the product is opened, due to the difference in the actual storage environment, the manufacturer cannot guarantee the validity of the validity period on the certificate, the standard liquid type product is recommended to be used as soon as possible after opening, the solid powder type pure product is recommended to be sealed after taking, and stored in low temperature and away from light.

5. Access to standard products

Before diluting the standard solution or weighing the pure product, the standard product should be placed in the operating environment in advance to ensure that the product is restored to room temperature, and the bottle body should be clean and dry before operation (water droplets can be wiped off the surface with absorbent paper).

Choose the right balance when weighing pure goods, usually four or five places after the decimal point, depending on the quality of the weighing required.

Before weighing the pure products, turn on the balance in advance to preheat the balance and adjust the level (push the small bubbles on the balance to the center).

There are increment method and subtraction method for weighing pure products, and increment method is commonly used.

Reduction method is suitable for small size pure products (such as 5mg and below specifications) completely dissolve and directly prepare mother liquor; Or a pure product has been taken several times, do not know the remaining content intended to dissolve all the situation.

The resources

Guidelines for Standard Sample Work (7) General requirements for the capacity of standard sample producers

Jjf1343-2012 General principles and statistical principles for the determination of standard substances

Cnas-cl04 :2017 Standard Substance/Standard sample Manufacturer Competency Accreditation Criteria

China Pharmacopoeia 2020 edition four general provisions 0291 National Pharmaceutical Standard Substances

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