The imported reference standard is a special measuring tool used to check the quality of medicines. It is the benchmark for measuring the quality of medicines, and it is also used as a material standard for calibrating testing instruments and methods. In drug inspection, it is a control to determine the authenticity of drugs and a tool to control the quality of drugs.
A high-quality imported reference standard product should have the following characteristics:
- The homogeneity of the reference substance and the measured substance. This kind of homogeneity mainly focuses on the fact that the two have the same structure during the measurement process, rather than homogeneity in the ordinary sense. It does not necessarily require that the structure of the reference substance in the solid state is the same as the structure of the messured substance in the solid state. For example: the reference substance of clavulanic acid is lithium clavulanate, and actual measured substance is potassium clavulanate.
- Material stability. Since the traceability of reference materials is its basic requirement, it is necessary to ensure that the selected products have physical and chemical stability. For example: prepare the reference substance with cefazolin acid without cefazolin sodium.
Notes on the management of imported reference standards:
- Newly opened products should be marked with the opening date on the bottle, and should be used in sequence according to the bottle number (except for the use of the whole bottle or sample delivery). For the reference standard product or working reference product of the same batch number, one bottle must be used up all before opening another bottle. During use, it is strictly forbidden to put the taken out back into the original bottle.
- Before use, take it out from the storage room and place it in a desiccator to balance to room temperature, and weigh it after standing for a certain period of time (depending on the specific situation). This is to avoid moisture absorption of the standard product due to temperature difference. Use it immediately after weighing. After the plastic cap is closed, seal it with a parafilm and store it according to the storage conditions on the bottle label.
- The number of times of opening and using the same bottle of product depends on the specific situation. When repacking the working reference substance that is rarely used or has hygroscopicity, one-time use should be considered.
Many substances do not meet the conditions of reference substances and are not suitable for directly preparing standard solutions. That is, it is first prepared to an approximate required concentration, and then the exact concentration is determined with a reference substance or a standard solution that has been calibrated by the reference substance.