Water vapor transmission capacity refers to the amount of water vapor through the specimen in a certain period of time under the specified temperature, relative humidity, and certain water vapor pressure. The main role of the drug bottle is to protect the safety of drugs in the process of storage and transportation, to ensure the stability of the validity period. Water vapor transmission amount can reflect the barrier performance of the bottle, if this indicator exceeds the standard, it is easy to cause moisture in the long storage of drugs, affecting the safety of medication. Whether the water vapor transmission capacity of the bottle meets the standard is related to the purity of the raw materials used, the control of the production process, the quality of the mold and other factors, high-quality packaging is the key to protect the safety of drugs, but also an effective way to improve the added value of the product.
Pharmaceutical solid bottles in the water vapor transmission amount of the test, is generally to be specified in the temperature and humidity, and water vapor pressure to be able to test, or there is a high risk of other accidents. If the test is done under the specified environment, then the permeability can be obtained within a certain period of time.
Mainly choose the cup method to determine, the operation steps are roughly as follow:
Weigh a certain amount of dried absorbent in the permeable cup, and fix the measured material on the permeable cup. Subsequently, molten sealing wax is poured into the groove of the permeable cup, and after the sealing wax has solidified, the permeable cup is put into the constant temperature and humidity box, and after a certain period of time, it is taken out from the box and put into the desiccator at a constant temperature, and the balance is weighed. After weighing, put the permeable cup back into the constant temperature and humidity chamber, and then every 2 times weighing time interval is 12 h, repeat the weighing.
Cup method to measure the water vapor transmission amount of the calculation formula is:
WVT: water vapor transmission, g·(m2·d)-1;
Δm1: In a certain time (t), the increment of sample mass;
Δm2: In a certain time (t), the increment of blank sample mass;
A: area of the sample permeable to water vapor, m2;
t: Interval time after mass increment stabilizes.
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