Relative humidity, storage testing

Storage conditions will be used. Standard conditions to simulate normal storage are temperatures of 25 or 30 °C and relative humidity of 60 or 65%. A minimum of 12 months real-time data is required for a marketing authorisation application. Real-time data should be supported by accelerated and intermediate stress testing at higher temperature/relative humidity. Photostability should be verified using a single batch. 

Long-term testing Stability studies under the recommended storage condition for the retest period or shelf life proposed (or approved) are performed with several drug substance batches in the stipulate packaging. In the general case, the storage condition is at a temperature of 25°C and 60% relative humidity. 

Wet cure was in saturated lime water until time 0 test dry cure was storage in laboratory air (about 25° C and 50% relative humidity) until time of test. 

For storage stability tests, a sufficient number of badges were exposed to an exposure dose level of approximately one-half the charcoal capacity at 80 percent relative humidity. Half the samples were refrigerated (40-45°F) and half were left at ambient temperatures (75-80°F). Badges were then analyzed at intervals ranging from one day to three weeks. 

Reference ICH-Q1A, September 1994. (For drugs to be stored at room temperature, i.e., 25°C, accelerated testing is defined as 40°C/75% relative humidity. For other storage conditions accelerated testing is to be carried out at 15°C above the long-term storage temperature.)... 

A distinction must be made between chemical and physical stability. While physical stability is important, particularly in the evaluation of solid propellants, the chemical stability is of prime importance in the estimation of the course of decomposition of nitrate esters. The nitrate esters which are processed for use as propellants - unlike nitro compounds, which are relatively stable under these conditions - undergo a steady decomposition, which is due to imperfect purification of the starting materials and to the effect of other parameters such as temperature and air humidity. The rate of this decomposition is auto-catalyzed by the acidic decomposition products and may in certain cases produce spontaneous ignition. In order to reduce the decomposition rate as much as possible, suitable stabilizers are added to the powders, which are capable of accepting the acid cleavage products with formation of the corresponding nitro compounds (- Stabilizers). The stability is controlled by means of several tests (- Hot Storage Tests). 

There are indications that polymeric binders may protect films to some extent against oxidation by moist air in storage. A few tests on a fully-burnished soft film with an inorganic binder also showed no deterioration during extended storage in air at 70% relative humidity and 60°C. This gives some confirmation to the concept that in a fully-burnished film the exposed surface consists almost entirely of inert basal planes, and is therefore more resistant to chemical attack. 

The purpose of this study was to evaluate laboratory formaldehyde release test methods for predicting real-life formaldehyde air concentrations human exposure levels, and health risk. Three test methods were investigated the European perforator test, the gas analysis method at 60 C and 3% RH, and the gas analysis method at 23 C and 55% RH. Different types of particleboard bonded with urea-formaldehyde and urea-melamine-formaldehyde resins were tested. The results were used to rank boards as a function of test method, conditioning, short-term humidity, and temperature variations during storage. Additional experiments were conducted in small experimental houses at a Dutch research institute. Our conclusions are that relative ranking of products is influenced by the test method and by change in relative humidity. The relationship between test method and release in real-life situations is not clear. In fact, it seems impossible to use laboratory measurements to predict real-life product performance of board if the board is not fully in equilibrium with the atmosphere. 

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