Temperature storage stability

Most formaldehyde producers recommend a minimum storage temperature for both stabilized and unstabilized solutions. Figure 3 is a plot of data (17,18,122,126) for uiiinhibited (<2.0 wt% methanol) formaldehyde. The minimum temperature to prevent paraformaldehyde formation in unstabilized 37% formaldehyde solutions stored for one to about three months is as follows 35°C with less than 1% methanol 21°C with 7% methanol 7°C with 10% methanol and 6°C with 12% methanol (127). 

Turker, N. et al., Effect of storage temperature on the stability of anthocyanins of a fermented black carrot Daucus carota var. L.) beverage shalgam, J. Agric. Food Chem., 52, 3807, 2004. 

As Figure 102 shows, heat can be supplied or extracted from a latent heat storage material without significant temperature change. PCM can therefore be applied to stabilize the temperature in an application, for example the indoor temperature in a building or the temperature of the interior of transport boxes. 

The low-melting sohd of limited thermal stability (max. safe storage temperature 20°C, self-heating decomposition detected above 30°C) will explode on heavy impact (150 kg cm), but is of low sensitivity to ignition. However, 3 cases of spontaneous decomposition in storage or transportation have been noted. 

The chemical stability of an amorphous formulation is usually also a function of its storage temperatme relative to Tg. The enhanced molecular mobility achieved near the glass transition translates into an increase in translational diffusion-dependent degradation pathways, such as aggregation in proteins. It should be noted that the reaction kinetics near the Tg do not obey Arrhenius kinetics, and that extrapolation of the accelerated stability data generated near the Tg to stability at the storage temperature should be viewed with extreme caution. Amorphous materials must be stored well below the glass transition (at least 10°C, and typically 40 to 50°C below Tg) to maintain their physical and chemical stability. 

The long-term deterioration of the SEI at elevated temperatures also was observed by McLamon and co-workers, who conducted postmortem analyses on the electrodes from consumer lithium ion cells that were stored at various temperatures between 40 and 70 °C for weeks. Using the IR absorption at 838 cm as the indicator of the SEI component, they quantitatively correlated the stability of the SEI on a carbonaceous anode against storage temperature and SOC. In an extreme situation where the cell was stored at 70 °C with 9% swing of SOC, no remaining SEI was found on the anode surface. 

Another step of the production process, equally important to the homogeneity measurement, is the stability measurement. The measurement method requirements are the same as those for the measurement of homogeneity for the same reasons. At this stage there are two additional requirements. The measurements are performed on samples stored at different temperatures, in order to determine the appropriate storage temperature and at different times, in order to determine the lifetime of the certified reference material. 

The quality of the compound collection is one key to high quality biological results. DMSO is a widely used solvent and many studies dealing with the long-term storage of compounds in this solvent have been conducted. The important parameters to maintain stability and concentration are Freeze/thaw cycles, storage temperature and duration, container material, humidity, and oxygen. 

Evidence of the stability and recovery of the seeds and banks should be documented. Storage containers should be hermetically sealed, clearly labelled and kept at an appropriate temperature. An inventory should be meticulously kept. Storage temperature should be recorded continuously for freezers and properly monitored for liquid nitrogen. Any deviation from set limits and any corrective action taken should be recorded. 

Tablets from each combination of filler-binder and disintegrant were stored under different storage conditions. After storage the crushing strength and the disintegration time were measured. The influence of standardized storage temperature and standardized relative humidity as well as the standardized disintegrant concentration, on the physical tablet stability (SIR of crushing strength and of disintegration time) were calculated, as described in Section 8.2.

---