Residual humidity

Suggested method characterized by relative standard deviation of 0.02-0.1 allows determination of water in organic solvents until 0.008 mass.%. Concentrations under mentioned above can not be detected by direct GC due to residual humidity of sorbent and parts of chromatographic equipment. 

Air-dry samples thoroughly at room temperature, which should not exceed 40°C (loss of Hg ) place the sample on the bag and turn over as necessary. Use gloves Any residual humidity will promote anaerobic reactions, including sulphate reduction, and must be avoided. When samples are properly dried, transfer to a new bag, if necessary (field bag may still be wet), seal and send to LAB IV. 

Drying of granulate in an oven to a given humidity residual humidity level -1 = 1% level -1-1 = 3%... 

We select 3% residual humidity as the optimum level for Xj on the basis of tablet hardness and cohesion. Calibration had no effect, so 1.25 mm is chosen. Lubrification time also had little effect and 3 minutes seemed to be optimum for tablet hardness. This value was therefore selected for plotting. We take therefore ... 

Figure 6.11 Response surface of global desirability as function of granulation time and volume, with fixed residual humidity 3%, sieve 1.25 mm, and lubrification time...

The factors X, (residual humidity) and X4 (sieve size) took only 2 levels and could be treated as qualitative factors. The mathematical model could not contain square terms in these factors. 

As for the neat PA6, it experiences a characteristic double yield (probably due to residual humidity) and starts its steady-state plastic regime at an upper yield stress of about 50 MPa. 

The candidate CRM was collected (30-40 cm top sediment layer) in the Ravenna Lagoon (Italy), sieved to pass apertures of 2 nun and air-dried at 25 °C in a drying chamber. The residual humidity was measured periodically when a constant humidity level was reached (3.5%), the material was manually crushed and sieved again at 2 nun (the fraction higher than 2 mm was discarded). The resulting material was stored in polyethylene bags and transported at the Joint Research Centre of Ispra (Italy). 

It is worth remarking that residual humidity can favor microbiological growth especially in some natural products used as excipients (starch, gelatine, etc.). From a physico-chemical point of view, residual humidity may have an impact on the hardness of the tablets as shown by Chowhan, Down and McMullen. ... 

Drying stage the particle loses its residual humidity ... 

Additionally, many experimental studies have shown that, for various protein systems, the storage stability improves as the residual humidity decreases and that the optimal final water content is generally around 1% or less. Water contents above the monolayer content increase the mobility of the water that becomes more available for protein degradation reactions with the other solutes of the concentrated phase. Moreover, water is a plasticizer of the amorphous phase that decreases the Tg value, which leads to more difficult storage conditions. Finally, it should be noted that the moisture content is generally not uniform within the vial, the top and the wall zones of the cake being the driest zones and these non-uniformities in the spatial distribution of the water content generally increase with the size of the vial. 

H2O) residual humidity restituieren/ wiederherstellen restitute Restitution/ Wiederherstellung restitution... 

Verweilzeitveiteihmg (im Extruder) residual dampness/ residual humidity Restfeuchte residual entropy Restentropie residual product/ side product/by-product Nebenprodukt residue (bottoms/heel)... 

A particular technique of mixture preparation is also used in the industry of traditional ceramics fdter-pressing. The various components (raw materials, dispersants, water) are mixed to form a fluid and homogenous slip. This slip is then filtered, under low pressure (0.5 MPa), through flexible filters ahgned on a frame to eliminate a large fraction of water and soluble species. The plastic paste obtained, with a small percentage of residual humidity, then exhibits a rheological behavior suitable for extrusion. 

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