Moisture content definition

In diying solids it is important to distinguish between hygroscopic and nonhygroscopic materials. If a hygroscopic material is maintained in contact with air at constant temperature and humidity until equilibrium is reached, the material will attain a definite moisture content. This moisture is termed the equilibrium moisture content for the specified conditions. Equilibrium moisture may be adsorbed as a surface film or condensed in the fine capillaries of the solid at reduced pressure, and its concentration will vaiy with the temperature and humidity of the surrounding air. However, at low temperatures, e.g., 15 to 50°C, a plot of equilibrium moisture content versus percent relative humidity is essentially independent of temperature. At zero humidity the equilibrium moisture content of all materials is zero. 

Classification is by definition used preponderantly in the treatment of raw materials. However, these raw materials find their way into chemical processing per se and thus become of interest to the chemical engineer, particularly when the products to be treated reaci better when of a defined cleanliness, size, gravity, or moisture content. 

The utilization of IR spectroscopy is very important in the characterization of pseudopolymorphic systems, especially hydrates. It has been used to study the pseudopolymorphic systems SQ-33600 [36], mefloquine hydrochloride [37], ranitidine HC1 [38], carbovir [39], and paroxetine hydrochloride [40]. In the case of SQ-33600 [36], humidity-dependent changes in the crystal properties of the disodium salt of this new HMG-CoA reductase inhibitor were characterized by a combination of physical analytical techniques. Three crystalline solid hydrates were identified, each having a definite stability over a range of humidity. Diffuse reflectance IR spectra were acquired on SQ-33600 material exposed to different relative humidity (RH) conditions. A sharp absorption band at 3640 cm-1 was indicative of the OH stretching mode associated with either strongly bound or crystalline water (Fig. 5A). The sharpness of the band is evidence of a bound species even at the lowest levels of moisture content. The bound nature of this water contained in low-moisture samples was confirmed by variable-temperature (VT) diffuse reflectance studies. As shown in Fig. 5B, the 3640 cm-1 peak progressively decreased in intensity upon thermal... 

Soil pH is perhaps the most critical and common soil measurement where a definite amount of water is added before a measurement is made. Soil pH is a particularly complicated measurement because the proton can and does exist as a hydronium ion in the soil solution, as an exchangeable ion on the cation exchange sites, and bonded to various soil constituents. Because of these complexities, a soil sample is usually brought to a standard moisture content before a pH measurement is made. By bringing different soils to a common moisture content, they can be compared and analytical results from different laboratories will be comparable. Although there is a number of ways to measure soil pH, typically it is carried out using a pH meter and a pH electrode. 

For each dmg substance, the maximum acceptable levels of the various impurities are described in the drug substance monograph or the specification included in the submissions to the regulatory authorities. In this chapter, the ICH Q6A [4] and Q6B [5] definition of specification is used. A specification consists of three parts the test (e.g. moisture content, impurities), references to the analytical procedure (e.g. high-performance liquid chromatography [HPLC], gas chromatography [GC]), and the acceptance criterion (e.g. not more than 0.50%). 

Figures listed are for best conditions (dry. sized and without dust)—The minimum angle will increase os site of particles decrease and with higher moisture content. For other conditions refer to S-A Engineers for definite recommendations.

Variable definitions AX (xylan conversion, %) AG (glucan conversion, %) l (inoculum amount, mg of P. ostreatus/g of stems) M (moisture content, g of H20/g of stems) t (time, d). 6 DOF, degrees of freedom for the regression analysis. 

Vn>en the area under the Log (S") versus temperature curve Is plotted against epoxy moisture content, there Is a definite Increase with Increased moisture content. One method for presentation of the data Is to simply plot the area under the loss compliance transition as a function of sample moisture content. This could be done for each epoxy under consideration. 

The definition of M as given above is equivalent to the term regain as used for certain other hygroscopic materials such as textiles (J). The term moisture content is defined on a wet rather than dry weight basis. The wet basis moisture content is then related to M by... 

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