Loss on Drying

Free Moisture. The free moisture of a filler is the water present on the surface of the particles. This weakly bound water can sometimes contribute to iaterparticle bonding (reinforcing) or filler—matrix iateraction, ie, biader adsorption or catalysis. A determination of free moisture is usually made by measuriag the percent loss on drying the sample at either 100 or 110°C. 

Moisture. In relatively pure sugar solutions, moisture is deterrnined as the difference between 100 and Brix. In crystalline products, it is usually deterrnined by loss-on-drying under specified conditions in an oven or by commercial moisture analyzers that have built-in balances. Moisture in molasses and heavy symps is deterrnined by a special loss-on-drying technique, which involves coating the sample onto sand to provide a greater surface area for oven drying. The result of this test is usually considered dry substance rather than moisture. 

Loss on drying. When miconazole is tested according to the general method (2.2.32), not more than 5%, determined on 1 g by drying in vacuo at 60 °C for 4 h. 

Loss on drying. Carry out the test according to the general procedure <731 > dry miconazole nitrate at 105 °C for 2 h it loses not more than 0.5% of its weight. 

The specific optical rotation of bromocriptine mesilate in different solvents is given below for 20° C corrected for loss on drying. A Perkin Eliper polarimeter 241 was used, the actual concentration being 10 mg/ml. 

The crystals of halcinonide are not solvated with water, based on a total volatile content of 0.3% obtained by thermal gravimetric analysis, a correct elemental analysis, and a loss-on-drying value of 0.6% (of. section 4.1, Elemental and Inorganic Analyses). 

Following are examples of gravimetric analysis when the analyte is physically separated from the matrix. 3.6.1.1 Loss on Drying... 

Evaline Robotham sets the sample tray in place in the loss-on-drying instrument. Notice the cylindrical enclosure with heating coil. 

What is the percent loss on drying if a sample weighs 4.5027 g before drying and 3.0381 g after drying ... 

Application of the loss-on-drying method is found in the pharmaceutical, food, and agricultural industries. 3.6.1.2 Loss on Ignition... 

In any case, the sample is usually contained in a crucible (prepared in advance by ignition without a sample) and placed in the oven or over the Meker burner for a specified period of time or to a constant weight, as in the loss on drying. The calculation is also similar to loss on drying, and the weight of the crucible will need to be subtracted if the tare feature of a balance is not used. 

See a method for loss on drying for pharmaceutical raw materials and formulations. Method 731 on p. 1954 of the U.S. Pharmacopeia-National Formulary, USP24-NF19 (2000). 

A number of experiments in this text require that a sample be dried before proceeding with the chosen method. Examples in this chapter include an unknown sulfate (see Experiment 6, step 1) and an unknown iron (see Experiment 7, step 1). An example in Chapter 4 is the KHP standard in Experiment 8 (see Experiment 8, step 1). In this experiment, the percent loss on drying of one of these materials will be determined. 

Repeat steps 3 and 4 until you have a constant weight (successive weights agreeing to within 0.001 g). Calculate and report the loss on drying as a percentage. Store your sample in your desiccator if the experiment that utilizes this material (Experiment 6,7, or 8) is to be performed. 

The water that is trapped within the crystal structure of some ionic compounds (the water of hydration) can be removed easily by heating. The amount of the water present in a given sample can be determined by weighing the sample before and after this heating. The weight loss that occurs is the weight of the water in the sample. The percent of water in the hydrate is calculated as it is in a loss-on-drying experiment. 

In an experiment in which the percent loss on drying in a sample was determined, the following... 

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