Mixing process product testing

The homogeneity of the product should be addressed. The adequacy of mixing processes should be shown (and confirmed with appropriate process validation data) and potential segregation discussed (as affected by surface properties, crystallinity, particle size, etc.). The Ph Eur uniformity of content requirements should apply to the dosage forms and uniformity of distribution needs to be shown between batches and within batches. The need for appropriate routine tests as part of the release specification should be discussed. 

Manufacturing validation data, which should aim to identify the critical process steps, especially for nonstandard manufacturing processes such as for new dosage forms, should be discussed in the development pharmaceutics section of the application. Validation data may be accepted based on closely related products. In-process control tests and acceptance limits should be included for any aspect where conformity with the finished product tests cannot otherwise be guaranteed (e.g., mixing, granulation, emulsification and nonpharmacopeial sterilization processes). 

In most chemical process industries, both qualitative and quantitative analyses are performed on many varieties of company products and the raw materials that go into these products. Some of the qualitative tests require a simple mixing of the test sample with a reagent to produce a color change. One such test can be run, for example, to confirm the contents of drums of tribasic calcium phosphate, which is a raw material for some pharmaceutical products. The test sample is dissolved in water, acidified, and then tested with a molybdate solution. A yellow precipitate indicates that the material is indeed tribasic calcium phosphate. 

Electrochemical Processes. The reductive cleavage of azo-group-containing dyes has been applied on a full scale for the decolorization of concentrates from batch dyeing. Depending on the color, decolorization of up to 80% of the initial absorbance can be obtained. Mixed processes consist of combinations of electrochemical treatment and precipitation by use of dissolving electrodes [43,49]. Such techniques have been described in the literature and have, in part, also been tested on a full scale. Anodic processes that form chlorine from oxidation of chloride have also been proposed to destroy dyes, but care has to be taken with regard to the chlorine and chlorinated products (AOX) formed [114,115]. 

The initial plastic state of the fresh concrete subsequent to the mixing process, where properties such as the air content, density and workability are normally measured by relevant standard tests, and utilized as a means of control of production. The magnitude of these properties is affected by the addition of water-reducing admixtures, either intentionally or as a side effect, which could result not only in a change in the characteristics in the plastic state, but could also be reflected in changed properties in the hardened state. 

Preliminary testing has shown these blocks to have strength and durability properties equal to or better than portland cement block standards. The viability of the process has been demonstrated on a small scale and mix designs and process conditions have been optimized. Ongoing work will involve scaled-up production along with extensive product testing. 

The caterpillar micromixer consists of a number of serial oriented unit cells that repeat and complete the same type of mixing process. Eight such cells are serially combined in the standard version that is commercially available. Dependent on the mixing problem, however, more or less units may be appropriate, which, especially for production, needs to be optimized to reduce the pressure drop to the limit really needed and for efficient power dissipation. For this reason, caterpillar devices (600 pm width and depth) with 0, 2, 4, 6, and 8 mixing cells have been manufactured to test mixing efficiency by a standardized protocol (Fig. 6.3) ]27]. 

The values of mean residence times based on Bi/ Pb activity ratios, of 2-78 days, and on Po/ Pb activity ratios, of 9-243 days (Table 4.3), are much greater than the values of the residence times obtained from the fission product radionuclide activity ratios. The fact that there is a large difference between these values may not necessarily be attributable to experimental errors. It is more likely that the differences are real and are attributable to the fact that, while the fresh fission product radionuclides were injected by the Chinese 22nd, 23rd and 24th tests almost exclusively into the troposphere, the radon decay product radionuclides found in rain are mixtures of two different components tropospheric and stratospheric. The radon decay products in the lower stratosphere descend rapidly during the winter and mix with the tropospherie component, while such a mixing process occurs less frequently in the summer and fall periods (Kuroda et al., 1978). 

The chloroplatinates prepared as above are sufficiently pure for direct analysis without recrystallisation. The chloroplatinates of the amines are usually freely soluble in hot water, but recrystallisation (when required) should not be attempted until the process has been found to be successful with a small test-portion of the chloroplatinate. The chloroplatinates of many primary and secondary amines decompose in hot water, the amine being oxidised, and the chloroplatinate reduced to the metal some amines furthermore co-ordinate readily with the metal when the chloroplatinate is boiled with water and a mixed product is obtained on cooling. 

Both the Toth and Alcoa processes provide aluminum chloride for subsequent reduction to aluminum. Pilot-plant tests of these processes have shown difficulties exist in producing aluminum chloride of the purity needed. In the Toth process for the production of aluminum chloride, kaolin [1332-58-7] clay is used as the source of alumina (5). The clay is mixed with sulfur and carbon, and the mixture is ground together, pelletized, and calcined at 700°C. The calcined mixture is chlorinated at 800°C and gaseous aluminum chloride is evolved. The clay used contains considerable amounts of silica, titania, and iron oxides, which chlorinate and must be separated. Silicon tetrachloride and titanium tetrachloride are separated by distillation. Resublimation of aluminum chloride is requited to reduce contamination from iron chloride. 

Table 3 Hsts the U.S. producers of methylene chloride and their rated yearly capacities. Since the product mix of a typical chloromethanes process is very flexible, production may be adjusted according to the demand for methylene chloride and chloroform. The demand for methylene chloride has taken a broad downturn as a result of the 1985 NTP carcinogenicity tests (Table 4). The 1988 and 1989 demands were 227,000 t and 216,000 t, respectively, with a forecast 1993 demand of 186,000 t. The historical growth rate (1979—1988) was —2.7% pet year. In the future this should decrease even further to —3 to...

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