Purity assay

Manufacture. Methanesulfonyl chloride is made commercially either by the chlorination of methyl mercaptan or by the sulfochlorination of methane. The product is available in 99.5% assay purity by Elf Atochem NA in the United States or by Elf Atochem SA in Europe. 

Solv Solv Solv Solv Solv Other Assay Assay Purity... 

Capillary electrophoresis (CE) has become a valuable technique in the analytical toolbox for pharmaceutical analysts. CE methods have been successfully applied for identification, assay, purity determination, and chiral separation. ICH guidelines should be followed in meeting regulatory approval if CE methods are used in a registration dossier. Here, the validation parameters required for different analytical procedures are described and a comprehensive overview of CE validation studies presented in literature is given. 

During the last decade capillary electrophoresis (CE) has become a mature separation technique for pharmaceutical analysis. Numerous validated methods from pharmaceutical R D lahoratories and academia have been reported in literature, including identity confirmation, main component assay, purity determination, enantiomeric separation, and stoichiometry determination. In addition, CE is frequently applied as an orthogonal technique during the development of stability indicating liquid chromatography methods. As a result CE... 

The density of liquid l-methyldiborane(6) at -126° is 0.546 g/mL, or 13.1 mmole/mL.s Its vapor pressure is 55 torr at -78.5° the compound is thermally unstable at this temperature and slowly disproportionates to diborane(6) and l,l-dimethyldiborane(6).1,6 Although the infrared spectrum can be used to identify this compound, similarities to the spectra of the disproportionation products present difficulties in assaying purity.7 The nB NMR spectrum is useful for identifying and assaying 1-CH3B2H5. At -110°, the "B NMR... 

The primary reference standard is normally prepared on a laboratory scale using pure starting materials, reagents, and solvents and should be of the highest purity that reasonably can be obtained. The synthetic procedure used to make it and the method(s) used for its purification, also should be provided. (If applicable, the method of manufacture section can be referenced.) The purification procedure is normally performed until little or no change is observed through two consecutive cycles in assay purity and levels of impurities. 

The importance of a reliable assay for the target protein cannot be overemphasised. When testing chromatographic fractions ensure that the buffers used for separation do not interfere with the assay. Purity of the target protein is most often estimated by SDS-PAGE, capillary electrophoresis, reversed phase chromatography or mass spectrometry. Lowry or Bradford assays are used most frequently to determine the total protein. 

FIGURE 4 Generalized validation process for an HPLC assay/purity method. 

Depending on the requirements of the validation, there can be a preferred order to efficiently perform the validation experiments. For the specific example of validation of an assay/purity HPLC method. Figure 4 suggests a rational approach. 

Assay Purity Solubility Temp Stability API/polymer solubUity Stability due to shear/temperature API vs polymer solubility in the wash Stabihty Stability... 

TABLE 3 Example Acceptance Criteria for an HPLC Assay/Purity Method... 

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