Purity testing

Maximum M alkalinity and conductivity or TDS limits must be consistent with acceptable steam purity, as determined by steam purity tests. In many cases, alkalinity limitations, rather than conductivity, determine BD requirements. 

Sampling for carry over and steam purity tests 602... 

UV (DAD) High resolution Component identity Peak purity testing Robust Limited to UV absorbing analytes Wide variability in compound absorptivities [31,48]... 

For nonpharmacopeial materials a full specification should be included in the application. This should include appropriate tests and requirements for physical characteristics, identification, relevant purity tests, and performance-related tests. Characteristics likely to influence bioavailability of the finished product should be controlled. Routine tests and specifications should be described. Methods should be validated. The material should be fully characterized, with full data on the chemistry concerned and including consideration of the safety of the excipient. Any relevant European Directive requirements or other international specifications should be met, but additional requirements might apply depending on the intended use of the product—e.g., for materials to be used in sterile products. 

This system was found optimal for the purity test. 

Color determination maleic anhydride purity test, 15 510 Color developers, 19 247-248... 

SokolieP, T., Koller, G. Approach to method development and vahdation in capillary electrophoresis for enantiomeric purity testing of active basic pharmaceutical ingredients. Electrophoresis 2005, 26, 2330-2341. 

Peak purity tests are used to demonstrate that an observed chromatographic peak is attributable to a single component. Mass spectrometry is the most sensitive and accurate technique to use for peak purity evaluation because of the specific information derived from the analysis. However, a good number of HPLC methods use mobile phase conditions that are incompatible with mass spectrometry detection. In this case, PDA spectrophotometers using peak purity algorithms may be used to support the specificity of the method. Almost all commercially available diode array detectors are equipped with proprietary software that will perform these calculations. Although this technique is more universal in application to HPLC methods, the data provided is neither particularly... 

Specific impurity tests are based on the same principle as general purity tests. Howevet, the method is limited to the quantification of one or several compounds only and will not be used for the determination of unknown impurities. 

Sanger-van de Griend, C. E., and Groningsson, K. (1996). Validation of a capillary electrophoresis method for the enantiomeric purity testing of ropivacaine, a new local anaesthetic compound. /. 

The LOD must be assessed for limit tests. In some cases, the LOD should also be defined for quantitative impurity/purity tests. The LOD is generally expressed as either the minimum level at which the analyte can be reliably detected or as a set amount above the SD from the repeated analysis of suitable sample, such as a blank or negative control sample. 

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