Specificity for Assay Method

1.0 OBJECTIVE: 

To lay down the procedure for Specificity for Assay Method

2.0 SCOPE:

This SOP is applicable for Specificity for Assay Method in company Name.

3.0 BACKGROUND: 

NIL

4.0 RESPONSIBILITY:

4.1 All Analytical research personnel shall follow the SOP. 

4.2 Group leader of Analytical research shall ensure the procedures to be followed. 

4.3 Head Analytical research or his designee to ensure overall compliance. 

5.0 PROCEDURE:

5.1 ICH defines “ Specificity is the ability to assess unequivocally the analyte in the presence of components which may be expected to be present. Typically these might include impurities, degradants, matrix, etc.” 

5.2  That means that the analyte of interest can be identified even in the presence of other components such as impurities, degradants and others in the solution.

5.3 In the Chromatographic analysis, this can be identified by observing the retention times of the analyte, impuruties and degradants etc.... and also the resolution between the two closely eluting peaks.

5.4  For example the major analyte RT at 10.880 min, AntiIsomer is at 11.818  and  Lactone Impurity is at 17.551 min and the resolution between the closest eluting peak to the major peak and AntiIsomer is 2.08. 

5.5 In cases where a non-specific assay is used, other supporting analytical procedures should be used to demonstrate overall specificity. For example, where a titration is adopted to assay the drug substance for release, the combination of the assay and a suitable test for impurities can be used.

5.6 Impurities are available

For the assay , this should involve demonstration of the discrimination of the analyte in the presence of impurities and/or excipients; practically, this can be done by spiking pure substances (drug substance or drug product) with appropriate levels of impurities and/or excipients and demonstrating that the assay result is unaffected by the presence of these materials (by comparison with the assay result obtained on unspiked samples).

5.6.1 Demonstration of specificity for assay method:

Demonstration of the specificity of the analyte in the presence of impurities, this can be done by spiking the pure substance  with appropriate (1%, 3% and 5%) levels of the impurities and demonstrating that the Assay result is unaffected by the presence of these impurities. Compare the results from unspiked sample.

% Level % Assay Spiked Sample % Assay of Unspiked Sample

Sample +1% spiked            98.97

Sample +3% spiked            98.86                                       98.98

Sample +5% spiked            98.96

5.6.2 The demonstration of the specificity of the analyte in the presence of impurities, this can be done by spiking the pure substance with appropriate (I%, 3% and 5%) levels of the impurities and demonstrating that the Assay result is unaffected by considering total weight (i.e,Drug subsntace and added impurity level) in the presence ofthese impurities. Compare the result from unspiked sample.

% Level                  % Assay Without considering % Assay Considering 
                                       Impurity weight Impurity weight

Sample +1% spiked           98.97                   97.07

Sample +3% spiked           98.86                   93.37

Sample +5% spiked           98.96                   90.16

5.7  Impurities are not available

If impurity or degradation product standards are unavailable, specificity may be demonstrated by comparing the test results of samples containing impurities or degradation products to a second well-characterized procedure e.g.: pharmacopoeial method or other validated analytical procedure (independent procedure). As appropriate, this should include samples stored under relevant stress conditions: light, heat, humidity, acid/base hydrolysis and oxidation. 

- for the assay, the two results should be compared;

5.7.1 Eg: Forcibly degrade Drug Substance sample under elevated temperature, Acid hydrolysis, Base hydrolysis, photo degradation and oxidation. All stress solutions should analyse using Photo diode array detector and calculate the Assay in each stress condition. For stressed conditions final degraded sample confirmed in the purity by HPLC and that same sample will be directly analyzed for assay content.

Peak purity tests may be useful to show that the analyte chromatographic peak is not attributable to more than one component (e.g., diode array, mass spectrometry).

6.0 ANNEXURES 

Nil