Relative Response Factors

1.0 OBJECTIVE:

To lay down the procedure for determination of relative response factor of Impurities/degradants.

2.0 SCOPE:

This sop is applicable for determination of relative response factor of impurity’s /Degradants in company.

3.0 BACKGROUND:

NIL

4.0 RESPONSIBILITY:

4.1 Scientist - Analytical Research to determine the relative response factors

4.2 Group leader – Analytical Research to ensure the procedure is followed.

4.3 Head – Analytical Research or his designee to ensure compliance.

5.0 PROCEDURE:

Note: To establish the relative response factor use either Method I or Method II.

5.1  Method-I

5.1.1 Prepare solution containing each impurity/degradant and drug substance having concentrations of Specification limit and double the specification limit (when  calculated on active ingredient) as per the test method.

5.1.2 Inject the above solutions in duplicate ( prepare the above solutions in duplicate and inject each solution in duplicate) into the HPLC system under test conditions as per the test method.

 5.1.3 Calculate the response factors of each impurity/degradents and drug substance.

 Response factor = Area per unit concentration =

 Average Area of impurity/degradant or Analyte peak / Concentration of impurity/degradant or analyte

 5.1.4 Calculate the Relative Response Factor for all the individual impurity/degradants at both the concentrations using the formula. 

Response factor of impurity / degradants/ Response factor of Analyte (Drug substance)

5.1.5 Take average RRF of individual impurities / degradants with respect to drug  substance and report as RRF values.

5.2 Method-II

5.2.1 Prepare not less than five preparations containing mixture of impurities / degradents and drug substance (If mutually interfering peaks of impurities / degradents and drug substance are not there, then inject solution containing mixture of impurities / degradents and drug substance) in the concentration range covering three points below the specification level and one points above specification level with respect to test concentration. Inject the above solution individually into HPLC system under test conditions as per the test method

5.2.2 Prepare not less than five preparations of impurities / degradents individually and drug substance individually in the concentration range covering three points below the specification level and one points above specification level with respect to test concentration. Inject the above solution individually into HPLC system under test conditions as per the test method.

5.2.3 Plot a graph of concentration versus response for impurities / degradents and drugs or areas on “Y” axis)

5.2.4 A graph shall be constructed using all data points following the linear equation ( i.e., y=   mx+c) using least squares regression.

5.2.5 The correlation coefficient is not less than 0.97 for drug substance and impurities degradant

5.2.6 Calculate the slope of a substance without including “Zero” in linearity plot. (concentrations on “X” axis and responsible individual impurity / degradant and drug substance. 

Slope of impurity / degradants /  Slope of Analyte (Drug substance)

6.0 VERSION HISTORY:

7.0 ANNEXURES

Nil