How to perform Precision in Analytical Method Validation

Introduction and outcome

Precision is one of the important parameter of analytical method validation. In this article, I will discuss procedure to perform Precision (System precision, Method precision, Method reproducibility and Intermediate precision) with case studies.

Precision

• Precision is subdivided into four categories:
  • System precision
  • Method precision
  • Method reproducibility
  • Intermediate precision

Case studies:

Let us consider a drug substance D has the following specifications and we have to perform precision test:

• Impurity A NMT: 0.20%
• Any unknown impurity NMT: 0.10%
• Total impurity NMT 0.50%
• Assay: 98 to 100%

Sample concentration is 1.0 mg/ml for both related substances test and assay test. QL of the method is 0.05%

System precision for impurity A and Drug substance D (Assay test)

Prepare impurity A standard solution at 0.2% or 2.0 mcg/ml and inject 6 time (as per chromatographic condition given in the monograph) and calculate RSD of six injections.

Prepare Drug substance D standard at 1.0mg/ml or 1000 mcg/ml and inject 6 times (as per chromatographic condition given in the monograph) and calculate RSD of of RTs and area response.

Conclusion

• RSD of RTs of impurity A is 1.18 ≤ 5.0%
• RSD of RTs of Drug substance D is 0.96 ≤ 5.0%
• RSD of area of impurity A is 0.39 ≤ 10%
• RSD of area of main analyte D is 0.11 ≤ 1.0%
• Hence, method passes the system precision test for impurity A and Drug substance (main analyte) D

Method precision for impurity A (RS test) and Main analyte D (Assay test)

Prepare sample solution containing impurity A at 2.0mcg/ (0.2%) and Drug substance D at 1000 mcg/ml and inject 6 time (as per chromatographic condition given in the monograph) and calculate RSD of area % for impurity A .

Calculate assay of main analyte ‘D‘ using main analyte standard solution in all six injections. Calculate the RSD of assay values.

Conclusion:

• RSD of value of impurity A is 5.4 ≤ 10%
• RSD of area of main analyte D is 0.12 ≤ 1.0%
• Hence, method passes the method precision test for impurity A and main analyte D

Method reproducibility

Reproducibility parameter is performed between the two labs using the following conditions:

• Labs: Sending lab and Receiving lab, for example Analytical lab and QC lab
• Analysts: Analyst of sending Lab and Receiving lab, for example analyt of Analytical lab and analyst of QC lab.
• Instruments: Each sending lab and Receiving lab should use instruments of different make, for example if analytical lab perform reproducibility on Shimadzu HPLC then QC will perform on water HPLC
• Column: Different lots of the same make
• Sample: 3^* different lots and duplicate injections

Note^*:

• If only 2 samples are available then one sample will be analyzed four times and second sample will be analyzed two times
• If only one sample is available then sample will be analyzed six times

Method reproducibility of Impurity A

Conclusion

Difference between average result between ARD Lab and QL lab for impurity A is≤ 30 in all three lots ( 6.8% for lot X 13.3% for lot Y and 0 for lot Z). Hence, sample passes the reproducibility test.

Method reproducibility test of Assay

Conclusion

• Difference between average result between ARD Lab and QL lab for Assay is≤ 4% in all three lots ( 0.10% for lot X, 0.20% for lot Y, and 0.10 for lot Z)
• Hence, method passes the method reproducibility test

Intermediate precision for Impurity A and Assay

• This test is performed same as reproducibility test except two different labs. It is performed in the same lab.
• If reproducibility is performed then there is no need to perform intermediate precision

Conclusion

Precision is one of the important parameter of the Analytical method validation. I hope this article, cleared all your doubts related to precision test and you can perform the same independently. For any opinion or suggestions related to this article, you can write in the comment section. For any further assistance you can contact me using contact form.

References

• https://www.americanpharmaceuticalreview.com/Featured-Articles/569734-Analytical-Method-Validation-for-Quality-Assurance-and-Process-Validation-Professionals/

Abbreviations

• mcg: microgram
• ml: milliliter
• QL: Quantitation limit
• RT: Retention time
• ARD: Analytical research and development
• QC: Quality control
• RT: Retention time
• RS: Related substances
• RSD: Relative standard deviation

Disclaimer: The numerical data used in the tables or calculations are not actual data. It is designed to explain the topic.

FAQs

How to perform precision in method validation?

Precision contains system precision, method precision and reproductivity or intermediate precision. In the system precision six injections are made at the specification level and acceptance criteria is decided on RSD of area response of six injections.

In the method precision six sample preparations are made, and assay or impurity is calculated for each solution. Acceptance criteria is decided on RSD of area response of six injections.

In method reproducibility, three samples are analysed between sending laboratory and receiving laboratory. Acceptance criteria is decided on % difference of result between the two laboratories.