Q&A ON VALIDATION OF ANALYTICAL PROCEDURES – ICH Q2 GUIDELINE PART -8
Question 1:
What validation approach can be used to validate an estimated value for the detection limit?
Answer 1:
An estimated value for the detection limit can be validated by the independent analysis of a suitable number of samples known to be near or prepared at the detection limit.
Question 2:
What are the different approaches for determining the quantitation limit?
Answer 2:
There are two main approaches for determining the quantitation limit:
Based on Visual Evaluation: This approach involves visual evaluation of samples with known concentrations of analyte to establish the minimum level at which the analyte can be quantified with acceptable accuracy and precision.
Based on Signal-to-Noise Approach: This approach, applicable to analytical procedures exhibiting baseline noise, involves determining the signal-to-noise ratio by comparing measured signals from samples with known low concentrations of analyte with those of blank samples. The minimum concentration at which the analyte can be reliably quantified is established, with a typical signal-to-noise ratio of 10:1.
Question 3:
How the quantitation limit is determined using the visual evaluation approach?
Answer 3:
The quantitation limit is determined by analyzing samples with known concentrations of analyte visually and establishing the minimum level at which the analyte can be quantified with acceptable accuracy and precision.
Question 4:
What is the typical signal-to-noise ratio used in the signal-to-noise approach for determining the quantitation limit?
Answer 4:
The typical signal-to-noise ratio used in the signal-to-noise approach for determining the quantitation limit is 10:1.
Question 5:
When can visual evaluation be used to determine the quantitation limit?
Answer 5:
Visual evaluation can be used for both non-instrumental methods and instrumental methods to determine the quantitation limit.
Question 6:
How is the quantitation limit (QL) expressed based on the standard deviation of the response and the slope of the calibration curve?
Answer 6:
The quantitation limit (QL) is expressed as: QL = 10σ / S, where σ represents the standard deviation of the response and S represents the slope of the calibration curve.
Question 7:
What methods can be used to estimate the standard deviation (σ) for determining the quantitation limit?
Answer 7:
The standard deviation (σ) for determining the quantitation limit can be estimated in the following ways:
Based on Standard Deviation of the Blank: This involves measuring the magnitude of the analytical background response by analyzing blank samples and calculating the standard deviation of these responses.
Based on the Calibration Curve: A specific calibration curve is studied using samples containing the analyte in the range of the quantitation limit (QL). The residual standard deviation of a regression line or the standard deviation of y-intercepts of regression lines may be used as the standard deviation.
Question 8:
What is the recommended data to be presented when determining the quantitation limit?
Answer 8:
When determining the quantitation limit, the quantitation limit itself and the method used for its determination should be presented.
Question 9:
How should the quantitation limit be validated?
Answer 9:
The quantitation limit should be validated by the analysis of a suitable number of samples known to be near or prepared at the quantitation limit after its determination.
Question 10:
Why is it important to validate the quantitation limit?
Answer 10:
Validating the quantitation limit ensures the reliability and accuracy of the analytical procedure by confirming the minimum level at which the analyte can be quantified with acceptable accuracy and precision.
