Standard Operating Procedure for Dilution Integrity Testing in BA/BE Bioanalytical Validation
| Department | BA-BE Studies |
|---|---|
| SOP No. | SOP/BA-BE/181/2025 |
| Supersedes | SOP/BA-BE/181/2022 |
| Page No. | Page 1 of 8 |
| Issue Date | 17/04/2025 |
| Effective Date | 20/04/2025 |
| Review Date | 17/04/2026 |
1. Purpose
To define the procedure for evaluating dilution integrity during method validation of LC-MS/MS methods for bioavailability/bioequivalence (BA/BE) studies, ensuring accurate quantification of samples above the upper limit of quantification (ULOQ) after dilution.
2. Scope
This SOP applies to all validated bioanalytical methods in BA/BE studies involving plasma sample analysis where dilution is required for samples exceeding the calibration range.
3. Responsibilities
- Analyst: Prepares dilution integrity samples and performs analysis according to protocol.
- Supervisor: Reviews dilution data, verifies calculations, and confirms result validity.
- QA Officer: Ensures that documentation, acceptance criteria, and reporting comply with ICH M10 and FDA requirements.
4. Accountability
The Bioanalytical Laboratory Head is accountable for ensuring that dilution integrity tests are executed, evaluated, and reported as part of the method validation dossier.
5. Procedure
5.1 Sample Preparation
- Prepare a stock solution at a concentration above the ULOQ (typically 1.5–2 times ULOQ).
- Prepare at least five replicates of diluted samples using blank plasma to achieve target dilution levels (e.g., 1:5, 1:10).
- Label each sample appropriately, including dilution factor, QC level, and preparation date.
- Document all preparation steps in Annexure-1: Dilution Integrity Preparation Log.
5.2 Analysis
- Analyze diluted samples with a freshly prepared calibration curve covering the validated range.
- Inject diluted samples using validated LC-MS/MS method and record analyte response.
- Calculate the concentration using the dilution factor applied to back-calculated values.
5.3 Acceptance Criteria
- Accuracy should be within ±15% of the nominal concentration after applying dilution.
- Precision (%CV) must be ≤15% across replicates.
- Any deviations or failures must be documented with rationale and justification.
- Record results in Annexure-2: Dilution Integrity Result Summary.
5.4 Documentation and Reporting
- Attach chromatograms, calculations, and accuracy/precision reports for each dilution set.
- Prepare a summary and include in the method validation report.
- Submit documentation to QA for approval and archival.
6. Abbreviations
- BA/BE: Bioavailability/Bioequivalence
- ULOQ: Upper Limit of Quantification
- %CV: Percent Coefficient of Variation
- QA: Quality Assurance
7. Documents
- Dilution Integrity Preparation Log – Annexure-1
- Dilution Integrity Result Summary – Annexure-2
8. References
- ICH M10: Bioanalytical Method Validation
- US FDA Guidance for Industry: Bioanalytical Method Validation (2022)
- Internal Method Validation Protocol
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Dilution Integrity Preparation Log
| Sample ID | Nominal Conc. (ng/mL) | Dilution Factor | Prepared Conc. | Prepared By | Date |
|---|---|---|---|---|---|
| DI-01 | 4000 | 1:5 | 800 | Rajesh Kumar | 16/04/2025 |
Annexure-2: Dilution Integrity Result Summary
| Replicate | Back Calculated Conc. (ng/mL) | Nominal Conc. | % Accuracy | Status |
|---|---|---|---|---|
| 1 | 810 | 800 | 101.2% | Accepted |
| 2 | 788 | 800 | 98.5% | Accepted |
Revision History:
| Revision Date | Revision No. | Details | Reason | Approved By |
|---|---|---|---|---|
| 01/01/2022 | 1.0 | Initial SOP Release | New SOP | QA Head |
| 17/04/2025 | 2.0 | Revised procedure with expanded documentation templates | ICH M10 Compliance | QA Head |