for determining the concentration of unknown samples by correlating peak response with known concentrations of standard solutions.

2. Scope

This procedure applies to all quantitative analytical methods developed and validated by the Analytical Method Development (AMD) department, including UV, HPLC, GC, and LC-MS methods. It covers selection of standard concentrations, preparation methodology, plotting the curve, statistical evaluation, and documentation.

3. Responsibilities

• Analytical Scientist: Responsible for preparing standards, executing calibration runs, analyzing data, and documenting results.
• QA Reviewer: Ensures that calibration documentation complies with applicable quality guidelines.
• Method Development Supervisor: Approves final calibration data and curve for use in analytical method validation or testing.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring that calibration procedures are accurately followed, reviewed, approved, and archived as per GMP and ICH guidelines.

5. Procedure

5.1 Selection of Concentration Range

1. Determine the target analyte concentration range based on product specification, dosage strength, and detection capability.
2. Select a minimum of five non-zero standard concentrations that span the expected sample concentration range (e.g., 80% to 120%).
3. Include a blank solution (without analyte) to evaluate baseline interference.

5.2 Preparation of Stock and Working Standards

1. Weigh a known quantity of certified reference standard using a calibrated analytical balance (Annexure-1).
2. Dissolve in suitable diluent to prepare a primary stock solution of known concentration.
3. Prepare serial dilutions from the primary stock to create working standard concentrations.
4. Use volumetric flasks, micropipettes, and Class A glassware for accurate dilutions.

5.3 System Setup and Instrumentation

1. Power on the analytical instrument (HPLC, UV, etc.) and allow sufficient warm-up time.
2. Prepare the mobile phase, if applicable, and equilibrate the column as per method SOP.
3. Ensure the detector is properly calibrated and baseline is stable before sample injection.

5.4 Sample Injection and Data Acquisition

1. Inject each standard solution into the system in ascending order of concentration.
2. Perform at least two replicate injections at each concentration level to evaluate repeatability.
3. Use consistent injection volume and method parameters for all standards.

5.5 Curve Construction

1. Record the average peak area (or height) for each concentration level.
2. Plot a graph of peak area versus concentration using validated software (e.g., Empower, LabSolutions, Excel).
3. Apply linear regression and determine the slope, intercept, correlation coefficient (r), and regression equation.
4. Acceptable linearity criteria: r ≥ 0.999, Y-intercept within acceptable limit, % RSD ≤ 2%.

5.6 Data Interpretation

1. Evaluate residuals and deviations from linearity across concentration range.
2. If non-linearity is observed, consider polynomial regression or reduce the concentration range.
3. Assess carryover by injecting a blank after the highest standard concentration.

5.7 Documentation and Reporting

1. Record raw data, chromatograms, injection sequence, regression plot, and statistical output in Annexure-2.
2. Include standard preparation records, weighing logs, and calculation sheets.
3. Review and approve the final calibration report for use in method validation.

6. Abbreviations

• HPLC: High Performance Liquid Chromatography
• UV: Ultraviolet Spectroscopy
• GC: Gas Chromatography
• LC-MS: Liquid Chromatography-Mass Spectrometry
• RSD: Relative Standard Deviation

7. Documents

1. Annexure-1: Standard Preparation Log
2. Annexure-2: Calibration Curve Worksheet
3. Annexure-3: Statistical Analysis Summary

8. References

• ICH Q2(R1): Validation of Analytical Procedures
• USP <1225>: Validation of Compendial Procedures
• FDA Guidance: Analytical Procedures and Methods Validation

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Vikas Menon	Neha Raj	Dr. Kavita Sinha
Designation	Analytical Scientist	QA Reviewer	Head – AMD
Department	Analytical Method Development	Quality Assurance	Analytical Method Development

11. Annexures

Annexure-1: Standard Preparation Log

Standard	Weight (mg)	Diluent	Stock Concentration (µg/mL)	Prepared By
API Std A	25.0	Acetonitrile:Water (50:50)	250	Vikas Menon

Annexure-2: Calibration Curve Worksheet

Concentration (µg/mL)	Peak Area	Average	% RSD
25	120345	120350	0.2%
50	240789	240780	0.3%
75	360123	360110	0.2%
100	480456	480450	0.1%
125	600890	600880	0.1%

Annexure-3: Statistical Analysis Summary

Regression Equation: y = 4800.4x + 100.5

Correlation Coefficient (r): 0.9996

Standard Error: 0.45

Linearity Range: 25–125 µg/mL

Remarks: Meets ICH criteria for linearity and precision.

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
01/06/2025	2.0	Updated curve plotting tools and statistical acceptance criteria	Annual SOP Review	Dr. Kavita Sinha
10/03/2022	1.0	Initial release	New SOP	QA Head