cations, and organic acids, in pharmaceutical substances and dosage forms.

2. Scope

This SOP applies to the Analytical Method Development (AMD) department for the implementation of ion chromatography techniques in compliance with ICH and pharmacopeial guidelines for raw materials, APIs, intermediates, and finished products.

3. Responsibilities

• Analytical Scientist: Develops and validates IC methods, ensures suitability of reagents and columns.
• Instrument Analyst: Operates IC equipment, monitors performance, and records system parameters.
• QA Officer: Reviews development data, validation reports, and ensures regulatory compliance.
• Head – AMD: Provides oversight and final approval of methods for use in regulated analysis.

4. Accountability

The Head of Analytical Method Development is accountable for the scientific soundness, compliance, and release of IC methods in routine quality control and regulatory submissions.

5. Procedure

5.1 Preliminary Method Design

1. Identify target analytes (e.g., chloride, sulfate, nitrate, sodium, ammonium, acetate).
2. Select detection technique: conductivity detector (with or without suppressor), UV, or PAD (Pulsed Amperometric Detection) for carbohydrates.
3. Choose appropriate IC mode: anion exchange or cation exchange.

5.2 Column and Mobile Phase Selection

1. Choose appropriate column (e.g., Dionex IonPac AS22 for anions, CS12A for cations).
2. Prepare eluent based on analyte type:
   • Anion eluent: carbonate/bicarbonate solution (3.2 mM Na₂CO₃, 1.0 mM NaHCO₃)
   • Cation eluent: methanesulfonic acid (MSA) solution (20 mM)
3. Use degassed and filtered deionized water for mobile phase preparation.

5.3 Instrument Configuration

1. Install and condition the column as per manufacturer instructions.
2. Set IC system parameters:
   • Flow rate: 1.0 mL/min
   • Column temp: 30°C
   • Injection volume: 25 µL
   • Suppressor current: as recommended
3. Calibrate conductivity detector or UV detector at the required wavelength (for UV-absorbing species).

5.4 Sample and Standard Preparation

1. Dissolve known quantity of sample in ultrapure water (or diluent).
2. Filter through 0.22 µm membrane filter and inject immediately.
3. Prepare calibration standards at 5 levels (e.g., 25, 50, 75, 100, 125% of target concentration).

5.5 System Suitability and Calibration

1. Inject system suitability solution containing target ions.
2. Verify:
   • Resolution between critical pairs ≥ 1.5
   • Retention time RSD ≤ 1.0%
   • Linearity R² ≥ 0.995
3. Document in Annexure-1: System Suitability Log.

5.6 Method Validation

1. Validate as per ICH Q2(R2):
   • Specificity – No interference at analyte RT
   • Linearity – R² ≥ 0.995
   • Accuracy – Recovery 95–105%
   • Precision – RSD ≤ 2%
   • LOD/LOQ – Based on S/N ratio 3:1 and 10:1
   • Robustness – Slight variations in flow, eluent, temperature
2. Record findings in Annexure-2: Validation Summary Sheet.

6. Abbreviations

• IC: Ion Chromatography
• RT: Retention Time
• LOD: Limit of Detection
• LOQ: Limit of Quantification
• RSD: Relative Standard Deviation
• SOP: Standard Operating Procedure

7. Documents

1. System Suitability Log – Annexure-1
2. Validation Summary Sheet – Annexure-2
3. Calibration Curve Log – Annexure-3

8. References

• ICH Q2(R2) – Validation of Analytical Procedures
• USP <1065> – Ion Chromatography
• EP 2.2.28 – Ion Chromatography
• FDA Guidance on Elemental and Ionic Impurities

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: System Suitability Log

Parameter	Result	Acceptance	Status	Analyst
Resolution	2.1	≥ 1.5	Pass	Sunita Reddy
RT RSD	0.7%	≤ 1.0%	Pass	Sunita Reddy

Annexure-2: Validation Summary Sheet

Parameter	Result	Criteria	Status
Linearity	R² = 0.9987	≥ 0.995	Pass
Recovery	97.4%	95%–105%	Pass

Annexure-3: Calibration Curve Log

Concentration (ppm)	Peak Area	Analyst
10	1453	Rajesh Kumar
25	3612	Rajesh Kumar
50	7435	Rajesh Kumar

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
04/05/2025	2.0	Expanded buffer selection and annexure section	Annual SOP Review