ICH Q3D Elemental Impurities Analysis of Tablets by EDX - Verification Based on USP <233> ELEMENTAL IMPURITIES-PROCEDURES

Topic Significance

The regulation of elemental impurities in pharmaceuticals is critical to ensure patient safety and comply with ICH Q3D and USP <232>/<233> guidelines. While ICP-MS and ICP-AES are standard techniques, this study demonstrates energy dispersive X-ray fluorescence (EDX) as a validated, cost-effective alternative for tablet analysis.

Study Objectives and Overview

The primary goal was to verify the Shimadzu EDX-7000 for quantifying eight elemental impurities (As, Hg, Pb, Cd, V, Co, Ni, Pd) in oral tablets per USP <233> limit procedures. The approach involved spiked sample preparation, calibration curve assessment, and comprehensive validation against criteria for detectability, specificity, and repeatability.

Methodology and Instrumentation

Sample Preparation:

• Tablet powders (0.5 g) were prepared as standard, spiked (100% and 80% of target concentration), and unspiked forms.
• Standard powders: cellulose matrix spiked with certified solutions.

Calibration:

• Three-point calibration at 0, 0.5 J, and 1.5 J (J = target concentration).
• Correlation coefficients ≥0.999 for all elements.

Instrumentation:

• Shimadzu EDX-7000 with SDD detector and Rh anode X-ray tube (50 kV).
• Filters: #1 (Cd, Pd), #2 (V), #4 (As, Hg, Pb, Co, Ni).
• Measurement settings: auto current, 10 mmφ collimator, 1800 s ×3 per filter, air atmosphere, dead time ≤30%.

Results and Discussion

Validation was performed following USP <233> protocols:

• Detectability: Spiked sample recoveries within ±15% of standard (observed deviations −3.1% to +3.6%).
• Sensitivity: 80% spiked levels remained below standard average values.
• Specificity: Matrix interference and spectral overlaps were corrected, yielding distinct peaks.
• Repeatability: Six replicates showed RSD between 0.5% and 6.6%, meeting ≤20% criteria.

Benefits and Practical Applications

EDX-7000 offers a reliable alternative to ICP methods for elemental impurity screening in tablets. Its straightforward sample preparation, robust validation performance, and reduced operational costs make it suitable for routine quality control of pharmaceutical formulations.

Future Trends and Potential Applications

Advancements in EDX technology, such as enhanced detector resolution and faster data acquisition, will expand its use across diverse dosage forms. Integration with automated sample handling and chemometric analysis may further streamline impurity profiling in manufacturing settings.

Conclusion

The Shimadzu EDX-7000 fulfills USP <233> limit procedures for elemental impurity analysis, validating its application for oral tablet quality management. Coupled with ICP-MS/AES, EDX provides a complementary, cost-effective tool for pharmaceutical compliance.

References

• USP <232> Elemental Impurities – Limits
• USP <233> Elemental Impurities – Procedures
• Shimadzu Application News No. X271
• ICH Q3D(R1) Guideline on Elemental Impurities (2019)