Organic bound fluorine in Ezetimibe by Combustion Ion Chromatography

Importance of the Topic

Ezetimibe is a widely used cholesterol‐lowering drug featuring two fluorophenyl moieties. Precise determination of organic‐bound fluorine in such APIs is critical for ensuring product quality, dosage accuracy and regulatory compliance in pharmaceutical manufacturing.

Objectives and Study Overview

This study aimed to quantify the fluorine content bound within the Ezetimibe molecule using Combustion Ion Chromatography (CIC). The approach enables direct assessment of organic fluorine levels while minimizing interference from free fluoride.

Methodology

Samples of 100 mg Ezetimibe were dissolved in 15 g ethanol to prevent excess fluoride introduction. Combustion was carried out at 1050 °C under a gas flow of 100 mL/min Argon and 300 mL/min Oxygen. Resulting combustion gases were absorbed in a peroxide solution and analyzed by Ion Chromatography employing an intelligent Partial Loop Injection Technique (MiPT) with flame sensor detection.

Used Instrumentation

• 930 Compact IC Flex with integrated Combustion Module and Absorber Module
• IC Conductivity Detector with MSM Rotor A and Suppressor Vario
• Autosampler MMS 5000 with liquid sampling kit
• Metrohm separation columns: Metrosep A Supp 5, Metrosep A PCC 2 HC, Metrosep I Trap 1 and Metrosep A Trap 1

Main Results and Discussion

Three replicate analyses yielded fluorine concentrations of 8.8%, 8.4% and 8.7% with relative standard deviations of 2.8%, 0.6% and 0.4%, respectively. Recoveries relative to the theoretical fluorine content ranged from 90.4% to 94.5%. These results demonstrate the method’s high precision, accuracy and suitability for routine fluorine quantification in fluorinated APIs.

Benefits and Practical Applications

• Accurate quantification of organic‐bound fluorine in pharmaceutical substances
• Robust quality control tool for manufacturing and release testing
• Supports regulatory dossiers by providing reliable impurity data

Future Trends and Potential Applications

Advances in detector sensitivity and automation are expected to further enhance detection limits and throughput. Coupling CIC with mass spectrometry could broaden analytical capabilities to more complex drug formulations and environmental samples. The method’s applicability may extend to other fluorinated compounds in pharmaceuticals, agrochemicals and food safety.

Conclusion

Combustion Ion Chromatography offers a precise, reproducible and adaptable approach for the determination of organic‐bound fluorine in Ezetimibe. Its demonstrated performance underlines its value for pharmaceutical analysis and potential for broader application.