Ion Chromatography Assay for Chloride and Sulfate in Adenosine

Significance of the topic

Quality control of chloride and sulfate impurities in adenosine drug products is critical for patient safety and regulatory compliance The current pharmacopeial turbidity assays are subjective generate hazardous waste and use toxic reagents A rapid objective ion chromatography method addresses these shortcomings and supports efficient high throughput analysis

Goals and overview of the study

This study presents development and validation of a fast robust ion chromatography assay for quantification of chloride and sulfate in adenosine The aim is to replace USP monograph turbidity methods with a reliable instrumental approach

Methodology and instrumentation

The assay uses a Thermo Scientific Dionex ICS 5000+ HPIC system equipped with an EG eluent generator cartridge for KOH an ERS 500 electrolytically regenerated suppressor and a Dionex IonPac AG18 4 µm guard and AS18 4 µm analytical column set A 10 µL injection loop and suppressed conductivity detection at 20 °C were employed Eluent concentrations of 28 mM or 40 mM KOH were used at flow rates of 0.8 mL/min or 1.5 mL/min Column temperature was maintained at 30 °C Sample preparation involves suspending 0.2 g of adenosine in 10 mL deionized water stirring filtering and analyzing within 24 hours Standards are prepared gravimetrically from a 1000 mg/L stock solution

Main results and discussion

Chromatographic separation of chloride and sulfate standards on the 4 µm column delivered baseline resolution with retention times of 3.6 min and 5.9 min at 0.8 mL/min The high pressure configuration at 1.5 mL/min and 40 mM KOH achieved complete separation in 3.5 min with backpressure of 4500 psi Peak asymmetry was 1.2 Recoveries for spiked adenosine samples ranged from 96 to 104 over three days demonstrating accuracy Precision studies yielded retention time RSD below 0.2 and peak area RSD below 2 Linearity was confirmed over 0.2 to 5 mg/L chloride (r2 0.9992) and 0.1 to 20 mg/L sulfate (r2 0.9999) Limits of detection were 0.005 mg/L for chloride and 0.013 mg/L for sulfate and limits of quantitation were 0.02 and 0.04 mg/L respectively Robustness trials varying flow rate eluent concentration temperature and column batch showed consistent resolution asymmetry and retention times

Benefits and practical applications

• Substantial reduction in analysis time increases sample throughput
• Objective quantitative detection replaces subjective turbidity comparison
• Elimination of silver nitrate barium chloride nitric and hydrochloric acids reduces hazardous waste
• Automated eluent generation and self regenerating suppressor improve productivity
• Compliance with pharmacopeial performance criteria ensures regulatory acceptance

Future trends and possibilities

• Extension of high pressure IC to other anionic impurities in pharmaceuticals
• Integration with mass spectrometry for structural confirmation
• Miniaturized high pressure systems for point of care and on site testing
• Automation of sample preparation and direct coupling to synthesis systems
• Application of advanced column chemistries for simultaneous multianalyte assays

Conclusion

The validated high pressure ion chromatography method enables rapid accurate and robust quantification of chloride and sulfate in adenosine It meets ICH USP guidelines for accuracy precision linearity detection limits and robustness and replaces traditional turbidity based assays offering enhanced safety productivity and confidence in pharmaceutical quality control

Reference

1 Adenosine monograph USP35 NF30 US Pharmacopeial Convention Rockville MD 2012
2 Validation of Compendial Procedures General Chapter 1225 US Pharmacopeia National Formulary Rockville MD