Quality control of dialysis concentrates

Significance of the Topic

Hemodialysis solutions play a critical role in replacing kidney function by removing metabolic waste and balancing electrolytes in patients with renal failure. Ensuring the accurate composition of dialysis concentrates is essential for patient safety and treatment efficacy. Quality control of these highly saline pharmaceutical fluids demands robust, sensitive, and high-throughput analytical methods.

Objectives and Study Overview

This study demonstrates a comprehensive ion chromatography (IC) approach for simultaneous determination of anions, including acetate, and cations in bicarbonate dialysis acid concentrates. The goal is to replace single-element techniques like atomic absorption spectroscopy (AAS) with a unified, automated, and efficient IC workflow for routine quality control in pharmaceutical and clinical laboratories.

Methodology and Instrumentation

Sample Preparation

• Two acid dialysis concentrates (A-concentrates #293 and #570) were sourced from a major manufacturer and diluted 1:500–1:750 with ultrapure water.
• Dilution ensures analyte concentrations fall within calibration ranges while minimizing matrix effects.

Used Instrumentation

The analysis employed a dual-channel Metrohm IC system controlled by Empower 3 software:

• Metrosep A Supp 19 ‑ 150/4.0 column for anion and acetate separation.
• Metrosep A Supp 19 Guard/4.0 for column protection.
• Metrosep C 6 ‑ 150/4.0 column for cation separation and Metrosep C 6 Guard/4.0.
• 940 Professional IC Vario TWO with sequential suppression and peristaltic regenerating pump.
• 889 IC Sample Center – cool refrigerated autosampler for sample stability.
• 947 Professional UV/VIS Detector Vario MW for additional detection of nitrite, nitrate, and bromide at 205 nm.

Main Results and Discussion

Simultaneous analysis of anions (fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfate, and acetate) and cations (sodium, ammonium, potassium, calcium, magnesium) was achieved in under 25 minutes.

• Recoveries ranged from 91 % to 106 % relative to manufacturer specifications.
• Repeatability showed RSDs below 1 % for all major analytes, confirming high precision.
• High-capacity columns prevented matrix overload despite elevated sodium and chloride levels, ensuring sharp, symmetric peaks and stable retention times.
• UV detection enhanced sensitivity for trace impurities in the presence of high background conductivity.

Benefits and Practical Applications

This IC-based method offers:

• Comprehensive simultaneous quantification of both anionic and cationic species from a single sample aliquot.
• Sub-25 minute analysis time, improving laboratory throughput.
• High accuracy and precision in challenging high-salinity matrices without additional sample cleanup steps.
• Automated, user-friendly operation compatible with common chromatography software platforms.

Future Trends and Potential Applications

Advancements may include online coupling of IC with mass spectrometry for enhanced specificity, development of novel high-capacity stationary phases to further reduce run times, and integration of real-time monitoring in dialysis units. Automation and cloud-based data management will continue to streamline quality control workflows in pharmaceutical and healthcare settings.

Conclusion

A dual-channel IC system with dedicated high-capacity columns provides a robust and efficient solution for quality control of hemodialysis concentrates. The method delivers precise, accurate, and high-throughput analysis of key electrolytes, buffers, carbohydrates, and trace impurities within a single run, meeting stringent pharmacopeial standards.

References

1. Hoenich N, Thijssen S, Kitzler T, Levin R, Ronco C. Impact of Water Quality and Dialysis Fluid Composition on Dialysis Practice. Blood Purif. 2008;26(1):6–11.
2. Hoenich NA, Ronco C. Haemodialysis Fluid: Composition and Clinical Importance. Blood Purif. 2007;25(1):62–68.
3. Coulliette AD, Arduino MJ. Hemodialysis and Water Quality. Semin Dial. 2013;26(4):427–438.
4. Parker JN, Parker PM. Hemodialysis: A Medical Dictionary, Bibliography, and Annotated Research Guide to Internet References. ICON Health Publications; 2004.
5. Catto GRD. Haemodialysis. Kluwer Academic Publishers; 1989.