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Isotachophoretic determination of urea-ammonium in plasma: a candidate reference method
P Pei1, F P Steiner, D J Vonderschmitt
1Institute of Clinical Chemistry, University Hospital, Zürich, Switzerland.
Journal of Clinical Chemistry and Clinical Biochemistry. Zeitschrift Fur Klinische Chemie Und Klinische Biochemie
|July 1, 1990
Summary
Capillary isotachophoresis can now determine neutral species like urea. This method, using urease hydrolysis and ammonium ion measurement, offers accurate and precise urea quantification for various applications.
Area of Science:
- Analytical Chemistry
- Biochemistry
Background:
- Capillary isotachophoresis (CITP) is a separation technique based on physical phenomena.
- CITP is proposed as a universal reference method for ionic constituents.
Purpose of the Study:
- To demonstrate the determination of neutral species using CITP.
- To establish a method for quantifying urea concentrations.
Main Methods:
- Urea was hydrolyzed to ammonia and bicarbonate using urease (EC 3.5.1.5).
- Ammonium ion concentration was measured directly by capillary isotachophoresis.
- Standard Reference Material 912a urea was used as a primary standard.
Main Results:
- The analytical linear range for urea determination extended to 64 mmol/L.
- Method precision ranged from 1.05-2.64% (CV) with excellent analytical recovery (99.4%).
- Analysis of NBS human reference serum (SRM 909) showed good agreement with the reference value (9.52 ± 0.085 mmol/L vs. 9.64 mmol/L).
Conclusions:
- Capillary isotachophoresis, after suitable enzymatic pretreatment, is effective for quantifying neutral species like urea.
- The developed method provides accurate and precise urea measurements, comparable to established coupled-enzyme methods.