Microchip Capillary Electrophoresis for Point-of-Care Analysis of Lithium

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 53; no. 1; pp. 117 - 123
• Main Authors: Vrouwe, Elwin X, Luttge, Regina, Vermes, Istvan, van den Berg, Albert
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.01.2007; American Association for Clinical Chemistry; Oxford University Press
• Subjects: Analytical, structural and metabolic biochemistry; Antimanic Agents - blood; Biological and medical sciences; Blood Specimen Collection - methods; Blood vessels; Chemical analysis; Clinical trials; Electrophoresis; Electrophoresis, Microchip; Fundamental and applied biological sciences. Psychology; Humans; Investigative techniques, diagnostic techniques (general aspects); Lithium; Lithium Compounds - blood; Magnesium; Medical sciences; Methods; Needles; Point-of-Care Systems; Testing; Lithium; Biochemistry; Molecular biology; Capillary electrophoresis; Point of care testing; Clinical biology
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1373/clinchem.2007.073726

Microchip capillary electrophoresis (CE) is a promising method for chemical analysis of complex samples such as whole blood. We evaluated the method for point-of-care testing of lithium. Chemical separation was performed on standard glass microchip CE devices with a conductivity detector as described in previous work. Here we demonstrate a new sample-to-chip interface. Initially, we took a glass capillary as a sample collector for whole blood from a finger stick. In addition, we designed a novel disposable sample collector and tested it against the clinical standard at the hospital (Medisch Spectrum Twente). Both types of collectors require < 10 microL of test fluid. The collectors contain an integrated filter membrane, which prevents the transfer of blood cells into the microchip. The combination of such a sample collector with microchip CE allows point-of-care measurements without the need for off-chip sample treatment. This new on-chip protocol was verified against routine lithium testing of 5 patients in the hospital. Sodium, lithium, magnesium, and calcium were separated in < 20 s. The detection limit for lithium was 0.15 mmol/L. The new microchip CE system provides a convenient and rapid method for point-of-care testing of electrolytes in serum and whole blood.