Use of disposable open tubular ion exchange pre-columns for in-line clean-up of serum and plasma samples prior to capillary electrophoretic analysis of inorganic cations

• Published in: Journal of Chromatography A Vol. 1218; no. 6; pp. 856 - 859
• Main Authors: Kiplagat, Isaac K., Doan, Thi Kieu Oanh, Kubáň, Pavel, Kubáň, Petr, Boček, Petr
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 11-02-2011; Amsterdam; New York: Elsevier; Elsevier
• Subjects: Analytical chemistry; Biological and medical sciences; Biological samples; Butadienes - chemistry; Calcium - blood; Calcium - isolation & purification; Capacitively coupled contactless conductivity detection; Capillary electrophoresis; Cations - blood; Cations - chemistry; Cations - isolation & purification; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, Ion Exchange - methods; Electric Conductivity; Electrophoresis, Capillary; Exact sciences and technology; Humans; Investigative techniques, diagnostic techniques (general aspects); Magnesium - blood; Magnesium - isolation & purification; Maleates - chemistry; Medical sciences; Metals - blood; Metals - chemistry; Metals - isolation & purification; Miscellaneous. Technology; On-line sample clean-up; Open-tubular ion exchange columns; Other chromatographic methods; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Polymers - chemistry; Potassium - blood; Potassium - isolation & purification; Reproducibility of Results; Sodium - blood; Sodium - isolation & purification; On-line sample clean-up; Capillary electrophoresis; Biological samples; Open-tubular ion exchange columns; Capacitively coupled contactless conductivity detection; Capillary column; Biological fluid; Butadiene copolymer; Chemical analysis; On line; Blood; Ion exchange chromatography; Alkaline earth metal Ions; Blood plasma; Direct method; Sample preparation; Clinical biology; Alkali metal Ions; Ion exchanger; Capacitive coupling; Adsorbent; Contactless conductimetry; Disposable; Coating material; Coupled method; Precolumn; Open tubular column; Electrochemical detector; Inorganic cation; Maleic acid copolymer; Blood serum; Interface
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2010.12.045

A simple analytical system using disposable, open-tubular ion exchange clean-up precolumns coupled in-line to capillary electrophoresis for direct injection of biological samples is presented. The clean-up precolumns were prepared from fused silica capillaries by thermally initiated layer-by-layer polymerization of poly(butadiene-maleic acid) (PBMA) directly on the capillary wall. Typically, 6
cm long precolumns with 4-layers of PBMA were used for sample pretreatment. A robust and reproducible coupling between the precolumn (75
μm ID) and the analytical capillary (50
μm ID) was achieved using an inexpensive, commercially available low dead volume union. No extra dispersion of the analyte zones was observed. Proteins and other high molecular weight compounds from biological sample matrices were retained on the cation-exchanger sites of the precolumn, which eliminated their adsorption on analytical capillary walls and ensured stable electroosmotic flow and migration times of target analytes. Unretained small inorganic cations migrated freely into the analytical capillary for separation and detection. Applicability of the sample clean-up procedure was proved by determination of major inorganic cations in blood serum and plasma samples using capillary electrophoresis with contactless conductivity detection. Separations were performed in background electrolyte solution consisting of 15
mM
l-arginine, 12.5
mM maleic acid, 3
mM 18-crown-6 at pH 5.5 and repeatabilities of migration times and peak areas were below 1.5% and 7.3%, respectively. Less than 1
μL of biological sample was required for injection.