Two methods of capillary electrophoresis with contactless conductivity detection have been developed for monitoring the levels of glucose and lactate in clinical samples. The separations are performed in uncoated fused silica capillaries with inner diameter 10 or 20 μm, total length 31.5 cm, length to detector 18 cm, using an Agilent electrophoretic instrument with an integrated contactless conductivity detector. Glucose is determined in optimized background electrolyte, 50 mM NaOH with pH 12.6 and 2-deoxyglucose is used as an internal standard; the determination of lactate is performed in 40 mM CHES/NaOH with pH 9.4 and lithium cations as an internal standard. Both substances are determined in minimal volumes of (1) nutrient media after cell incubation, and (2) microdialysates of human adipose tissue; after dilution and filtration as the only treatment of the sample. The migration time of glucose is 2.5 min and that of lactate is 1.5 min with detection limits at the micromolar concentration level. The developed techniques are suitable for sequential monitoring of glucose and lactate over time during metabolic experiments.

• Klíčová slova
• Capillary electrophoresis, Cell incubation, Contactless conductivity detection, Glucose, Lactate, Microdialysis, Rapid determination,
• MeSH
• elektrická vodivost * MeSH
• elektroforéza kapilární metody   MeSH
• glukosa analýza   MeSH
• kalibrace MeSH
• kultivační média chemie   MeSH
• kultivované buňky MeSH
• kyselina mléčná analýza   MeSH
• lidé MeSH
• mikrodialýza metody   MeSH
• tuková tkáň MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• glukosa MeSH
• kultivační média MeSH
• kyselina mléčná MeSH

Capillary electrophoresis (CE) with contactless conductivity detection (C4D) represents a strong tool for determining amino acids in clinical samples. This chapter provides detailed instructions for CE/C4D determination of the branched-chain amino acids (BCAAs) valine, isoleucine, and leucine in human plasma, which can be readily employed in physiological studies. Baseline separation of all the BCAAs is achieved on a short separation length equal to 18 cm in optimized background electrolyte consisting of 3.2 M acetic acid dissolved in 20% v/v methanol with addition of 1.0% v/v INST-coating solution. The analysis time does not exceed 3 min and the limit of detection is 0.4 μM for all BCAAs. The pretreatment of human plasma is very simple and is based on fourfold plasma dilution by acetonitrile and subsequent filtration. Only 50 μL of plasma is used for the analysis. The high sensitivity of the CE/C4D method is achieved by injecting a large volume of sample, combined with application of negative pressure to flush the acetonitrile zone out of the capillary.

• Klíčová slova
• Branched-chain amino acids, Capillary electrophoresis, Contactless conductivity detection, Human plasma, Large-volume sample stacking, Pressure-assisted analysis, Rapid determination,
• MeSH
• elektrická vodivost * MeSH
• elektroforéza kapilární metody   MeSH
• fyziologie * MeSH
• kalibrace MeSH
• lidé MeSH
• referenční standardy MeSH
• větvené aminokyseliny krev   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• větvené aminokyseliny MeSH