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1.
J Chromatogr A ; 1303: 94-9, 2013 Aug 16.
Article in English | MEDLINE | ID: mdl-23866123

ABSTRACT

A new variant of large-volume sample stacking injection (LVSS) was used in the capillary electrophoresis with capacitively coupled contactless conductivity detection (CE/C(4)D) determination of the neurotransmitters γ-aminobutyric acid (GABA), glycine (Gly) and glutamate (Glu) in microdialysates of periaqueductal gray matter (PAG). The separation capillary was filled to 98% from the injection side with a sample of microdialysate in acetonitrile. Simultaneously with turning on the separation voltage, the sample zone was forced out by the background electrolyte by increasing the pressure in the terminal capillary outlet vessel. As a consequence of the stacking effect, the analyte was concentrated from the large sample volume into a narrow zone at the sample/background electrolyte boundary close to the injection end of the capillary. Under these conditions, LOD values of 9, 10 and 15nM were determined in the model samples for GABA, Gly and Glu, respectively; RSD equalled 0.5% for the migration times and 1.0-1.9% for the peak areas, respectively. In analysis of microdialysates of PAG, LOD values of 29, 29 and 37nM were determined for GABA, Gly and Glu, respectively; RSD equalled 0.5-0.7% for the migration times and 2.6-8.2% for the peak areas, respectively. The determined basal levels of the neurotransmitters in PAG microdialysates are 0.08, 4.7 and 0.8µM for GABA, Gly and Glu, respectively. Carrageenan-induced hyperalgesia increases the Gly and Glu levels and reduces GABA in PAG microdialysate. Peroral administration of paracetamol in hyperalgesia effectively reduces the Gly value and has no effect on Glu and GABA.


Subject(s)
Electrophoresis, Capillary/methods , Glutamic Acid/analysis , Glycine/analysis , Neurotransmitter Agents/analysis , Periaqueductal Gray/chemistry , gamma-Aminobutyric Acid/analysis , Animals , Electrophoresis, Capillary/instrumentation , Microdialysis , Rats
2.
Anal Chim Acta ; 698(1-2): 1-5, 2011 Jul 18.
Article in English | MEDLINE | ID: mdl-21645652

ABSTRACT

A capillary electrophoresis (CE) procedure with contactless conductivity detection (C(4)D) has been developed for monitoring of neutral mono- and disaccharides in drinks and foodstuffs. The separation of a mixture of seven neutral saccharides (glucose, fructose, galactose, mannose, ribose, sucrose and lactose) employed a quartz capillary, 5 µm i.d., with an effective length of 18.3 cm, and 75 mM NaOH (pH 12.8) as the background electrolyte (BGE). The limit of detection (LOD) values obtained lied within a range from 0.4 µmol L(-1) for lactose to 0.9 µmol L(-1) for ribose, with a separation time shorter than 140 s. The procedure was successfully applied to determinations of saccharides in fruit juices, Coca-Cola, milk, red and white wines, yoghurts, honey and a foodstuff additive.


Subject(s)
Beverages/analysis , Disaccharides/analysis , Electrophoresis, Capillary/methods , Food Additives/analysis , Food Analysis/methods , Monosaccharides/analysis , Animals , Electric Conductivity , Electrophoresis, Capillary/instrumentation , Food Analysis/instrumentation , Limit of Detection , Ribose/analysis , Time Factors
3.
J Sep Sci ; 33(16): 2394-401, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20535751

ABSTRACT

CE with contactless conductivity detection has been used to separate 28 biogenic amino acids in a short capillary with an effective length of 18 cm. All the tested amino acids can be mutually separated in 0.5-10 mol/L acetic acid electrolytes. The time of analysis does not exceed 6 min and the LODs vary from 0.1 to 1.7 micromol/L. The CVs lie within the intervals 0.01-0.4% and 0.9-4% for the migration times and the analyte peak areas, respectively. The procedure has been successfully applied to the determinations of the whole amino acid spectra in blood plasma, urine, saliva and cerebrospinal fluid samples.


Subject(s)
Amino Acids/analysis , Electrophoresis, Capillary/methods , Amino Acids/blood , Amino Acids/cerebrospinal fluid , Amino Acids/urine , Electric Conductivity , Humans , Reference Values , Saliva/chemistry , Sensitivity and Specificity
4.
Electrophoresis ; 31(12): 2037-43, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20564696

ABSTRACT

A CE procedure employing capacitively coupled contactless conductivity detection has been developed for direct determination of the glycerol and mannitol polyalcohols in biological and pharmacological samples. Both glycerol and mannitol are fully separated from the sample matrix within very short times of 3.0 and 3.9 min, respectively, when using the optimized BGE, 60 mM H3BO3+30 mM LiOH (pH 9.1). The LODs amount to 0.5 microM for glycerol and 0.3 microM for mannitol. The repeatability of the glycerol determination in real biological materials is characterized by the coefficient of variation values, 0.5 and 3.2%, for the migration time and the peak area, respectively. The procedure has been used to monitor the free glycerol concentration in adipose tissue microdialyzates. A physiological study has demonstrated that the lipolysis occurring during a sporting action can be stimulated by local application of adrenaline. The procedure has further been utilized to determine mannitol in a pharmacological preparation.


Subject(s)
Adipose Tissue/chemistry , Electrophoresis, Capillary/methods , Exercise/physiology , Glycerol/analysis , Mannitol/analysis , Acetonitriles/chemistry , Bicycling/physiology , Boric Acids/chemistry , Calibration , Electric Conductivity , Glycerol/metabolism , Humans , Hydrogen-Ion Concentration , Linear Models , Lipolysis/physiology , Lithium Compounds/chemistry , Mannitol/metabolism , Reproducibility of Results , Sensitivity and Specificity
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