A capillary system formed by combining 25 and 100 μm id capillaries was used in the short-end injection mode to determine creatinine and uric acid in human urine. The separation was performed at an electric field intensity of 2.3 kV/cm. Creatinine was determined in a BGE with a composition of 20 mM citric acid/NaOH (pH 3.0), and uric acid was determined in 20 mM MES/NaOH (pH 6.0). Under these conditions, migration times of 12.2 s for creatinine and 8.6 s for uric acid were achieved. The LOD value is 2.4 mg/L for creatinine and 0.9 mg/L for uric acid; the RSD for the migration time varies in the range 0.7-1.1% (intra day) to 1.0-7.5% (inter day); RSDs for the peak areas equalled 3.4-4.0% (intra day) and 4.3-4.7% (inter day). The determined creatinine values in seven urine samples vary in the range 221-1394 mg/L for creatinine and 87-615 mg/L for uric acid. t-Test did not reveal any statistically significant difference between the developed CE methodologies and reference methods - Jaffé reaction for creatinine and enzymatic uricase test for uric acid.
- MeSH
- Time Factors MeSH
- Adult MeSH
- Electrophoresis, Capillary instrumentation methods MeSH
- Creatinine urine MeSH
- Uric Acid urine MeSH
- Humans MeSH
- Limit of Detection MeSH
- Linear Models MeSH
- Reproducibility of Results MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
A capillary formed by connecting a 9.7 cm-long separation capillary with id 25 μm with an auxiliary 22.9 cm-long capillary with id 100 μm (coupled capillary) was tested for electrophoretic separation at high electric field intensities. The coupled capillary was placed in the cassette of a standard electrophoresis apparatus. It was used in the short-end injection mode for separation of a mixture of dopamine, noradrenaline, and adrenaline in a BGE of 20 mM citric acid/NaOH, pH 3.2. An intensity of 2.7 kV/cm was attained in the separation part of the capillary at a separation voltage of 30 kV, which is 2.9 times more than maximum intensity value attainable in a capillary with the same length with uniform id. At these high electric field intensities, the migration times of the tested neurotransmitters had values of 12.3-13.3 s and the attained separation efficiency was between 2350 and 2760 plates/s. It is thus demonstrated that an effective separation instrument - a coupled capillary - can be used for very rapid separation in combination with standard, commercially available instrumentation.
- MeSH
- Time Factors MeSH
- Models, Chemical MeSH
- Electrophoresis, Capillary instrumentation methods MeSH
- Sodium Hydroxide chemistry MeSH
- Catecholamines analysis chemistry isolation & purification MeSH
- Citric Acid chemistry MeSH
- Neurotransmitter Agents analysis chemistry isolation & purification MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
GC with nitrogen phosphorus detection and HPLC with UV detection were used to determine midazolam (MDZ) levels in rabbit plasma following ocular and nasal administration. For GC with nitrogen phosphorus detection, the analyte was extracted from the plasma using a three-step liquid-liquid extraction including extraction with an isopropanol/butyl chloride mixture in an alkaline solution, followed by extractions with 1 M HCl, and finally with an alkaline solution of butyl chloride. The recovery of MDZ was dependent on the sample alkalization time prior to the final extraction. The procedure increased the recovery of MDZ up to 99.6%. Improved sample preparation led to a significant increase in the sensitivity of the determination by GC with nitrogen phosphorus detection. The achieved detection limit was 0.34 ng/mL, which is ten times lower than that obtained using HPLC with UV detection. The small plasma volume was another advantage of the GC with nitrogen phosphorus detection method (200 μL per assay). Both administration routes of the anesthetic (nasal and ocular) resulted in comparable plasma MDZ levels. Kinetic simulation of the MDZ plasma was performed for both administration routes.
- MeSH
- Administration, Intranasal MeSH
- Administration, Ophthalmic MeSH
- Chromatography, Gas methods MeSH
- Hypnotics and Sedatives administration & dosage blood MeSH
- Rabbits MeSH
- Limit of Detection MeSH
- Midazolam administration & dosage blood MeSH
- Chromatography, High Pressure Liquid methods MeSH
- Animals MeSH
- Check Tag
- Rabbits MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
- Research Support, Non-U.S. Gov't MeSH
A fused-silica capillary with a common outer diameter, 360 μm, but containing seven internal channels, each 28 μm in diameter (a multichannel capillary), has been tested on electrophoretic separations of mixtures of dopamine, adrenaline, and noradrenaline, using a contactless conductivity and UV photometric detection. It has been demonstrated that the sensitivity of the detection of these neurotransmitters in multichannel capillary, in comparison with those obtained for a standard singlechannel capillary with similar cross-sectional area, is comparable to that for the contactless conductivity and is about 50% higher for the UV photometry. The sensitivity is increased without loss of the separation efficiency, in contrast to UV detection with bubble cell. Further possibilities of using a multichannel capillary are demonstrated on separations of mixtures of inorganic cations (K⁺, Ba²⁺, Na⁺, Mg²⁺, and Li⁺) and mixtures of glucose and ribose. The main advantage of multi-channel capillary in comparison with a singlechannel capillary with the same cross-sectional area becomes apparent in separations in background electrolytes of high conductivity.
- MeSH
- Epinephrine isolation & purification MeSH
- Equipment Design MeSH
- Dopamine isolation & purification MeSH
- Electric Conductivity MeSH
- Electrophoresis, Capillary instrumentation MeSH
- Neurotransmitter Agents isolation & purification MeSH
- Norepinephrine isolation & purification MeSH
- Sensitivity and Specificity MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
- Research Support, Non-U.S. Gov't MeSH
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.
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.
- MeSH
- Acetonitriles chemistry MeSH
- Exercise physiology MeSH
- Bicycling physiology MeSH
- Electric Conductivity MeSH
- Electrophoresis, Capillary methods MeSH
- Glycerol analysis metabolism MeSH
- Calibration MeSH
- Hydrogen-Ion Concentration MeSH
- Boric Acids chemistry MeSH
- Humans MeSH
- Linear Models MeSH
- Lipolysis physiology MeSH
- Mannitol analysis metabolism MeSH
- Reproducibility of Results MeSH
- Sensitivity and Specificity MeSH
- Lithium Compounds chemistry MeSH
- Adipose Tissue chemistry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
CE with contactless conductivity detection has been used to determine the glycine neurotransmitter in periaqueductal gray matter (PAG) of rats. The LOD for glycine has been decreased to a value of 0.2 microM by adding 75% v/v of ACN to the samples and increasing the sample zone introduced to a value of 20% of the overall capillary length. The repeatabilities of the analyte migration times and the zone areas amount to 2.1 and 2.7%, respectively. The optimized CE/contactless conductivity detection method makes it possible to determine the micromolar concentrations of glycine in PAG microdialyzates without the necessity of sample derivatization. It follows from a pharmacological study that a local inflammation initiated by an application of carrageenan increased the glycine concentration in the rat PAG seven times, compared with a control. The glycine level in PAG can be decreased and the pain suppressed by administering paracetamol.
- MeSH
- Pain drug therapy chemically induced MeSH
- Electric Conductivity MeSH
- Electrophoresis, Capillary methods MeSH
- Glycine analysis metabolism MeSH
- Carrageenan pharmacology MeSH
- Rats MeSH
- Analgesics, Non-Narcotic pharmacology MeSH
- Acetaminophen pharmacology MeSH
- Rats, Wistar MeSH
- Reproducibility of Results MeSH
- Sensitivity and Specificity MeSH
- Periaqueductal Gray chemistry MeSH
- Animals MeSH
- Check Tag
- Rats MeSH
- Male MeSH
- Animals MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
Using a short separation path makes it possible to achieve very fast electrophoretic separations. Such paths are available in capillary electrophoresis instruments on the condition that a sample is introduced into the capillary from the short end side. This procedure was successfully used in the determination of uric acid in allantoic fluid of chicken embryos. The LOD of the optimized method is 0.8 ?m?l l?1 and the separation time is shorter than 1 min.
Intact heparin was characterized and determined in model samples, in infusion solutions and in blood plasma by capillary electrophoresis (CE) with contactless conductivity detection. The CE separation of polydisperse heparin took place in open silica capillaries, in electrolytes containing a polymer (hydroxyethyl)cellulose, poly(ethylene glycol) or dextran. The best separation of heparin from excess inorganic ions present in real samples was attained in a background electrolyte consisting of 0.8 M acetic acid and 1% (w/v) dextran (100 kDa). The limit of detection (LOD) was 1.3 µmol l-1. This electrolyte was used in determination of heparin in blood plasma and in infusion solutions.
CE with capacitively coupled contactless conductivity detection (C(4)D) was used to determine waste products of the nitrogen metabolism (ammonia and creatinine) and of biogenic inorganic cations in samples of human urine. The CE separation was performed in two BGEs, consisting of 2 M acetic acid + 1.5 mM crown ether 18-crown-6 (BGE I) and 2 M acetic acid + 2% w/v PEG (BGE II). Only BGE II permitted complete separation of all the analytes in a model sample and in real urine samples. The LOD values for the optimized procedure ranged from 0.8 microM for Ca(2+) and Mg(2+) to 2.9 microM for NH(4)(+) (in terms of mass concentration units, from 7 microg/L for Li(+) to 102 microg/L for creatinine). These values are adequate for determination of NH(4)(+), creatinine, Na(+), K(+), Ca(2+) and Mg(2+) in real urine samples.
