Short capillary separation Dotaz Zobrazit nápovědu
A computer-controlled hydrodynamic sample introduction method has been proposed for short-capillary electrophoresis. In the method, the BGE flushes sample from the loop of a six-way sampling valve and is carried to the injection end of the capillary. A short pressure impulse is generated in the electrolyte stream at the time when the sample zone is at the capillary, leading to injection of the sample into the capillary. Then the electrolyte flow is stopped and the separation voltage is turned on. This way of sample introduction does not involve movement of the capillary and both of its ends remain constantly in the solution during both sample injection and separation. The amount of sample introduced to the capillary is controlled by the duration of the pressure pulse. The new sample introduction method was tested in the determination of ammonia, creatinine, uric acid, and hippuric acid in human urine. The determination was performed in a capillary with an overall length of 10.5 cm, in two BGEs with compositions 50 mM MES + 5 mM NaOH (pH 5.1) and 1 M acetic acid + 1.5 mM crown ether 18-crown-6 (pH 2.4). A dual contactless conductivity/UV spectrometric detector was used for the detection.
- Klíčová slova
- Creatinine, Human urine, Hydrodynamic sampling, Short capillary separation, Uric acid,
- MeSH
- amoniové sloučeniny moč MeSH
- analýza moči přístrojové vybavení metody MeSH
- design vybavení MeSH
- elektrická vodivost MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- kationty moč MeSH
- kreatinin moč MeSH
- lidé MeSH
- limita detekce MeSH
- lineární modely MeSH
- reprodukovatelnost výsledků MeSH
- spektrofotometrie ultrafialová MeSH
- tlak MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- amoniové sloučeniny MeSH
- kationty MeSH
- kreatinin MeSH
Electrokinetic sample injection using two piezoelectric micropumps has been proposed for electrophoresis in short capillaries. The sample is brought to the injection end of the capillary using one of them. Then, the high-voltage source is turned on and the sample is injected electrokinetically for a defined time. The injection is terminated by removal of the sample zone by the flowing separation electrolyte pumped by the second piezoelectric micropump. The RSD value, expressing the repeatability of the injection, does not exceed 4%. The injection apparatus does not contain any mobile mechanical components, there is no movement of the capillary and both its ends remain constantly in the solution during both the sample injection and separation. Thus, the micropumps replace the six-way injection valve and linear pump in similar types of injection apparatuses. The injection was tested in the separation and determination of ammonium and potassium ions in two samples of mineral fertilizers. The separation was performed in background electrolyte containing 500 mM of acetic acid + 20 mM Tris + 2 mM 18-crown-6 (pH 3.3) in a capillary with id 50 μm and total length/length to the contactless conductivity detector of 10.5/8 cm. The injection and separation took place at a voltage of 5 kV and the separation time equaled 20 s. The measured values of the analyte contents corresponded to the value declared by the manufacturer within the reliability interval, where RSD equaled between 3.5 and 4.7%.
- Klíčová slova
- Ammonium ions, Electrokinetic injection, Liquid fertilizer, Piezoelectric micropump, Short capillary separation,
- MeSH
- amoniové sloučeniny chemie izolace a purifikace MeSH
- crown ethery chemie MeSH
- design vybavení MeSH
- draslík chemie izolace a purifikace MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- reprodukovatelnost výsledků MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- 18-crown-6 MeSH Prohlížeč
- amoniové sloučeniny MeSH
- crown ethery MeSH
- draslík MeSH
An automatic micro-injector was developed for electrophoretic analysis of a microlitre amount of clinical samples, enabling injection of the sample from a Hamilton syringe. The outlet of the syringe needle is located directly opposite the inlet of the separation capillary at a defined distance of the order of hundreds of μm in the injection space. During the injection, the background electrolyte is forced out by air from this space and a drop of the sample is forced out of the syringe by a micro-pump so that it is caught at the entrance to the capillary. From the drop the sample is injected into the capillary by applying a negative pressure pulse or simply by spontaneous injection. The injection space is then filled with background electrolyte, which washes away excess sample and separation is commenced. The injector was tested in electrophoretic separation of a model sample with equimolar concentrations of 100 μM NH4+, K+, Na+, Mg2+ and Li+ in a short capillary with total/effective length of 16.5/11.5 cm. The repeatability of the migration time and peak area expressed as the RSD value is 2% and 4%, respectively. The practical applicability of the injector was verified on the determination of the antiparasitic pentamidine in 10 μL of rat plasma. Electrophoretic separation of pentamidine was performed in 100 mM of acetic acid/NaOH at pH 4.55, the sample consumption per analysis is 125 nL, the separation time is 45 s and the attained LOQ using contactless conductivity detection is 8 μM.
- Klíčová slova
- Capillary electrophoresis, Pentamidine, Rat plasma, Sample injection, Short capillary,
- MeSH
- amoniové sloučeniny analýza MeSH
- automatizace MeSH
- draslík analýza MeSH
- elektroforéza kapilární přístrojové vybavení MeSH
- hořčík analýza MeSH
- injekční stříkačky * MeSH
- jehly MeSH
- krysa rodu Rattus MeSH
- lithium analýza MeSH
- mikroinjekce * MeSH
- sodík analýza MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- amoniové sloučeniny MeSH
- draslík MeSH
- hořčík MeSH
- lithium MeSH
- sodík MeSH
An electrophoretic apparatus with a flow-gating interface has been developed, enabling hydrodynamic sequence injection of the sample into the separation capillary from the liquid flow by underpressure generated in the outlet electrophoretic vessel. The properties of the apparatus were tested on an artificial sample of an equimolar mixture of 100μM potassium and sodium ions and arginine. The repeatability of the injection of the tested ions expressed as RSD (in%) for the peak area, peak height and migration time was in the range 0.76-2.08, 0.18-0.68 and 0.28-0.48, respectively. Under optimum conditions, the apparatus was used for sequence monitoring of the reaction between the antidiabetic drug phenyl biguanide and the glycation agent methyl glyoxal. The reaction solution was continuously sampled by a microdialysis probe from a thermostated external vessel using a syringe pump at a flow rate of 3μLmin-1 and was injected into a separation capillary at certain time intervals. The electrophoretic separation progressed in a capillary with an internal diameter of 50μm with a length of 11.5cm and was monitored using a contactless conductivity detector.
- Klíčová slova
- Antidiabetic drug, Flow-gating interface, Hydrodynamic injection, Microdialysis, Sequence analysis, Short capillary separation,
- MeSH
- arginin MeSH
- biguanidy chemie MeSH
- časové faktory MeSH
- draslík MeSH
- elektroforéza kapilární přístrojové vybavení metody MeSH
- hydrodynamika * MeSH
- hypoglykemika chemie MeSH
- mikrodialýza MeSH
- pyruvaldehyd chemie MeSH
- roztoky MeSH
- sodík MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- arginin MeSH
- biguanidy MeSH
- draslík MeSH
- hypoglykemika MeSH
- phenyl biguanide MeSH Prohlížeč
- pyruvaldehyd MeSH
- roztoky MeSH
- sodík MeSH
A method has been developed for the simultaneous determination of taurine and caffeine using a laboratory-made instrument enabling separation analysis in a short 10.5 cm capillary. The substances are detected using a contactless conductometry/ultraviolet (UV) photometry detector that enables recording both signals at one place in the capillary. The separation of caffeine and taurine was performed using the MEKC technique in a BGE with the composition 40 mM CHES, 15 mM NaOH, and 50 mM SDS, pH 9.36. Under these conditions, the migration time of caffeine is 43 s and of taurine 60 s; LOD for caffeine is 4 mg/L using photometric detection and LOD for taurine is 24 mg/L using contactless conductometric detection. The standard addition method was used for determination in Red Bull energy drink of caffeine 317 mg/L and taurine 3860 mg/L; the contents in Kamikaze drink were 468 mg/L caffeine and 4110 mg/L taurine. The determined values are in good agreement with the declared contents of these substances. RSD does not exceed 3%.
- Klíčová slova
- Caffeine, Dual detection, Energy drinks, Micellar electrokinetic chromatography, Short capillary separation, Taurine,
- MeSH
- chromatografie micelární elektrokinetická kapilární ekonomika přístrojové vybavení MeSH
- design vybavení MeSH
- elektrická vodivost MeSH
- energetické nápoje analýza MeSH
- fotometrie ekonomika přístrojové vybavení MeSH
- kofein analýza MeSH
- konduktometrie ekonomika přístrojové vybavení MeSH
- limita detekce MeSH
- taurin analýza MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kofein MeSH
- taurin MeSH
An original electrophoresis apparatus for simultaneous rapid determination of cations and anions has been designed and tested. The separation part of the apparatus consists of two identical fused-silica capillaries, each with a length of 10.5cm and inner diameter of 25μm. The injection space is formed by the crossing of four channels in a plexiglass cross-piece. The capillaries pass through two opposing channels and their injection ends are located opposite one another at a distance of approx. 0.5mm in the centre of the crossing point. The exit ends of the capillaries are placed in vessels containing the background electrolyte in which are immersed the electrodes of a high-voltage source. Contactless conductivity detectors with semi-cylindrical electrodes are located 2cm from the exit ends of the capillaries. The injection part of the apparatus consists of two piezoelectric micro-pumps bringing the solution through another channel in the cross-piece to the injection ends of the capillary. During the injection, the sample is brought through one of them and is injected electrokinetically for a defined time. Then the sample zone is forced out of the injection space by a stream of background electrolyte from the second micro-pump. The timing of the injection process is computer-controlled. Thus the equipment can be considered to constitute electrophoresis in one capillary with injection into its centre. The use of short capillaries and miniature micro-pumps without other mechanical components enabled the construction of the apparatus on a board with dimensions of 20×25cm. The proposed equipment was used to test simultaneous separation of a mixture of cations and anions, NH4(+), K(+), Ca(2+), Mg(2+), Sr(2+), Ba(2+), Cl(-), NO3(-), SO4(2-), ClO3(-) and F(-), in BGE with composition 500mM HAc+20mM Tris+2mM 18-crown-6 (pH 3.3). Baseline separation of all the components was achieved in time less than 1min. Quantification of the content of nitrate nitrogen (determined as NO3(-)), ammoniacal nitrogen (determined as NH4(+)), K2O (determined as K(+)) and SO3 (determined as SO4(2-)) was performed on a real-world sample of mineral fertiliser. The determined compositions differed from the declared contents by an amount of 0.5-5.6%; the RSD value expressing the repeatability of the determination was in the range 3.4-7.5%. The LOD values were in the range from 6.9μM (K(+)) to 10.6μM (NH4(+)).
- Klíčová slova
- Dual-channel electrophoresis, Inorganic ions, Mineral fertiliser, Piezoelectric micropump, Short capillary separation,
- MeSH
- anionty analýza MeSH
- crown ethery MeSH
- elektrody MeSH
- elektroforéza kapilární metody MeSH
- elektrolyty MeSH
- kationty dvojmocné analýza MeSH
- kationty jednomocné analýza MeSH
- polymethylmethakrylát MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- 18-crown-6 MeSH Prohlížeč
- anionty MeSH
- crown ethery MeSH
- elektrolyty MeSH
- kationty dvojmocné MeSH
- kationty jednomocné MeSH
- polymethylmethakrylát MeSH
For the first time, capillary electrophoresis has been successfully employed for the fast and highly efficient separations of a novel type of stereoisomers - planar rotamers (planamers) of four newly synthesized 5-nitrosopyrimidine derivatives. These derivatives can form two rotamers differing in the orientation of nitroso group due to strong intramolecular hydrogen bonds. Partial separation of rotamers of two 5-nitrosopyrimidines was achieved in alkaline 50 mM sodium tetraborate, pH 9.3, and in acidic 18.5/42 mM Tris/phosphate, pH 2.3, background electrolytes (BGEs) free of stereoselectors. To improve the separation of these rotamers and to attain the baseline or better separation of rotamers of other two 5-nitrosopyrimidines, various BGEs and different cyclodextrins-based stereoselectors were tested. The most effective, i.e. the fastest and baseline or better separations of rotamers of all analyzed 5-nitrosopyrimidines were achieved within a short time, 3.7-9.3 min, in the above alkaline or acidic BGEs using β-cyclodextrin (β-CD) or carboxymethyl-β-CD as stereoselectors. Moreover, since the experiments with β-CD resulted in good separations of rotamers of all the investigated 5-nitrosopyrimidines, the apparent binding constants of their complexes with this selector were determined from the dependence of their effective mobilities on the β-CD concentration in the BGEs. The examined complexes were found to be relatively weak, with the apparent binding constants in the range 11.3-153.0 L/mol.
- Klíčová slova
- 5-Nitrosopyrimidines, Affinity capillary electrophoresis, Binding constant, Capillary electrophoresis, Cyclodextrins, Planar rotamers,
- MeSH
- beta-cyklodextriny chemie MeSH
- elektroforéza kapilární metody MeSH
- elektrolyty MeSH
- koncentrace vodíkových iontů MeSH
- nitrososloučeniny analýza chemie izolace a purifikace MeSH
- pyrimidiny analýza chemie izolace a purifikace MeSH
- stereoizomerie MeSH
- vodíková vazba MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- beta-cyklodextriny MeSH
- elektrolyty MeSH
- nitrososloučeniny MeSH
- pyrimidiny MeSH
Carrier ampholyte-based capillary electrophoresis (CABCE) has recently been introduced as an alternative to CE (CZE) in the classical buffers. In this study, isoelectric BGEs were obtained by fractionation of Servalyt pH 4-9 carrier ampholytes to cuts of typical width of 0.2 pH unit. CABCE feasibility was examined on a series of insect oostatic peptides, i.e. proline-rich di- to decapeptides, and phosphinic pseudopeptides--tetrapeptide mimetics synthesized as a mixture of four diastereomers having the -P(O)(OH)-CH(2)- moiety embedded into the peptide backbone. With identical selectivity, the separation efficiency of CABCE proved to be as good as classical CE for the insect oostatic peptides and better for diastereomers of the phosphinic pseudopeptides. In addition, despite the numerous species present in the narrow pH cuts of carrier ampholytes, CABCE seems to be free of system zones that could hamper the analysis. Peak symmetry was good for moderately to low mobile peptides, whereas some peak distortion due to electromigration dispersion, was observed for short peptides of rather high mobility.
- MeSH
- amfolytové směsi chemie MeSH
- elektroforéza kapilární metody MeSH
- koncentrace vodíkových iontů MeSH
- kyseliny fosfinové chemie MeSH
- peptidy analýza izolace a purifikace MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
- Názvy látek
- amfolytové směsi MeSH
- kyseliny fosfinové MeSH
- peptidy MeSH
It has been already three decades, since the fluorescent nanocrystals called quantum dots (QDs) appeared and attracted attention of a broad scientific community. Their excellent not only optical but also electronic properties predetermined QDs for utilization in a variety of areas. Besides lasers, solar cells, and/or computers, QDs have established themselves in the field of (bio)chemical labeling as well as medical imaging. However, due to the numerous application possibilities of QDs, there are high demands on their properties that need to be precisely controlled and characterized. CE with its versatile modes and possibilities of detection was found to be an effective tool not only for characterization of QDs size and/or surface properties but also for monitoring of their interactions with other molecules of interest. In this minireview, we are giving short insight in analysis of QDs by CE, and summarizing the advantages of this method for QDs characterization.
- Klíčová slova
- Capillary electrophoresis, Conjugation, Quantum dots, Separation,
- MeSH
- elektroforéza kapilární metody MeSH
- kvantové tečky chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
