Micellar Electrokinetic Capillary Chromatography Analysis Research Articles

Antioxidant activity of a polysaccharide from Dictyophora indusiata volva and MECC analysis of its monosaccharide composition

In this paper, a crude polysaccharide (PDI) was extracted from D. indusiata volva. The antioxidant activities of PDI were examined by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical, hydroxyl radical and ABTS radicals scavenge assay. The results showed that PDI had antioxidant activities in all these assays, indicating that it could be used as an antioxidant. Then a rapid and highly efficient micellar electrokinetic capillary chromatography (MECC) method coupled with diode array detector was developed to determine the monosaccharides composition of the polysaccharide sample. The optimum conditions were as follows: 20 ​mM borate (pH ​= ​9.3) and 15 ​mM SDS as the electrophoresis medium, the separation temperature was 20 ​°C. Under these conditions, monosaccharides could be separated within 8 ​min. The polysaccharide of the volva was mainly composed of glucose, mannose, galactose and arabinose.

Magnetic solid-phase extraction of four β-lactams using polypyrrole-coated magnetic nanoparticles from water samples by micellar electrokinetic capillary chromatography analysis

In the present research, the application of a polypyrrole coating on Fe3O4 magnetic nanoparticles (PPy/Fe3O4 MNPs) as a sorbent was confirmed. The synthesized magnetic composites were characterized by TEM, FTIR spectroscopy, and XRD. Four β-lactams (oxacillin (OXA), cloxacillin (CLOX), dicloxacillin (DIC), and flucloxacillin (FLU)) were selected as analytes for the experiment. The extracted β-lactams were determined by micellar electrokinetic capillary chromatography-diode array detector (MEKC-DAD). The crucial parameters influencing the extraction efficiency and separation were studied and optimized. Under the optimal conditions, the limits of detection are 1.0 µg L−1 for OXA, CLOX, FLU, and 0.8 µg L−1 for DIC. The calibration curves are linear in the range of 2.5–200.0 µg L−1. The proposed method was applied for the determination of the β-lactams in water samples with satisfactory results. The intra-day relative standard deviations and the inter-day relative standard deviations range from 1.09% to 4.58% and from 2.95% to 7.80%, respectively. It can be concluded that this method is sensitive, convenient, and feasible for the determination of the β-lactams in water samples.

Characterization of molds isolated from smoked paprika by PCR-RFLP and micellar electrokinetic capillary electrophoresis

Molds are common contaminants of paprika meat products. The drying and storage stages of paprika processing are critical because they can provide molds with the conditions particularly appropriate for their growth and proliferation. Thus, an efficient and accurate characterization of the toxigenic molds of paprika is necessary. An RFLP analysis of the rRNA genes was performed by using a TaqI restriction enzyme. In addition, a micellar electrokinetic capillary chromatography (MECC) method was tested to analyze secondary metabolites produced by mold strains commonly found in paprika. This study was confirmed with a 5.8S-ITS region sequence analysis. A total of 31 isolates were identified by RFLP and MECC analysis. These showed stable RFLP profiles that were clearly different for the different genera and species, and were grouped into clusters together with the profiles of the 16 reference strains. MECC analysis provided additional characteristic peak patterns for the characterization of the mold species present. The characterized isolates were species of the genera Fusarium spp., Aspergillus spp., Penicillium spp., Cladosporium spp., Mucor spp. and Phlebia spp. The identifications were confirmed by the 5.8S-ITS region sequence analysis and by a BLAST search of the GenBank database. RFLP patterns with TaqI restriction enzyme and MECC profiles, either singly or combined, could be of great interest to distinguish molds in paprika.

Application of micellar electrokinetic capillary chromatography for routine analysis of different materials

Micellar electrokinetic capillary chromatography (MEKC) has become a popular mode among the several capillary electro-migration techniques. Most drug analysis can be performed by using MEKC because of its wide applicability. Separation of very complex mixtures, determination of drugs in the biological materials, etc., can be successfully achieved by MEKC. This review surveys typical applications of MEKC analysis. Recent advances in MEKC, especially with solid-phase extraction and large-volume sample stacking, are described. Modes of electrokinetic chromatography including MEKC, a separation theory of MEKC, environmental friendly analysis, and selectivity manipulation in MEKC are also briefly mentioned.

Determination of the Active Components in Chinese Herb Cortex Moutan by MEKC and LC

Cortex Moutan is one important traditional Chinese herb used in many traditional prescriptions. Paeonol (PN) and paeoniflorin (PF) are two active components contained in Cortex Moutan. In the present work, micellar electrokinetic capillary chromatography (MEKC) was applied to the determination of these active components in Cortex Moutan, and the analytical results were compared with that obtained by high-performance liquid chromatography (HPLC). The optimized buffer system containing 10 mM borate and 25 mM SDS at pH 9.5 was employed in MEKC analysis and the linearities between peak areas and the concentrations of the analytes were investigated. The excellent linear behavior was exhibited over the investigated concentration ranges (R2: 0.9945 for PN and 0.9992 for PF in MEKC, while 0.9993 for PN and 0.9998 for PF in HPLC). The recoveries of the developed MEKC method ranged 97.1–104.4% for PN and 95.3–103.2% for PF, respectively. It was shown that no significant difference was found in the analysis of Cortex Moutan by the developed MEKC and HPLC methods.

Characterization of Molds from Dry-Cured Meat Products and Their Metabolites by Micellar Electrokinetic Capillary Electrophoresis and Random Amplified Polymorphic DNA PCR

Molds are common contaminants of dry-cured meat products in which mycotoxins could be synthesized if stored under favorable conditions. Thus, efficient and accurate characterization of the toxigenic molds from dry-cured meat products is necessary. A micellar electrokinetic capillary chromatography (MECC) method was tested to analyze secondary metabolites produced by 20 mold strains commonly found in dry-cured meat products. In addition, their random amplified polymorphic DNA (RAPD) genotypes were determined by using a PCR method. Although peak profiles of the secondary metabolites differed among mold strains of different species, they were similar in the same species. MECC analysis showed that 10 of the 20 molds tested produced mycotoxins, including patulin, penicillic acid, cyclopiazonic acid, mycophenolic acid, aflatoxin B1, sterigmatocystin, and griseofulvin. The RAPD analysis yielded a different pattern for each of the mold species tested. However, strains of the same species showed similar RAPD profiles. A high correlation between RAPD analysis and MECC was observed, since strains of the same species that showed similar RAPD patterns had similar profiles of secondary metabolites. RAPD patterns with primer GO2 and MECC profiles, either singly or combined, could be of great interest to distinguish toxigenic from nontoxigenic molds in dry-cured meat products.

Screening of Cerebrospinal Fluid and Blood Sera of Multiple Sclerosis Patients for Oligoclonal Immunoglobulins by Capillary Electrophoresis

Multiple sclerosis (MS) is an autoimmune disease characterized by the production of specific types of immunoglobulins into the central nervous system. These immunoglobulins appear as oligoclonal bands (OCBs) in agarose isoelectric focusing (IEF) of cerebrospinal fluid (CSF). Among the cases with clinically definite MS, up to 95% have oligoclonal IgG bands in their CSF. In this report, we describe a micellar electrokinetic capillary chromatography (MEKC) method for the separation of CSF and serum proteins. MEKC was performed using 25 mM borate buffer, pH 10, containing 25 mM SDS at 20 kV and normal polarity. High values of repeatability in migration times and of reproducibility in peak areas were obtained (R.S.D. values were less than 2%). Calibration graphs were linear up to 2000 mg L−1. LOQ was 6.5 mg L−1 and LOD determined as a signal to noise ration of 3:1 was 4.5 mg L−1. Analysis of CSF and serum samples from patients with clinical definite MS and healthy individuals demonstrated the presence of two peaks migrating as γ-globulins in the CSF samples of patients. These peaks were absent from controls and the serum of the same patients. Correlation of the data obtained from IEF and MEKC analysis for 25 patients showed that the diagnostic sensitivity and specificity of MEKC were ca 89% and 92% respectively. The obtained results indicate that this MEKC method may be helpful for the diagnosis of multiple sclerosis. Capillary electrophoresis compared to flat bed IEF provides reproducible results, requires shorter analysis time, and allows direct quantitative determination.

Determination of lignans in Schisandra chinensis using micellar electrokinetic capillary chromatography.

Micellar electrokinetic capillary chromatography (MEKC) has been developed as a promising method for the determination of lignans in plant samples. The separation conditions have been optimized with respect to the different parameters including sodium dodecyl sulfate (SDS) and acetonitrile concentration, pH of the background electrolyte, separation voltage, and capillary temperature. The background electrolyte consisting of 40 mM SDS and 35% acetonitrile in 10 mM tetraborate buffer (pH 9.3) was found to be the most suitable electrolyte for this analysis. The applied voltage of 28 kV (positive polarity) and the capillary temperature 25 degrees C gave the best separation of lignans. The interday reproducibility of the peak areas and the migration times was below 2.0%. The results of MEKC analyses were compared with those obtained by capillary electrochromatography (CEC) and reversed-phase high-performance liquid chromatography (RP-HPLC). The possibilities of using this method for the determination of lignans in drug and in serum samples were also tested.

Micellar electrokinetic capillary chromatography analysis of diuretics in pharmaceutical formulations

This paper describes the development of an electrophoretic method used to analyse diuretics, and its use in the analysis of pharmaceutical formulations. Chlorthalidone, furosemide, hydrochlorothiazide and triamterene were separated in 5 min by micellar electrokinetic capillary chromatography using a carrier containing sodium dodecylsulphate as surfactant, and were subsequently detected spectrophotometrically using a diode-array detector. The limits of detection ( S/N=3) were in all cases less than 1.2 μg ml −1 for all compounds. Satisfactory repeatability was obtained for migration times (<1.6%) and corrected peak areas (<5.3%) in the analysis of pharmaceutical formulations. The reproducibility was less than 4% for all samples tested. The average recoveries obtained, which ranged between 97 and 100%, testify to the accuracy of the proposed method.

Micellar electrokinetic capillary chromatography analysis of water-soluble vitamins

This paper describes the development of an electrophoretic method used to analyse seven water-soluble vitamins, and its use in the analysis of pharmaceutical formulations. Thiamine, nicotinamide, nicotinic acid, pyridoxine, ascorbic acid, folic acid and riboflavin were separated from one another in 7min by micellar electrokinetic capillary chromatography using a carrier containing sodium dodecyl sulphate as surfactant, and were subsequently detected spectrophotometrically using a diode-array detector. The limits of detection (S/N=3) ranged between 0.08μgml–1 for folic acid and 0.25μgml–1 for nicotinamide and thiamine. The relative standard deviation of the proposed method was less than 6% for all formulation samples.

Quality evaluation by capillary electrophoresis of amphotericin B injection after filtration through various membrane filters.

The determination of amphotericin B, an antifungal agent, was developed using micellar electrokinetic capillary chromatography (MEKC) with a diode array detector. Repeatability and intermediate precision of MEKC analysis were acceptable. A high correlation was found between amphotericin B levels in pharmaceutical solutions obtained by MEKC and those by high-performance liquid chromatography (HPLC) (r = 0.994). This MEKC method is therefore useful for the determination of amphotericin B. The concentration of amphotericin B did not significantly change after filtration through polyethersulfone (PES, 0.2 microm) and polyvinylidene difluoride (PVDF, 0.45 microm) membrane filters. When the Fungizone injection was filtered through PES (0.2 microm) and added to 5% dextrose for injection (500 mL), particulate matters larger than 10 microm decreased by 64% to a level under the standard defined by United States Pharmacopoeia (USP XXIII). PVDF filtration (0.45 microm) did not have this effect. Our results suggest that filtration of Fungizone injection through PES (0.2 microm) membrane filters is recommended for the preparation of intravenous amphotericin B fluid.

Micellar electrokinetic capillary chromatography for therapeutic drug monitoring of zonisamide

The simultaneous determination of zonisamide, a new type of antiepileptic drug, and the typical antiepileptic drugs phenobarbital, phenytoin and carbamazepine in human serum was developed using micellar electrokinetic capillary chromatography (MECC) with a diode array detector. A high correlation was revealed between the zonisamide levels in human serum obtained by MECC and those obtained by high-performance liquid chromatography ( r=0.981). The serum levels of phenobarbital, phenytoin and carbamazepine determined by MECC were almost equal to those obtained by fluorescence polarization immunoassay. The reproducibility of separation and quantification with MECC analysis was appropriate for the intra- and inter-day assay coefficients. Therefore, the MECC method established here could provide a simple and efficient therapeutic drug monitoring method for antiepileptic drugs in patients, especially those treated with a combination of zonisamide and other antiepileptic drugs.

Determination of phase II drug metabolites in equine urine by micellar electrokinetic capillary chromatography

Micellar electrokinetic capillary chromatography (MECC) using diode array detection has been investigated for the determination of phase I and phase II metabolites of drugs in biofluids. Methods were optimised for the determination of morphine, morphine-3-glucuronide, morphine-6-glucuronide, normorphine, meclofenamic acid and its metabolites in equine urine. Solid-phase extraction procedures were developed to concentrate and purify the analytes from spiked and post administration urines for MECC analysis. A simple on-line procedure for monitoring the kinetics of hydrolysis of morphine-glucuronide conjugates by β-glucuronidase was demonstrated.

Micellar electrokinetic chromatography separations and analyses of biological samples on a cyclic planar microstructure.

Micellar electrokinetic capillary chromatography (MECC) separations and analyses of biological samples on a planar glass microchip capillary electrophoresis device with laser-induced fluorescence solute detection are discussed. A cyclic channel system which permits dead volume free repeated column switching and thus the use of various channel lengths together with a relatively low applied separation voltage is described. It features an unbiased, dead volume free electrokinetic sample inlet system of approximately 12 pL. Because of the small cross section and favorable heat dissipation in glass microstructures, MECC separations with an electric field strength of up to 2000 V/cm achieving efficiencies of submicrometer plate heights can be performed. After a separation length of 2 cm, six fluorescein isothiocyanate labeled amino acids are shown to be separable within a few seconds and with an imprecision for peak areas (or heights) and detection times of < 2% and < 0.5%, respectively. Without application of electrokinetic solute stacking, the detection limit of fluorescein isothiocyanate labeled arginine is 3.3 nM, corresponding to approximately 40 zmol injected. Furthermore, the feasibility of directly applying human urine and serum samples onto the uncoated channel system is demonstrated and first data of the successful performance of a chip-based MECC immunoassay for serum theophylline are presented. Compared to MECC in conventional fused-silica capillaries, MECC analyses on microchips can be performed 1-2 orders of magnitude faster, with higher efficiency and at no expense of accuracy and precision. Furthermore, versatility is shown to be much increased with the use of a cyclic rather than a single-path channel system. The MECC separation efficiency of fluorescein isothiocyanate labeled amino acids is shown to be comparable to that obtained by gel electrophoresis performed in the same chip layout.

Micellar electrokinetic capillary chromatography of limonoid glucosides from citrus seeds

This report presents the results of an investigation into the application of micellar electrokinetic capillary chromatography (MECC) for the analysis of limonoid glucosides in a citrus seed extract. MECC based on sodium dodecyl sulphate (SDS) was used to provide highly efficient separations of the closely related structures. A phosphate-borate buffer containing SDS was used to optimize the separation conditions for a mixture containing standard compounds of the glucosides of limonin, obacunone and nomilin. The study showed that MECC analysis of limonoid glucosides requires minimal sample clean-up steps and achieves excellent separations within a relatively short analysis time. The technique developed was used to quantify two limonoid glucosides in a methanol extract of the seeds of Citrus nobilis (nartjie) and Citrus limon (lemon).

Microchip Separations of Neutral Species via Micellar Electrokinetic Capillary Chromatography

Micellar electrokinetic capillary chromatography (MECC) of three neutral coumarin dyes was performed on glass microchips. Manifolds of channels for analyte injection and separation were machined into one surface of the glass substrates using standard photolithographic, etching, and deposition techniques. Cover plates were then directly bonded over these channels to form capillary networks, with fluid flow in these networks controlled by varying the applied high-voltage potentials at the outlets. The separation capillary was 16.5 cm long for a serpentine channel chip and 1.3 cm long for a straight channel chip. Detection of analyte zones was accomplished by laser-induced fluorescence using the UV lines (nearly 350 nm) of an argon ion laser. At low applied electric field strengths, MECC analyses with on-chip injections gave high reproducibilities in peak areas and migration times ( 400 V/cm), analysis times were shorter, but separation efficiency decreased at later migration times. These peaks showed significant broadening, consistent with mass transfer effects. 14 refs., 6 figs., 2 tabs.

Application of Micellar Electrokinetic Capillary Chromatography to Forensic Analysis of Barbiturates in Biological Fluids

Micellar electrokinetic capillary chromatography (MECC) is a form of capillary zone electrophoresis. Addition of a surfactant produces micelles in an aqueous/organic buffer. Separation of drugs is obtained via differences in the electrophoretic mobilities of the analytes within the capillary, resulting from their electrophoretic velocity and the electroosmotic flow of the buffer in a given electric field. The migration order is determined by the differential partitioning of the drugs between the micelles and the aqueous/organic phase. Barbiturates were extracted from various biological fluids at pH 4.5 with TOXI-TUBES B. MECC analyses were performed using a Waters Quanta 4000 Capillary Electrophoretic System with a 745 Data Module with a 75 microns x 60 cm capillary and an aqueous/organic buffer of 85% 10 mM borate, 10 mM phosphate, 100 mM sodium dodecyl sulfate and 15% acetonitrile at a pH of 8.5 with a voltage of 20 kV using ultraviolet absorption detection at 214 nm. Migration times were: phenobarbital, 7.78 min.; butalbital, 8.01 min.; butabarbital, 8.23 min.; mephobarbital (internal standard), 8.88 min.; amobarbital, 9.41 min.; pentobarbital, 10.03 min. and secobarbital, 10.79 min. Correlation coefficients (r) between peak areas and concentration ranges of 3 to 60 micrograms/mL were from 0.964 to 0.999. Coefficients of variation (CV) ranged from 2.6 to 8.6% between days and 2.3 to 9.8% within day. Application of this methodology to four forensic cases of butalbital intoxication detected concentrations of 0.7 to 12.7 micrograms/mL in blood; 0.8 to 1.9 micrograms/mL in vitreous humor and 1.5 to 7.6 micrograms/mL in urine. MECC is applicable to forensic analysis of barbiturates extracted from biological fluids.

Micellar electrokinetic capillary chromatography analysis of water-soluble vitamins and multi-vitamin integrators.

Micellar electrokinetic capillary chromatography (MECC) was applied to the determination of water-soluble vitamins (WSV) in pharmaceutical preparations. The analytical procedure employed in the WSV separation by MECC showed a satisfactory average column efficiency (195,000 N) and resolution (more than 100 theoretical peaks separable). The mean reproducibility in the retention time of consecutive and day-to-day runs was 1.1% and 5.1%, respectively. Analyses were performed after extraction of active ingredients by solid phase extraction. Recoveries (92-103%) and relative variation coefficients (less than 5%) confirmed the potential of MECC in the field of pharmaceutical analysis.

Micellar electrokinetic capillary chromatography analysis of the behavior of bilirubin in micellar solutions

The capacity factor of bilirubin is determined by micellar electrokinetic capillary chromatography (MECC) techniques in three different surfactant systems. The capacity factor of bilirubin in cholic acid, taurocholic acid, and taurochenodeoxycholic acid solutions are compared to each other as a function of pH. The pH range studied is 6.5 to 9.5 which includes the pH range of bile, and includes the most likely p K a values of bilirubin carboxyl groups. MECC techniques are used to estimate these apparent p K a values for bilirubin as well as to determine the capacity factors for the separate ionization states of bilirubin in the three different surfactants. Due to the complexity of the bilirubin—bile salt system, it appears as though it is not possible to use MECC to accurately determine the bilirubin apparent p K a values. Separations are performed in 75 μm capillaries, typically 36 to 52 cm in length. UV detection, electrokinetic injection, and run voltages of 7 kV are typical. Solutions of 25 m M of each bile salt are prepared in a 20 m M phosphate—borate buffer system.

Micellar electrokinetic capillary chromatography of the enantiomers of amphetamine, methamphetamine and their hydroxyphenethylamine precursors

The separation of the enantiomers of amphetamine, methamphetamine, ephedrine, pseudoephedrine, norephedrine and norpseudoephedrine in a single run via micellar electrokinetic capillary chromatography (MECC) is described. The procedure, which involves preliminary derivatization with 2,3,4,6-tetra-O-acetyl-β- d-glucopyranosyl isothiocyanate (GITC) followed by MECC analysis, is far superior with respect to both resolution and speed of analysis versus similar efforts utilizing high-performance liquid chromatography. The MECC separation was obtained at 20 kV on a 48 cm × 50 ωm I.D. (26 cm length to detector) capillary at 30°C using a run buffer consisting of 20% methanol and 80% sodium dodecyl sulfate (SDS) solution [100 m M SDS, 10 m M phosphate, 10 m M borate (pH 9.0)]. The effects of organic modifier type, organic modifier concentration, voltage, temperature and SDS concentration on the resolution of the GITC derivatives are described. The application of the above methodology to forensic samples is presented.