Micellar Electrokinetic Capillary Chromatography Research Articles

Determination of vitamins K1 and K3 in green tea and in pharmaceutical supplements by capillary micellar electrokinetic chromatography

A method based on capillary micellar electrokinetic chromatography (MEKC) was developed for vitamin K1 and K3 determination. Experimental and instrumental parameters optimized for electrophoretic separation with better peak efficiency were: borate buffer at 0.05 mol L−1, pH 8.5, cetyltrimethylammonium bromide (CTAB) at 0.05 mol L−1, acetonitrile 20 % v/v, 25 °C and a negative potential difference of 30 kV. Sample introduction was made by hydrodynamic at 50 mbar for 15 s. Migration times for vitamins K1 and K3 were (5.2 ± 0.1) and (3.4 ± 0.1) min respectively. Limits of detection and quantification were on the order of 10−5 g L−1 and 10−4 g L−1. For vitamin K1, the precision was between 2 and 7 % for the peak area. Recoveries were 101 ± 2 % and 103 ± 2 % for green tea and vitamin supplement samples, respectively. For vitamin K3, recoveries were 99 ± 3 % for vitamin supplement. Comparative tests were performed with the reference method based on liquid chromatography with agreement of results. The uncertainty and the contribution of the relevant sources was carefully evaluated. The method was found adequate to enable reliable and sensitive measurements of different forms of vitamin K with low consumption of solvents and less generation of waste.

Development of a sustainable multianalyte MEKC method for quantitation of the antihyperlipidemic drugs ezetimibe together with three statins. Greenness and whiteness appraisal studies

Implementing powerful and sustainable research that complies with green analytical chemistry (GAC) and white analytical chemistry (WAC) fundamentals can downsize the environmental compliance costs and fruitfully affects practical and economic issues. Within this framework, rapid and white analytical micellar electrokinetic capillary chromatography (MEKC) methodology was developed for the synchronized estimation of the antihyperlipidemic drugs Ezetimibe (EZE), Atorvastatin (ATO), Rosuvastatin (ROS) and Simvastatin (SIM). The technique was established using fused silica capillary (50 cm, 50 µm id) and the background electrolyte was 0.025 M borate buffer pH 9.2 containing 0.025 M sodium dodecyl sulfate (SDS) and 10% v/v acetonitrile as the organic modifier. Diode array detector was adjusted at 243 nm for ATO and ROS and 237 nm for EZE and SIM. Separation was accomplished within 10 min with migration times of 4.12, 5.42, 8.23 and 8.74 min for ROS, ATO, EZE and SIM respectively. The 4 drugs were quantitated in the concentration range of 10–100 μg/mL and the correlation coefficients were not less than 0.9993. The high sensitivity was illustrated by values of the detection and quantitation limits. The limits of detection for ROS, ATO, EZE and SIM were 0.52, 0.75, 0.42 and 0.64 μg/mL, respectively, whereas, the limits of quantitation values were 1.73, 2.50, 1.40 and 2.13 μg/mL for the studied drugs, respectively. In addition to validation, as reported by the ICH guidelines, greenness and whiteness assessment using the novel AGREE calculator and the holistic functionality model RGB12 were performed. The results proved the efficiency and whiteness of the suggested technique to be routinely implemented in quality control laboratories for the assay of the four drugs and the binary mixtures of EZE with either ATO, ROS or SIM in fixed-dose combined tablets.

Capillary electrophoresis: Recent advancements and applications of micellar electrokinetic capillary chromatography

The article discusses capillary electrophoresis (CE) as an advanced technique used for the separation and detection of various pharmaceutical drugs. CE involves the application of high voltages across buffer-filled capillaries to produce separation based on various separation theories, including capillary zone electrophoresis (CZE), micellar electrokinetic capillary chromatography (MEKC), capillary gel electrophoresis, and capillary isoelectric focusing. While traditional CZE is not suitable for the separation of neutral substances, MEKC was developed by Shigeru Terabe in the early 1990s to expand the use of CE to neutral analytes that cannot be separated using straightforward free solution CE. MEKC employs an ionic micellar solution that interacts with the analytes through partitioning processes like a chromatographic technique. To create a pseudostationary phase, a surfactant such as sodium dodecyl sulfate (SDS) is added to the buffer solution at a concentration higher than its critical micellar concentration. The anionic SDS micelles are electrostatically drawn towards the anode, while the electro-osmotic flow carries the bulk solution toward the negative electrode due to the negative charge on the inside surface of the silica capillaries. When a neutral analyte is introduced into the micellar solution, a portion is integrated into the micelle, while the remaining fraction of the analyte migrates with the electroosmotic velocity. Separation depends on the individual partitioning equilibrium of the various analytes between the micellar and the aqueous phase. The bigger percentage of analyte dispersed inside the micelle, the slower it will travel. This article provides an in-depth understanding of the separation principle and the mechanism involved in MEKC, highlighting its usefulness in separating neutral analytes that cannot be separated using traditional CZE.

Simultaneous MEKC-DAD and smart spectrophotometric assays of thiocolchicoside and etoricoxib in challenging concentration ratio mixtures

Abstract Potent muscle relaxant (thiocolchicoside, TCC) and nonsteroidal anti-inflammatory drug (etoricoxib, ETXB) fixed-dose combination is formulated at relatively high 1:15 and 1:7.5 ratios for TCC and ETXB, respectively. Since the minor component (TCC) has lower absorptivity, assay of TCC/ETXB tablets presents an analytical challenge. The current study presents two novel methods: first is a micellar electrokinetic capillary chromatography (MEKC). Background electrolyte is borate buffer (40 mM, pH 9.2) containing 30 mM sodium dodecyl sulfate and methanol (ratio 80:20%, v/v), measured at 210 nm. Second is a direct double A max spectrophotometric method; minor component, TCC, is measured directly at its distant λ max (373 nm), at zero absorption of ETXB. Then, a ten-fold dilution step is carried out to eliminate TCC spectral interference and ETXB is determined at its λ max (282 nm). Both drugs’ concentrations disclose obedient linearities at 2–100 μg·mL−1 in MEKC, versus 3–25 and 40–350 μg·mL−1 for TCC and ETXB, respectively, in spectrophotometry. All ICH validation elements have been fulfilled for the developed methods. MEKC and spectrophotometric assays achieve accuracy, precision, selectivity, and robustness to be recommended for industrial quality control routine analysis of TCC/ETXB pills formulated at cited ratios or even higher.

Validated green micellar electrokinetic capillary chromatography for simultaneous determination of simvastatin and sitagliptin phosphate binary mixture in pharmaceutical formulation

AbstractDiabetics are liable to fatal atherosclerotic cardiovascular diseases. It is clinically attributed to their imbalanced plasma lipoproteins. Fixed‐dose combination “polypill” of simvastatin (10 mg) and sitagliptin phosphate (100 mg) is mainly indicated for the treatment of diabetic dyslipidemia. Novel green micellar electrokinetic capillary chromatographic method has been developed for simultaneous determination of simvastatin and sitagliptin phosphate in binary synthetic mixtures and their pharmaceutical formulation. Separation was achieved using a deactivated fused silica capillary (50 cm effective length × 50 μm id) through a background running electrolyte of 100 mM borate buffer (pH 9.1) and 100 mM sodium dodecyl sulfate. Diode array detection was set at 238 and 210 nm for simvastatin and sitagliptin phosphate, respectively. All experimental parameters were closely varied and optimized. Both drugs declared good linearities over the range of 10–100 μg/mL. Proposed study was validated according to International Council for Harmonization guidelines. It was applied to the assay of laboratory‐made binary mixtures and marketed tablets. Electrophoretic assay was compared with a reported spectrophotometric one. Satisfactory t‐test and F‐ratio indicated insignificant differences between both methods. Moreover, it is the first capillary electrophoretic simultaneous assay for simvastatin and sitagliptin phosphate, and fits a linear correlation with the green analytical attributes.

Development and comprehensive greenness assessment for MEKC and HPTLC methods for simultaneous estimation of sertaconazole with two co-formulated preservatives in pharmaceutical dosage forms

Four greenness assessment tools: National Environmental Methods Index (NEMI), Ecoscale Assessment (ESA), Green Analytical Procedure Index (GAPI) and the most recent Analytical GREEness metric (AGREE) were tested to evaluate two proposed MEKC and HPTLC methods for the simultaneous determination of the antifungal drug sertaconazole (SER) and two co-formulated preservatives methyl paraben (MEP) and sorbic acid (SOR). Method I was micellar electrokinetic capillary chromatography (MEKC). Electrophoretic conditions were optimized to improve separation, sensitivity, and rapidity. The proposed method used a fused silica capillary (50 cm × 50 μm id), and the background electrolyte was 50 mM acetate buffer pH 4.6 containing 15 mM SDS with 17 s injection time. The applied voltage was 30 kV. The diode array detector (DAD) was set at 210 nm for measurement of SER and 254 nm for both MEP and SOR. The Three compounds were resolved in less than 6 min with migration times 3.07, 4.29, and 5.97 min for SER, MEP, and SOR respectively. The described method was linear over the range of 5–100 μg/mL for SER, MEP and SOR with correlation coefficients >0.9995. For method II: high-performance thin-layer chromatography (HPTLC) analysis was carried out on aluminum-backed sheet of silica gel using chloroform-ethyl acetate (3:7) as mobile phase. Retardation factors were 0.20, 0.71, and 0.88 for SER, MEP, and SOR respectively. Quantification was achieved with UV densitometry at 210 nm for SER and 254 nm for MEP and SOR. The linearity ranges were 0.1–1 μg/spot for the three drugs with correlation coefficients >0.9998. The analytical performance of both methods was thoroughly validated according to International Conference on Harmonization (ICH) guidelines with respect to system suitability, linearity, ranges, precision, accuracy, specificity, robustness, detection and quantification limits. The proposed MEKC and HPTLC methods were successfully applied for estimation of the studied drugs in laboratory prepared mixtures and in the cream and spray dosage forms.

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.

Determination of artemisinin and its analogs in Artemisia annua extracts by capillary electrophoresis – Mass spectrometry

The applicability of micellar electrokinetic capillary chromatography (MEKC) with mass spectrometric detection for the determination of artemisinin and its analogs (e.g. ascaridole, artemisia ketone, casticin, deoxyartemisinin, arteannuic acid, artemetin, dihydroartemisinic acid) was studied. 40 mM ammonium perfluorooctanoate (pH 9.5) with 2% isopropanol (IPA) was used as background electrolyte (BGE) and the sheath liquid was 50 % (v/v) IPA:water containing 0.1 % formic acid. Separation was performed in a bare fused silica capillary. Artemisinin was detected at 283.1545 m/z as [M+H]+ ion. For artemisinin the linear range was found to be 0.6 μg/mL - 60 μg/mL and the limit of detection was 0.18 μg/mL. The RSD% values were 2.6 % for migration times and 4.8 % for peak areas (N = 6). In the ethanolic extracts of Artemisia annua leaves, in addition to artemisinin, a large number of other organic components could be separated and determined. MEKC-MS revealed the existence of diastereomers of several compounds (artemisinin, deoxyartemisinin, dihydroartemisinic acid) in the plant extracts.

Simultaneous separation and determination of three huperzine alkaloids in Huperzia serrata and its preparations by cyclodextrin-modified mixed micellar electrokinetic capillary chromatography

In this study, a simple and sensitive cyclodextrin-modified mixed micellar electrokinetic capillary chromatography (CD-MEKC) method has been developed for the simultaneous separation and determination of Huperzine A (HupA), Huperzine B (HupB) and Huperzine C (HupC) in Huperzia serrata (H. serrata). The optimal conditions (pH 9.3) were composed of 10 mM sodium tetraborate solution, 40 mM sodium dodecyl sulfate (SDS), 50 mM sodium cholate (SC) and 3.0 mM mono-(6-ethylenediamine-6-deoxy)-β-cyclodextrin (ED-β-CD). The separation and determination process were performed on a P/ACE MDQ capillary electrophoresis system, the separation voltage was 15 kV, the temperature was 25 °C and the detection wavelength was 308 nm. Under the optimum conditions, the migration time was less than 9 min. The LOD and LOQ were between 0.38 and 0.80 μg/mL and 1.2–2.3 μg/mL, respectively. The developed method, with excellent precision and accuracy, was applied for the determination of three alkaloids in H. serrata and its formulations.

Micellar electrokinetic chromatography as a powerful analytical tool for research on prebiotic chemistry

Capillary electromigration techniques have proven their capabilities in detection of variety of analytes from inorganic ions and small organic molecules through bio(macro)molecules to large analytes such as cells or nano/micro particles. Also broad range of potential applications includes food and environmental analysis, biomedical and pharmaceutical investigations or even diagnostics.In this work, it was demonstrated that capillary micellar electrokinetic chromatography is an excellent tool extremely helpful in investigations focused on prebiotic synthesis of molecules essential for formation of life on early Earth – nucleobases. In particular, rapid separation of nucleobases (< 2 min) was achieved in 40 mM borate buffer separation electrolyte containing 60 mM sodium dodecyl sulfate as an additive. This approach enabled detection of nucleobases formed in thermolysed formamide under conditions simulating the environment occurring on early Earth. Moreover, polydopamine-based molecularly imprinted polymers specific to thymine and uracil improved detection of these low abundant products.

Targeted inactivation of soybean proteinase inhibitors using zinc

In this study the potential targeted use of zinc to inactivate proteinase inhibitors (PI) has been investigated as an alternative to the widely applied heat treatment used industrially for inactivation of PI. Zinc was utilized for the reduction of disulfide bonds leading to the structural changes in proteins, thus affecting the decreased affinity between PI and proteinases. The protein disulfide bond reduction mechanism was studied using a newly developed micellar electrokinetic capillary chromatography (MECC) with the glutathione redox reaction with dithiothreitol (DTT) as model system. This model proved efficient in monitoring the reduction of disulfide bonds in the Kunitz trypsin inhibitor (KTI) and Bowman-Birk inhibitor (BBI). The use of zinc as a reductant resulted in a significant reduction of trypsin inhibitor activity (TIA) of 72% for KTI and 85% for BBI, highlighting zinc as a promising potential agent to reduce the activity of PI as an alternative to heat treatment.

Application of MEKC and UPLC with Fluorescence Detection for Simultaneous Determination of Amlodipine Besylate and Bisoprolol Fumarate.

Two chromatographic methods were described for simultaneous determination of the antihypertensive drugs amlodipine besylate (AML) and bisoprolol fumarate (BIS). Method I applies micellar electrokinetic capillary chromatography using a deactivated fused silica capillary (25 cm effective length × 50 μm internal diameter). The background electrolyte consisted of 0.01 M borate buffer (pH 9.2) containing 0.025 M sodium dodecyl sulphate and methanol in the ratio of 80:20 (v/v). Valsartan (VAL) was used as an internal standard. Diode array detector was set at 238, 224, and 210 nm for measuring AML, BIS, and VAL, respectively. Method II involves using ultra-performance liquid chromatography with fluorescence detection. Zorbax SB-C8 column (2.1 × 100 mm, 1.8 μm particle size) was used with isocratic elution of the mobile phase composed of 0.1% trifluoroacetic acid, acetonitrile, and methanol in the ratio of 55:35:10 (v/v) at a flow rate of 0.6 mL/min. Fluorescence detection was done using excitation wavelengths 230 and 370 nm and emission wavelengths 305 and 450 nm for BIS and AML, respectively. Validation parameters were carefully studied including linearity, ranges, precision, accuracy, robustness, detection, and quantification limits. Method I showed good linearity over the range 10-100 μg/mL for both dugs. Method II's linear ranges were 0.001-0.1 and 0.02-1 µg/mL for BIS and AML, respectively. The proposed methods were successfully validated and applied for assay of the studied drugs in their fixed-dose combination tablets. To the best of our knowledge, this study suggests the first electro-chromatographic and LC with fluorescence detection methods for simultaneous determination of amlodipine and bisoprolol.

Application of micellar electrokinetic capillary chromatography for identification, quantitative detection and unfolding analysis of interleukin-12

To establish a micellar electrokinetic capillary chromatography-based method for identification and quantitative detection of interleukin-12 (IL-12) and analysis of its unfolding process. An uncoated fused-silica capillary (inner diameter 50 μm) with a total length of 48.5 cm (40 cm to the detector) was used for the experiment. The factors influencing the separation efficiency of IL-12 were analyzed, and a standard curve of IL-12 concentration was established. The mixture of IL-12 and anti-IL-12 antibody was incubated in a water bath at 38 ℃ for 40 min, and capillary electrophoresis was then performed under the same conditions. The results were compared with those of IL-12 and anti-IL-12 antibody to identify IL-12. IL-12 and dithiothreitol (DTT) were incubated at 60 ℃ in water bath for different lengths of times, and the unfolding process of IL-12 was analyzed based on electrophoresis results of IL-12 in different states. A micellar capillary electrophoresis on-line sweep method was established with 80 mmol/L borate (pH=9.3) containing 30 mmol/L sodium dodecyl sulfate (SDS) as the buffer solution. This system showed a good linear relationship between the peak area and the mass concentration of IL-12 with a linear correlation coefficient of 0.9991 within the linear range of 2 to 120 ng/L. As the incubation time of IL-12 and DTT prolonged, the disulfide bond of IL-12 gradually opened and resulted in distinct changes in the protein peak. This capillary electrophoresis-based method is simple and sensitive for IL-2 analysis and allows rapid detection of changes in IL-12 content in the setting of tumors and analysis of the possible causes.

Optimal conditions for extraction and simultaneous determination of sulfamethoxazole and trimethoprim in pharmaceuticals by micellar electrokinetic capillary chromatography

A micellar electrokinetic capillary chromatography was performed at 25°C and 30 kV (under pressure of 15 mbar), with 30 mM borate buffer (pH 9.0), 60 mM sodium dodecysulfate, and 10% (v/v) ethanol as background electrolyte for the determination of sulfamethoxazole and trimethoprim. UV detection was at 205 nm. Recoveries were optimal and acceptable after extraction with ethanol/deionized water (1:1, v/v) for both investigated compounds from laboratory mixtures of standards. The method was shown to be specific, accurate (recoveries were 99.9 ± 0.4% for sulfamethoxazole and 99.8 ± 0.3% for trimethoprim), linear over the tested ranges (correlation coefficients ≥ 0.9990) and precise (RSD below 0.6%). The method was applied to determine sulfamethoxazole and trimethoprim in tablets, powder for cutaneous use and solution for infusion.

Study on the adulterated chemical drugs in rheumatic and analgesic traditional Chinese medicine by MEKC

A micellar electrokinetic capillary chromatography was developed to identify adulterants in rheumatic and analgesic traditional Chinese medicine. This chromatographic technique was carried out using a buffer of (pH 9.0) 0.02M sodium tetraborate and sodium dihydrogenphosphate (contain 0.15 M sodium lauryl sulfate). This method was applied to simultaneously analyze 14 synthetic chemical drugs adulterated in traditional Chinese medicine within 25 minutes. They represented five pharmacological categories: antipyretic analgesics, glucocorticoids, CNS stimulants, muscle relaxants and sedatives, and included: acetaminophen, aminopyrine, bucetin, diclophenac sodium, ethoxybenzamide, indomethacin, ketoprofen, mefenamic acid, phenylbutazone, dexamethasone, prednisolone, chlorzoxazone, diazepam, and caffeine. The recovery of synthetic chemical drugs add to Dwu-Hwo-Jih-Sheng-Tang ranged from 92.1 to 102.5%. This method was used to assess two traditional Chinese medicines sold by distributors of Chinese natural drugs collected by the consumer centers of local health bureaus from Oct. 1991 to Jun. 1992. In sample A, acetaminophen, caffeine, phenylbutazone, prednisolone were found, and their content in each pill were measured at 4.9, 2.2, 26.6 and 1.5mg, respectively. The relative standard deviation ranged between 2.2-3.1%(intraday) and 2.9-5.1%(interday). In sample B, aminopyrine, caffeine and ethoxybenzamide were found, and their content of each pill were measured at 11.8, 5.6. and 3.6mg, respectively. The relative standard deviation ranged between 2.0-3.5%(intraday) and 2.4-4.7% (interday). MEKC was found to be an efficient and sensitive chromatographic technique with which to measure adulterants in samples of rheumatic and analgesic traditional Chinese medicine.

Analysis of malachite green, gentian violet and their leuco metabolites in catfish and carp by micellar electrokinetic capillary chromatography

A simple, reproducible and sensitive micellar electrokinetic chromatography (MEKC) method was developed for the separation and determination of malachite green (MG), leucomalachite green (LMG), gentian violet (GV) and leucogentian violet (LGV) from catfish and carp. Field-enhanced sample injection with reverse migrating micelles (FESI-RMM) was used for on-line concentration of the analytes. The buffer contained 50 mM H3PO4-NaOH, 140 mM sodium dodecyl sulfate (SDS), 15% acetonitrile and 15% 2-propanol, at the pH of 2.0. The sample solution was diluted with water containing 5 mM SDS and injected for 15 s with -8 kV after injection of 2 s water plug. The effects of concentration of SDS and organic modifier, the sample matrix, the injection time of water plug, the injection voltage and injection time of sample on the separation and stacking efficiency were investigated. Under the optimum conditions, the analytes were well separated and by optimizing the stacking conditions, about 121, 146, 150 and 87 fold improvement in the detection sensitivities were obtained for GV, MG, LMG and LGV, respectively. The instrument detection limits (S/N = 3) of GV, MG, LMG and LGV were 40, 70, 50 and 50 ng/mL, respectively. The recoveries of GV, MG, LMG and LGV in the extracts of catfish were 87.8-96.7%, 87.9-100.2%, 96.7-101.4% and 89.8-94.2%, respectively. The GV, MG, LMG and LGV in spiked (1 μg/mL) catfish and carp extracts were successfully determined with satisfactory repeatability and recovery.

Determination of polar constituents in scrophulariae radix by micellar electrokinetic capillary chromatography

Determination of polar constituents in scrophulariae radix by micellar electrokinetic capillary chromatography

Detection of caffeine and its main metabolites for early diagnosis of Parkinson's disease using micellar electrokinetic capillary chromatography.

Caffeine (CA) is a common xanthine alkaloid found in tea leaves, coffee beans, and other natural plants, and is the most widely used psychotropic substance in the world. Accumulating evidence suggests that low plasma levels of CA and its metabolites may serve as reliable diagnostic markers for early Parkinson's disease (PD) patients. In this study, we demonstrated a new MEKC method for determining CA and its three main downstream metabolites, paraxanthine (PX), theobromine (TB), and theophylline (TP), in human plasma. Plasma samples were collected, and analyzed using MEKC, after SPE. The running buffer was composed of 35mM phosphate, pH of 10.5, and 25mM SDS. The separation voltage was 15kV and the detection wavelength was at 210nm. Under the optimum conditions, four distinct analytes were completely separated and detected in less than 12min. Method limits of detection were as low as 7.5ng/mL for CA, 5.0ng/mL for TB, and 4.0ng/mL for both PX and TP. The recoveries were between 88.0% and 105.9%. This method was successfully applied to 27 human plasma samples. The results indicate that the plasma concentrations of the four analytes are significantly lower in patients with early PD than in control subjects (p < 0.05). The area under curve was improved to 0.839 when CA and its three main metabolites were included, suggesting that MEKC testing of CA, TP, TB, and PX may serve as a potential method for early diagnosis of PD.

Determination of fluoroquinolones in milk, honey and water samples by salting out-assisted dispersive liquid-liquid microextraction based on deep eutectic solvent combined with MECC.

A simple and sensitive salting out-assisted dispersive liquid-liquid microextraction method using deep eutectic solvent combined with back extraction and micellar electrokinetic capillary chromatography (SO-DLLME-DES-BE-MECC) was developed for the determination of fluoroquinolones in milk, honey and water samples. Several parameters affecting the extraction efficiency including DES volume, vortex time, centrifugation time, salt type and amount, sample pH and volume, etc. were investigated. Good linearity were obtained for fluoroquinolones in a range of 0.020-3.200μgmL-1 and 0.030-4.800μgmL-1 with LODs less than 0.010μgmL-1. The recoveries were in the ranges of 95.0-104.9%, 90.1-110.2% and 87.8-114.1% for water, honey and milk samples, respectively. The relative standard deviations for reproducibility were all below 7.6%. Under the optimized conditions, the enrichment factors for analytes were achieved in the range from 531 to 858 folds. The presented method was successfully applied for the determination of fluoroquinolones in milk, honey and water samples.

Simple and Rapid Micellar Electrokinetic Chromatography Method for Simultaneous Determination of Febuxostat and its Related Impurities

A micellar electrokinetic capillary chromatography (MEKC) method has been developed and validated for simultaneous analysis of febuxostat and its related substances in active pharmaceutical ingredients and pharmaceutical formulations. Analysis was performed in an uncoated fused silica capillary (34 cm effective length, 50 µm diameter). Method sensitivity was enhanced using an extended light path capillary, with an optical path 150 µm and the choice of 320 nm detector operating wavelength due to lower background noise and higher selectivity. BGE consisted of 20 mM borate buffer pH 9.3 and 50 mM SDS and 2% acetonitrile. Analysis was performed at 30 kV separation voltage and 32 °C capillary temperature. The method was linear over the range 1.0–10.0 µg mL−1 for each impurity corresponding to reporting limits regarding the ICH Q3A guidelines. The method has proven to be selective, precise, accurate and robust. Proposed MEKC method has been successfully applied for the quantitative determination of febuxostat and purity assay of active pharmaceutical ingredient and tablet dosage forms.