Nonaqueous Capillary Electrophoresis Method Research Articles

Characterization of isomeric lipid A species from Pseudomonas aeruginosa PAO1 by non-aqueous capillary electrophoresis with positive and negative ion electrospray tandem mass spectrometry

Pseudomonas aeruginosa is a priority target pathogen for antibiotic research and development because of its high resistance to a wide range of antibiotics. Acquisition of resistance is sometimes associated with modifications of the lipid A component present in the outer membrane of most Gram-negative bacteria. For a deeper understanding of subtle chemical variations of lipid A in relation to biological properties, the structural elucidation of lipid A species within a bacterial strain is of crucial importance. However, the simultaneous presence of monophosphorylated positional isomers in naturally heterogeneous lipid A samples cannot easily be recognized with direct MS measurements or with conventional LC-MS strategies. Herein, we present the application of a non-aqueous capillary electrophoresis (NACE) method coupled to positive and negative ion electrospray tandem mass spectrometry with collision-induced dissociation (CID) activation technique for the in-depth analysis of the lipid A isolate of P. aeruginosa PAO1. The main advantage of our NACE strategy is its separation power regarding the site of phosphorylation of the lipid A structures, which makes it a good orthogonal technique to chromatographic characterizations of the bacterial lipid A composition, where the separation is mainly based on acylation differences of the species. Overall, the results of this electrophoretic approach revealed hitherto unreported isomeric monophosphorylated PAO1 lipid A constituents, including both phosphate and acyl chain positional isomers. The parallel fragmentation in the complementary positive and negative ion modes enabled the unequivocal assignment of the phosphorylation site and position of acyl chains in lipid A compounds of three acylation families ranging from tetra- to hexa-acylation. Moreover, C1-monophosphorylated lipid A species have been identified in P. aeruginosa for the first time.

Simultaneous determination of triclosan，triclocarban and p-chloro-m-xylenol in disinfectant，personal care products and oiltment by nonaqueous capillary electrophoresis

Triclosan （TCS）， triclocarban （TCC）， and p-chloro-m-xylenol （PCMX） are some of the most widely used antibiotics because of their broad-spectrum and highly-efficient bactericidal effects. In the context of disinfection， the National Standard GB 38598-2020 stipulates that the contents of the effective ingredients present in a disinfectant must be specified， wherein their range must fall within 90%-110% of the specified central value. To ensure a suitable product quality， analysis by high performance liquid chromatography （HPLC） is recommended by both the GB/T 27947-2020 and GB/T 34856-2017. However， the results analyzed according to the National Standard method often exceed the declared contents， thereby indicating the necessity to establish a new method based on a completely different principle （e. g.， capillary electrophoresis）， especially since it was not possible to analyze TCS， TCC， and PCMX in a single injection using the National Standard method. Moreover， using this method， large amounts of methanol were consumed， which could be potentially harmful to both operators and the environment. In terms of their water solubilities， this decreases in the order of PCMX>TCS>TCC， wherein TCC is insoluble in water. As such， the use of nonaqueous capillary electrophoresis （NACE） based on running buffer solutions prepared in pure organic solvents （e. g.， methanol or acetonitrile） is necessary. In this paper， a new NACE approach combined with an ultraviolet detection method was developed for the simultaneous analysis of TCS， TCC， and PCMX in disinfectants， personal care products， and ointments. For this purpose， an uncoated fused silica capillary （20 cm×50 μm， total length=30.2 cm） was used as the separation column with a separation buffer composed of 14 mmol/L sodium borate， 2 g/L polyethylene glycol （PEG） 20000， and 0.5 mmol/L dodecyltrimethylammonium bromide （DTAB） in methanol. Following optimization of the separation parameters， the complete and simultaneous separation of TCS， TCC， and PCMX was achieved when the sample solution was prepared using 5 g/L PEG 20000 in methanol-acetonitrile （50∶50， v/v）. It was possible to directly inject the sample into the analysis system after a simple dilution with the sample medium， and no interference was observed in any of the sample electropherograms when a separation voltage and detection wavelength of -12 kV and 214 nm were employed， respectively. Furthermore， TCS， TCC， and PCMX showed good linear relationships with their corrected peak areas within a mass concentration range of 1-100 mg/L， and the correlation coefficients （r） were all greater than 0.99. Moreover， the limits of detection （LODs， S/N=3） and limits of quantification （LOQs， S/N=10） were determined to be 0.2 and 1 mg/L， respectively. The spiked recoveries ranged from 94.5% to 104.4% with relative standard deviations of ≤4.8% in all cases. Subsequently， the established method was used to analyze 31 commercial samples， including hand sanitizer， disinfectant， baby powder， and antibacterial cream. A comparative analysis of HPLC， the developed NACE method， and our previously reported micellar electrokinetic chromatographic （MEKC） method was also carried out for the quantitative determination of TCS， TCC， and PCMX. Although no statistically significant differences were observed among the three methods， the results determined for 16 out of the 31 samples did not match the claimed contents. These results therefore indicate the necessity to further control the compositions of disinfectant products. Our results indicate that the newly established NACE method can be an important alternative to HPLC for routine laboratory analyses， especially considering that it minimizes waste generation， requires only a simple sample pretreatment process， and exhibits a good selectivity to the target compounds. It is therefore hoped that the NACE method will be incorporated into the National Standard method in the near future.

A Non-aqueous Capillary Electrophoresis for Determination of Eugenol in Cloves and Dental Preparations

A total non-aqueous capillary electrophoresis method was developed and applied for the first time for the quantification of eugenol in cloves and dental preparations. The optimized conditions included a buffer consisting of 150 mM sodium acetate and 300 μL 1 M acetic acid methanol solution (30 mM), an applied voltage of 25 kV, and a temperature of 25 °C and an applied wavelength of 214 nm. The developed method of determining the eugenol was characterized by the following parameters: a detection time within 1.97 min, good linearity (R2 = 0.9989–0.9999), detection limit at the level from 0.19 to 0.35 µg mL−1, very good extraction yield of 99.6–100.6% from both methanol standard solutions, clove buds’ matrix, and dental preparations. Limit of quantitation at the level from 0.81 to 0.98 µg mL−1. The method is based on the developed one-step extraction procedure. Moreover, the developed method does not require the use of any eugenol solubility enhancers such as SDS.

Separation and Determination of Matrine, Oxymatrine and Sophoridine in Composite Preparations by Non-aqueous Capillary Electrophoresis

A new, simple, and quick method for the simultaneous determination of three alkaloids (matrine, sophoridine, and oxymatrine) in composite preparations by nonaqueous capillary electrophoresis has been developed. A running buffer composed of 60% acetonitrile + 0.75% acetic acid + 25 mM ammonium acetate in methanol was found to be the most suitable for this separation. The limits of detection for three alkaloids were over the range of 0.45–0.6 μg/ml. In the tested concentration range, good linear relationships between peak areas and concentrations of the analytes were obtained. This method has been successfully applied to simultaneous determination of the three alkaloids with recoveries over the range of 95.6 to 97.2%. This new non-aqueous capillary electrophoresis method established has been successfully used for the simultaneous separation and determination of sophoridine, matrine and oxymatrine in complex preparations in 5 minutes.

Determination of the enantiomers of salmeterol xinafoate in salmeterol fluticasone powder inhalant by chiral nonaqueous capillary electrophoresis

昔萘酸沙美特罗是目前治疗哮喘夜间发作和哮喘维持治疗的理想药物之一,它在临床上以外消旋体形式给药。昔萘酸沙美特罗的两个对映体在药理活性和毒理作用等方面差异较大,建立昔萘酸沙美特罗对映体的手性分离分析方法对提高手性药物质量、保证临床用药安全有效具有重要意义。该文以L(+)-酒石酸-硼酸络合酸为手性选择剂,建立了测定沙美特罗替卡松粉吸入剂中昔萘酸沙美特罗对映体含量的非水毛细管电泳法。实验考察了L(+)-酒石酸浓度、硼酸浓度和表观pH(apparent pH, pH* )对手性分离效果的影响。优化的缓冲溶液为:含120.0 mmol/L L(+)-酒石酸和120.0 mmol/L硼酸的甲醇溶液,pH* 为0.93;其他实验条件为:未涂层弹性熔融石英毛细管(内径50.0 μm,总长度64.5 cm,有效长度55.5 cm),重力进样17.5 cm×10.0 s,检测波长225 nm,室温,工作电压20.0 kV。在优化的实验条件下,昔萘酸沙美特罗的两个对映体在18.0 min内获得了2.18的分离度;在27.5~800.0 mg/L质量浓度范围内,与峰面积呈现良好的线性关系,相关系数(r)大于0.9990;检出限和定量限分别为7.5和25.0 mg/L;加标回收率为98.1%~101.9%,相对标准偏差为1.2%~1.9%。随机购买市面上出售的沙美特罗替卡松粉吸入剂,对其昔萘酸沙美特罗对映体的含量进行了分析检测。结果显示,昔萘酸沙美特罗对映体1和对映体2的标示量百分含量均为98.7%, RSD分别为2.5%和2.7%。该方法操作简便易行,结果准确可靠,消耗低,可用于市售沙美特罗替卡松粉吸入剂中昔萘酸沙美特罗对映体的含量测定。

Enantioselective recognition of sutezolid by cyclodextrin modified non-aqueous capillary electrophoresis and explanation of complex formation by means of infrared spectroscopy, NMR and molecular modelling

A method for the enantioseparation of sutezolid, the next analogue after linezolid and tedizolid, belonging to the truly new class of antibacterial agents, the oxazolidinones, was developed based on non-aqueous capillary electrophoresis (NACE), using a single isomer of cyclodextrins as a chiral pseudophase. During the experiment, the enantioseparation of sutezolid together with its predecessor, linezolid, both weak base antibacterial agents, was evaluated using anionic single-isomers of cyclodextrins from hydrophilic, up to hydrophobic: heptakis-(2,3-dihydroxy-6-sulfo)-β-cyclodextrin, heptakis-(2,3-diacetyl-6-sulfo)-β-cyclodextrin (HDAS-β-CD), as well as heptakis-(2,3-dimethyl-6-sulfo)-β-cyclodextrin (HDMS-β-CD), respectively. Based on the observed results, the cyclodextrins, HDAS-β-CD and HDMS-β-CD which carry the acetyl and methyl groups at the C2 and C3 positions, respectively, provided the baseline separation of sutezolid enantiomers. However, HDMS-β-CD led to a reversal of enantiomer migration order (EMO) in comparison to HDAS-β-CD. Instead, enantiomers of linezolid were separated only by HDMS-β-CD. During the experiments, different organic solvents and their mixtures in various ratios were tested. The selectivity and separation efficiency were critically affected by the nature of the buffer system, the type of organic solvent, and the concentrations of trifluoroacetic acid (TFA) in the NACE buffer system.Focusing on the desired EMO in which the eutomers (S)-sutezolid and (S)-linezolid migrated last, the highest enantioresolution using the NACE method was achieved at normal polarity mode with 45 mM HDMS-β-CD dissolved in MeOH/ACN (85:15, v/v) containing 200 mM TFA/20 mM ammonium formate. Moreover, infrared spectroscopy, NMR and molecular modelling were investigated to provide information about complex formation.

Migration behavior of organic dyes based on physicochemical properties of solvents as background electrolytes in non-aqueous capillary electrophoresis

The migration behavior of organic fluorescent dyes (i.e., crystal violet, methyl violet base, methyl violet B base, rhodamine 6G, and rhodamine B base) in non-aqueous capillary electrophoresis (NACE) was investigated by focusing on the physicochemical properties of various organic solvents [ethanol, methanol, 2-propanol, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)] in background electrolyte (BGE). Laser-induced fluorescence (LIF) and UV/Vis detectors were employed to observe both the migration time of organic dyes and the electroosmotic flow (EOF) in NACE, respectively. As seen in conventional aqueous BGE, the mobility of EOF in organic solvents tended to rise when the ratio between the dielectric constant and the solvent’s viscosity (ε/η) increased in accordance with Smoluchowski’s equation. However, unlike the ε/η of pure organic solvents, the migration order of dyes changed as follows: methanol (60.0) > DMF (45.8) > ethanol (22.8) > DMSO (23.4) > 2-propanol (9.8). Since the amount of acetic acid added to balance the pH depends on the pKa of each solvent, EOF changed when the difference in the ε/η value was small. This resulted from the inhibition of mobility, and its difference was dependent on the ε/η of BGEs with high ionic strength. In particular, the actual mobility of dyes in DMF showed excellent compliance with the Debye–Hückel–Onsager (DHO) theory extended by Falkenhagen and Pitts, which enabled us to analyze all dyes within 15 min with excellent resolution (Rs > 2.5) under optimum NACE conditions (10 mM sodium borate and 4661 mM acetic acid in 100% DMF, pH 4.5). In addition, the NACE method was successfully applied for analyzing commercially available ballpoint ink pens. Thus, these results could be used to anticipate the migration order of organic dyes in a 100% NACE separation system.

Enantiomeric separation of seven β-agonists by NACE—Study of chiral selectivity with diacetone-d-mannitol–boric acid complex

A rapid and effective nonaqueous capillary electrophoresis (NACE)–ultraviolet (UV) method was developed for the enantiomeric separation of seven β-agonists. Diacetone-d-mannitol–boric acid complex was used as a new chiral selector. It was in situ synthesized by the reaction of diacetone-d-mannitol and boric acid in methanol medium containing triethylamine. The effects of diacetone-d-mannitol, boric acid, and triethylamine concentrations on the enantioseparation were carefully investigated. Under the optimized conditions, baseline enantioseparation could be obtained for six of the tested β-agonists within 12min. These results were better than that obtained with d-mannitol–boric acid complex in previous work. 11B nuclear magnetic resonance (11B NMR) was applied to determine the fraction of boron species and confirm the formation of diacetone-d-mannitol–boric acid complex. Validation of the established NACE method was also carried out according to ICH guidelines. Calibration curves showed good linearity with correlation coefficients (r)≥0.9992 over a certain concentration range for each enantiomer of the tested five β-agonists. The relative standard deviations (RSDs) of intra-day precisions and inter-day precisions of migration times were ≤1.4% (n=6), and ≤6.3% (n=10), respectively. That of peak areas were ≤3.7% (n=6), and ≤5.6% (n=10), respectively. The limits of detection (LODs) and the limits of quantitation (LOQs) based on the signal-to-noise ratios of 3 and 10 were found below 1.25μgmL−1 and 5.00μgmL−1, respectively. The proposed method was successfully applied to the determination of clenbuterol enantiomers in a multi-component pharmaceutical dosage form called “Ambroxol Hydrochloride and Clenbuterol Hydrochloride Oral Solution”.

Determination of Curcuminoids and Their Degradation Products in Turmeric (Curcuma longa) Rhizome Herbal Products by Non-aqueous Capillary Electrophoresis with Photodiode Array Detection

Non-aqueous capillary electrophoresis (NACE) method was optimised for simultaneous determination of major bioactive curcuminoids (CCD) viz., curcumin (CC), desmethoxycurcumin (DC) and bisdesmethoxycurcumin (BC), and some of the degradation products viz., vanillin (VN), vanillic acid (VA), ferulic acid (FA) and 4-hydroxybenzaldehyde (HB) in turmeric milk and herbal products. Separation was achieved using non-aqueous background electrolyte (NA-BGE), consisting of a mixture of sodium tetraborate, sodium hydroxide, methanol and 1-propanol in a single run by capillary electrophoresis (CE). In the present study, a novel ultrasonication-assisted phase separation method (US-PS) was used for extracting the analytes in turmeric milk and the extract was directly injected into the capillary without any pretreatment. High-performance thin layer chromatographic (HPTLC) method for the separation of the analytes was also evaluated on pre-coated silica gel plate. Two different high-performance liquid chromatographic (HPLC) conditions were reported in the literature for the separation of above-mentioned target compounds. The proposed method NACE is simple, fast, convenient and economical.

Chiral separation by nonaqueous capillary electrophoresis using l-sorbose–boric acid complexes as chiral ion-pair selectors

A chiral nonaqueous capillary electrophoresis (NACE) method using l-sorbose–boric acid complexes as the chiral ion-pair selectors was developed for enantioseparation of nineteen chiral analytes.

Quantitation of sunitinib, an oral multitarget tyrosine kinase inhibitor, and its metabolite in urine samples by nonaqueous capillary electrophoresis time of flight mass spectrometry

A rapid, sensitive, and specific method was developed and validated using a nonaqueous-capillary electrophoresis method with TOF-MS for determination of sunitinib and N-desethyl sunitinib in human urine. In order to avoid ionic suppression a urine samples dilution with methanol 1:10 previous step was used. This was the only treatment step to urine samples before the injection. Despite this dilution of the urine, the detection limit was as low as 0.07 mg/L for sunitinib and 0.15 mg/L for N-desethyl sunitinib. Separation of compounds was achieved with a mixture of 5 mM ammonium formate in methanol. The calibration curves were linear over the range of 0.5-50.0 mg/L for the two analyzed compounds. The within-run and between-run precisions were within 5%, while the accuracy ranged from 96.0 to 100.4%. This method can be used in routine clinical practice to monitor sunitinib and N-desethyl sunitinib drugs in the urine of cancer patients treated with once daily administration.

Determination of gambogic acid in Gamboge by non-aqueous capillary electrophoresis

Gambogic acid (GA), a kind of caged xanthones, has low solubility in water. A non-aqueous capillary electrophoresis (NACE) was established for the determination of GA in Gamboge based on the optimized conditions. The effect of 20% - 60% methanol or acetonitrile spiked in running solution was investigated. The effects of compositions, concentration, pH, additives like β-cyclodextrin in running buffer were thoroughly studied. Applied voltage and applied temperature were also observed. Optimal electrophoretic conditions were as follows: 20 mmol/L sodium borohydride solution (pH 9. 86) containing 40% (v/v) acetonitrile, 10 mmol/L β-cyclodextrin as running buffer, applied voltage of 10 kV, capillary temperature of 30 °C and detection wavelength of 280 nm. The calibration curve had good linearity in the range of 2-2 000 mg/L with the correlation coefficient of 0. 999 6. The limit of quantification (S/N= 3) of the method was 2 mg/L. The quantifications of GA in Gamboge from different producing places including Vietnam, Thailand, Burma, India were 1. 67-472.40 mg/g with the RSD (n= 3) of 1.12% -2.60%. The content of Gamboge from Vietnam is obviously low while the others are high. The recoveries of GA spiked in real samples ranged from 95. 2% to 105. 6%. The method of NACE is simple, efficient and of good reproducibility, can be served as a novel reference to identify and control the quality of Gamboge.

Development and validation of an analytical method for the separation and determination of major bioactive curcuminoids in Curcuma longa rhizomes and herbal products using non-aqueous capillary electrophoresis.

A simple, fast and efficient non-aqueous capillary electrophoresis method (NACE) was developed for the simultaneous determination of three major bioactive curcuminoids (CMNs) in Curcuma longa rhizomes and its herbal products. Good separation, resolution and reproducibility were achieved with the background electrolyte (BGE) consisting a mixture of 15.0 mM sodium tetraborate and 7.4 mM sodium hydroxide (NaOH) in 2:10:15 (v/v/v) of water, 1-propanol, and methanol. The influences of background electrolyte, sodium hydroxide, water, sodium dodecyl sulfate and hydroxylpropyl-β-cyclodextrin on separations were investigated. The separation was carried out in a fused-silica capillary tube with reverse polarity. Hydrodynamic injection of 25mbar for 12s was used for injecting samples and a voltage of 28 kV was applied for separation. The ultrasonication method was used for the extraction of CMNs from the turmeric herbal products and the extract was filtered and directly injected without any further treatments. The limits of detection and quantification were less than 5.0 and 14.6 µg/ml respectively for all CMNs. The percentage recoveries for CMNs were >97.2% (%RSD, <2.62). The results obtained by the method were compared with existing spectrophotometric and HPLC methods. The related compounds in the extract did not interfere in the determination of CMNs. The proposed NACE method is better than existing chromatographic and electrophoretic methods in terms of simple electrophoretic medium, fast analysis and good resolution.

Development and validation of a non-aqueous capillary electrophoresis method for the determination of imatinib, codeine and morphine in human urine

A non-aqueous capillary electrophoresis (NACE) method that separates a tyrosine kinase inhibitor, imatinib, together with its main metabolite and two analgesics, codeine and morphine, from human urine is proposed. After a solid phase extraction step in urine, the four drugs were separated through a fused-silica capillary at 22 kV and 25 °C and detected at 207 nm. For this purpose 15 mM ammonium acetate and 1% acetic acid in methanol were used as the background electrolyte. Detection limits of 130 and 80 μg L−1 for imatinib and its metabolite and 40 and 60 μg L−1 for codeine and morphine were obtained. According to the validation study, the developed method was proved to be accurate, precise, sensitive and specific. The developed method is simple, rapid and sensitive and has been used to determine imatinib, codeine and their metabolites at clinically relevant levels in human urine from different patients under leukemia or analgesic treatment.

A novel nonaqueous capillary electrophoresis method for effective separation and simultaneous determination of aurantio-obtusin, emodin and rhein in semen cassiae and cassia seed tea

A novel method using nonaqueous capillary electrophoresis-UV detection was used for the effective separation and rapid simultaneous determination of anthraquinones, aurantio-obtusin, emodin and rhein, in semen cassiae and cassia seed tea.

Application of a non-aqueous capillary electrophoresis method to the analysis of triclosan in personal care products

The application of a non-aqueous capillary electrophoresis method to the analysis of triclosan in personal care products.

Ionic Liquids as Modifiers to Improve the Separation Efficiency of Nonaqueous Capillary Electrophoresis with High Electric Field Strengths

A method of nonaqueous capillary electrophoresis based on ionic liquids was developed with a high electric field (800 V/cm). The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was used as modifier to improve the separation efficiency; trishydroxymethylaminomethane and sodium cholate were used as background electrolytes in methanol and acetonitrile. The ionic liquids used in this paper have the ability to assist in the separation of hydrophobic mixtures while maintaining adequate background current. They can also improve the efficiency of heat diffusion in the capillary because they demonstrate high thermal conductivity. The developed method was used to analyze kaempferol-3-O-glucoside, 7-hydroxy-8-methoxycoumarin and 8-hydroxycoumarin-7-O-glucoside in samples of Sinacalia tangutica. The obtained quantities of the three analytes in the flower of Sinacalia tangutica were 0.27, 0.18 and 0.57%, respectively. The recovery was determined with standard addition and the results were 85.1-100.4%.

Determination and Characterization of Glycerophospholipids in Olive Fruit and Oil by Nonaqueous Capillary Electrophoresis with Electrospray-Mass Spectrometric Detection

A nonaqueous capillary electrophoresis method with electrospray-mass spectrometric detection was developed to study the glycerophospholipid fraction in olive fruit and olive oil samples. In olive fruits, where the information available about the phospholipid fraction was very scarce, results obtained in this work allowed us to complete and improve this knowledge. The glycerophospholipid fraction of the olive fruit samples analyzed was composed of phosphatidylcholine (PC), phosphatidylethanolamine (PE), lysophosphatidylethanolamine (lyso-PE), phosphatidylinositol (PI), phosphatidic acid (PA), lysophosphatidic acid (lyso-PA), and phosphatidylglycerol (PG). Differences in the relative abundance of the glycerophospholipid classes determined were observed as a function of the botanical and geographical origin of the olive fruits analyzed. Interestingly, the olive stone and pulp analyzed also showed different glycerophospholipid compositions. For olive oil, five glycerophospholipids (lyso-PA, PC, PE, lyso-PE, and PG) were detected. Finally, identification of the main molecular species in the different glycerophospholipid classes for the olive fruit samples analyzed was accomplished by tandem mass spectrometric experiments and information from the literature.

Comparative validations of non-aqueous capillary electrophoresis and high-performance liquid chromatography methods for the simultaneous determination of histamine H2 receptor antagonists in human urine

This paper reports a previously optimised method based on non-aqueous capillary electrophoresis (NACE) using UV detection for the separation and simultaneous determination of cimetidine (CIM), ranitidine (RAN), roxatidine (ROX), nizatidine (NIZ) and famotidine (FAM) in human urine. Separation is performed at 25°C and at a separation voltage of 15kV. Methanol containing 10mM ammonium acetate and 0.2% acetic acid was used as background electrolyte, and detection at 214nm. These conditions allow the five analytes to be separated within 4min. In addition in the present paper a HPLC method using diode-array as well as detector, was proposed as standard analytical method, which chromatography conditions were following: a mobile phase consisting of 80:20 20mM phosphate buffer (pH 7.5)/acetonitrile, and using 1mLmin-1 as flow rate of the mobile phase. Detection limits were evaluated on the basis of baseline noise and were establishing between 8 and 15μgL-1 for NACE and between 16 and 162μgL-1 for HPLC. The methods showed good precision with overall intra- and inter-day variations of 0.5-2.0% and 0.7-3.8%, respectively. Finally the proposed methods were successfully applied to the screening determination of the analytes in human urine, with recoveries between 97 and 105%, being able the use as pharmacokinetic data in clinical urine samples.

Development and validation of a non-aqueous capillary electrophoresis method for simultaneous estimation of mebendazole and levamisole hydrochloride in compound mebendazole tablets

A Non-aqueous capillary electrophoresis (NACE) method was employed for the separation of mebendazole and levamisole hydrochloride in compound mebendazole tablets. The optimum separation in NACE, by measuring at 210 nm, was obtained in a 60 cm (50.5 cm effective length) × 75 μm I.D. capillary using a nonaqueous solution system of 40 : 60 (v/v) methanol–acetonitrile containing 10 mmol L−1 ammonium chloride, and applied voltage of 25 kV with hydrodynamic injection. The migration time of levamisole hydrochloride and mebendazole are 2.65 min and 3.78 min, respectively. The linearity of the method was evaluated from 5 to 200 μg mL−1 for each analyte and the correlation coefficient was not less than 0.999. Good results were obtained for different aspects including suitability of the system, linearity, and precision. Detection limits of 0.017 μg mL−1 and 0.022 μg mL−1 were obtained for levamisole hydrochloride and mebendazole. Compared with the aqueous CE, the proposed NACE method has the advantages of shorter separation time and lower detection limits.