Simultaneous determination of first-line anti-tuberculosis drugs by capillary zone electrophoresis using direct UV detection

An alternative methodology for simultaneous analysis of ethambutol, isoniazid, rifampicin and pyrazinamide in pharmaceutical formulations by capillary zone electrophoresis under UV direct detection with an analysis time of 8.0 min is proposed. Background running was based on the effective mobility curve of the analytes and an optimum separation condition was achieved using a 3³ Box-Behnken design, with Brij 35, Cu²⁺ and acetic acid/sodium acetate buffer as factors. An electrolyte consisting of 50.0 mmol L⁻¹ of acetic acid/sodium acetate buffer, 12.5 mmol L⁻¹ of CuSO₄, and standard and sample solutions prepared in 2.00 mmol L⁻¹ of Brij 35 and 12.5 mmol L⁻¹ of CuSO₄ were optimized. After evaluating validation parameters, the method was successfully applied to the analysis of samples in the form of tablets and sachets.     

Direct determination of sialic acids in serum by capillary electrophoresis with UV detection

Summary A novel method for the determination of N-acetylneuraminic acid (NANA) and N-glycolylneuraminic acid (NGNA) has been developed using high-performance capillary electrophoresis with UV detection at 195 nm, without pre or post-column derivatisation. The acids were separated in a 50-cm, fused-silica capillary (50μ i.d, 45.5-cm effective length) with Na₂B₄O₇−Na₂HPO₄ buffer. The detection limit for NANA is a concentration of 9.6×10⁻⁶ M or, in terms of mass:3.879×10⁻¹⁴ mol (39 fmol). This method is applicable to determination of NANA in normal human serum. The results were also compared with those of the colorimetrie method.     

Separation and direct UV detection of lanthanides complexed with cupferron by capillary electrophoresis

Separation and detection of lanthanides by capillary zone electrophoresis in the presence of cupferron (N-nitroso-N-phenylhydroxylamine) as UV absorbing complexing agent were investigated. The resolution of partially complexed positively charged cupferron complexes is improved by using a buffer ligand competing with cupferron for metal ions. When hydroxyisobutyric acid (HIBA) is used as buffer and competing ligand, it provides complete separation of all 14 lanthanides with good peak shapes. An on-column separation of 14 lanthanides was achieved in only 7 min using 0.1 mmol/l cupferron, 15 mmol/1 HIBA at pH 4.9. The separation efficiencies for the optimum separation condition are between 77,000 and 208,000 theoretical plates. Determination of lanthanide complexes was performed by direct UV detection at 210 nm. Detection limits (signal-to-noise ratio=3) are ca. 0.24-0.47 microg/ml for lanthanides. Under optimum conditions, the complete separation of thorium and uranium from mixed lanthanides was achieved.     

微芯片毛细管电泳非接触电导法快速测定盐酸倍他洛尔

建立了微芯片毛细管电泳非接触电导检测法快速测定盐酸倍他洛尔滴眼液中盐酸倍他洛尔的含量。探讨了缓冲液类型、浓度、分离电压及进样时间等因素对分离检测的影响。实验采用1.5 mmol·L-1HAc-1.5mmol·L-1Na Ac(p H=4.69)为缓冲溶液,分离电压为2.1 k V,进样时间10.0 s。此条件下于0.7 min内实现了盐酸倍他洛尔的快速分离测定。盐酸倍他洛尔的浓度在5.0~200.0μg·m L-1线性良好(r=0.9997,n=6),检出限为1.0μg·m L-1(S/N=3),RSD为0.8%,样品的加标回收率为100.4%~102.0%。滴眼液中的辅料在该条件下不干扰测定,可成功测定盐酸倍他洛尔滴眼液中盐酸倍他洛尔的含量。     

Trace determination of arsenic species by capillary electrophoresis with direct UV detection using sensitivity enhancement by counter- or co-electroosmotic flow stacking and a high-sensitivity cell

Stacking techniques used independently and also with a high-sensitivity cell (HSC) were employed to optimise sensitivity and detection limits in the direct photometric detection of the following eight arsenic species by capillary zone electrophoresis (CZE): arsenite, arsenate, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), 4-hydroxy-3-nitrophenylarsonic acid (Roxarsone), p-aminophenylarsonic acid (p-ASA), 4-nitrophenylarsonic acid (4-NPAA), and phenylarsonic acid (PAA) (target analytes). The stacking mechanisms, optimised stacking and separation conditions, and concentration sensitivity enhancement factors were discussed and compared for (i) normal stacking mode (NSM, sometimes also referred to as field-amplified stacking) in an uncoated fused-silica capillary in the counter-electroosmotic flow (EOF) mode, (ii) large-volume sample stacking (LVSS) with polarity switching, and (iii) the less often applied stacking method of co-EOF NSM stacking with EOF reversal using a poly(diallydimethylammonium chloride) (PDDAC)-coated capillary. The optimal injection volumes were 7.4, 60 and 17.2% of the total capillary volume, for the above three methods, respectively. LVSS with polarity switching gave the lowest limit of detection (LOD). The use of the HSC further reduced the LOD of each target analytes by a factor of 5-8 times. By combining LVSS and HSC, LODs of the target analytes could be reduced by a factor of 218-311, to 5.61, 9.15, 11.1, and 17.1 microg/L for As(III), DMA, MMA, and As(V), respectively. The method was demonstrated to be applicable to the determination of the target analytes in tap water and lake water, with recoveries in the range of 89.4-103.3%.     

盐酸二甲双胍的毛细管电泳法快速测定

建立了毛细管电泳高频电导法快速测定片剂中盐酸二甲双胍的方法。考察了缓冲溶液、有机溶剂添加剂、毛细管长度以及分离电压和进样条件等因素对分离检测的影响。在最佳条件下5.0 min内即可实现盐酸二甲双胍分离检测,盐酸二甲双胍的线性范围为1.50μg/mL~130μg/mL,检出限为1.0μg/mL。该方法成功地测定了盐酸二甲双胍片剂中的盐酸二甲双胍。     

高效毛细管电泳紫外检测法分离检测射干苷和鸢尾黄素

建立了毛细管电泳法测定射干药材中的射干苷和鸢尾黄素.探讨了检测波长、缓冲体系、缓冲液浓度和pH、分离电压等对分离的影响.在最优条件为20 mmol/L硼砂(pH 9.0),分离电压20 kV,被测物在10 min内实现基线分离.射干苷和鸢尾黄素的回收率分别为94.4%、93.5%,RSD分别为3.3%、2.8%.该法已...     

Simultaneous determination of amphoteric surfactants in detergents by capillary electrophoresis with indirect UV detection

A simple, rapid and simultaneous determination of four types of amphoteric surfactants, i.e., C8, C10, C12, C14, C16 and C18-homologues of alkyldimethylamine N-oxide (AO), alkylamidopropylamine N-oxide (APAO), alkylbetaine (Bt) and alkylamidopropylbetaine (APB), was performed by using capillary electrophoresis (CE) with indirect UV detection. To optimize the separation conditions, effects of pH of background solution (BGS), organic modifier and chromophore for indirect UV detection on the CE separation of the amphoteric compounds were investigated. Addition of 50% (v/v) acetonitrile to the BGS under a lower pH condition brought a good separation performance due to the suppression of micelle formation for the analytes and the adsorption onto the inner surface of the capillary. Under an optimal condition, the 24 amphoteric analytes were completely separated in a single run within 17min. The relative standard deviation of the migration time was ranging from 0.20 to 0.23% and the limit of detection values for AO, APAO, Bt and APB homologues were 10-20, 20, 20-50 and 50microg/mL, respectively. Furthermore, the developed method can provide a high resolution separation of the amphoteric surfactants in commercially available detergents and shampoo without any sample pretreatments.     

Determination of alkylphosphonic acids by capillary zone electrophoresis using indirect UV detection

Capillary zone electrophoresis with indirect UV detection was used for the determination of a series of alkylphosphonic acids. For this purpose, a few UV-absorbing background electrolytes were tested and phenylphosphonic acid, which has a mobility close to that of the analysed compounds, was shown to be the most suitable. The influence of several parameters such as concentration of the UV-absorbing background electrolyte and concentration of borate on both sensitivity and efficiency was investigated. An increase in the borate concentration produced an improvement of the signal-to-noise ratio. Conversely, the sensitivity decreased with increasing concentration of the phenylphosphonic acid. The reproducibility of the method was very satisfactory and limits of detection were less than 0.21 pmol injected.     

Direct determination of bromide ions in seawater by capillary zone electrophoresis using polyethyleneimine-coated capillaries

A rapid and simple capillary electrophoretic method was developed for the direct determination of bromide ion in seawater. We have found an effective method, based on the use of polyethyleneimine-coated capillaries and the addition of sodium chloride to the background electrolyte. The use of coated capillaries with a cationic polymer changes the direction of the electroosmotic flow in the capillary, which favors the migration speed of the bromide ion and enables the use of low salt concentrations in the separation electrolyte. Bromide ion in seawater can be determined within 2 min using this system and 20 mmol L^-1 NaCl-containing separation electrolyte. The detection limit for the bromide ion was 0.45 g ml^-1. The method was applied to the determination of bromide ion in seawater samples collected from the Bosphorus and the Black Sea. Bromide contents in samples from 0 to 72 m depths varied between 33.2 and 72.8 mg L^-1 with a mean 3.0% RSD.     

Simultaneous determination of inorganic anions, carboxylic and aromatic carboxylic acids by capillary zone electrophoresis with direct UV detection

Co-electroosmotic capillary zone electrophoresis (CZE) with direct UV detection was developed for simultaneous determination of inorganic anions, carboxylic and aromatic carboxylic acids. These solutes were separated using a 30 mM phosphate buffer containing 1.0 mM tetradecyltrimethylammonium bromide (TTAB) and 20% (v/v) acetonitrile at pH of 6.5 and directly detected by UV at 190 nm. Calibration curves were linear in the range 0.01-2.0 mM, depending of the solutes. The detection limits ranged from 1.0 to 8.0 microM and the relative standards deviations (n=5) in range from 1.9 to 3.6% for the peak area. The proposed method was used to determine inorganic anions and carboxylic and aromatic acids in soil and plant tissue extracts.     

Separation of perfluorocarboxylic acids using capillary electrophoresis with UV detection

A capillary electrophoretic method with UV detection for separation and quantitation of perfluorocarboxylic acids (PFCAs) from C6-PFCA to C12-PFCA has been developed. The optimization of measurement conditions included the choice of the most appropriate type and concentration of buffer in the background electrolyte (BGE), as well as the type and the content of an organic modifier. The optimal separation of investigated PFCAs was achieved with 50 mM phosphate buffer and 40% isopropanol in the BGE using direct UV detection. The optimum wavelength for direct UV detection was optimized at 190 nm. For indirect detection, several chromophores were studied. Five mM 3,5-Dinitrobenzoic acid (3,5-DNBA) in 20 mM phosphate buffer BGE and indirect UV detection at 280 nm gave the optimal detection and separation performance for the investigated PFCAs. The possibility of on-line preconcentration of solutes by stacking has been examined for indirect detection. The detection limits (LODs) determined for direct UV detection ranged from 2 microg/mL for C6-PFCA to 33 microg/mL for C12-PFCA. The LODs obtained for indirect UV detection were comparable to those obtained for direct UV detection.     

微芯片毛细管电泳快速测定盐酸洛美沙星

采用微芯片毛细管电泳非接触电导检测法快速测定了盐酸洛美沙星胶囊中盐酸洛美沙星的含量。探讨了缓冲液类型、浓度,添加剂种类、浓度及分离电压、进样时间等因素对分离检测的影响。实验采用5.0mmol/L HAc(pH=2.5)+5%乙醇为缓冲溶液,分离电压3.0 kV,在1 min内实现了盐酸洛美沙星的快速分离测定。优化条件下盐酸洛美沙星的线性范围为20.0～250.0μg/mL,检出限为10.0μg/mL(S/N=3),RSD=2.0%,加标回收率为98.6%～103%。     

Separation of haloacetic acids in water by capillary zone electrophoresis with direct UV detection and contactless conductivity detection

The separation of haloacetic acids (HAAs) in water by capillary zone electrophoresis with direct UV and contactless conductivity detection was investigated using phosphate, citrate, and borate buffers, and the experimental data were compared to simulation data predicted by a computational program known as PeakMaster. Good agreement between the experimental data and simulation data predicted by PeakMaster was found. Using the phosphate buffer or the citrate buffer and electrokinetic injection it was possible to quantitate HAAs at 0.1 ppm levels in water.     

Separation and determination of inorganic cations in beverages by capillary electrophoresis with indirect UV detection

A rapid, simple and reliable capillary electrophoresis method for the separation and quantitation of inorganic cations with indirect UV detection at 214 nm was developed. The electrolyte was: 12 mM imidazole as background absorbance provider; 5 mM malic acid and 1.0 mM 18-crown-6 ether as complexing agents; and 20% D₂O (v/v) to improve ion mobility. The pH was 4.25. The applied voltage was 22 kV at 22°C. Nine ions were completely separated and determined with correlation coefficients of 0.9979-0.9992. The relative standard deviations (RSD) were less than 0.5% for migration time and less than 5.2% for peak area (n=8). The detection limits (S/N=3) were from 0.08 mg L⁻¹ (for Na⁺) to 0.51 mg L⁻¹ (for Cu²⁺). To assess the reliability atomic absorption (AA) was also used to determine the same samples. Satisfactory results were obtained for real samples of jasmine tea drink and coconut milk.      

Separation of metal cations in acidic solution by capillary electrophoresis with direct and indirect UV detection

Methods for the detectionn of metal cations under acidic conditions, near PH 2, in capillary electrophoresis (CE) were investigatged. Conditions for direct UV detection of UV absorbing metal cations such as Cr³⁺, Cu²⁺, Fe³⁺, UO₂²⁺, VO²⁺, and VO²⁺ were established With aqueous HCl or HClO₄ as the electroyte carrier. The speciation of vanadium(IV) and vanadium(V) at PH 2.3 by CE was achieved with direct detection at 185 nm. With the strong absorbance at 185 nm, no complexation was needed to detect the metal cations. An indirect UV detrection scheme for acidic conditions was also investigated. Several background carrier electolytes (BCES) were studied including 4-methylbenzylamince, nicontinamide, pyridazine, guanidine, 3-picoline, and chromium (III) to determine their effectivencess under very acidic conditions. The efect of ioni c surfactants and the nonionic surfactant, Trition X-100, on the peak heights and N Values was also studied.     

Characterization of cationic copolymers by capillary electrophoresis using indirect UV detection and contactless conductivity detection

For many industrial applications, the combination of two different monomers in statistical or diblock copolymers enhances the properties of the corresponding polymer. However, during the polymerization reaction, homopolymers might be formed and can influence the properties for the applications. Consequently, the separation and the quantification of the homopolymers contained in copolymer samples are crucial. In addition, the charge density distribution of the statistical copolymer is an important characteristic for the applications. The purpose of this work was to study the characterization of a statistical copolymer of acrylic acid (AA) and diallyldimethyl ammonium chloride (DADMAC) by capillary electrophoresis (CE) in acidic conditions (cationic copolymers). For that purpose, a free solution electrophoretic separation was carried out according to the charge rate (chemical composition) independently of the molar mass. The second objective was to compare contactless conductivity detection and indirect UV absorbance modes for the quantification of DADMAC homopolymers present in copolymer samples. Different coated capillaries based on neutral or positively charged modification were also compared. The comparison of indirect absorbance UV and contactless conductimetric detection demonstrated that both detection modes can be used for a complete CE characterization of non-UV absorbing PAA-DADMAC copolymers.     

毛细管电泳电致化学发光法测定洛贝林的研究

基于稀土掺杂类普鲁士蓝化学修饰电极对Ru(bpy)32 的电催化氧化可增敏电致发光信号,建立了一种毛细管电泳-电致化学发光测定洛贝林的新方法。研究了工作电极电位、缓冲液的酸度及其浓度、分离电压和进样时间等实验参数对洛贝林测定的影响。在优化的实验条件下,其线性范围为1.5×10-7mol/L~1.5×10-4mol/L,检出限(S/N=3)为5.0×10-8mol/L。本法可直接用于注射液和空白人尿中洛贝林的测定,回收率为98.3%~101.2%。     

Determination of dioxopromethazine hydrochloride by capillary electrophoresis with electrochemiluminescence detection

The paper presents a rapid method for the determination of dioxopromethazine hydrochloride (DPZ), an antihistamine drug, by the capillary electrophoresis with electrochemiluminescene detection (CE–ECL) using tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) reagent. This CE–ECL detection method has high sensitivity, good selectivity and reproducibility for DPZ analysis. Under the optimized conditions: separation capillary, 38 cm length (25 μm i.d.); sample injection, 10 s at 8 kV; separation voltage, 12.5 kV; running buffer, 20 mmol L⁻¹ sodium phosphate of pH 6.0; detection potential, 1.15 V; 50 mmol L⁻¹ of phosphate buffer (pH 7.14) containing 5 mmol L⁻¹ of Ru(bpy)₃²⁺ in ECL detection cell, the detection limit of DPZ was 0.05 μmol L⁻¹ (S/N = 3). The linear range extended from 5 to 100 μmol L⁻¹. The linear curve obtained was Y = 181.62 + 9.28X with a correlation coefficient of 0.9970. The relative standard deviations of the ECL intensity and the migration time for six continuous injections of 5 μmol L⁻¹ DPZ were 3.7% and 0.92%, respectively. The CE–ECL method was applied to analyze DPZ in real samples including tablets, rat serum and human urine, and satisfactory results were obtained without interference from samples matrix. The CE–ECL technique was proved to be a potential method for the detection of DPZ in clinic analysis.     

Solid-state UV laser-induced fluorescence detection in capillary electrophoresis

Two solid-state UV lasers were applied to the laser-induced fluorescence (LIF) detection of various groups of compounds after separation by capillary electrophoresis. These lasers are thermoelectric-cooled, highly compact, and inexpensive. Such lasers provide few mW of quasi-continuous wave (CW) power which are sufficient and stable for LIF detection. Native fluorescence detection of tryptophan-containing proteins and peptides and related indoles was achieved at the nM level with the laser operating at 266 nm. Detection of fluorescamine-labeled amino acids and peptides was also possible at the nM level with the laser operating at 355 nm. Amino acids at a concentration as low as 10 ng/mL could be labeled with fluorescamine. Solid-state UV-LIF detection of the tryptic digest of cytochrome c after fluorescamine derivatization was demonstrated.