Easy sample treatment for the determination of enrofloxacin and ciprofloxacin residues in raw bovine milk by capillary electrophoresis

An easy, selective, and sensitive method has been developed for the determination of enrofloxacin (ENR) and its main active metabolite, ciprofloxacin (CIP), in raw bovine milk using CE with UV detection at 268 nm. Milk samples were prepared by a clean‐up/extraction procedure based on protein precipitation with hydrochloride acid followed by being defatted by centrifugation and SPE using a hydrophilic‐lipophilic balance cartridge. Optimum separation was obtained using a 50 mM phosphoric acid at pH 8.4 and the total electrophoretic run time was 6 min. Sample preparation by this method yielded clean extracts with quantitative and consistent mean recoveries from 89 to 97% for CIP and from 93 to 98% for ENR. LODs obtained were lower to the maximum residue limits for these fluoroquinolones. The precision of the ensuing method is acceptable; thus, the RSD for peak area and migration time was less than 8.5 and 0.5% for CIP and 9.9 and 0.9% for ENR, respectively. The results showed that the proposed method was efficient showing good recoveries, sensitivity, and precision for the studied compounds and could be satisfactorily applied in routine analysis for the monitoring of ENR and CIP residues in milk, due to its ruggedness and feasibility demonstrated.     

Separation and determination of enkephalin-related peptides using capillary electrophoresis

CZE with UV-absorption detection has been used for the separation and determination of enkephalin-related peptides. The experimental conditions, such as pH and concentration of running buffer, applied voltage, injection method, and time, were investigated in detail. Excellent separation efficiency could be obtained for ten enkephalin-related peptides with a 50 microm (ID) x 58 cm capillary using sodium dihydrogen phosphate as the running buffer (pH 3.11) when 20 kV of applied voltage was used. The concentration detection limits were found to be in the range of 0.31-1.94 microg/mL (defined as S/N = 3). The proposed method has been applied to analyze the spiked cerebrospinal fluid (CSF) sample, and the results showed that CZE is a powerful technique for separation and detection of the above biological peptides.     

Development and application of a capillary electrophoresis-electrochemiluminescent method for the analysis of enrofloxacin and its metabolite ciprofloxacin in milk

Enrofloxacin (ENR) is a fluoroquinolone developed exclusively for the use in veterinary practice for the treatment of respiratory and gastrointestinal infections, and ciprofloxacin (CIP) is its main active metabolite. Their contents are regulated by the EU Council Regulation no. 2377/90 in animal edible tissues. We developed a sensitive and rapid method for the determination of ENR and CIP by capillary electrophoresis (CE) with electrochemiluminescence (ECL) detection. The method is based on the detection of aliphatic tertiary or secondary amino moieties in ENR and CIP with end-column tris(2,2-bipyridyl)ruthenium(II) electrochemiluminescence. Parameters that affect separation and detection were optimized. Under the optimized conditions, the calibration functions were linear in the range of 0.03–1 μg ml⁻¹ for ENR and 0.05–1.2 μg ml⁻¹ for CIP. The detection limits of ENR and CIR were 10 ng ml⁻¹ and 15 ng ml⁻¹, respectively, based on the signal-to-noise ratio of 3. The relative standard derivations of the peak height and the migration time for ENR and CIP were less than 4.13%. The developed method was successfully applied to determine ENR and CIP in milk with a solid-phase extraction procedure.     

肌肽类生物活性肽的毛细管电泳在线富集技术

建立了毛细管区带电泳(CZE)在线富集3种肌肽类活性肽(肌肽、鹅肌肽和高肌肽)的两种简便有效的方法。一种是大体积进样反向压力排除基体富集（LVSRP）技术,即通过流体动力学进样,在不改变电源极性的条件下,利用反向压力排除样品基体,电堆积富集后进行CZE分离;另一种是大体积进样电渗流排除基体富集（LVSEP）技术,即通过流体动力学进样,于运行缓冲液中加入溴化十六烷基三甲基铵(CTAB)动态修饰毛细管表面,通过电渗流排除样品基体,改变电源极性后进行CZE分离。与常规CZE相比,LVSRP技术和LVSEP技术使检测灵敏度提高了40~60倍。对影响两种富集过程的一些因素进行了研究,在最优富集条件下考察本方法的线性范围为0.080~5.0 μmol/L。对3种生物活性肽的检测限(S/N=3)分别为LVSRP 41~58 nmol/L,LVSEP 35~43 nmol/L。     

毛细管电泳-安培检测法用于7-甲基鸟苷与丝裂霉素C分离检测的研究

建立了一种同时分离检测7-甲基鸟苷与丝裂霉素C的毛细管电泳-安培检测方法。在950 mV电极(工作电极:0.3 mm微型石墨圆盘电极;参比电极:Ag/AgCl;辅助电极:Pt丝)电位下,于20 mmol/L的磷酸盐缓冲体系(pH 9.4)中,采用18 kV的分离电压进行分离。在最佳条件下,7-甲基鸟苷与丝裂霉素C在10 min内实现分离,7-甲基鸟苷与丝裂霉素C的线性范围均为0.50~50 mg/L,检测限分别为0.050 mg/L与0.025 mg/L。将该方法用于模拟尿样和模拟兔血清样的检测,7-甲基鸟苷与丝裂霉素C的回收率为93.0%～97.2%,结果令人满意。     

Simultaneous determination of aripiprazole and its active metabolite,dehydroaripiprazole, in plasma by capillary electrophoresis combining on‐column field‐amplified sample injection and application in schizophrenia

A sensitive high‐performance CZE combining on‐column field‐amplified sample injection (FASI) has been developed for simultaneous determination of aripiprazole and its active metabolite, dehydroaripiprazole, in human plasma. A sample pretreatment by means of liquid–liquid extraction (LLE) (diethyl ether) with subsequent quantitation by FASI‐CZE was used. The separation of aripiprazole and dehydroaripiprazole was performed using a BGE containing 150 mM phosphate buffer (pH 3.5) with 40% methanol and 0.02% PVA as a dynamic coating to reduce interaction of analytes with the capillary wall. Before sample loading, a methanol plug (0.3 psi, 6 s) was injected to permit FASI for stacking. The samples were injected electrokinetically (10 kV, 30 s) to introduce sample cations and the applied voltage was 20 kV with on‐column detection at 214 nm. Several parameters affecting the separation and sensitivity of the drug and its active metabolite were studied, including reconstitution solvent, organic modifier, pH and concentration of phosphate buffer. The linear ranges of the method for test drug and its active metabolite, in plasma using amlodipine as an internal standard, were over the range 5.0–100.0 ng/mL. One female volunteer (25 years old) was orally administered a single dose of 10 mg aripiprazole (Abilify^®, Otsuka) and blood samples were drawn over a 60 h period for pharmacokinetic study. The method was also applied to monitor the concentration of aripiprazole and dehydroaripiprazole in plasma collected after oral administration of 20 or 30 mg aripiprazole (Abilify^®, Otsuka) daily at steady state in one schizophrenic patient.     

微芯片毛细管电泳法快速测定黄花鱼中的碱性嫩黄O

采用微芯片毛细管电泳非接触电导检测法,对黄花鱼中非法添加的工业染料碱性嫩黄O进行了分析。 探讨了缓冲液种类、浓度,分离电压和进样时间等因素对分离检测的影响。 实验选择5.0 mmol/L乳酸缓冲液(pH=3.29)、1.8 kV分离电压,在1.0 min内实现了碱性嫩黄O的快速分离测定。 在优化条件下,碱性嫩黄O浓度的线性范围为5.0～100.0 mg/L,黄花鱼中碱性嫩黄O的检出限为0.2 mg/kg,该法可成功测定黄花鱼中碱性嫩黄O的含量。     

Combined use of ionic liquid and sulfobutylether‐β‐cyclodextrin as electrolyte additives for separation and determination of camptothecin alkaloids by CZE

This work reported that ionic liquid (IL) ([Bmim] [PF₆]) and sulfobutylether‐β‐CD (SBE‐β‐CD) were used as electrolyte additives for the separation and determination of camptothecin (CPT) alkaloids by CZE. Separation parameters such as the buffer type, pH, and concentration of the running buffer, the concentration of SBE‐β‐CD and IL, temperature, and separation voltage were all investigated in order to achieve the maximum possible resolution. The four analytes were baseline separated within 10 min in capillary at the separation voltage of 15 kV with a running buffer consisting of 20 mM borate buffer, 20 mM IL, and 100 mM SBE‐β‐CD at pH 9.0. Under such conditions, good linearity about two orders of magnitudes of peak areas was achieved for the investigated CPT alkaloids with the correlation coefficients ranging from 0.9946 to 0.9985. For all analytes, detection limits (S/N = 3) and quantitation limits (S/N = 10) range from 0.05 to 0.92 μg/mL and 0.17 to 3.06 μg/mL, respectively. The proposed method has not only been successfully applied to the separation and determination of CPT alkaloids but also showed that IL seemed to be a promising additive in CZE separation.     

Determination of carbonyl compounds in air by electrochromatography

A new analytical procedure based on electrochromatography was developed for the separation and quantitation of 14 aldehydes and ketones (formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, butanone, crotonaldehyde, isobutyraldehyde/butyraldehyde, 2-pentenaldehyde, isovaleraldehyde, valeraldehyde, benzaldehyde and hexanaldehyde) in ambient air currently to be regulated by the Hong Kong Environmental Protection Department. A volatile mobile phase using ammonium acetate compatible with mass spectrometry detection was developed and optimized as follows. Methanol: acetonitrile: aqueous buffer (4 mM ammonium acetate) = 65:5:30% v/v. With electrokinetic injection at 5 kV for 2 s, aqueous buffer pH adjusted to 8, applied voltage controlled at 25 kV, and detection at 360 nm in a fused-silica column packed with 3 microm ODS, a satisfactory separation was obtained for the 14 carbonyl compounds investigated. The working ranges in acetonitrile solution were found to vary from 0.25 to 79 mg/L with a correlation coefficient greater than 0.99, detection limits from 0.10 to 0.63 mg/L, and precision (relative standard deviation, n = 3) from 2.3 to 9.2%. Under an air flow rate of 0.3 L/min for a sampling time of 1 h, the working ranges varied from 0.030 to 11,000 microg/m3 and detection limits from 0.011 to 0.084 microg/ m3. The method has been successfully applied to monitor three carbonyl compounds in four urban and rural sites in Hong Kong and gave hourly readings of three carbonyl compounds for all the sites investigated with a separation time less than 25 min.     

Pre-capillary derivatisation and capillary zone electrophoresis for amino acids analysis in beverages

A simple and rapid method for the simultaneous analysis of amino acids has been developed. Amino acids were derivatised based on pre-capillary derivatisation with 1,2-naphthoquinone-4-sulfonate (NQS) in basic medium (pH 10.0) and developed reaction at 70 degrees C. Their derivatives were analysed by capillary zone electrophoresis (CZE). The parameters affecting CZE separation were investigated including buffer (pH, type and concentration), organic modifier and separation voltage. The optimum condition was 70 mmol L(-1) borate (pH 10.0) containing 10% acetonitrile, separation voltage of 12 kV, and sample injection (0.5 psi, 5s) and on-capillary detection at 240 nm. The separation of seven amino acids was achieved within 17 min. The detection limit was 1.0 mg L(-1) for all studied amino acids. The calibration curves were linear in the concentration range of 1.0-100.0 mg L(-1). The repeatability, intra-day and inter-day analysis were < or = 1.0% and < or = 2.0% for migration time and < or = 5.0% and 6.0% for peak area. The proposed method has been applied to several beverage samples with only a simple dilution and filtration treatment of sample before derivatisation and analysed by CZE.     

胶束毛细管电泳在线推扫技术分离检测猪肉组织中痕量喹诺酮类药物

利用胶束毛细管电泳法结合在线推扫富集技术对组织中残留的痕量环丙沙星、氧氟沙星和恩诺沙星进行了检测, 弥补了毛细管电泳检测灵敏度低的缺点, 大大减化了操作过程, 为动物食品组织中残留的痕量药物检测提供了一种新的简便可靠的方法.     

Poly(methacrylic acid-ethylene glycol dimethacrylate) monolith in-tube solid-phase microextraction applied to simultaneous analysis of some amphetamine derivatives in urine by capillary zone electrophoresis

A method based on in-tube solid-phase microextraction and capillary zone electrophoresis (CZE) was proposed for simultaneously determining four amphetamines (amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, and 3,4-methylenedioxymethamphetamine) in urine. A poly(methacrylic acid-ethylene glycol dimethacrylate) monolithic capillary column, which can provide sufficient extraction efficiency, was introduced for the extraction of amphetamines from urine samples. The hydrophobic main chains and acidic pendant groups of the monolithic column make it a superior material for extraction of basic analytes from aqueous matrix. After extraction, the samples were analyzed by CZE. The best separation was achieved using a buffer composed of 0.1 M disodium hydrogen phosphate (adjusted to pH 4.5 with 1 M hydrochloric acid) and 20% methanol v/v, with a temperature and voltage of 25 degrees C and 20 kV, respectively. By applying electrokinetic injection with field-amplified sample stacking, detection limits of 25-34 microg/L were achieved. Excellent method of reproducibility was found over a linear range of 0.1-5 mg/L. Determination of these analytes from abusers' urine sample was also demonstrated.     

Method development and validation for the separation and determination of omeprazole enantiomers in pharmaceutical preparations by capillary electrophoresis

A new capillary zone electrophoresis (CZE) method for the separation of omeprazole enantiomers has been developed. Methyl-β-cyclodextrin (methyl-β-CD) was chosen as the chiral selector, and several parameters, such as cyclodextrin structure and concentration, buffer concentration, pH, and capillary temperature were investigated in order to optimize separation and run times. Analysis times, shorter than 8 min were found using a background electrolyte solution consisting of 40 mM phosphate buffer adjusted to pH 2.2, 30 mM β-cyclodextrin and 5 mM sodium disulphide, hydrodynamic injection, and 15 kV separation voltage. Detection limits were evaluated on the basis of baseline noise and were established 0.31 mg/l for the omeprazole enantiomers. The proposed method was applied to five pharmaceutical preparations with recoveries between 84 and 104% of the labeled contents.     

毛细管区带电泳法同时分离测定香兰素和邻位香兰素异构体

建立了同时测定香兰素和其异构体邻位香兰素的毛细管区带电泳法(CZE)。考察了缓冲溶液的种类、浓度和pH以及分离电压等因素对分离结果的影响。在缓冲溶液为50 mmol/L硼砂-150 mmol/L磷酸氢二钠(pH 7.5)、分离电压15 kV的优化条件下,6 min内即可实现分离。香兰素和邻位香兰素在10～240 mg/L范围内线性关系良好,相关系数分别为0.9999和0.9997;方法的检出限均为1.0 mg/L (信噪比为3);样品的加标回收率为99.4%～101.2%,相对标准偏差为0.19%～0.73%。该方法操作简单、快速,已应用于实际样品的分析,并获得了令人满意的结果。     

Development and validation of a capillary electrophoresis method for the determination of phenothiazines in human urine in the low nanogram per milliliter concentration range using field-amplified sample injection

A capillary zone electrophoresis (CZE) method with ultraviolet-visible detection has been established and validated for the determination of five phenothiazines: thiazinamium methylsulfate, promazine hydrochloride, chlorpromazine hydrochloride, thioridazine hydrochloride, and promethazine hydrochloride in human urine. Optimum separation was obtained on a 64.5 cm x 75 microm bubble cell capillary using a buffer containing 150 mM tris(hydroxymethyl)aminomethane and 25% acetonitrile at pH 8.2, with temperature and voltage of 25 degrees C and 20 kV, respectively. Naphazoline hydrochloride was used as an internal standard. Field-amplified sample injection (FASI) has been applied to improve the sensitivity of the detection. Considering the influence of parameters affecting the on-line preconcentration (nature of preinjection plug, sample solvent composition, injection times, and injection voltage) and due to the significant interactions among them, in this paper we propose for the first time the application of a multivariate approach to carry out the study. The optimized conditions were as follows: preinjection plug of water for 7 s at 50 mbar, electrokinetic injection for 40 s at 6.2 kV, and 32 microm of H3PO4 in the sample solvent. Also, a solid-phase extraction (SPE) procedure is developed to obtain low detection limits and an adequate selectivity for urine samples. The combination of SPE and FASI-CZE-UV allows adequate linearities and recoveries, low detection limits (from 2 to 5 ng/mL), and satisfactory precisions (3.0-7.2% for an intermediate RSD %).     

Determination of enrofloxacin and its primary metabolite, ciprofloxacin, in pig tissues. Application to residue studies

A simple and sensitive HPLC method has been developed for the simultaneous determination of enrofloxacin (ENR) and ciprofloxacin (CIP) in pig tissue using difloxacin (DIF) as internal standard. Tissue sample preparations were carried out by adding phosphate buffer (pH 7.4, 0.1 m), followed by extraction with trichloromethane. Fluoroquinolones were separated on a reversed-phase column and eluted with aqueous buffer solution-acetonitrile (80:20, v/v). The concentrations of CIP, ENR and DIF eluted from the column, with retention times of 2.20, 2.73 and 4.38 min, respectively, were monitored by fluorescence detection at lambda(ex) 276 and lambda(em) 442 nm. The detection and quantitation limit were 8 and 25 ng/g, respectively, for both compounds. Standard curves were linearly related to concentration in the range 25-400 ng/g. The consequences of the introduction of minor reasonable variations (ruggedness studies) have also been analysed. Finally, the measurement of the tissue levels of ENR and CIP in the pig tissues after oral administration confirmed the utility of the proposed method.     

高效毛细管电泳法测定牛奶和奶粉中残留的三聚氰胺

建立了牛奶和奶粉中三聚氰胺的高效毛细管电泳-二极管阵列检测器(HPCE-DAD)检测方法。使用长度58.5 cm、内径75 μm的毛细管柱,分离电压25 kV,进样量3.5 kPa (35 mbar)×8 s,分离温度25 ℃,缓冲溶液20 mmol/L 柠檬酸-40 mmol/L 磷酸氢二钠(pH 2.6),检测波长232 nm。分析物在1~100 mg/L 范围内线性良好,r2>0.997;牛奶和奶粉的定量限分别为0.5 mg/kg和1.0 mg/kg。在添加水平为定量限浓度至50 mg/kg时的回收率为72.2%~97.3%,相对标准偏差为2.1%~3.9%。     

胶束在线扫集毛细管电泳法测定三聚氰胺

研究胶束在线扫集毛细管电泳法测定三聚氰胺的可行性,结果表明,与区带毛细管电泳相比,胶束在线扫集毛细管电泳法富集倍数提高约60倍。缓冲体系为140 mmol/L SDS+20 mmol/L NaH2PO4(pH 2.20)+10%(体积分数)甲醇,分离电压-18 kV,进样时间30 s,测量波长214 nm。考察了SDS浓度、pH、进样时间、运行电压等因素对分离测定的影响情况。在优化条件下,三聚氰胺在9 min时出峰,峰面积RSD≤3.7%。方法检出限、线性范围、相关系数分别为:0.13μg/mL、0.50~32.0μg/mL、0.9997。方法可用于奶粉中三聚氰胺的分离测定。     

微流控芯片非接触电导法测定药品中的精氨酸布洛芬含量

建立了微流控芯片非接触电导检测快速测定精氨酸布洛芬含量的方法。考察了缓冲液种类和浓度、添加剂、分离电压以及进样时间等因素对分离检测的影响。优化条件为:20 mmol/L Tris-20 mmol/L H3BO3(p H 8.6)为缓冲溶液、不加添加剂、分离电压2.0 k V、进样时间10.0 s,在45.0 s内可实现精氨酸布洛芬的快速分离测定。结果表明,布洛芬和精氨酸在80.0~1.00×103mg/L范围内线性关系良好,相关系数(r)分别为0.998和0.997,检出限(S/N=3)为60 mg/L,相对标准偏差分别为1.9%和1.8%,加标回收率分别为97.9%~103%和97.3%~102%。该方法快速、简便,为精氨酸布洛芬非甾体抗炎药物的分析和质量控制提供了一种新方法。     

Isotachophoretic focusing and mass spectrometry detection as tools for improving the determination of aromatic sulfonates in capillary electrophoresis

We explored isotachophoresis-capillary zone electrophoresis (ITP-CZE) with diode array detection on a single capillary to find out how to increase the injection volume and decrease the detection limits of aromatic sulfonates in CZE. The ITP was performed by applying a negative voltage in conjunction with hydrodynamic backpressure programming, and the terminating buffer was removed before the CZE separation, which resulted in highly sensitive determinations. The ITP increased the signal response of conventional hydrodynamic injection by a factor of 100, whereas the separation efficiency was unaffected. The limits of detection of the method were between 3 and 5 nugL(-1). The method was successfully used to determine these compounds in water samples. Experimental conditions for capillary electrophoresis-mass spectrometry were optimized and applied to determine aromatic sulfonates in water samples. These techniques enables the 2-naphthalenesulfonate to be determined in water samples.