Determination of biogenic amines by capillary zone electrophoresis with conductometric detection

A capillary zone electrophoresis (CZE) method with conductometric detection of biogenic amines (cadaverine, putrescine, agmatine, histamine, tryptamine and tyramine) is described. The optimised background electrolyte was the following: 15 mM histidine + 5 mM adipic acid + 1.5 mM sulphuric acid + 0.1 mM ethylenediaminotetraacetic acid + 0.1% hydroxyethylcellulose + 50% methanol. A clear separation of six biogenic amines from other components of acidic sample extract was achieved within 10 min. Method characteristics, i.e., linearity (0-100 micromol/ml), accuracy (recovery 86-107%), intra-assay repeatability (2-4%), and detection limit (2-5 micromol/l) were evaluated. Low laboriousness, sufficient sensitivity, speed of analysis, and low running cost are important attributes of this method. The developed method was successfully applied on the determination of biogenic amines in selected food samples.     

毛细管电泳分离几种神经递质的研究

研究了不同毛细管预处理方法对组胺、5-羟色胺及儿茶酚胺类神经递质电泳分离的影响，采用优化的毛细管预处理方法及电泳分离条件基线分离了组胺、5-羟色胺、去甲肾上腺素和肾上腺素。利用多巴胺和5-羟色胺在毛细管内壁吸附效应的不同，对电泳淌度极为相近的多巴胺和5-羟色胺进行了分离和鉴定。以PC22细胞为研究对象，证实了该细胞中所含大量神经递质是多巴胺，不是5-羟色胺。     

Determination of biogenic amines by capillary electrophoresis using a chameleon type of fluorescent stain

A method was developed for the determination of biogenic amines (BAs) via micellar electrokinetic chromatography along with laser induced fluorescence detection using the amino-reactive chameleon stain Py-1. A labeling protocol was established for seven primary BAs by optimizing the reaction conditions in terms of the amount of reagents, reaction temperature, reaction time and solvent. Derivatization was accomplished within 30 min and is visible by the naked eye because it is accompanied by a color change from blue to red. Separation of the labeled BAs was achieved within 15 min with a background buffer of pH 2.5 containing phosphate, Tween®80, and methanol. The LODs range from 0.1 to 0.9 µmol·L^?1, with RSDs ranging from 1.1 to 4.2% at 10 µmol·L^?1. The method was applied to the determination of histamine in various fish samples.     

Selective and rapid determination of biogenic amines by capillary zone electrophoresis

Summary A rapid separation of 21 amines by high-performance capillary zone electrophoresis with indirect photometric detection is presented. The electrolyte is based on copper(II) as primary constituent. Factors affecting the separation by this electrolyte have been investigated and include the composition of the buffer, the voltage, the temperature and the mode of injection. External calibration was used to characterize the analytical response to each amine. The detection limits were approximately 0.05 μg mL⁻¹ for almost all the amines. After electrokinetic or hydrodynamic injection calibration plots of peak area against concentration were linear between 0.05 and 10 μg mL⁻¹. The method has been applied to the analysis of biogenic amines in synthetic samples; the recoveries of the amines from such samples, determined by the standard addition technique, were in the range 90 to 110%.     

Sensitive profiling of biogenic amines in human urine by capillary electrophoresis with field amplified sample injection

In order to monitor biogenic amines in human urine, a method based on field‐amplified sample injection combined with capillary electrophoresis and direct UV absorption detection was developed. Dopamine, tyramine, tryptamine, serotonin and epinephrine were effectively separated and identified in human urine samples, and detection limits were 0.072, 0.010, 0.027, 0.010 and 0.120 µmol/L, respectively. Detection limits comparable to laser‐induced fluorescence detection or solid phase extraction combined with capillary electrophoresis were achieved. Parameters affecting electrophoretic system detection sensitivity were investigated. Optimal separation conditions were obtained using as background electrolyte a pH 6.5 mixture of 2‐(morpholino)ethanesulfonic acid 20 mmol/L and 30 mmol/L phosphate buffer, containing 0.05% hydroxypropylcellulose and 10% v/v methanol. Injections of the sample solution were performed by applying a voltage of 12 kV for 50 s. Recovery and accuracy ranged between 89.4 and 94.9%, and 89 and 112%, respectively. The method was successfully applied on actual urine samples (from a healthy volunteer): target bioamine content was consistent with endogenous levels reported in the literature. The proposed method is simple, fast and inexpensive and can be conveniently employed in work‐related stress studies. The affordability and noninvasive sampling of the method allow epidemiological studies on large number of exposed persons to be performed. Copyright © 2013 John Wiley & Sons, Ltd.     

Direct analysis of biogenic amines in water matrix by modified capillary zone electrophoresis with 18-crown-6

We report on a method for the determination of the biogenic amines (BAs) spermine, spermidine, histamine, cadaverine, β-phenylethylamine, tyramine and tryptamine. It is based on capillary zone electrophoresis in the presence of 18-crown-6 (180?mM), and is making use of amperometric detection. Under optimized conditions, seven BAs could be well separated within 29?min at a separation voltage of 14?kV in a buffer solution of pH 3.6. The limits of detection for seven BAs are around 10?ng.mL^?1 for standard mixtures. The method does not require preconcentration and derivatization steps, and thus provides an attractive alternative to quantitative multi-analysis of BAs in water samples.

Quantification of biogenic amines by microchip electrophoresis with chemiluminescence detection

A highly sensitive microchip electrophoresis (MCE) method with chemiluminescence (CL) detection was developed for the determination of biogenic amines including agmatine (Agm), epinephrine (E), dopamine (DA), tyramine, and histamine in human urine samples. To achieve a high assay sensitivity, the targeted analytes were pre-column labeled by a CL tagging reagent, N-(4-aminobutyl)-N-ethylisoluminol (ABEI). ABEI-tagged biogenic amines after MCE separation reacted with hydrogen peroxide in the presence of horseradish peroxidase (HRP), producing CL emission. Since no CL reagent was added to the running buffer, the background of the CL detection was extremely low, resulting in a significant improvement in detection sensitivity. Detection limits (S/N = 3) were in the range from 5.9 × 10⁻⁸ to 7.7 × 10⁻⁸ M for the biogenic amines tested, which were at least 10 times lower than those of the MCE–CL methods previously reported. Separation of a urine sample on a 7 cm glass/poly(dimethylsiloxane) (PDMS) microchip channel was completed within 3 min. Analysis of human urine samples found that the levels of Agm, E and DA were in the ranges of 2.61 × 10⁻⁷ to 4.30 × 10⁻⁷ M, 0.81 × 10⁻⁷ to 1.12 × 10⁻⁷ M, and 8.76 × 10⁻⁷ to 11.21 × 10⁻⁷ M (n = 4), respectively.     

Determination of surfactants by capillary electrophoresis

Capillary electrophoresis has been increasingly used during the past few years for the separation and determination of surfactants. These substances are applied in many household and industrial products such as laundry detergents, cosmetics and pharmaceuticals, often as homologous and isomeric mixtures. Product development and control as well as toxicological and environmental analyses require selective and sensitive analytical methods. This review presents capillary electrophoretic techniques to determine important representatives of cationic, anionic, and neutral surfactants. The application of different buffer additives such as organic solvents, cyclodextrins or micelles to enhance the resolution of complex mixtures is discussed. Besides direct and indirect UV and fluorescence detection, examples for conductivity and mass spectrometric detection are also given. Derivatization procedures to improve the detectability and implement charge in neutral analytes are described. The successful use of capillary electrophoresis for surfactant determinations has proven that it can serve as a routine technique in many real-world applications. Robust, validated methods for the quantitation of single compounds, such as alkylbenzene sulfonates, sodium dodecyl sulfate and benzalkonium salts, are now available. Characteristic peak patterns (fingerprint analysis) can be used for the identification of surfactants in multicomponent formulations (e.g. ethoxylates and phosphonates).     

Determination of polyhexamethyleneguanidine by capillary electrophoresis

The electrophoretic behavior of polyhexamethyleneguanidine hydrochloride (PHMG HC), hexamethylenediamine (HMDA), and guanidine hydrochloride (GHC) was studied. It was shown that PHMG HC and the initial toxic components of its synthesis, GMDA and GHC, can be separated. A procedure was developed for determining PHMG HC oligomers, GMDA, and GHC in aqueous solutions in concentrations from 0.007 to 0.05 mg/mL by capillary electrophoresis. The procedure was applied to the analysis of model mixtures of these compounds.     

Determination of aromatic amines in water samples by capillary electrophoresis with electrochemical and fluorescence detection

Two capillary electrophoresis methods have been compared for the determination of aniline derivatives in environmental water samples. With the first method the anilines were separated as cations by free zone electrophoresis at low pH, and detected by amperometry. For this, the separation capillary was connected through a palladium field decoupler to an electrochemical detection cell which had been modified to match the volume scale of the separation. Most anilines tested, except chlorinated compounds, could be detected with full sensitivity at a detection potential of +0.7 V. Detection limits with this detection scheme were on a low microg/l level. The alternative method involved the derivatization of the anilines with fluorescamine, the separation of the derivatives formed by micellar electrokinetic chromatography, and fluorescence detection. For detection a lamp-based, fibre optics instrument was used. Detection limits with fluorimetry were comparable with those obtained with amperometric detection (in the order of 1 microg/l). Still, this method was preferred since it gave a higher separation efficiency and shorter analysis times (approximately 4 min). The most important argument, however, was its higher reliability and ease-of-handling. Preliminary experiments with water samples collected in areas where pollution with anilines may be expected showed that the method is highly specific, with few interferences showing up in the electropherograms.     

Determination of heterocyclic aromatic amines by capillary electrophoresis coupled to mass spectrometry using in-line preconcentration

This paper shows the potentiality of capillary electrophoresis (CE) coupled to mass spectrometry (MS) for the analysis of heterocyclic aromatic amines obtaining good results in terms of sensitivity and precision. These compounds have a special interest since they can be carcinogenic for humans. The optimization of a CE-MS method was performed and the best conditions were obtained using a 16 mM formic acid/ammonium formate solution at pH 4.5 with 60% methanol as running electrolyte. For CE-MS coupling, a sheath liquid methanol/20 mM formic acid (75/25) solution at a flow rate of 3 microL/min and hydrodynamic injection of methanol mixtures for 10 s were used. Detection limits ranging from 18 ng/g to 360 ng/g and precisions up to 1.4% and 12% for migration time and concentration, respectively, were obtained. In order to improve sensitivity, field-amplified sample injection was applied as an in-line preconcentration method. Methanol/5 mM formic acid (50/50) as a sample solvent, 3 s hydrodynamic injection (0.5 psi) of a methanol plug, and 25 s of electrokinetic injection (10 kV) of the sample were found to be the optimum conditions. Detection limits up to 25 times lower and similar precisions than those reported for hydrodynamic injection were obtained.     

A modified electrode for the electrochemical detection of biogenic amines and their amino acid precursors separated by microchip capillary electrophoresis

The use of a mixed-valent ruthenium oxide/hexacyanoruthenate polymeric film electrochemically deposited onto glassy carbon electrodes is proposed here for the detection of biogenic amines and their amino acid precursors, following their separation by microchip capillary electrophoresis. The ability of this ruthenium coating to electrocatalyze the oxidation of aliphatic and heterocyclic amines, as well as their amino acid precursors, was checked by using ethanolamine, tryptamine and tryptophane as prototype compounds and adopting a 25 mM sulphuric acid as the electrolyte in the detection cell, where a constant potential of 1.05 V versus Ag/AgCl, 3 M KCl was applied to the modified working electrode. Optimization of parameters affecting both detection and separation steps led to satisfactory separations when performed by using a 20 mM phosphate running buffer (pH 2.5) and applying a high voltage of 2.5 kV both in the separation and in the electrokinetic injection (duration 4 s). The recorded peaks were characterized by good repeatability (RSD ≤ 3.6%), high sensitivity and a wide linear range. Detection limits of 23 μM (1.4 mg/L), 27 μM (4.3 mg/L) and 34 μM (6.8 mg/L) were inferred for ethanolamine, tryptamine and tryptophane, respectively. The approach proposed here was also applied for the analysis of some double malt dark beers spiked with a controlled amount of the analytes considered.     

A polydimethylsiloxane/glass capillary electrophoresis microchip for the analysis of biogenic amines using indirect fluorescence detection

A polydimethylsiloxane-glass capillary microchip is fabricated for the rapid analysis of a mixture of common biogenic amines using indirect fluorescence detection. Using a running buffer of phosphate and 2-propanol, and Rhodamine 110 as a background fluorophore, both co-ionic and counter-ionic systems are explored. Studies demonstrate the separation and analysis of cations using indirect fluorescence detection for the first time in a chip-based system. Resulting electrophoretic separations are achieved within a few tens of seconds with detection limits of approximately 6 microM. The reduced sample handling and rapid separations afforded by the coupling of indirect fluorescence detection with chip-based capillary electrophoresis provide a highly efficient method for the analysis and detection of molecules not possessing a chromophore or fluorophore. Furthermore, limits of detection are on a par with reported chip-based protocols that incorporate precolumn derivatisation with fluorescence detection. The current device circumvents lengthy sample preparation stages and therefore provides an attractive alternative technique for the analysis biogenic amines.     

Determination of trace metals by capillary electrophoresis

A new analytical procedure is developed using a strong complexing agent, 1,10-phenanthroline (Phen), for direct UV detection of Zn, Mn, Cu, Co, Cd, and Fe at microg/L concentrations in environmental water samples. The metal chelates formed showed different electrophoretic mobilities and solved the comigration problem for capillary electrophoresis (CE) separation of free metal ions. To obtain stable metal-Phen chelates during the capillary zone electrophoresis (CZE) run, both pre-column and on-column complexation are required and threefold excess of Phen over metal ions should be added to the sample. The optimized background electrolyte (BGE) consists of 30 mM hydroxylamine hydrochloride and 0.1% methanol at pH 3.6. Under hydrodynamic sampling, CE run at + 20 kV in 65 cm x 0.05 mm ID fused-silica column with detection at 265 nm, baseline separation, satisfactory working ranges (10 microg/L to 5.5 mg/L), sensitive detection limits (1-3 microg/L), good repeatability for migration times (relative standard deviation, RSD 0.36-0.81%, n = 5), peak area (RSD 3.2-4.2%, n = 5) and peak height (RSD 3.2-4.5%, n = 5) were obtained for the metal cations investigated. The reliability of the method was established by parallel determination using the inductively coupled plasma-atomic emission spectrometry (ICP-AES) method giving results within statistical variation. The procedure developed is shown to provide a quick, sensitive, precise, and economic method for simultaneous determination of metal cations that can form stable chelates with Phen.     

Determination of cationic surfactants by capillary electrophoresis

A method is described for the separation of quaternary alkylbenzylammonium compounds as well as alkyl pyridinium salts by capillary electrophoresis using direct UV detection. The influence of the organic buffer modifier on the electrophoretic behaviour of the analytes is discussed. In addition to fused silica capillaries, also C8, C18 and neutral surface coatings are used. Separation is also performed in completely non-aqueous media. The results of method development are applied to the determination of cationic surfactants in cosmetics and pharmaceuticals. A comparison with HPLC with respect to efficiency, reproducibility and detection limits is presented. Received: 1 July 1996 / Revised: 6 November 1996 / Accepted: 10 November 1996     

毛细管电泳-场强放大样品堆积法检测染发剂中的7种苯胺类物质

建立了毛细管电泳-场强放大样品堆积测定染发剂中4,4′-二氨基二苯甲烷、苯胺、邻甲氧基苯胺、对氨基苯甲醚、3,4-二甲基苯胺、间氨基苯酚、1-萘胺7种苯胺类物质的分析方法。在优化的缓冲溶液体系(0.15 mol/L NaH2PO4,0.015 mol/L 三乙醇胺, pH 2.3)下7种分析物在6.5 min内实现基线分离。考察了样品中添加的磷酸浓度和乙腈浓度、水柱长度、电动进样时间与电压对场强放大富集效率及重现性的影响。最佳的富集条件为: 水柱注入3.45 kPa(0.5 psi)×6 s,样品中添加40%(v/v)乙腈和0.6×10~3mol/L磷酸,进样电压与进样时间为10 kV×10 s。线性范围为3～1000 μg/L(R2＞0.996),检出限为0.26～2.75 μg/L,将已有方法的检测灵敏度提高了1～3个数量级。在2种市售黑色染发剂中均检测到间氨基苯酚,含量分别为7.32 mg/g和1.34 mg/g。平均加标回收率为74%～108%。该方法灵敏度高、快速、重现性好、成本低,可供多种样品基质中痕量苯胺类污染物及其他阳离子物质的测定借鉴使用。     

毛细管区带电泳法测定粉针剂中头孢拉定的含量

用毛细管区带电泳法测定头孢拉定的含量 ,未涂层毛细管柱 (75 μm×48.5cm ,有效长度 40cm) ,电压 2 8kV ,检测波长 2 3 0nm ,温度 2 0℃ ,进样 5×1 0 3Pa× 3s。运行缓冲液为 2 5mmol/L硼砂缓冲液。方法的线性范围 3 1 .2 2μg/mL～ 749.2 8μg/mL ,检测限为 1 .1 7μg/mL。     

未衍生化卡托普利的毛细管电泳法测定

采用毛细管电泳高频电导法测定了未衍生化的卡托普利。考察了分离检测条件的影响。实验选择10．00mmoL／L Tris-5．0mmol／LH3BO3-20．0％CH3OH为电泳介质,在优化条件下,卡托普利的线性范围为1．00μg/mL-200μg／mL,检出限为0．3μg／mL。成功地检测了血清和尿液中的卡托普利。     

Determination of enantiomeric excess by capillary electrophoresis

Capillary electrophoresis (CE) is becoming an established method for the determination of chiral trace impurities. This paper provides an overview of the state of the art of CE for such determinations. Detection limits of 0.1% impurity is widely accepted as a minimum requirement for chiral trace impurity determinations. This can be relatively easily achieved with CE. However, determination of lower concentrations requires careful optimization of the separation system. Four factors that are of particular significance for trace enantiomeric determinations: resolution, limit of detection, linear range and type of detection, are discussed. Further, the advantages and disadvantages of derivatization in this context are treated as well as the separation approach, ie., direct chiral separation or separation after the formation of diastereomers. It is concluded that the limit of impurity detection can be about 0.05% when UV detection is employed. Using laser-induced fluorescence detection, a quantitative determination at the 0.005% level is often possible.