Field-amplified sample injection and in-capillary derivatization for sensitivity improvement of the electrophoretic determination of histamine

The feasibility of the combination of field-amplified sample injection (FASI) and in-capillary derivatization was explored for improving sensitivity of histamine in capillary electrophoresis (CE). Naphthalene-2,3-dicarboxaldehyde (NDA) was used as derivatization reagent. The reagent and sample was introduced by tandem mode. The derivatization was accomplished by at-inlet mode with standing time of 1.5 min. The combination of FASI and in-capillary derivatization was successfully achieved with about 400-fold concentration sensitivity enhancement compared to pre-capillary derivatization at the same set-up. The detection limit of concentration for histamine reached 1.25 x 10(-11) M by CE and fluorescence detection with S/N = 3. Parameters affecting FASI and in-capillary derivatization process including sample matrix, buffer concentration and reagent injection amount, were investigated.     

Field-amplified sample injection and in-capillary derivatization for capillary electrophoretic analysis of metal ions in local wines

In-capillary derivatization and field-amplified sample injection (FASI) coupled to capillary zone electrophoresis (CZE) was evaluated for the analysis of metals (Co(II), Cu(II), Ni(II), and Fe(II)) using 2-(5-Nitro-2-Pyridylazo)-5-(N-Propyl-N-Sulfopropylamino)Phenol (Nitro-PAPS) as the derivatizing agent. For FASI, the optimum conditions were water as sample solvent, 1 s hydrodynamic injection (0.1 psi) of a water plug, 5 s of electrokinetic introduction (10 kV) of the sample. The in-capillary derivatization was successfully achieved with zone-passing strategy in order tandem injection of Nitro-PAPS reagent (0.5 psi, 7 s), a small water plug (0.1 psi, 1 s), and metal ion introduction (10 kV, 5 s). The solution of 45 mmol L^− 1 borate pH 9.7 and 1.0 × 10^− 5 mol L^− 1 Nitro-PAPS containing 20% acetonitrile was used as the running buffer. The limit of detection obtained by the proposed method was lower than those from pre-capillary derivatization about 3–28 times. The recovery of the method was comparable to pre-capillary derivatization method. In-capillary derivatization-FASI-CZE was applied to analysis of metals in wine samples. The results were compared with those obtained by CZE with pre-capillary derivatization method and atomic absorption spectrometry (AAS).     

Capillary electrophoresis determination of biogenic amines by field-amplified sample stacking and in-capillary derivatization

A sensitive CE method for determining biogenic amines in wines based on in-capillary derivatization with 1,2-naphthoquinone-4-sulfonate is presented. In this method, reagent and buffer solutions are introduced hydrodynamically into the capillary whereas the sample is injected electrokinetically, thus, allowing a selective preconcentration of the analytes by field-amplified sample stacking. Amines are labeled inside the capillary using a zone-passing derivatization approach in mixed tandem mode. The most relevant variables influencing on the derivatization and separation as well as significant interactions have been evaluated using experimental design. Multi-criteria decision making is utilized for the simultaneous optimization of interacting variables through overall desirability response surfaces. The validation of the method has proven an excellent separation performance and accuracy for the determination of biogenic amines such as histamine, tryptamine, phenylethylamine, tyramine, agmatine, ethanolamine, serotonin, cadaverine, and putrescine in red wines. Detection limits range from 0.02 mg/L for ethanolamine to 0.91 mg/L for serotonin. The RSDs for migration time and peak area are around 1.2 and 6.2%, respectively. Red wines from different Spanish regions have been analyzed using the proposed method.     

Determination of chloroacetic acids in water by capillary zone electrophoresis with field-amplified sample injection

A simple and sensitive method has been developed for the determination of chloroacetic acids and acetic acid in water using capillary zone electrophoresis under modified electroosmotic flow with indirect UV detection. Potassium hydrogen phthalate at pH 5.40 was used as background electrolyte (BGE), and hexadecyltrimethylammonium bromide was used as electroosmotic flow modifier. Field-amplified sample injection (FASI) method was used to enhance the sensitivity. Results showed that the limit of detection for these analytes was enhanced more than 15-fold and the repeatabilities were good with relative standard deviations (RSDs %) of migration time and corrected peak areas being below 0.33%, 4.45% (intra-day) and 0.87%, 9.67% (inter-day), respectively. An off-line liquid–liquid extraction (LLE) process with methyl tert-butyl ether was carried out to detect these compounds in water samples. The dissociation constants of acetic acid and monochloroacetic acid (MCA) were determined with two methods and the results obtained were consistent with the reference values.     

毛细管电泳法测定水体中四环素类抗生素的基质效应及场放大进样技术的应用

比较了毛细管电泳（CE）和高效液相色谱（HPLC）技术对水体中4种四环素类抗生素（四环素、土霉素、金霉素及强力霉素）的分离效果。实验考察了水体的基质效应（pH值和水硬度）对分离的影响,优化了电泳条件,在压力进样模式（HDI）下,9.0 min内4种抗生素可达到基线分离,与HPLC相比,CE可以节省一半左右的分析时间。该方法具有良好的线性关系,检出限（LOD）在0.28~0.62 mg/L之间,迁移时间和峰面积的相对标准偏差（RSD）（n=6）分别为0.42%~0.56%及2.24%~2.95%;自来水和鱼塘水中加标回收率分别在96.3%~107.2%之间和87.1%~105.2%之间。此外,利用场放大电动进样（FASI）对目标物进行柱内预浓缩,检测灵敏度较HDI进样模式提高,LOD降至17.8~35.5 μg/L,迁移时间和峰面积的RSD（n=6）分别为0.85%~0.95%及1.69%~3.43%。CE具有样品前处理简单、分析速度快的特点,对环境水体中抗生素的检测具有明显的优势。     

Fluorescent detection of peptides and amino acids for capillary electrophoresis via on-line derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole

An in-capillary derivatization of amino acids and peptides with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was developed for their subsequent capillary electrophoretic analysis with laser-induced fluorescence detection (λ _ex=488 nm). The in-capillary derivatization was achieved in zone-passing mode by introducing successive plugs of sample and NBD-F into a fused silica capillary previously equilibrated with an alkaline borate buffer. To prevent NBD-F hydrolysis and to achieve a reliable derivatization, NBD-F was prepared daily in absolute ethanol and a plug of absolute ethanol was introduced between the sample and NBD-F reagent plugs. Various parameters influencing the derivatization efficiency were investigated and the optimum conditions were as follows: background electrolyte (BGE), 20 mM borate buffer (pH 8.8); introduction time, 4 s for sample and 2 s for NBD-F; molar ratio of NBD-F/sample, above 215; temperature, 45 °C for amino acids and 35 °C for peptides; applied voltage, +15 kV. The validation of the in-capillary derivatization method under optimal conditions showed a good linearity between the heights of the derivative peaks and the concentrations of the amino acids. The intra-day relative standard deviations of the migration times and the peak heights were less than 1.3% and 4.6%, respectively. The efficient derivatization and separation of a mixture of valine, alanine, glutamic acid and aspartic acid were achieved using this technique. Peptides such as buccaline and β-protein fragment 1–42 could also be derivatized using the developed in-capillary derivatization procedure. In‑capillary derivatization and separation of amino acids with different concentrations. From the top to bottom the concentrations are 1.11×10⁻⁵ M, 5.55×10⁻⁶ M, 2.78×10⁻⁶ M, 6.95×10⁻⁷ M. for valine; 1.26×10⁻⁵ M, 6.30×10⁻⁶ M, 3.15×10⁻⁶ M, 7.88×10⁻⁷ M for alanine; 3.78×10⁻⁵ M, 1.89×10⁻⁵ M, 9.45×10⁻⁶ M, 2.36×10⁻⁶ M for glutamic acid;, 4.27×10⁻⁵ M, 2.14×10⁻⁵ M, 1.07×10⁻⁵ M, 2.68×10⁻⁶ M for aspartic acid. Experiment conditions: injection order: 4s for sample, 1s for absolute ethanol, and then 2s for 5.24×10⁻² M NBD‑F; BGE: 20 mM borate pH 8.77; Applied voltage: 15 kV.     

Solvent-bar microextraction of herbicides combined with non-aqueous field-amplified sample injection capillary electrophoresis

Solvent-bar microextraction (SBME) based on two-phase (water-to-organic) extraction was for the first time used as the sample pretreatment method for the non-aqueous capillary electrophoresis (NACE) of herbicides of environmental concern. Due to the compatibility of the extractant organic solvent and the NACE separation system, the extract could be introduced directly to the CE system after SBME. Through investigations of the effect of sample pH, extraction time, agitation speed and salt addition on extraction efficiency, the most suitable extraction conditions were determined: sample solution at a pH of 1, without added salt, and stirring at 700 revolutions per minute for 30 min. SBME as applied here was also compared with single-drop microextraction and hollow fiber-protected liquid-phase microextraction. SBME showed the highest extraction efficiency. In addition, field-amplified sample injection with pre-introduced organic solvent plug removal using the electroosmotic flow as a pump (FAEP) was used to enhance the sensitivity further in NACE. Based on studies of the effect of different organic solvents, different lengths of the organic plugs and different volumes of sample injection on stacking efficiency under the most suitable separation conditions, methanol was found to be the most efficient solvent for on-line preconcentration. Combined with SBME, FAEP-NACE achieved limits of detection of between 0.08 ng/mL and 0.14 ng/mL for the studied analytes. This preconcentration approach for NACE was demonstrated to be amenable to aqueous environmental samples by applying it to spiked river water.     

Inverse-flow derivatization for capillary electrophoresis of DNA fragments with laser-induced fluorescence detection

A novel method is presented to detect DNA fragments separated by capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection using inverse-flow derivatization. In electrophoresis, the intercalating dye, thiazol orange was only added to the separation buffer at the positive polarity. The negatively charged DNA fragments migrated from the negative polarity to the positive polarity, while the positively charged dye migrated in the opposite direction. When DNA fragments met with dye ions, the DNA–dye complexes were formed. The complexes continued migrating to the positive end, due to their net negative charges. When the complexes passed through the detection window, the fluorescent signals were generated. Importantly, DNA fragments migrated as their native state before DNA–dye complexes were formed. This procedure was used to detect double stranded DNA (dsDNA) and single stranded DNA (ssDNA) fragments, and polymerase chain reaction (PCR) products. The excellent resolution and good reproducibility of DNA fragments were achieved in non-gel sieving medium. This procedure may be useful in genetic mutation/polymorphism detections.     

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。     

液液萃取-场放大进样-毛细管电泳非接触式电导分离检测酱油中的安赛蜜

采用场放大进样(FASI)-毛细管电泳非接触式电导检测法(CE-C⁴D),结合液液萃取(LLE)的样品净化预处理技术,分离检测了酱油中人工合成甜味剂安赛蜜。酱油样品经酸化后,用乙酸乙酯作为萃取剂,成功地消除了酱油中含有的大量无机盐等复杂基体对微量安赛蜜的干扰。实验对影响LLE萃取效率和FASI-CE-C⁴D分离检测的关键因素进行了讨论,特别是对样品净化前处理过程中萃取剂及用量、样品酸化pH值、萃取时间、萃取温度等条件进行了优化。结果表明,酱油中的安赛蜜可获得良好分离和灵敏检测,检出限和定量限分别为0.15 mg/kg和0.48 mg/kg。对市售酱油样品进行安赛蜜的加标回收测定,得到加标回收率为92.3%～108.1%,相对标准偏差<8.0%。该法具有简单快速、灵敏高效、分析成本低的优点,能满足酱油中安赛蜜的分析检测要求。     

Isoelectric focusing sample injection for capillary electrophoresis of proteins

Carrier ampholyte-free isoelectric focusing (IEF) sample injection (concentration) for capillary electrophoresis (CE) is realized in a single capillary. A short section of porous capillary wall was made near the injection end of a capillary by HF etching. In the etching process, an electric voltage was applied across the etching capillary wall and electric current was monitored. When an electric current through the etching capillary was observed, the capillary wall became porous. The etched part was fixed in a vial, where NaOH solution with a certain concentration was added during the sample injection. The whole capillary was filled with pH 3.0 running buffer. The inlet end vial was filled with protein sample dissolved in the running buffer. An electric voltage was applied across the inlet end vial and etched porous wall. A neutralization reaction occurs at the boundary (interface) of the fronts of H+ and OH-. A pH step or sharp pH gradient exists across the boundary. When positive protein ions electromigrate to the boundary from the sample vial, they are isoelectricelly focused at points corresponding to their pH. After a certain period of concentration, a high voltage is applied across the whole capillary and a conventional CE is followed. An over 100-fold concentration factor has been easily obtained for three model proteins (bovine serum albumin, lysozyme, ribonuclease A). Furthermore, the IEF sample concentration and its dynamics have been visually observed with the whole-column imaging technique. Its merits and remaining problem have been discussed, too.     

Analysis of urinary neurotransmitters by capillary electrophoresis: sensitivity enhancement using field-amplified sample injection and molecular imprinted polymer solid phase extraction

Capillary electrophoresis (CE) has been investigated for the analysis of some neurotransmitters, dopamine (DA), 3-methoxytyramine (3-MT) and serotonin (5-hydroxytryptamine, 5-HT) at nanomolar concentrations in urine. Field-amplified sample injection (FASI) has been used to improve the sensitivity through the online pre-concentration samples. The cationic analytes were stacked at the capillary inlet between a zone of low conductivity - sample and pre-injection plug - and a zone of high conductivity - running buffer. Several FASI parameters have been optimized (ionic strength of the running buffer, concentration of the sample protonation agent, composition of the sample solvent and nature of the pre-injection plug). Best results were obtained using H₃PO₄–LiOH (pH 4, ionic strength of 80 mmol L⁻¹) as running buffer, 100 μmol L⁻¹ of H₃PO₄ in methanol–water 90/10 (v/v) as sample solvent and 100 μmol L⁻¹ of H₃PO₄ in water for the pre-injection plug.In these conditions, the linearity was verified in the 50–300 nmol L⁻¹ concentration range for DA, 3-MT and 5-HT with a determination coefficient (r²) higher than 0.99. The limits of quantification (10 nmol L⁻¹ for DA and 3-MT, 5.9 nmol L⁻¹ for 5-HT) were 500 times lower than those obtained with hydrodynamic injection. However, if this method is applied to the analysis of neurotransmitters in urine, the presence of salts in the matrix greatly reduces the sensitivity of the FASI/CE–UV method.Therefore, a solid phase extraction (SPE) on a dedicated imprinted polymer (MIP) was developed to extract specific neurotransmitters, catecholamines, metanephrines and indolamines, from urine. Matrix salts were thus discarded after sample extraction on AFFINIMIP™ Catecholamine & Metanephrine (100 mg) cartridge.Therefore, lower limits of quantification were determined in artificial urine (46 nmol L⁻¹ for DA, 11 nmol L⁻¹ for 3-MT and 6 nmol L⁻¹ for 5-HT).The application of this protocol MIP-SPE/FASI–CE–UV analysis of neurotransmitters in human urine gave rise to electropherograms with a very good base line and signal to noise ratios above 15.     

毛细管电泳结合压力辅助电动进样测定水样中4种酚类雌激素

在毛细管电泳的胶束电动色谱（MEKC）模式下,采用压力辅助电动进样（PAEKI）的进样方式在线富集4种酚类雌激素（PEs）。对影响PAEKI的进样电压、进样时间等进行考察,并与传统的压力进样比较。结果表明,在最优的PAEKI条件下（-9 kV,0.3 psi（约2.1 kPa）,0.4 min）,4种PEs在7 min内基线分离,线性关系良好,相关系数（r）大于0.9936,己烷雌酚和双烯雌酚的线性范围为0.05~5 mg/L、双酚A和己烯雌酚的线性范围为0.1~10 mg/L;检出限（S/N=3）为0.0071~0.017 mg/L,富集倍数为11~15。使用该MEKC-PAEKI法对自来水和湖水水样进行测定,得到定量限（S/N=10）分别为0.029~0.064 mg/L和0.033~0.079 mg/L;加标回收率为75.6%~110.1%,相对标准偏差（n=5）为4.6%~11.8%。PAEKI不需要使用其他试剂,只需对电泳仪的参数进行适当调整即可实现对分析物的在线富集,简单、快速、自动化程度高。     

Rapid and sensitive determination of phosphorus-containing amino acid herbicides in soil samples by capillary zone electrophoresis with diode laser-induced fluorescence detection

A straightforward and sensitive method has been developed for the analysis of phosphorus-containing amino acid herbicides (glufosinate and aminomethylphosphonic acid, the major metabolite of glyphosate) in soil samples. For this purpose, the analytical features of two indocyanine fluorescent dyes, sulfoindocyanine succinimidyl ester (Cy5) and 1-ethyl-1-[5-(N-succinimidyl-oxycarbonyl)pentyl]-3,3,3,3-tetramethyl-indodicarbocyanine chloride, as labeling reagents for the determination of these herbicides by CZE with diode LIF detection were investigated. Practical aspects related to the labeling chemistry and CZE separation showed that the two probes behave similarly, Cy5 being the best choice for the determination of these herbicides on account of its higher sensitivity. The optimum procedure includes a derivatization step of the pesticides at 25 degrees C for 30 min and direct injection to CZE analysis, which is conducted within about 14 min using ACN in the running buffer. The lowest detectable analyte concentration ranged from 0.025 to 0.18 microg/L with a precision of 3.6-5.4%. These results indicate that indocyanine fluorescence dyes are useful as rapid and sensitive labels for the determination of these herbicides when compared with typical fluorescein dyes such as FITC and 5-(4,6-dichloro-s-triazin-2-ylamino) fluorescein, because they provide faster labeling reactions even at room temperature and the excess of reagent practically does not interfere the determination. Finally, the Cy5 method was successfully applied to soil samples without a preliminary clean-up procedure, and the herbicides were measured without any interference from coexisting substances. The recoveries of these compounds in these samples at fortification levels of 100-500 ng/g were 90-93%.     

场放大样品堆积毛细管区带电泳检测尿液中苯丙胺类毒品

建立了毛细管区带电泳(CZE)中场放大样品堆积(FASS)技术分析尿液中苯丙胺类毒品的方法。采用体积分数30%甲醇的100 mmol/L磷酸盐(pH 3)为分离缓冲液,利用缓冲体系与样品溶液体系电导率的差异,在毛细管中浓缩样品组分,对苯丙胺、甲基苯丙胺、3,4-(亚甲二氧基)苯丙胺(MDA)、3,4-(亚甲二氧基)甲基苯丙胺(MDMA)4种毒品进行了分离和定量测定,与常规毛细管区带电泳比较,检测灵敏度提高约2000倍。采用利多卡因为内标,对添加上述4种毒品的尿液进行提取和测定,分析的相对标准偏差在15%范围之内,可检测到的上述毒品质量浓度为0.002μg/mL,相对回收率在70%~120%内。该方法可用于生物检材中苯丙胺类毒品的检测。     

On-line concentration by head-column field amplified sample injection for the analysis of berberine, palmatine and jatrorrhizine in herbal medicine by flow injection-micellar electrokinetic chromatography

A simple, sensitive and continuous on-line stacking technique using head-column (HC)-field amplified sample injection (FASI) and sweeping was developed by combination of flow injection with micellar electrokinetic chromatography. Berberine, palmatine and jatrorrhizine were selected as model mixture to demonstrate this stacking method. Based on the characteristic of a 16-way injection valve (16-V), a sample was injected electrokinetically into a capillary after the introduction of a plug of water. Under optimum conditions, 64–86-fold improvement in the detection sensitivity was obtained for the analytes and the sample throughput can reach up to 24 h⁻¹ using the background electrolyte containing 240 mM ammonium acetate (pH 4.7), 30% (v/v) ethanol, and 2% (v/v) polyoxyethylene sorbitan monolaurate (Tween 20). The repeatabilities (n = 4) reached relative standard deviation values of 1.2, 2.7 and 3.1% for the peak areas and 1.6, 3.3 and 3.8% for peak heights of berberine, palmatine and jatrorrhizine, respectively. The limit of detection for the berberine, palmatine and jatrorrhizine was found to be 27, 26, 22 ng mL⁻¹ (S/N = 3).     

A capillary electrophoresis chip with hydrodynamic sample injection for measurements from a continuous sample flow

A microchip-based capillary electrophoresis device supported by a microfluidic network made of poly(dimethylsiloxane), used for measuring target analytes from a continuous sample flow, is presented. The microsystem was fabricated by means of replica molding in combination with standard microfabrication technologies, resulting in microfluidic components and an electrochemical detector. A new hydrodynamic sample injection procedure is introduced, and the maximum number of consecutive measurements that can be made with a poly(dimethylsiloxane) capillary electrophoresis chip with amperometric detection is investigated with respect to reproducibility. The device features a high degree of functional integration, so the benefits associated with miniaturized analysis systems apply to it.     

Determination of tetracyclines in human urine samples by capillary electrophoresis in combination with field amplified sample injection

A sensitive method using CZE‐UV detection has been developed for the determination of five tetracycline antibiotics in human urine samples. To improve the sensitivity of the method, an on‐line preconcentration strategy, named field‐amplified sample injection, has been developed, based on the electrokinetic injection of the sample, which requires only a 1:100 dilution with sample solvent before injection. Under optimum conditions, sensitivity enhancement factors ranged from 450 to 800 for the studied compounds. The applicability of the proposed method was demonstrated by the determination of these antibiotics in spiked urine samples. The limits of quantification were lower than 0.8 mg/L and the precision (intra‐ and inter‐day), expressed as %RSD was below 14%. Recoveries ranged from 92.1 to 96.7%. Thus, the proposed procedure is a simple, fast and efficient strategy which could be used as therapeutic drug monitoring in human urine samples.     

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 %).     

Field‐amplified sample injection combined with capillary electrophoresis for the simultaneous determination of five chlorophenols in water samples

A sensitive method of CZE‐ultraviolet (UV) detection based on the on‐line preconcentration strategy of field‐amplified sample injection (FASI) was developed for the simultaneous determination of five kinds of chlorophenols (CPs) namely 4‐chlorophenol (4‐CP), 2‐chlorophenol (2‐CP), 2,4‐dichlorophenol (2,4‐DCP), 2,4,6‐trichlorophenol (2,4,6‐TCP), and 2,6‐dichlorophenol (2,6‐DCP) in water samples. Several parameters affecting CZE and FASI conditions were systematically investigated. Under the optimal conditions, sensitivity enhancement factors for 4‐CP, 2‐CP, 2,4‐DCP, 2,4,6‐TCP, and 2,6‐DCP were 9, 27, 35, 43, and 43 folds, respectively, compared with the direct CZE, and the baseline separation was achieved within 5 min. Then, the developed FASI‐CZE‐UV method was applied to tap and lake water samples for the five CPs determination. The LODs (S/N = 3) were 0.0018–0.019 µg/mL and 0.0089–0.029 µg/mL in tap water and lake water, respectively. The values of LOQs in tap water (0.006–0.0074 µg/mL) were much lower than the maximum permissible concentrations of 2,4,6‐TCP, 2,4‐DCP, and 2‐CP in drinking water stipulated by World Health Organization (WHO) namely 0.3, 0.04, and 0.01 µg/mL, respectively, and thereby the method was suitable to detect the CPs according to WHO guidelines. Furthermore, the method attained high recoveries in the range of 83.0–119.0% at three spiking levels of five CPs in the two types of water samples, with relative standard deviations of 0.37–8.58%. The developed method was proved to be a simple, sensitive, highly automated, and efficient alternative to CPs determination in real water samples.