毛细管电泳大体积进样在柱复合富集技术

提出场放大进样和酸堆积结合的大体积样品复合富集方法,实现了毛细管电泳对高盐样品中阳离 子的有效富集和分离。向样液中添加70%(V/V)乙腈,场放大进样600s后,电动注入强酸做酸堆积,预富集 样品带用毛细管区带电泳分离仍能获得满意的分离度。此法的富集倍数约为常规电动进样的800倍。普萘 洛尔和美托洛尔的检出限分别达到1×10-4mg/L和7×10-4mg/L     

便携式电动流动分析系统同时富集测定矿泉水中铬(Ⅵ)和镉(Ⅱ)

研究了电渗泵性能的改进以及双向电堆积系统各种参数对富集倍数的影响。提出一种电渗驱动与双向电堆积相结合的便携式电动流动分析系统,并采用石墨炉原子吸收法对矿泉水中铬(Ⅵ)和镉(Ⅱ)进行了同时富集和测定。检出限为9ng/L Cr(Ⅵ)和10ng/L Cd(Ⅱ)(n=11,3倍空白标准偏差)。加入相当于样品含量的Cr(Ⅵ)和Cd(Ⅱ),回收率分别为(105～107)±2％和(104～106)±2％(n=3)。     

微乳毛细管电色谱电动进样-场放大堆积法检测化妆品中糖皮质激素

采用反向微乳毛细管电色谱电动进样联用场放大堆积,建立了在线富集检测化妆品中6种糖皮质激素分析方法。微乳毛细管电色谱缓冲体系为2.4%(w/w)十二烷基硫酸钠,6.6%(w/w)正丁醇,0.6%(w/w)正辛烷,20 mmol/L磷酸盐缓冲液(pH 2.2),分离电压!20 kV,进样!20 kV×54 s,进水15 kPa×40 s,检测波长240 nm。讨论了样品基质、进样时间和电压、水柱长度对富集效果的影响。在优化条件下,6种激素的富集倍数分别为100~186倍,在0.05~15.0 mg/L范围内呈线性关系,相关系数0.9986~0.9997。检出限为20~60μg/L(S/N=3),标准加入量为50μg/L时平均回收率85.9%~103.8%,相对标准偏差均小于5.8%。迁移时间和峰高的日内精密度分别为2.2%和7.9%,日间精密度分别为2.9%和9.0%。     

高效毛细管电泳大体积样品堆积在线富集法测定蒲公英中阿魏酸、绿原酸和咖啡酸

采用大体积样品堆积(LVSS)在线富集模式,建立了高效毛细管电泳(HPCE)测定蒲公英中阿魏酸、绿原酸和咖啡酸含量的方法。主要考察了在毛细管区带电泳(CZE)分离模式下,缓冲液的pH和浓度对分离效果的影响,以及在LVSS在线富集模式下,进样时间对富集效果的影响。在最优条件下阿魏酸、绿原酸和咖啡酸可在12 min内得到分离,3个成分在0.5~25.0μg/mL浓度范围内均有较好的线性关系(r2=0.999),平均加样回收率分别为104.9%,98.0%和100.1%,RSD(n=6)分别为3.6%,2.6%和1.0%。定量限(S/N=10)分别为0.10,0.10和0.03μg/mL,检出限(S/N=3)分别为0.03,0.03和0.01μg/mL。相对于常规CZE模式,本方法的富集效果倍数为17~19倍。建立的方法可用于蒲公英的日常检测与质量控制。     

在线扫集-毛细管胶束电动色谱法对石榴与石榴叶中没食子酸含量的测定

建立了一种在线扫集-胶束电动色谱法测定没食子酸的新方法。考察了背景溶液pH值、十二烷基硫酸钠(SDS)浓度、样品基体组成和进样时间对富集效果的影响。使用未涂层的毛细管柱(48.5 cm×75μmi.d.,有效柱长40 cm),pH9.0的20 mmol/L硼酸盐+50 mmol/LSDS为背景溶液,在紫外检测波长272 nm、运行电压18 kV的条件下,200 s内的富集倍数可达20倍。线性范围为0.62~10.30 mg/L(r=0.999),检出限(S/N=3)为0.08 mg/L,平均回收率为104%。没食子酸迁移时间和峰面积的相对标准偏差分别为1.2%和1.6%。方法快速、准确可靠、灵敏度高、重复性好,可检测石榴不同部位和石榴叶以及饮料中没食子酸的含量。     

中空纤维液-液-液微萃取/HPLC分析人尿液中麻黄碱及伪麻黄碱

建立了中空纤维液-液-液微萃取高效液相色谱对人尿液中的麻黄碱和伪麻黄碱进行纯化、分离、富集以及测定的方法。采用中空纤维三相微萃取装置,考察了影响萃取的因素,确定了萃取条件:中空纤维壁上的有机相为正辛醇,以50μL盐酸溶液(pH 2.0)为接受相,在室温下萃取60 min。该条件下麻黄碱和伪麻黄碱的富集倍数分别为180倍和220倍,两者的线性范围分别为0.01～5 mg/L和0.005～0.75 mg/L,相关系数(r)分别为0.998 2、0.997 8,定量下限分别为0.01、0.005 mg/L。该方法使用极少量的有机溶剂,便可有效地对尿样中麻黄碱和伪麻黄碱进行纯化、分离和富集,萃取效率高,可用于尿液中麻黄碱和伪麻黄碱的同时测定。     

电堆积与等速电泳结合的毛细管电泳进样富集方法的研究

 提出电堆积与等速电泳结合的毛细管电泳进样富集方法 ,并对电堆积和等速电泳进样富集的最佳条件进行了研究。在 15kV电压 ,电堆积进样 70s和等速电泳富集 40s条件下 ,对两种结构相近的药物普萘洛尔和美托洛尔用毛细管区带电泳法进行了分离。pH 4.0 ,30mmol/L醋酸钠 醋酸、30mmol/Lβ 丙氨酸 醋酸和 1.5 mmol/L醋酸钠 醋酸溶液分别作背景 (或前导 )、尾随和样品缓冲液。与常规电迁移进样方法比较 ,信号增强因子约为 2 5 0和16 0 ;总分析时间与常规法相近。     

利用瞬间等速电泳的毛细管区带电泳大体积电动进样的研究

采用添加乙腈引发的场放大进样与瞬间等速电泳结合的预富集方法,实现了在毛细管内大体积高盐样品中阳离子的有效富集与分离。详细讨论了影响富集的缓冲体系、尾随离子种类、毛细管有效长度、进样时间和等速电泳时间等重要因素。选择在400 mmol/L LiAc-HAc缓冲液(pH 4.5)和400 mmol/L　β-丙氨酸-HAc尾随液(pH 4.5)及10 kV下样品和尾随溶液电动注入时间分别为270和90 s的条件下对高盐溶液中两种结构相近的药物普萘洛尔和美托洛尔进行了富集和分离。该方法富集倍数约为常规电动进样的280倍,普萘洛尔和美托洛尔的检出限分别为2×10-3和8×10-3 mg/L。     

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。     

电堆集富集非水毛细管电泳同时测定水杨酸、肉桂酸、阿魏酸和香草酸

建立了同时分离测定水杨酸、肉桂酸、阿魏酸和香草酸的电堆集富集-非水毛细管电泳(NACE)的新方法。运行缓冲溶液为40mmol/L乙酸钠-2.5mmol/L氢氧化钠甲醇溶液,电压-25kV,在225nm波长下紫外检测。对电压、乙酸钠浓度、氢氧化钠浓度、进样时间、样品溶液等因素对电堆集及分离的影响做了系统的研究。水杨酸、肉桂酸、阿魏酸和香草酸分别在1.4~28mg/L、0.40~8.0mg/L、0.7~18mg/L和0.7~30mg/L范围内线性关系良好(r=0.9999、r=0.9997、r=0.9994、r=0.9997);回收率分别为95.8~99.6%、96.2~98·2%、95.7~105%和98.9~103%,基于3倍信噪比(S/N=3),4种有机酸的检出限分别为0.069、0.051、0.107和0.089mg/L。     

非均匀电场的电堆积理论研究

基于样品区非均匀电场电势分布的测试结果并利用异性双点电荷电场的理论模型,研究了非均匀电场电堆积效应,提出了非均匀电场电堆积作用的理论模型.采用一种改进的非均匀电场电堆积系统,以矿泉水中痕量Cr(Ⅵ)和Pb(Ⅱ)为考察对象,同时对其进行分离富集和测定,为理论模型提供了实验依据.     

On-line bi-directional electrostacking for As speciation/preconcentration using electrothermal atomic absorption spectrometry

A method using bi-directional electrostacking (BDES) in a flow system is presented for As preconcentration and speciation analysis. Some parameters such as electrostacking time and applied voltage, support buffers and their concentrations were investigated. Boric acid plus sodium hydroxide at 0.1 mol/l concentration was selected as support buffer to improve the pre-concentration factor (PF) for As(V). An analytical range from 2.0 to 50.0 μg l⁻¹, and 0.35 μg l⁻¹ as limit of detection, when applied 750 V for 20 min, were achieved. Under these conditions, a pre-concentration factor of 4.8 was obtained. The proposed method was applied to determine As(V) in mineral water and natural water samples (river, fountain and gold mine) from Ouro Preto city. Recoveries from 93.5 to 106.4% were achieved at 10 μg l⁻¹ added As level (R.S.D.s between 3 and 7%). Potassium permanganate (10 mg l⁻¹) was used for oxidising As species in order to determine total As, being established the concentration of As(III) from the difference between total As and As(V).     

Electrostacking with ion flow superposition as a method of concentration in electrophoresis

A method of online concentration in electrophoresis named “electrostacking with flow superposition” is offered that is an alternative to the standard “stacking”. The method is based on monitoring of the rate of ion motion in crossed channels of a cross-shaped interface due to the changes in the electric circuit parameters. Monitoring of the rate of ion motion allows carrying out the concentration by combining two principles: “electrostacking” and “superposition of ion flows”. The possibility of concentration is shown experimentally by the example of the anionic form of Methyl Orange in the electrostacking mode with superposition of ion flows. The suggested method allows obtaining tenfold values of the concentration factor with an experimental error s _r = 4–15%.     

Sample stacking for charged phenol derivatives in capillary zone electrophoresis

10 selected phenol derivatives are separated by capillary zone electrophoresis in an alkaline phosphate/borate buffer at pH 10. Resolution and selectivity of the separation are increased using methanol as an organic modifier. The conductivity in the sample zone, mainly due to the high pH, needed for the formation of phenolates and the electroendosmotic flow are considerably lowered by adding about 40% methanol. Detection limits are improved by a specially optimized electrostacking procedure. The improvement is in the range of two orders of magnitude compared to hydrodynamic injection. Detection limits are found to be in the low ppb range. This optimization for electrostacking may also be used for other slow anionic analytes forming charged molecules only at a very high pH.     

On-line sequential preconcentration of inorganic anions by anion-selective exhaustive injection and base-stacking in capillary zone electrophoresis

A sequential electrostacking method based on anion-selective exhaustive injection (ASEI) and base-stacking (BS) is presented for the preconcentration and determination of inorganic anions by capillary zone electrophoresis (CZE) in this paper. Tetradecyltrimethylammonium bromide as an electroosmotic flow (EOF) modifier was added into the buffer to suppress EOF of the capillary. Firstly, a water plug was hydrodynamically injected into the capillary. During ASEI under negative high voltage, the sample anions migrated quickly towards the boundary between the water plug and buffer in the capillary. Then an alkaline zone was injected electrokinetically to concentrate the anions further. With the sequential electrostacking method, the preconcentration factor of (0.8-1.3) x 10(5) was obtained compared with the conventionally electrokinetic injection and the relative standard deviation of peak area was 3.3-5.3% (n = 5). The detection limits of ASEI-BS-CZE for six inorganic anions were 6-14 ng/L. The proposed method has been adopted to analyze six anions in cigarette samples successfully.     

样品堆积——毛细管电泳的柱上浓缩技术

评叙了样品堆积，一种毛细管电泳提高检测灵敏度的柱上浓缩技术。样品堆积包括电堆积富集与场增加进样两种方法，分别在流动动力进样与电动进样过程中实现。本文从理论上说明了实现样品堆积及优化样品堆积富集效率须采取的实验措施，并对样品堆积目前的应用状况进行了全面介绍。     

胶束电动毛细管色谱在柱富集和分离7种植物激素

利用胶束电动毛细管色谱在柱样品电堆积的预富集方法,以十二烷基硫酸钠胶束作准固定相,对七种植物激素进行了富集和分离。研究了各种分离条件的影响,并分别在高电渗流和聚丙烯酰胺涂层抑制电渗流条件下对植物激素进行在柱电堆积富集,各种植物激素的检出限比文献报道降低1～2个数量级。在最佳条件下对植物样品中的脱落酸进行了测定,其相对标准偏差为2．4％;回收率为75％。     

Determination of chromium(VI) and lead(II) in drinking water by electrokinetic flow analysis system and graphite furnace atomic absorption spectrometry

An electrokinetic flow analysis system (EKFA) using an electroosmotic pump (Peo) and a bi-directional electrostacking (BDES) unit is introduced in this paper. Large flow range, moderate carrier pressure, low performance voltage and stable flow rate, especially in mulmin(-1) level, are the main specialties of the Peo. Diethanolamine, 0.5 mM, is selected as its carrier to improve the pump efficiency and stability further. Moreover, BDES, a feasibility investigation for the simultaneous separation and pre-concentration of cations and anions, and graphite furnace atomic absorption spectrometry (GFAAS) determination are presented. The calibration series for both of Cr(VI) and Pb(II) are from 0.2 to 40 mugl(-1) with 10 mul pipette volume and GFAAS determination directly. The detection limit of Cr(VI) and Pb(II) with 10 min BDES is 10 and 13 ngl(-1)(3sigma of blank, n=11), respectively. The recovery of Cr(VI) and Pb(II) is (103-105)+/-1% and (95.9-96.9)+/-1.0% with three independent determinations, respectively. The investigated method is also suitable for the simultaneous separation and pre-concentration of trace cations and anions in low conductivity sample solutions with different detection instruments.