毛细管超薄池光度吸附测量新技术

在毛细管超薄池光度检测中首次采用吸收光强测量新技术,显著提高了测量的灵敏度和改善了信噪比。在内径50μm的石英毛细管超薄池以及由石英光导纤维构成的十字交叉超薄光学吸收池上,分别测量了系列高锰酸钾溶液吸收光强。吸收光强与高锰酸钾溶液浓度之间呈现良好的线性关系。对于10μg/mL的高锰酸钾稀溶液,毛细管超薄池吸收光强测量的信噪比相对于吸光度测量的有较大的改善。十字交叉池的光程约为40μm,容积约为0.02μL,具有较大的光能量,可望发展成为一种新型的电泳光度检测池。     

高效毛细管电泳的电导检测和紫外光度检测研究

本文自制商效毛细管电泳装置.研究了毛细管区带电泳电导检测和毛细管胶束电动色谱紫外光度检测。在电导检测中,制作铂丝微电导池,并由用电池隔膜制作的导电接口连接电泳毛细管和电导池,高压被有效隔离,实现柱后电导检测,用内径200μm、长70cm(到接口)石英毛细管在10kV电压下分离检测Li~-、Na~-、K~-。在电动色谱中将高效液相色谱仪与高压电源组成电泳装置,用内径100μm,长50cm(到检测器)石英毛细管和SDS胶束溶液在14kV电压下分离检测电中性化合物。     

薄池吸收宽带紫外光度检测器的研制

设计和制作了利用宽带吸收技术进行宽带表观吸光度测定的薄池宽带紫外光度检测器(，large-bandwidth UV absorption detector，简称LBUAD)，并进行了性能表征。该检测器在光学系统上采用氘灯做为紫外光源，通过宽带紫外玻璃得到入射宽带光，并利用中心对称的双透镜聚焦光学系统对宽带光进行聚焦，聚好的光斑通过蓝宝石球进一步会聚后照射吸收池，然后进行检测。毛细管薄池中系列高锰酸钾溶液的表观吸光度测定结果表明：该仪器的动态范围为2-3个数量级，对硝基苯肼的表观吸光度测定结果表明，其检出限达到10^-6AU，基线漂移小于0．001AU／h。与商品DD2000紫外检测器的比较以及在实际电泳分离中的检测进一步表明：该仪器具有很好的检测性能。     

激光光热折射光谱法测量毛细管内液体样品的微弱吸收

本工作采用毛细园柱管为样品池，证实在激光束通过毛细管不发生衍射的情况下，可采用激光光热折射光谱进行“在线”检测。我们还提出了一种通过监测第二针孔光栏产生的菲涅尔衍射条纹，提高检测灵敏度的新方法。检测了内径为３００μｍ毛细管内１．８×１０＾－＾１＾６ｍｏｌ的结晶紫，相应的最小吸光度为３×１０＾－＾７。     

高效毛细管电泳-紫外检测法测定饮料等包装材料中的双酚A

建立了饮料等包装材料中双酚A的高效毛细管电泳-紫外检测法.以无水乙醇为提取溶剂,采用硼砂-十二烷基硫酸钠-乙腈溶液为运行缓冲液(pH 9.5);分离毛细管为50cm×50μm,有效长度41cm的熔融石英毛细管;电泳温度为20℃;检测波长为195n m;重力进样,进样时间为15s.以相对迁移时间定性,标准曲线法定量.方法...     

微流蒸发光散射检测器的研制及评价

构建了适用于纳升级到微升级流量的毛细管分离体系的微流蒸发光散射检测器(μELSD),实现了其与毛细管液相色谱(eLC)的联用.对雾化器孔径和雾化毛细管内径、蒸发管内径和长度、光散射池尺寸、雾化毛细管位置和辅助载气流量等参数进行了优化.在最优条件下,微流蒸发光散射检测器检出限为直接进样葡萄糖1 ng(S/N＞ 10),线性范围0.01～1.0 μg,重复性好,峰面积RSD(n=6)为0.4％,峰高RSD(n=6)为0.3％.本检测器已成功应用cLC-μELSD平台,使用C18毛细管色谱柱(内径250 μm),0.1％甲酸铵溶液(pH 4.5)-甲醇(60∶40,V/V)为流动相,分离检测了3种常用甜味剂,表明本研究构建的系统可以应用于实际分离检测中,具有分析时间快、溶剂消耗量少、样品需求量小的优点.     

稀土离子及胺和氨基酸的高效毛细管区带电泳电导检测

用自制高效毛细管电泳装置研究毛细管电泳电导检测，由用阴离子交换膜管制作的导电接口连接电泳毛细管和电导池，高电压被有效隔离，实现柱后电导检测，用长６０ｃｍ、内径５０μｍ石英毛细管，以ｐＨ４．０的７×１０￣（－３）ｍｏｌ／ＬＮａＡｃ￣（－２）×１０￣（－３）ｍｏｌ／ＬＨＩＢＡ－ＨＡＣ溶液为载体，在１８ｋＶ电压下，轻重三种稀土Ｎｄ、Ｇｄ、Ｙｂ的混合物８ｍｉｎ内完成分离检测。用上述毛细管，以ｐＨ为５．８的５×１０￣（－３）ｍｏｌ／ＬＮａＡｃ－ＨＡＣ溶液为载体，在２０ｋＶ电压下乙二胺、三乙胺、组氨酸、谷氨酸混合有机物７．５ｍｉｎ内完成分离检测。     

高效毛细管电泳电导检测器的研制

研制了一种毛细管电泳电导检测器。采用激光烧蚀毛细管涂层、HF腐蚀和阴离子交换膜封堵制作在柱导电接口连接电泳毛细管和电导池,高压电场被有效隔离,以铂丝为工作电极实现柱后电导检测,在内径为50μm毛细管上分离检测了几种氨酸和金属离子,结果表明该系统性能优良。     

毛细管胶束电动色谱法检测4种有机磷农药

用毛细管胶束电动色谱电化学检测的方法对对氧磷、甲基对硫磷、乙基对硫磷、扑灭松等4种常见有机磷农药进行分离检测。使用30 cm×20μm i.d.的石英毛细管,当分离电压为12 kV,工作电极电势为-0.6V,在pH值为5.0的20 mmol/L乙酸-乙酸钠缓冲液与20 mmol/L十二烷基硫酸钠溶液中,对氧磷、甲基对硫磷、乙基对硫磷、扑灭松4种组分在11 m in内得到基线分离,检出限分别为0.086、0.64、0.67、3.4 pg。将该方法用于地表水样品的检测,加标回收率为94%~102%。     

CE法测定CD45-FITC荧光抗体溶液中的游离FITC

建立了测定CD45-FITC荧光抗体样品溶液中游离FITC浓度的毛细管电泳(CE)方法。熔融石英毛细管45 cm(有效长度30 cm)×75μm i.d.;0.05 mol·L-1磷酸氢二钠-磷酸二氢钠缓冲液(含5g·L-1PEG4000,p H=7.14);分离电压+12 k V;进样压力0.5 psi(3.45 k Pa),进样时间3.0 s;分离温度25℃;UV-Vis检测器检测波长200 nm。该方法能有效测定CD45-FITC荧光抗体样品溶液中游离的FITC含量,线性回归方程相关系数r=0.9900,检测限LOQ=0.20μg·m L-1。样品加标回收率为105.49%,相对标准偏差小于5.36%。该方法快速、灵敏、重现性好,能用于CD45-FITC荧光抗体样品溶液中游离FITC的快速测定。     

New Absorption Measurement Technique for a Super-thin Cell and its Application as a CE Detector

There are some increasing needs to consider the light absorption of a super-thin optical path. For example, in the areas of microelectronics and mechanics system (MEMS),it is possible now to fabricate an absorption flow cell in a few nm or μm scale for the optical path. In the other area of molecule separation, chemists and biochemists often apply the high-performance capillary electrophoresis (HPCE) to separate proteins and other big bio-molecules. The commonly used detector in HPCE is based on the UV-VIS light absorption, and has a thin cell in a diameter of 20-50 μm with the detection limit of 10^-5 to 10^-6 mol/L. It is understood that the problems associated with such a thin absorption cell are the low sensitivity and worse signal-to-noise (S/N) ratio. These problems restrict many useful applications of the super-thin cell in various purposes of light absorption measurements.     

Determination of nanomolar concentrations of phosphate in natural waters using flow injection with a long path length liquid waveguide capillary cell and solid-state spectrophotometric detection

A flow injection manifold incorporating a 1 m liquid waveguide capillary cell and a miniature fibre-optic spectrometer for the determination of low phosphorus concentrations in natural waters is reported. The limit of detection (blank + 3 S.D.) was 10 nM using the molybdenum blue chemistry with tin(II) chloride reduction. The sensitivity of the flow injection manifold was improved by 100-fold compared with a conventional 1 cm flow cell. The response was measured at 710 nm and background corrected by subtracting the absorbance at 447 nm. Interference from silicate was effectively masked by the addition of 0.1% (m/v) tartaric acid and results were in good agreement (P = 0.05) with a segmented flow analyser reference method for freshwater samples containing 1 μM phosphate.     

Capillary scale light emitting diode based multi-reflection absorbance detector

We describe a light emitting diode (LED) based multi-reflection capillary scale absorbance detector based on both square and round capillaries and compare their performance with a conventional single-pass on-tube detector. The optical path length is extended by silver coating, the external surface of the capillary. The reflective geometry has been reported to be less prone to artifacts induced by refractive index changes; we do find this to be true. Although the detection volume/illuminated volume is increased some, a multi-reflection cell based on a 180 μm bore capillary with a ∼2-cm long illuminated volume shows over a 50-fold gain in signal-to-noise (S/N) compared to a single-pass on-tube configuration with the same capillary. The limit of detection (LOD) is 4.4 fmol (2.6 pg, 1 μL of 22.0 nM injected dye) BTB under pulseless (pneumatic) flow conditions. The cells behave as multipath devices where the effective path lengths are greater at low absorbance values. In our experiments, where non-coherent light is launched through optical fibers that are large compared to capillary bore dimensions, increase in the effective path length of the cell do not occur in a predictable fashion with the angle of incidence of the light beam. Although the effective path length almost linearly increases with increasing distance between the light entry and exit windows, the absolute values of the effective path lengths are always lower than this physical distance, suggesting that after some passage through the solution, light largely travels through or along the glass wall. Square capillaries have better light transmission and offer some performance advantages. Multi-reflection cells can indeed be of value for sensitive detection in microflow systems.     

A versatile total internal reflection photometric detection cell for flow analysis

A total internal reflection (TIR) flow-through cell that is highly tolerant of schlieren effects, has limited hydrodynamic dispersion and does not trap gas bubbles, and which is suitable for sensitive photometric measurements in flow analysis, is described. Light from an optical fibre is introduced into a short length of quartz capillary through the sidewall at an incident angle of ca. 53°. Under this condition, incident light undergoes total internal reflection from the external air-quartz interface and is propagated by successive reflections from the external walls through the aqueous liquid core of the cell. Detection of the transmitted beam is enabled by intentionally introducing an optical coupling medium at a predetermined distance along the capillary wall, which allows the internally reflected light to be captured by a second optical fibre connected to a charge-couple device detector.This configuration embodies a number of the desirable features of a liquid core waveguide cell (i.e. total internal reflection), a multi-reflection (MR) flow cell (i.e. minimum susceptibility to schlieren effects, low hydrodynamic dispersion and little tendency to trap bubbles), and a conventional Z-cell (wide dynamic range). When employed with a flow injection system, a limit of detection of 2.0 μg PL⁻¹ was achieved for the determination of reactive phosphate using the TIR cell, compared with LOD values of 3.8 μg PL⁻¹ and 4.9 μg PL⁻¹ obtained using the MR and Z-cells with same manifold.The combined advantages of schlieren-tolerance and lack of bubble entrapment of the MR cell with the higher S/N ratio and wider dynamic range of a conventional Z-cell, make the TIR cell eminently useful for photometric measurements of samples with widely differing refractive indices.     

Separation and determination of six catechins in tea by pressurized capillary electrochromatography

An efficient pressurized capillary electrochromatography (pCEC) method has been successfully developed for the determination of six catechins in tea. The separation was performed on a reversed-phase EP-100-20/45-3-C18 capillary column (total length of 45?cm, effective length of 20?cm, diameter of 100?μm, ODS packing inside for 3?μm). The mobile phase ratio of organic phase, the concentration of phosphate buffer and sodium heptanesulfonate, separation voltage, and other experimental conditions were investigated and optimized. The mobile phase was 15?mM NaH₂PO₄ and 12?mM sodium heptanesulfonate (pH 3.0)/methanol (64:36) at a flow rate of 0.04?mL/min. Under optimal conditions including applied voltage of ?4?kV and a UV detection wavelength of 230?nm, the six catechins in the tea were well separated. The calibration curves for the analytes had good linearity in the range of 8.02?μg/mL–202.13?μg/mL with a correlation coefficient of 0.9928–0.9997. The limits of detection (LOD) for the six catechins were 4.62?μg/mL–11.63?μg/mL (S/N?=?3). The recoveries of the six catechins were 96.2%–108.4% with a relative standard deviation (RSD) between 0.78% and 4.51%. The method has been used for the determination of six catechins in tea samples with good results.     

Forward-scattering degenerate four-wave mixing as a potential laser-based absorption detection method in liquid separation systems: Coupling to conventional-size liquid chromatography

An explorative study on the compatibility of liquid separation systems, such as (micro) liquid chromatography (LC) and capillary electrophoresis (CE), and forward-scattering degenerate four-wave mixing (F-D4WM) as a detection method is presented. F-D4WM is a laser-based technique showing some analogy with holographic spectroscopy: a signal on a theoretical dark background is observed as a result of light absorption by an analyte. Parameters considered are solvent composition focussing on acetonitrile, methanol and water; mobile phases in LC and CE), detector cell construction, and influences of laser beam powers. A specially designed detector cell has been developed to meet the Brewster condition, both at the air-quartz and the quartz-liquid boundaries. For practical reasons, the tested cell has an optical pathlength of 1 mm; reduction to 100 μm is required to apply the cell in microseparations. The F-D4WM technique has been involved for detection in a conventional-size, reversed-phase LC separation of 1- and 2-aminoanthraquinones. The detection limit obtained (for the 1 mm cell) is 2 × 10⁻⁵ absorbance units. The experiments indicate that further reduction of background deserves explicit attention.     

气相色谱-串联质谱法测定蔬菜和水果中三氯生及甲基三氯生的含量

提出了应用气相色谱-串联质谱法测定蔬菜(西红柿、黄瓜等)和水果(橙子、苹果等)中潜在的污染物三氯生(TCS)和甲基三氯生(MTCS)的含量的方法,以期有助于对此污染物在蔬菜、水果等食品中的污染问题的研究,并应用于农产品质量的安全监测之中。将样品分别去皮后切块,匀浆后于-22℃保存。称取样品5.00g,先后2次用乙酸乙酯(每次10mL)超声提取10min后离心10min,合并2次的提取液。将提取液吹氮蒸发至近干。加入衍生试剂体积比为99∶1的N,O-双(三甲基硅烷基)三氟乙酰胺-三甲基氯硅烷混合溶液100μL,在60℃下进行衍生化反应40min。反应结束后,将溶液吹氮至近干,用乙酸乙酯1.0mL溶解残渣。所得溶液供气相色谱-串联质谱法分析。用DB-17MS毛细管色谱柱(30m×0.25mm,0.25μm)在150~290℃区间按程序升温条件进行分离,在电子轰击离子源及多反应监测模式下进行质谱测定。经试验确定,用两种扫描程序分别扫描,TCS衍生物的母离子和子离子依次为m/z 362,347和m/z 360,345,MTCS的母离子和子离子则均为m/z 304,254。测得TCS衍生物和MTCS的标准曲线的线性范围均为0.4~20.0μg·L^-1,其检出限(3S/N)为4~6ng·kg^-1。按标准加入法进行回收试验,测得TCS衍生物和MTCS在4种蔬菜、水果中的回收率为91.5%~107%和94.7%~111%。     

Nanomolar detection with high sensitivity microfluidic absorption cells manufactured in tinted PMMA for chemical analysis

We describe a novel, cost effective and simple technique for the manufacture of high sensitivity absorption cells for microfluidic analytical systems. The cells are made from tinted polymethyl methacrylate (PMMA) in which microfluidic channels are fabricated. Two windows (typically 250 μm thick, resulting in little optical power loss) are formed at either end of the channel through which light is coupled. Unwanted stray light from the emitter passes through a greater thickness of the tinted substrate (typically the length of the cell) and is preferentially absorbed. In effect, this creates a pin-hole configuration over the length of the absorption cell, providing improved performances (sensitivity, S/N ratios, baseline noise and limit of detection) when used as an absorption cell compared to clear substrates. The method is used to achieve a LOD of 20 nM with a colourimetric iron assay and a LOD of 0.22 milli-absorption units with a pH assay.     

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。     

Capillary electrophoretic determination of dithiocarbamates and ethyl xanthate

A simple and sensitive capillary electrophoretic method was developed for the separation and determination of sodium methyldithiocarbamate (metham), manganese ethylenebisdithiocarbamate (maneb) and ethyl xanthate in boric acid buffer by direct UV absorbance detection at lambda = 254 nm. The separation is dependent on pH and nature of the buffer. The detection limits (S/N = 3) are 1.7 x 10(-6) mol/L for ethyl xanthate, 1.3 x 10(-6) mol/L for metham and 2.1 x 10(-6) mol/L for maneb. The method has been successfully applied to the analysis of wheat samples spiked with maneb and in a commercial sample.