Opekar František, Tůma Petr
Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, Albertov 2030, 128 43 Prague 2, Czech Republic.
Charles University in Prague, Third Faculty of Medicine, Institute of Biochemistry, Cell and Molecular Biology, Ruská 87, 100 00 Prague 10, Czech Republic.
J Chromatogr A. 2016 May 13;1446:158-63. doi: 10.1016/j.chroma.2016.04.015. Epub 2016 Apr 8.
An original electrophoresis apparatus for simultaneous rapid determination of cations and anions has been designed and tested. The separation part of the apparatus consists of two identical fused-silica capillaries, each with a length of 10.5cm and inner diameter of 25μm. The injection space is formed by the crossing of four channels in a plexiglass cross-piece. The capillaries pass through two opposing channels and their injection ends are located opposite one another at a distance of approx. 0.5mm in the centre of the crossing point. The exit ends of the capillaries are placed in vessels containing the background electrolyte in which are immersed the electrodes of a high-voltage source. Contactless conductivity detectors with semi-cylindrical electrodes are located 2cm from the exit ends of the capillaries. The injection part of the apparatus consists of two piezoelectric micro-pumps bringing the solution through another channel in the cross-piece to the injection ends of the capillary. During the injection, the sample is brought through one of them and is injected electrokinetically for a defined time. Then the sample zone is forced out of the injection space by a stream of background electrolyte from the second micro-pump. The timing of the injection process is computer-controlled. Thus the equipment can be considered to constitute electrophoresis in one capillary with injection into its centre. The use of short capillaries and miniature micro-pumps without other mechanical components enabled the construction of the apparatus on a board with dimensions of 20×25cm. The proposed equipment was used to test simultaneous separation of a mixture of cations and anions, NH4(+), K(+), Ca(2+), Mg(2+), Sr(2+), Ba(2+), Cl(-), NO3(-), SO4(2-), ClO3(-) and F(-), in BGE with composition 500mM HAc+20mM Tris+2mM 18-crown-6 (pH 3.3). Baseline separation of all the components was achieved in time less than 1min. Quantification of the content of nitrate nitrogen (determined as NO3(-)), ammoniacal nitrogen (determined as NH4(+)), K2O (determined as K(+)) and SO3 (determined as SO4(2-)) was performed on a real-world sample of mineral fertiliser. The determined compositions differed from the declared contents by an amount of 0.5-5.6%; the RSD value expressing the repeatability of the determination was in the range 3.4-7.5%. The LOD values were in the range from 6.9μM (K(+)) to 10.6μM (NH4(+)).
设计并测试了一种用于同时快速测定阳离子和阴离子的新型电泳仪。该仪器的分离部分由两根相同的熔融石英毛细管组成，每根毛细管长度为10.5厘米，内径为25微米。进样空间由有机玻璃十字部件中的四条通道交叉形成。毛细管穿过两条相对的通道，其进样端在交叉点中心彼此相对，距离约为0.5毫米。毛细管的出口端置于装有背景电解质的容器中，高压源的电极浸入其中。带有半圆柱形电极的非接触式电导检测器位于距毛细管出口端2厘米处。该仪器的进样部分由两个压电微型泵组成，它们将溶液通过十字部件中的另一条通道输送到毛细管的进样端。进样时，样品通过其中一个微型泵输送，并在规定时间内进行电动进样。然后，第二个微型泵输送的背景电解质流将样品区从进样空间挤出。进样过程的计时由计算机控制。因此，该设备可视为在一根毛细管中心进样的电泳装置。使用短毛细管和微型微型泵且无其他机械部件，使得该仪器能够构建在尺寸为20×25厘米的板上。所提出的设备用于测试在含有500mM HAc + 20mM Tris + 2mM 18 - 冠 - 6（pH 3.3）的背景电解质中阳离子和阴离子混合物NH4(+)、K(+)、Ca(2+)、Mg(2+)、Sr(2+)、Ba(2+)、Cl(-)、NO3(-)、SO4(2-)、ClO3(-)和F(-)的同时分离。所有组分在不到1分钟的时间内实现了基线分离。对矿物肥料的实际样品进行了硝酸盐氮（以NO3(-)计）、氨态氮（以NH4(+)计）、K2O（以K(+)计）和SO3（以SO4(2-)计）含量的定量分析。测定的组成与申报含量的差异为0.5 - 5.6%；表示测定重复性的相对标准偏差（RSD）值在3.4 - 7.5%范围内。检测限（LOD）值在6.9μM（K(+)）至10.6μM（NH4(+)）范围内。
