Kitagawa Fumihiko, Sato Sora, Suzuki Tomohiro, Kawai Takayuki
Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-Cho, Hirosaki, Aomori, 036-8561, Japan.
Department of Chemistry, Graduate School of Science, Kyushu University, 744 Moto-Oka, Nishi-Ku, Fukuoka, 819-0395, Japan.
Anal Sci. 2024 Dec;40(12):2117-2124. doi: 10.1007/s44211-024-00647-y. Epub 2024 Aug 20.
In our previous study, the combination of two on-line sample preconcentration techniques, large-volume sample stacking with an electroosmotic flow (EOF) pump (LVSEP) and transient isotachophoresis (tITP), in microchip electrophoresis (MCE) was developed, which was named large-volume dual preconcentration by isotachophoresis and stacking (LDIS). LDIS was apparently effective for improving the sensitivity and the peak shape. In LDIS, however, there was a limit to the improvement of the sensitivity enhancement factor (SEF) since the amount of analytes to be concentrated was limited to the channel volume. To overcome this issue, in the present article, LDIS was coupled with field-amplified sample injection (FASI) technique on Y-shaped channel microchips. The use of a Y-channel in LDIS-FASI allowed consecutive LVSEP, FASI and tITP enrichments with a simple voltage control. In conventional LVSEP and LDIS analyses of a standard analyte, the SEFs were evaluated to be 2630 and 13,100, respectively, whereas in LDIS-FASI that was increased to 27,900 even at the FASI injection time of 0 s. To achieve higher SEFs, furthermore, the FASI injection time was increased to 150 s, resulting in the best SEF of 58,500. It should be emphasized that the peak width in LDIS-FASI was quite narrow, only 0.3-3.1 s, while in normal LVSEP that was 13 s. Furthermore, the LDIS-FASI technique was applied to the analysis of oligosaccharide mixture. Due to the focusing effect by LDIS-FASI, the resolutions were improved from 0.97-1.57 to 2.08-2.73.
在我们之前的研究中，开发了两种在线样品预富集技术的组合，即基于电渗流（EOF）泵的大体积样品堆积（LVSEP）和瞬态等速电泳（tITP），用于微芯片电泳（MCE），该技术被命名为等速电泳和堆积大体积双重预富集（LDIS）。LDIS在提高灵敏度和峰形方面显然是有效的。然而，在LDIS中，灵敏度增强因子（SEF）的提高存在一定限制，因为待浓缩的分析物量限于通道体积。为了克服这个问题，在本文中，LDIS与Y形通道微芯片上的场放大进样（FASI）技术相结合。在LDIS-FASI中使用Y通道，通过简单的电压控制即可实现连续的LVSEP-FASI和tITP富集。在标准分析物的常规LVSEP和LDIS分析中，SEF分别评估为2630和13100，而在LDIS-FASI中，即使在FASI进样时间为0秒时，SEF也提高到了27900。此外，为了获得更高的SEF，将FASI进样时间增加到150秒，从而得到了最佳的SEF为58500。应该强调的是，LDIS-FASI中的峰宽非常窄，仅为0.3 - 3.1秒，而在正常LVSEP中为13秒。此外，LDIS-FASI技术被应用于寡糖混合物的分析。由于LDIS-FASI的聚焦作用，分辨率从0.97 - 1.57提高到了2.08 - 2.73。
