Faculty of Physics, Babeş-Bolyai University, Kogalniceanu 1, 400084 Cluj-Napoca, Romania.
Anal Bioanal Chem. 2010 Mar;396(6):2341-8. doi: 10.1007/s00216-010-3468-3. Epub 2010 Feb 3.
A new, simple, and efficient approach for on-column surface-enhanced Raman scattering (SERS) detection in capillary electrophoresis (CE) is reported. A approximately 50-microm SERS substrate spot was prepared by laser-induced growth of silver particles in the 100-microm inner diameter CE capillary window or in a flow cell consisting of a 250-microm inner diameter fused silica capillary connector. For this purpose, the Raman laser was focused by a 20x objective into the detection window filled with a 0.5 mM silver nitrate and 10 mM citrate buffer solution. During the CE runs, the silver substrate spot was formed in a few seconds after the analyte injection, hence the analytes adsorbed sequentially to the silver surface when the detection window was reached, followed by desorption from the silver surface and continuing the electrophoretic migration to the capillary end. Thus, beyond migration time, valuable molecular specific information was delivered by the SERS spectra. Accurate separations and high-intensity SERS spectra are shown by CE-SERS time-dependent 3D electropherograms for the analytes rhodamine 6G, 4-(2-pyridylazo)resorcinol (PAR), PAR complex with Cu(II) and methylene blue at 0.25-25 ppm concentrations, by using 1.4-3.6 mW HeNe laser power and an acquisition time of 5 s for each spectrum. Before and after each analyte passes the detection window, clean background spectra were recorded and no memory effects perturbed the SERS detection. The silver substrate is characterized by a fast preparation rate, good reproducibility, a preparation success rate of over 95% and no mentionable influence on the electrophoretic migration time, the CE-SERS and CE-UV electropherograms being in good agreement. The successful coupling of CE and on-column SERS detection opens new perspectives for monitoring CE separations.
一种新的、简单的、高效的毛细管电泳（CE）中柱面增强拉曼散射（SERS）检测方法。通过在 100 微米内径 CE 毛细管窗口或由 250 微米内径熔融石英毛细管连接器组成的流动池中激光诱导生长银颗粒，制备了大约 50 微米的 SERS 衬底斑点。为此，拉曼激光通过 20x 物镜聚焦到充满 0.5mM 硝酸银和 10mM 柠檬酸盐缓冲溶液的检测窗口中。在 CE 运行期间，在分析物注入后几秒钟内形成银衬底斑点，因此当检测窗口到达时，分析物依次吸附在银表面上，然后从银表面解吸，并继续电泳迁移到毛细管末端。因此，在迁移时间之外，SERS 光谱提供了有价值的分子特异性信息。通过 CE-SERS 时间相关的 3D 电泳图显示了准确的分离和高强度的 SERS 光谱，用于分析物罗丹明 6G、4-（2-吡啶偶氮）间苯二酚（PAR）、PAR 与 Cu（II）的配合物和亚甲蓝，浓度为 0.25-25ppm，使用 1.4-3.6mW HeNe 激光功率和每个光谱 5s 的采集时间。在每个分析物通过检测窗口之前和之后，都记录了干净的背景光谱，并且没有记忆效应干扰 SERS 检测。银衬底的制备速率快、重现性好、制备成功率超过 95%，对电泳迁移时间没有明显影响，CE-SERS 和 CE-UV 电泳图吻合良好。CE 与柱面 SERS 检测的成功耦合为监测 CE 分离开辟了新的前景。
