On-Line Fourier Transform Infrared Detection in Capillary Electrophoresis

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• 作者：Malin K&ouml ; lhed ; Peter Hinsmann ; Peter Svasek ; Johannes Frank ; Bo Karlberg ; and Bernhard Lendl
• 刊名：Analytical Chemistry
• 出版年：2002
• 出版时间：August 1, 2002
• 年：2002
• 卷：74
• 期：15
• 页码：3843 - 3848
• 全文大小：142K
• 年卷期：v.74,no.15(August 1, 2002)
• ISSN：1520-6882

文摘

The coupling of Fourier transform infrared (FT-IR) spectroscopy as a new on-line detection principle in capillaryelectrophoresis (CE) is presented. To overcome theproblem of total IR absorption by the fused-silica capillaries that are normally employed in CE separations, amicromachined IR-transparent flow cell was constructed.The cell consists of two IR-transparent CaF₂ plates separated by a polymer coating and a titanium layer producingan IR detection window, 150 s/entities/mgr.gif">m wide and 2 mm long,with a path length of 15 s/entities/mgr.gif">m. The IR beam was focusedon the detection window using an off-axis parabolic mirrorin an optical device (made in-house) attached to anexternal optical port of the spectrometer. The connectionsbetween the fused-silica capillaries and the flow cell weremade by a small O-ring of UV-curing epoxy adhesive onthe sharply cut ends of the capillaries, allowing thecapillaries to be easily replaced. Aqueous solutions comprising mixtures of adenosine, guanosine, and adenosinemonophosphate were used to test the system's performance. Conventional on-line UV detection was employedto obtain reference measurements of analytes after the IRdetection flow cell. The limit of FT-IR detection for allanalytes (in absolute amounts) was in the nano- topicogram range corresponding to concentrations in thelow-millimolar range.