A Raman Waveguide Detector for Liquid Chromatography

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• 作者：Brian J. Marquardt ; Paul G. Vahey ; Robert E. Synovec ; and Lloyd W. Burgess
• 刊名：Analytical Chemistry
• 出版年：1999
• 出版时间：November 1, 1999
• 年：1999
• 卷：71
• 期：21
• 页码：4808 - 4814
• 全文大小：137K
• 年卷期：v.71,no.21(November 1, 1999)
• ISSN：1520-6882

文摘

A novel real-time liquid core Raman waveguide detectordesigned for liquid chromatographic applications is described. The Raman waveguide detector provides enhanced selectivity over typical high-performance liquidchromatography (HPLC) detectors. The waveguide detector also greatly improves the sensitivity of a typical Ramanmeasurement without resorting to surface enhancementor resonance approaches and is compatible with thetypical peak width volumes eluted by microbore andminibore HPLC (packed 1-2-mm-i.d. columns). Detection limit enhancements of over 1000-fold have beenachieved for the measurement of alcohols in the aqueousphase with the Raman cell utilizing liquid core waveguidetechnology. The liquid core waveguides demonstrated inthis study were constructed using Teflon AF 2400 tubingwith a refractive index of 1.29. The low refractive indexof the polymer material allowed HPLC separations withRaman detection to be performed with an aqueous mobilephase. A calibration curve for aqueous solutions of 2-propanol was generated and a limit of detection (LOD) of 2ppm was determined. The Raman waveguide detector isdemonstrated for the HPLC analysis of alcohol testmixtures, with LODs in the low-ppm range at the detector.By coupling the temporal separation achieved by HPLCwith the vibrational information gleaned from Ramandetection, an information-rich multivariate data matrix isobtained that can be deconvoluted to provide chemicalspeciation even when the HPLC resolution is poor. In thispaper, we will discuss the physical and optical design ofthe Raman waveguide detector and the demonstration ofthe detector for HPLC detection.