title: High performance liquid chromatography with mid-infrared detection based on a broadly tunable quantum cascade laser.
abstract: This work introduces a tunable mid-infrared (mid-IR) external cavity quantum cascade laser (EC-QCL) as a new molecular specific detector in liquid chromatography. An EC-QCL with a maximum tunability of 200 cm(-1) (1030-1230 cm(-1)) was coupled to isocratic high performance liquid chromatography (HPLC) for the separation of sugars with a cation exchange column (counter ion: Ca(2+)) and distilled water as the mobile phase. Transmission measurements in a 165 μm thick flow cell allowed for on-line coupling and independent quantification of glucose, fructose and sucrose in the concentration range from 5 mg mL(-1) to 100 mg mL(-1) in several beverages. The results obtained with the EC-QCL detector were found to be in good agreement with those obtained using a differential refractive index detector as a reference. The standard deviation of the method for the linear calibration was better than 5 mg mL(-1) for all sugars and reached a minimum of 1.9 mg mL(-1), while the DRI detector reached a minimum of 1 mg mL(-1). Besides the quantification of sugars for which a calibration was performed, also chromatographic peaks of other components could be identified on the basis of their IR absorption spectra. This includes taurine, ethanol, and sorbitol.
authors.affiliation: Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 18, 76131 Karlsruhe, Germany.
authors.forename: Timo F
authors.initials: TF
authors.lastname: Beskers
authors.forename: Markus
authors.initials: M
authors.lastname: Brandstetter
authors.forename: Julia
authors.initials: J
authors.lastname: Kuligowski
authors.forename: Guillermo
authors.initials: G
authors.lastname: Quintás
authors.forename: Manfred
authors.initials: M
authors.lastname: Wilhelm
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lendl
mesh_terms: D001628:Beverages / Q000032:analysis; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D012015:Reference Standards; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation / Q000379:methods*