Journal of Chromatography A, 1080 (2005) 132–139 Flow-through microdispenser for interfacing -HPLC to Raman and mid-IR spectroscopic detection Izabella Surowiec a,c , Josefa R. Baena a , Johannes Frank a , Thomas Laurell b , Johan Nilsson b , Marek Trojanowicz c , Bernhard Lendl a,∗ a Institute for Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9-164, A-1060 Vienna, Austria b Department of Electrical Measurement, Lund Institute of Technology, Lund University Ole R¨ omers v¨ ag, P.O. Box 118, S-22100 Lund, Sweden c Departmentof Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland Received 19 April 2005; received in revised form 19 April 2005; accepted 27 April 2005 Abstract A flow-through microdispenser has been coupled to a micro HPLC separation system and used as a solvent elimination interface for Fourier transform infrared (FTIR) and Raman spectroscopic detection of the separated compounds. Using the microdispenser picoliter sized droplets can be generated and deposited on an appropriate target placed on a computerized x, y-stage. Evaporation of volatile solvent and buffer is rapid and allows analysis of the obtained dry deposits by various techniques. Due to the destruction free character of Raman and FTIR spectroscopy they can be applied sequentially to interrogate the same deposit. In the reported application five phenolic acids typically present in wine have been separated on a C-18 column technique using a mixture of water, methanol and acetic acid as mobile phase. For spectrum acquisition infrared and Raman microscopes have been used. The spectra recorded from the dried deposits of the separated compounds agreed well with the reference spectra of corresponding components. © 2005 Elsevier B.V. All rights reserved. Keywords: Raman microspectrometry; FTIR microscopy; HPLC; Flow through microdispenser 1. Introduction In infrared and Raman spectroscopy important instru- mental developments continue to be made especially when considering the analysis of micro-samples. In case the sample can be properly presented to the detector often surprisingly minute amounts of material is sufficient for obtaining a mid- infrared or Raman spectrum with good signal-to-noise ratio. Single bacterial cells [1], organic monolayers [2] or a few femtograms of almost any material are generally enough for obtaining a meaningful spectrum [3]. Development of different detectors to be coupled to modern separation systems is an ongoing field of research. For analyte identification modern spectroscopic techniques ∗ Corresponding author. Tel.: +43 1 58801 151940; fax: +43 1 58801 15199. E-mail address: blendl@mail.zserv.tuwien.ac.at (B. Lendl). that provide a full spectrum are required. Among these Raman and mid-infrared spectroscopy are of special interest due to the molecular specific fingerprint that they provide. Furthermore, their non-destructive character allows their use in sequence as well as coupling with other more sensitive detection schemes. Raman and infrared spectroscopy provide complementary, structural information that can be used for quantitative as well as qualitative analysis. Whereas application of mid-IR spectroscopic detection in liquid chromatography is made difficult by strong absorption of the solvent, in particular of water, Raman spectroscopy is less affected by solvent bands. However, direct application of Raman spectrometry for on-line detection in solution is made difficult by the low concentration sensitivity of this technique [4]. A Raman measurement of the separated analytes in solution has been achieved by diverting the flow to an off-line sampling cell. In doing so long integration times could be applied which allowed for improved sensitivity [5]. Another 0021-9673/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2005.04.082