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S. Armenta Estrela, B. Lendl:
"Capillary liquid chromatography with off-line mid-IR and Raman micro-spectroscopic detection: Analysis of chlorinated pesticides at ppb levels";
Analytical and Bioanalytical Chemistry, 397 (2010), 397; 297 - 308.

A flow-through microdispenser was used as a
solvent elimination interface, allowing vibrational spectroscopic
detection in capillary liquid chromatography in
addition to standard UV detection. Using a flow-through
microdispenser, robust and stable deposition of picoliter-sized
droplets on a CaF2 plate window was achieved. The CaF2
window was placed on a thermostated sample holder (80 °C)
mounted on a computerized x, y stage for achieving fast
solvent evaporation and enabling recording of the chromatogram
as a trace of deposited material. The dried residues that
were formed had diameters of a few tens of micrometers and
were analysed by mid-IR and Raman micro-spectroscopy.
Conditions were optimized for high sensitivity of measurement
and maintaining chromatographic resolution during the
deposition step. Due to the destruction-free character of
Raman and FTIR spectroscopy, these techniques could be
applied sequentially to interrogate the same deposits. To
test the usefulness of the methodology for environmental
analysis, the determination and unambiguous identification
of chlorinated pesticides (chlortoluron, diuron, atrazine,
and terbuthylazine) in river water was used as an example,
obtaining limits of identification of 2 ng analyte on-column
and precision of approximately 10% RSD. The application
of the developed method to spiked real river samples
demonstrated the identification power of the proposed
method as, in addition to the four previously studied pesticides,
two additional pesticides (simazine and isoproturon) could
also be detected and identified.

http://dx.doi.org/10.1007/s00216-010-3590-2