In previous papers on HPLC/FT-IR from Ohio University, we have stressed the substantial reduction in detection limits that can be achieved if the mobile phase is completely removed from the solute prior to the measurement of the infrared spectrum of each solute (or "HPLC peak"). The most effective way of achieving this end which we have described to date1, 2; has been to concentrate the solution eluting from the chromatograph by differential evaporation, and to deposit each peak onto a hollow cup containing KCl powder. After a final solvent elimination step, the diffuse reflectance infrared Fourier transform (DRIFT) spectrum of each peak is measured, with the operation of the entire HPLC/FT-IR interface being controlled by a microcomputer.