Solvent -elimination HPLC /FT -IR has become a viable combination of two important techniques, and we have been developing a system which is adaptable to both normal and reversed -phase liquid chromatography.The interface involves the deposition of HPLC eluites onto a KCI -laden train with subsequent analysis via diffuse reflectance spectroscopy, and with minor modifications, the system can be used with microbore and analytical columns. With aqueous solvents, the water is converted to methanol and acetone in a post -column reaction with 2,2-dimethoxypropane before the eluites are deposited.A number of different samples have been used to demonstrate the interface and its flexibility. Steroids, analgesics, and other pharmaceutical preparations have been separated with reverse -phase solvents and identified by their infrared spectra. For some of the compounds studied, different infrared spectra of a given compound have been found to exhibit intensity variations, which arise from different crystalline states. The differences can be concentration dependent and may be useful in obtaining semi -quantitative information from the infrared spectra.Applications involving both gradient elution and isocratic separations have been successful. The former provides the same advantages for HPLC /FT -IR as one finds in conventional HPLC. More recent work has been applied to the use of buffers such as those frequently used in bioanalytical separations.In trying to simplify the post -column reaction with water, we have immobilized dehydration reagents onto silica particles and packed these materials into a column which is inserted in -line after the analytical column. Of the reagents utilized to date, 3, 3-dimethoxypropyltrimethoxysilane has been found to perform most efficiently. It has advantages over the simpler reagents because it can be regenerated in the reaction column.Results and the efficiency of the dehydration process and its relation to the type of reagent and its coverage will be discussed.Solvent-elimination HPLC/FT-IR has become a viable combination of two important techniques, and we have been developing a system which is adaptable to both normal and re versed-phase liquid chromatography. The interface involves the deposition of HPLu eluites onto a KCI-laden train with subsequent analysis via diffuse reflectance spectroscopy, and with minor modifications, the system can be used with microbore and analytical columns. With aqueous solvents, the water is converted to methanol and acetone in a post-column reaction with 2,2-dimethoxypropane before the eluites are deposited.A number of different samples have been used to demonstrate the interface and its flexibility. Steroids, analgesics, and other pharmaceutical preparations have been separated with reverse-phase solvents and identified by their infrared spectra. For some of the compounds studied, different infrared spectra of a given compound have been found to exhibit intensity variations, which arise from different crystalline states. The differences can be concentratio...

The Raman spectra ( 4 W 1 0 0 em-') of liquid and solid cyclohexylphosphine were recorded, together with the infrared spectra (4000-400 cm-') of the vapor and solid. Both the Raman and infrared spectra indicate the existence of axial conformers, presumably with gauche and trum orientations of the PH, group, in addition to the more stable equatorial form. The likelihood of the existence of two equatorial forms of cyclohexylphosphine is discussed, although such a result has not been confirmed experimentally. Variable-temperature experiments monitoring the very weak Raman lines for the axial conformers give enthalpy differences in the range 1.6-1.8 kcal mol-'. A complete set of vibrational assignments is proposed based on data from the PD, species and analogy with related substituted cyclohexanes.

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