Applications of infrared reflectance and Raman scattering spectroscopy to developments in HPLC detection, vibrational analysis and lipid-antibiotic interactions

A solvent-elimination HPLC/FTIR interface designed for both normal- and reversed-phase solvents and microbore and analytical columns is reported here. For aqueous solvents, water reacts with 2,2-dimethylpropane to form methanol and acetone before the eluites are deposited onto KCl for diffuse reflectance analysis.;Several steroids have been separated with reversed-phase solvents under gradient elution and identified by their infrared spectra. For some compounds the infrared spectra have been found to exhibit intensity variations which arise from different crystalline states. This is true for benzamide and salicylamide, but the effects were absent when the N,N-dimethyl analogue was studied. The differences are concentration dependent and may be useful in obtaining semi-quantitative information.;A preliminary study of combining this interface with Raman spectroscopy was also performed.;Dehydration reagents were immobilized onto silica particles and packed into a column which was inserted after the analytical column. Of the reagents utilized to date, 3,3-dimethoxypropyltrimethoxysilane (DPS) has been found to perform most efficiently because it can be regenerated easily.;In order to analyze rusted surfaces by reflectance-absorbance (R-A) spectroscopy, an optical set-up utilizing a diffuse reflectance accessory was used. Infrared R-A spectra of nonrusted, partially rusted and totally rusted samples were analyzed. Results showed that for metal treated with rust-proofing maintenace the oil used could be identified.;Raman spectra of a homogeneous dipalmitoyl-phosphatidylcholine (DPPC) bilayer and a DPPC bilayer with antibiotic trimethoprim were recorded between 2800 and 3000 cm...