Size-exclusion chromatography with on-line ultraviolet, proton nuclear magnetic resonance and mass spectrometric detection and on-line collection for off-line Fourier transform infrared spectroscopy.

The coupling of HPLC with UV detection and on-line NMR spectroscopy and mass spectrometry combined with a dedicated interface for the collection of the chromatographic eluent for subsequent Fourier transform (FT) IR has been investigated using a number of polymer additives as model compounds. Size-exclusion chromatography was performed using deuterated chloroform as eluent with the separation monitored on-line by UV detection at 254 nm and on-flow 1H-NMR and MS. The effluent from the NMR probe was directed to a dedicated HPLC interface where it was deposited on a germanium plate for subsequent FT-IR. NMR and MS spectra were successfully obtained for 2,6-di-tert.-butyl-4-methylphenol, octadecyl-3-(3,5-di-tert.-butyl-4-hydroxyphenyl) propionate (Irganox 1076) and diisooctyl phthalate on-line and FT-IR spectra for all three compounds were obtained off-line. Practical problems encountered with this multiple hyphenation are described.