Analysis of additives in a polymer by LC/IR using surface enhanced infrared absorption spectroscopy

Liquid chromatography/infrared spectroscopy (LC/IR) using surface-enhanced infrared absorption spectroscopy (SEIRAS) was designed in order to develop a highly sensitive and speedy analysis method of polymer additives. A metal film on the substrate for LC/IR was prepared using the diode sputtering method. The conditions for the preparation of the metal film and the LC/IR measurement were optimized. It was found that the highest sensitivity was obtained by using the following conditions: a metal film of Ag, a substrate of BaF2, and a flow rate of N-2 gas for spraying the LC eluent of 3.0 l/min. By LC/IR under these conditions, the determination of triphenylphosphate became possible at a 10 ng detection limit. An enhancement factor of about 90 was obtained. The actual applications to the analysis of additives in commercial polypropylene proved that this method is useful for a highly sensitive analysis of polymer additives.