Analysis of additives in polymers by thin-layer chromatography coupled with Fourier transform-infrared microscopy

A new, fast and convenient method based on coupled thin-layer chromatography (TLC) and Fourier transform-infrared (FT-IR) microscopy is developed to separate, detect and identify the additives in polymers. After the TLC development, the analytes were transferred on to a barium fluoride (BaF₂) salt plate via a special capillary technique and analysed by FT-IR microscopy. The additives used for stabilization of polypropylene and the plasticisers used for poly(vinyl chloride) were analysed as examples to illustrate this technique. The overall time taken for the experiment including transferring three marked spots and then identifying them was about 20 min. An amount as small as 0.5 μg can be easily detected and identified. It was a very convenient and reliable method to separate and evaluate complex additives for polymers without the interference from TLC adsorbent, because of a special transferring and identifying method, which is suitable to FT-IR microscopy.