Highly sensitive determination of a polymeric hindered amine light stabilizer in polypropylene by reactive thermal desorption–gas chromatography using nitrogen-specific detection

Highly sensitive and specific determination of trace amounts of a polymeric hindered amine light stabilizer (HALS) in polypropylene (PP) materials could be established by improving reactive thermal desorption–gas chromatography (RTD–GC) in the presence of an organic alkali, tetramethylammonium hydroxide. By using nitrogen–phosphorus detection, highly selective detection of the HALS-related components was attained. In addition, the use of a polar poly(ethylene glycol) separation column alleviated the adsorption of minor specific pyrolysis products. This modified RTD–GC method allowed the determination of the polymeric HALS (Mr 1900) in PP even for trace concentrations between 100 and 500 ppm, through observing selectively the characteristic products containing a tetramethylpiperidine moiety, which had been impossible to detect under the previous RTD–GC conditions using a non-polar separation column and conventional flame ionization detection.