Quantitative analysis of an oligomeric hindered amine light stabilizer in polypropylene by matrix-assisted laser desorption/ionization mass spectrometry using a solid sampling technique.

A small amount of an oligomeric hindered amine light stabilizer (HALS) (Adekastab LA-68LD) in polypropylene (PP) materials was directly determined by solid sampling matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) using an internal standard method. First the matrix reagent (dithranol), 20 mg, and the empirically selected internal standard, angiotensin I (MW = 1296.5), 5 microg, were premixed in the solid state.

Determination of a polymeric hindered amine light stabilizer in polypropylene formulated with magnesium hydroxide flame retardant by reactive thermal desorption-gas chromatography.

A polymeric hindered amine light stabilizer (HALS), Tinuvin 622 (MW [symbol: see text] 4000), in PP materials formulated with a magnesium hydroxide flame retardant was determined by reactive thermal desorption (RTD) gas chromatography (GC). Two kinds of the HALS components that were formed through the RTD in the presence of tetramethylammonium hydroxide [(CH3)4NOH, TMAH] were clearly observed in the chromatograms of the PP samples, with negligible interference from the other additives and the PP substrate. Here, the coexisting flame retardant was proved to affect significantly the RTD process of the occluded HALS.

Direct analysis of an oligomeric hindered amine light stabilizer in polypropylene materials by MALDI-MS using a solid sampling technique to study its photostabilizing action.

A novel method for the direct analysis of small amounts of an oligomeric hindered amine light stabilizer (HALS) occluded in polypropylene (PP) material was developed to study its photostabilizing action on the basis of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) using a solid sampling technique while avoiding troublesome solvent extraction. In this sampling protocol, the powdered mixture of PP composite sample containing trace amounts of an oligomeric HALS, Adekastab LA-68LD (MW = 1900), and the matrix reagent (dithranol) was spotted on the sample plate, then ion exchanged water was deposited onto the mixture to make a suspension, and finally, the dried mixture adhered on the plate was subjected to MALDI-MS measurement. On the mass spectrum thus obtained by the solid sampling MALDI, the molecular ions of the HALS desorbed from the PP composite were clearly observed as three major series of the HALS components in the range up to about m/z 7000 with little interference by the PP substrate and the other additives.

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.