A novel method for the direct detection of light stabilizer Tinuvin 622 in polymer additives by gel permeation...

Tinuvin 622, an oligomeric light stabilizer, is widely used in plastics to reduce light and heat induced degradation and extend their service life, therefore its detection is of great importance for quality control of plastic products. However, the classical analytical methods of Tinuvin 622, such as chromatography and mass spectrometry, are difficult to achieve direct qualitative and quantitative analysis, and simultaneously to obtain the molecular weight and molecular weight distribution information. Herein, we propose for the first time the combination of gel permeation chromatography with multi-angle laser light scattering as a simple and direct method to detect Tinuvin 622 in polymers and simultaneously to obtain its molecular weight distribution information. The linearity of the method was good in the concentration range of 0.1-5.0 mg/mL Tinuvin 622 with correlation coefficient (R² = 0.9999), and the recoveries of Tinuvin 622 at three addition levels ranged from 94.0% to 98.7%, with relative standard deviations of no more than 1.73%. The proposed method has been successfully used to detect Tinuvin 622 in actual samples of polymer additives. Compared with existing analytical methods, Tinuvin 622 has a single peak shape in our method, which is easy to identify and quantify accurately; more importantly, our method can simultaneously characterize the molecular weight and molecular weight distribution of Tinuvin 622, which makes up for the shortcomings of other approaches and provides a new tool for quality monitoring of polymer additives.