Antioxidants size-exclusion chromatography

Figure 12 Separation of Irganox 1076 and Irganox PS802 by size exclusion chromatography (duplicate solution injections of each antioxidant showing the reproducibility of the technique).

A reliable procedure for determination of molecular parameters number, weight and z-averages of the molecular weight (Mj, i = n, w and z respectively) for polyethylenes, PE, by means of Size Exclusion Chromatography, SEC, has been developed. The Waters Sci. Ltd. GPC/LC Model 150C was used at 135 C with trichlorobenzene, TCB, as a solvent. The standard samples as well as commercial stabilized and not stabilized PE-resins were evaluated. The effects of sampling, method of solution preparation, addition of antioxidant(s), thermal and shear degradation were studied. The adopted procedure allows reproducible determination of and M , with a random error of 4% and M2, with 9%, within 2 to 72 hrs from the initial moment of preparation of solutions. 

Single electron transfer (SET), as antioxidant mechanism 844, 896, 897 Size exclusion chromatography 953 Slash pine bark, phenolic compounds in 944 Smiles rearrangement 466-470, 759 S Ar reactions 673 Soil samples, phenolic compounds in, analysis of 932, 965, 972, 985 field screening of 938 Sol-gel technique 1082 Solid acid catalysis 612-621 Solid-phase extraction (SPE) 930-933, 936, 942, 944-950, 955, 958, 960, 962-964, 969, 972, 985, 986, 995, 1354 Solvation energy 500, 992 Solvation free energy 5 Solvatochromic comparison method, for solvent hydrogen-bond basicity 591 Solvent effects,... 

Greene, S.V. Gatto, V.J. Size-exclusion chromatography method for characterizing low molecular mass antioxidant lubricant additives. J. Chromatogr. A, 1999, 841,45-54. 

Nerfin, C. Salafranca, J. Cacho, J. Rubio, C. Separation of polymer and on-line determination of several antioxidants and UV stabilizers by coupling size-exclusion and normal-phase high-performance liquid chromatography columns. J. Chromatogr., A 1995, 690, 230-236. 

After the extraction step has been completed, the antioxidants and other additives present in the solvent can be readily analyzed. The majority of the analytical methods used for measuring the antioxidant content of polymer extract solutions are based on chromatography, such as high performance or high pressure liquid (HPLC), gas (GC), and gel permeation (GPC) or size exclusion (SEC). As most polymer antioxidants contain a phenyl ring or other chromophoric moiety in their structure, UV detection (usually between 200 and 280 nm) is ideally suited for their measurement. The chromatogram shown in Figure 1 aptly demonstrates the utility of... 

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