Pushing the limits: Quantification of chromophores in real-world paper samples by GC-ECD and EI-GC-MS.

Widening the methodology of chromophore analysis in pulp and paper science, a sensitive gas-chromatographic approach with electron-capture detection is presented and applied to model samples and real-world historic paper material. Trifluoroacetic anhydride was used for derivatization of the chromophore target compounds. The derivative formation was confirmed by NMR and accurate mass analysis. The method successfully detects and quantifies hydroxyquinones which are key chromophores in cellulosic matrices. The analytical figures of merit appeared to be in an acceptable range with an LOD down to approx. 60ng/g for each key chromophore, which allows for their successful detection in historic sample material.

Aging of paper - Ultra-fast quantification of 2,5-dihydroxyacetophenone, as a key chromophore in cellulosics, by reactive paper spray-mass spectrometry.

The detection of individual chromophores that contribute to the overall discoloration of paper or pulp ("yellowing") is a challenge because these substances are only present in extremely small amounts (ppm to ppb range). In this work, paper spray (PS) coupled with mass spectrometry was used to detect a low-concentrated cellulosic key-chromophore, 2,5-dihydroxyacetophenone (DHAP). Sensitivity was enhanced by derivatization with Girard's reagent T (GT). DHAP was successfully detected in historic paper samples and also was applied to model papers in order to investigate different factors that influence its generation: temperature, time, relative humidity, and the presence of iron ions, by means of a full factorial design. The main factors, temperature and relative humidity, have the most impact on the generation of DHAP, but the interactions between the factors are also significant and are therefore important for the degradation process. The historical papers containing DHAP were then compared to the artificially aged samples. The results were confirmed by independent, accurate mass measurements.