Approaches to applying internal standards for the quantification of paper additives by Py-GC/MSD

In the present study, five different methods of internal standard (IS) application with different IS substances were used for the quantification of typical chemical additives in paper such as wet strength or sizing agents by the combination of analytical pyrolysis with gas chromatographic separation and mass selective detection (Py-GC/MSD). The advantages and disadvantages are described. One approach only followed variations of the response of the MSD. A further approach, the injection of an IS solution within the pyrolyzer interface, compensated for variations only in the GC/MSD part. In the other three approaches the IS followed the whole analytical pathway. When different IS applications in the same run were used, sources for variations could be identified. The best reproducibility with relative standard deviations (RSDs) of 4-8% for the paper additives was obtained by using degradation products from the cellulosic matrix as internal standards. The shortcoming of this approach is that the matrix has to be known. Solutions to solve this problem are demonstrated. (C) 2003 Elsevier Science B.V. All rights reserved.