Resins chemical workup

Preliminary tests, color reactions, and spot tests [10.7] were formerly used to identify individual resins but are no longer important because they are not sufficiently specific and they do not provide quantitative results. They have been largely replaced by modern spectroscopic and chromatographic methods, which often require preliminary chemical workup of the sample. 

Chemical Workup. Chemical decomposition of resins followed by qualitative and quantitative analysis is still an important technique because, apart from NMR spectroscopy, none of the instrumental analytical methods provides reliable quantitative values. Chemical workup is also essential for low concentrations of resin building blocks that are often unknown it simplifies and enables the desired substances to be concentrated. Qualitative and quantitative determination is carried out by instrumental methods. 

The assessment of mutagenic activity in cooked foods requires tedious extraction work in order to isolate and quantify the responsible chemicals at the nanogram level. Efforts have been made to develop a rapid and efficient method to obtain chromatograms free of interfering material. Coextracted matrix components influence analyte detection limits more than does absolute detector sensitivity (182). The sample workup therefore is the most critical part of the analysis (183). Solid-phase extraction with different coupled columns provides an improvement (176) over LLE and the use of large columns filled with XAD resin. The determination of PAHs and PANHs in food has been carried out by different chromatographic techniques, including LC with fluorescence (164,171,184) and/or UV detection (185,171) and GC with FID (168,186) or MS detection (187). 

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