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A procedure for the rapid simultaneous determination of anthraquinone and bisphenol A in paper and cardboard is proposed based on a combination of extraction with subcritical methanol and subsequent analysis of the extracts by HPLC‒tandem mass spectrometry. The achieved limits of detection are 25 and 250 µg/kg for anthraquinone and bisphenol A, respectively, and fully meet present-day safety requirements for pulp and paper products. The total duration of the analysis, including sample preparation, is not more than 45 min. The sensitivity of anthraquinone determination is 1‒2 orders of magnitude higher than that of the known procedures, including those with the preconcentration of analytes. The results obtained were successfully used to study paper and cardboard samples, in most of which unacceptably high levels of the anthraquinone concentration were found. [ABSTRACT FROM AUTHOR]

Capillary electrophoresis was used for determining Belofors, which are used as optical bleaching agents for improving the whiteness of writing paper. Sodium dodecyl sulfate (SDS) was used as a modifier of capillary walls in the separation of water-soluble Belofors. An optimum buffer electrolyte for separating and determining Belofors was as follows: 0.5 mM sodium hydrogen phosphate, 12.2 mM sodium tetraborate, and 30 mM SDS; pH 9.1. Bleaching agents in 39 samples of paper manufactured in Russia, Finland, Sweden, France, the Czech Republic, and Austria were determined and characterized. Common features for classifying paper types in accordance with brands and manufacturers were found. [ABSTRACT FROM AUTHOR]