Effect of the water content of cardboard on the static headspace extraction of volatile aldehydes

Abstract

Due to their sensorial activity, quantification of linear, short-chained aldehydes is a routine operation in quality control in the paper and cardboard industry, especially when cellulose-based products are intended for hygienic or food packaging purposes. The ease of operation and automation favors static headspace extraction systems for the separation of volatiles from the matrix. Since the analytes are extracted into the gas phase, the determination is mostly performed by gas chromatography with flame ionization or mass selective detection. An absolute prerequisite for correct static headspace analysis is the establishment of a partition equilibrium of the analytes between the sample phase and the gas phase in the sample vial. Especially in the analysis of solid samples, this requirement is not easy to fulfil and matrix effects may severely hamper analytical work. This paper describes the effect of the water content of the cellulose matrix on the static headspace extraction of pentanal, hexanal, and heptanal. Special attention was given to performing the measurements under conditions which may be result from the climatic environment during storage. For homogenization purposes cardboard samples were cut to a size of 15 mm length and 1.5 mm width. Different water contents were established by conditioning the samples in desiccators over supersaturated salt solutions. The analytical results were compared with those obtained for untreated samples and those of samples which had been spiked with defined amounts of water. The measurements clearly indicate a significant influence of the water content of the cardboard samples on the static headspace extraction of volatile aldehydes.