DETERMINATION OF METHYLENE-BIS-THIOCYANATE BIOCIDE IN EFFLUENTS AND IN EXTRACTS OF FORTIFIED TISSUE PAPER SAMPLES

An analytical method for the determination of methylene-bis-thiocyanat e (MBT) biocide at sub-ppm concentrations in effluents and water sampl es has been developed. It consists of preconcentration of the biocide, from dilute solutions, onto a column of styrene-divinylbenzene resin with a high surface area, elution with methanol, and measurement by hi gh-pressure liquid chromatography. Effluent matrix interferences in th e SPE (solid-phase extraction) step were reduced by sorption onto an o ctadecylsilica precolumn. Analysis of stream samples from a tissue mil l using the biocide showed that there were 0.19 and 0.02 mg/L MBT in w hitewater and primary effluent, respectively, and none was present in the secondary effluent after biological treatment. Release of the bioc ide from the spiked tissue paper samples was studied. The results show ed that the biocide was strongly bound to fibres. When the tissue was soaked in hot water, the extracts contained only small fractions of sp iked MBT amounts.