Behavior of [¹⁴C]Atrazine, [¹⁴C]Terbutylazine, and Their Major Metabolites in the Brewing Process

The behavior of some s-triazine herbicides and metabolites ([¹⁴C]atrazine, [¹⁴C]deethylatrazine, [¹⁴C]-deisopropylatrazine, [¹⁴C]hydroxyatrazine, [¹⁴C]terbutylazine, and deethylterbutylazine) during beer production was studied. In the mashing process reduction of the triazine concentration in brewing liquor is caused by adsorption on spent grains. Adsorption affinity depends on the polarity of the triazine component: the more polar the triazine, the lower the adsorbed amount. Terbutylazine was found almost completely in the spent grains, whereas the major part of the dealkylated atrazine metabolites was detected in the wort. Adsorption on spent hops in the cooking process and on kieselguhr in the filtration step was insignificant. During fermentation hydroxylated triazines were formed. Top-fermenting yeasts (Saccharomyces cerevisiae) were able to convert atrazine into its hydroxylated analogue with first-order kinetics and a half-life of 98 days. The reactivity of bottom-fermenting yeasts (Saccharomyces carlsbergensis) was negligible. Isolation of hydroxyatrazine and hydroxyterbutylazine in beer required several cleanup steps before determination by HPLC with UV/DAD detection and identification by GC-MS.