Monitoring of concentrations of trenbolone. (a) Recovery of Trenbolone in stock solutions; (b) recovery of Trenbolone in tanks. Note that in (b) in week 5, due to a technical issue during samples processing, data for 10−10 M are missing. Nominal Tb-concentrations in tanks (b) comprised (0.027 µg/L (10−10 M, red), 0.27 µg/L (10−9 M, green), 2.7 µg/L (10−8 M, violet). Controls were free of Tb, apart from one measurement in study week (0.05 ng/L in one tank); see text for technical details on measurements.