The widely distributed pollutant tributyltin (TBT) was analyzed in different environmental samples (waters and sediments) combining preconcentration on a nylon membrane, excitation–emission fluorescence matrices directly measured over the membrane and second-order multivariate calibration. The latter was implemented using unfolded partial least-squares with residual bilinearization (U-PLS/RBL), a flexible algorithm achieving second-order advantage, even under severe spectral overlapping among sample components. Matrix-specific calibrations were required to overcome matrix effects, resulting in good analytical performance. TBT was determined in the concentration ranges 0.043–1.42ng Sn mL−1 in water and 24–400μg Sn kg−1 in sediments, with adequate detection limits in the range 0.03–0.15ng Sn mL−1.