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 0.043-1.42 ng Sn mL(-1) in water and 24-400 mu g Sn kg(-1) in sediments, with adequate detection limits in the range 0.03-0.15 ng Sn mL(-1). (C) 2015 Elsevier B.V. All rights reserved.