An extensive clean-up method for extraction of 17β-estradiol from eel aquaculture waste solids for quantitation via high-performance liquid chromatography tandem-mass spectrometry

Abstract

The use of 17β-estradiol (E2) in aquaculture feed increases growth and promotes feminization in freshwater eels. E2 and its metabolites (estrone (E1) and estriol (E3)) must be accurately measured in solid and liquid waste streams to ensure proper management. For reliable quantitation of estrogens in complex aquaculture waste solids, a rigorous clean-up method is imperative. The focus of this study was to assess, optimize, and validate a quick, easy, cheap, effective, rugged, and safe (QuEChERS) technique for extraction of estrogens from aquaculture waste solids and quantitation via liquid chromatography tandem-mass spectrometry (LC-MS/MS). Waste solids were collected from a recirculating aquaculture system containing American eels. Waste solids samples (2 g) were spiked to 50 μg kg−1 of E1, E2, and E3 and processed using 800 mg magnesium sulfate (MgSO4) and 400 mg of sodium acetate (NaOAc) as extraction salts. Two dispersive solid phase extraction (dSPE) steps were implemented to achieve optimal E2 recovery efficiency (RE (%)) in preliminary experiments (RE (%) = 102%; RSD = 5%). RE (%) for E1 and E3 were 87% (RSD = 54%) and 60% (RSD = 83%), respectively. Method performance characteristics were further assessed for E2 only and included specificity, linearity, accuracy (RE (%) and process efficiency (PE (%))), precision (intra-day precision, and inter-day precision), matrix effects, method detection limit (MDL), and limit of quantitation (LOQ). MDL and LOQ values for E2 were 0.7 and 2.3 μg kg−1, respectively. PE (%) and RE (%) were excellent (99–101% and 99–100%, respectively) and matrix effects were minimal (99 and 101%). The results of this study indicate that this method can be used for quantitation of E2 in aquaculture waste solids.