Determination of steroid hormone residues in farmed fish using high-resolution orbital ion trap mass spectrometry

Abstract

A method for the determination of 15 steroid hormones in farmed fish by liquid chromatography–orbital ion trap mass spectrometry has been developed and validated. The method involved sample preparation with acetonitrile extraction and clean-up, and separation in the LC using a C₁₈ column. The orbital ion trap MS was operated at a resolution of 35 000 FWHM in selected ion monitoring mode. An ion source with heated electrospray ionization was used in positive ionization mode. The samples were prepared by solid-phase extraction. The limit of quantification of steroid hormones in fish samples was 2 μg kg⁻¹. Good linearity was observed since correlation coefficients were more than 0.99 for all compounds. Recoveries of spiked fish samples (2 μg kg⁻¹ and 20 μg kg⁻¹) ranged from 80.8% to 112.6% with relative deviations less than 15%. The method was successfully applied to detect steroid hormones in real farmed fish samples at the μg kg⁻¹ level.