Determination of Selected Corticosteroids in Sewage-treatment-plant Samples by Liquid Chromatography-mass Spectrometry

An analytical method was developed for simultaneous determination of trace amounts of nine corticosteroids in sewage-treatment-plant (STP) samples. The compounds studied were prednisolone, dexamethasone, betamethasone, triamcinolone acetonide, fluocinolone acetonide, prednisolone acetate, hydrocortisone acetate, betamethasone valerate, and betamethasone dipropionate. The method involves concentration and purification of analytes by solid-phase extraction, subsequent separation by liquid chromatography, and detection by mass spectrometry. Quantitative analysis was performed by the standard addition method. Instrument detection limits were in the range 1.6-9.4 pg for the target compounds. Recoveries were 57.2-106.7% in the STP influent sample and 59.1-112.5% in the STP effluent sample with relative standard deviations of 8.7-19.2% and 7.3-17.1%, respectively. This method was used for the determination of these chemicals in STP samples from Takase (Funabashi, Japan); some corticosteroids were determined at levels as low as single nanograms per liter.