抄録
A liquid chromatography tandem-mass spectrometry (LC/MS/MS) method has been developed for highly sensitive determination of diethylstilbestrol (DES) in water.
Two grams of ascorbic acid and five nano grams of diethylstilbestrol-d8 as the surrogate were added to every 2000 mL of water sample. The sample was filtrated with glass fiber filter (GS25) and adjusted to pH2.5 with 6 mol/L of HCl followed by solid phase extraction with a cyclohexyl silica cartridge (InertSep CH). The fraction eluted with 5 mL of methanol was passed through a multilayer solid phase extraction cartridge (GC/SAX/PSA) to remove matrices. The analyte was eluted from the cartridge with 12 mL of methanol. The elute was concentrated to volume approximately 0.25 mL in a test tube at 40°C in water bath under nitrogen gentle stream, and then it was filled up to 0.5 mL with pure water for LC/MS/MS measurement.
Negative electrospray ionization (ESI-negative) was used to ionize diethylstilbestrol and the internal standard (i.e. diethylstilbestrol-d8). The determination was performed by the selected.reaction-monitoring (SRM) method using precursor/ product ion transition m/z 267.45 to 237.41 for diethylstilbestrol and m/z 275.43 to 245.47 for diethylstilbestrol-d8.
The method detection limit (MDL) and the method quantification limit (MQL) are 0.005 ng/L and 0.013 ng/L, respectively. The average recoveries (n =5) from river water and sea water spiked with 0.5 ng of diethylstilbestrol are 104% (RSD 4.0%) and 106% (RSD 2.9%), respectively.
In all the river waters and sea waters sampled in Nagoya city, the concentrations of diethylstilbestrol were below the MDL.
