Determination of hormones in milk by hollow fiber-based stirring extraction bar liquid–liquid microextraction gas chromatography mass spectrometry

• A new, rapid and sensitive method for hormones determination was developed.
• The method has the advantages of both SBSE and HF-LPME technique.
• The stirring extraction bar is easier isolated from the sample matrix.
• The stirring extraction bar makes extraction, clean-up and concentration in one-step.
• The stirring extraction bar was used as stirring bar and extractor of the analytes.

The hollow fiber-based stirring extraction bar liquid–liquid microextraction was applied to the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, 17-α-hydroxyprogesterone, medroxyprogesterone, progesterone and norethisterone acetate, in milk. The present method has the advantages of both hollow fiber-liquid phase microextraction and stirring bar sorptive extraction. The stirring extraction bar was used as both the stirring bar of microextraction, and extractor of the analytes, which can make extraction, clean-up and concentration be carried out in one step. When the extraction was completed, the stirring extraction bar was easy isolated from the extraction system with the magnet. Several experimental parameters, including the type of extraction solvent, the number of hollow stirring extraction bar, extraction time, stirring speed, ionic strength, and desorption conditions were investigated and optimized. The analytes in the extract were derived and determined by gas chromatography mass spectrometry. Under optimal experimental conditions, good linearity was observed in the range of 0.20–20.00 ng mL−1. The limits of detection and quantification were in the range of 0.02–0.06 ng mL−1 and 0.07–0.19 ng mL−1, respectively. The present method was applied to the analysis of milk samples, and the recoveries of analytes were in the range of 93.6–104.6% with the relative standard deviations ranging from 1.6% to 6.2% (n = 5). The results showed that the present method was a rapid and feasible method for the determination of hormones in milk samples.

The improved stirring extraction bar (a) and the HF-SEBLLME procedure (b).Figure optionsDownload as PowerPoint slide