RÉSUMÉ
A method for simultaneous determination of 20 Perfluorinated alkyl substances ( PFAS) in animal liver using QuEChERs and HPLC_MS/MS technique was developed. The samples were extracted with 0. 1%hydrochloric acetonitrile and cleaned up with C18 , N_Propylethylendiamine ( PSA ) and graphitized carbon blacks ( GCB ) . The analytes were separated by a reversed phase C18 column and gradiently eluted with a mixed solution of 5 mmol/L ammonium acetate methanol and 5 mmol/L ammonium acetate. The samples were quantified using isotope internal standard and external standard with the matrix matched standard calibration curve method. Good linearity was obtained for all the 20 PFAS at the concentration of 0. 1-10 μg/L with the linear correlation coefficients more than 0. 9995. The limits of detection (LOD) and the limits of quantification ( LOQ) for PFAS were 0. 05-0. 2 μg/kg and 0. 4-0. 5 μg/kg, respectively. The recoveries at three different concentration levels ( 0 . 5 , 2 and 5 μg/kg ) were in the range of 70 . 3% -108 . 1%. The repeatability expressed as relative standard deviations (RSD) was ranged from 2. 1% to 11. 9% (n=6).
RÉSUMÉ
A method was developed for the determination of eight steroid hormones ( estrone, α/β-estradiol, estriol, testosterone, epitestosterone, progesterone and testosterone propionate ) in butter samples by gel permeation chromatography ( GPC) purification-followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were first extracted by ethylacetate/cyclohexane (1:1, V/V) and the extract was later degreased by GPC column. Then, the GPC concentrate was separated using a C18 column ( 100 mm í2. 0 mm i. d. , 3. 0 μm) with gradient elution of acetonitrile/water. Finally, the steroid hormone components were qualitatively and quantitatively determined by mass spectrometer with electrospray ionization in multi reaction monitoring mode. Using matrix matched external standard method, good linearity in response could be obtained in the concentration range of 1 . 0-20 . 0 μg/kg with correlation co-efficiency larger than 0 . 999 . The detection limits of the method were 0. 04-0. 30 μg/kg and the quantification limit was 1. 0 μg/kg. At the spike levels of 1. 0, 2. 0 and 4. 0μg/kg, the recoveries of hormones were within the range of 64. 1%-110%, and the relative standard deviation ( RSD) was less than 11%. The results show that the method is accurate and reliable, and meets the requirements for determination of 8 steroid hormones in butter samples.