ABSTRACT
A method was developed for analyzing the stable carbon isotope ratio of five volatile components ( Ethanol, Glycerol, Acetic acid, Ethyl lactate, 2-methyl-butanol ) in wine using gas chromatography-combustion-isotope ratio mass spectrometer ( GC-C-IRMS ) . The sample injection volume was less than 0. 5 μL, and the analytical time of each run was less than 14 min. The precision of this method was 0. 08‰-0. 25‰ for analyzing standards, while 0. 09‰-0. 36‰ for wine samples. Compared to element analysis-isotope ratio mass spectrometry ( EA-IRMS) results, the deviations were lower than 0. 5‰. Fifty-four wine samples from France, Australia, America and China were considered. The δ13 C of five volatile components were measured using GC-C-IRMS. Discriminant analysis ( DA) was employed for analyzing the geographical origin traceability of selected wine. The result indicated that δ13 C of volatile components could be used to distinguish the origin of wines. The method was shown to be effective in improving detection of the origin traceability of wine.
ABSTRACT
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.