Quantification of 17 beta-estradiol residues in bovine serum by liquid chromatography-tandem mass spectrometry with atmospheric pressure chemical ionization.
A method for the quantification of the natural hormone 17 beta-estradiol (17 beta-E2) in bovine serum by liquid chromatography atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS-MS) was developed. Ethinylestradiol (EE2) was used as internal standard. Analytes were extracted from serum using acetate buffer, purified by C18 solid-phase extraction (SPE) and chromatographed on a polymeric reversed-phase (PLRP-S) LC column. They were ionized in a heated nebulizer (HN) interface operating in the negative ion mode, where only the intact deprotonated molecules, [M - H]-, were generated at m/z 271 and 295 for 17 beta-E2 and EE2, respectively. These served as precursor ions for collision-induced dissociation (CID) and diagnostic product ions were identified for the unambiguous hormone confirmation by selected reaction monitoring (SRM) LC-APCI-MS-MS. The method was validated on bovine serum and the limit of quantification (LOQ) was 30 pg ml-1 for 17 beta-E2. The inter-day precision (relative standard deviation, RSD) and accuracy (relative error, RE) derived from the analyses of validation samples at three concentrations ranged from 1.76 to 3.76 and from -4.18 to -2.01%, respectively. This method is currently being successfully applied to measure the bovine serum concentration of 17 beta-E2 in order to discriminate between the physiological concentrations of 17 beta/E2 and the hormone levels resulting from illegal administration.
Draisci
R
R
Lab. Medicina Veterinaria, Istituto Superiore di Sanità, Roma, Italy.
Palleschi
L
L
Ferretti
E
E
Marchiafava
C
C
Lucentini
L
L
Cammarata
P
P
D045930:Anabolic Agents / Q000032:analysis*; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D002853:Chromatography, Liquid; D004350:Drug Residues / Q000032:analysis*; D004958:Estradiol / Q000097:blood*; D006728:Hormones / Q000097:blood; D013058:Mass Spectrometry
D045930:Anabolic Agents; D006728:Hormones; D004958:Estradiol