Improvement of estradiol esters monitoring in bovine hair by dansylation and liquid chromatography/tandem mass spectrometry analysis in multiple reaction monitoring and precursor ion scan modes.

RATIONALE: The control of forbidden anabolic practices in cattle in the European Union has become challenging since endogenous compounds such as estradiol derivatives can potentially be used as growth promoters. Due to the great difficulty in establishing a reference threshold value for endogenous steroids, the direct detection of steroid esters in hair is an efficient strategy for the detection of 'natural' steroid abuse in cattle. METHODS: The present study aimed to develop and validate according to the current European standards a specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) analytical strategy to monitor estrogen esters in bovine hair. The analysis was performed by positive ion electrospray ionisation (ESI+) after dansylation. Two acquisition modes were then assessed: single reaction monitoring and precursor ion scanning. RESULTS: The results showed that the introduction of a dansylation step strongly improves the sensitivity of the detection of estradiol-17-esters by LC/(ESI+)-MS/MS. The CCα values are in the range 1-10 ng g(-1) after optimisation, except for estradiol decanoate for which the derivatisation is not efficient. In addition, this LC/MS/MS approach makes it possible to carry out a precursor ion scan to screen for the presence of these estradiol 17-esters in hair samples. CONCLUSIONS: Based on the specific product ions, i.e. m/z 255 in native conditions or m/z 171 after dansylation, this strategy has the advantage of detecting any (un)known estradiol ester and of giving access to the [M + H](+) ion of the suspected ester through only a single analysis.

Correlación de las concentraciones de estradiol y diámetro folícular con la madurez del ovocito en tres distintos esquemas de estimación ovarica / Correlation of concentrations of estradiol an follicular diament with ovocyte maturity in three ovarian stimulation schemes

Fueron estudiadas las respuestas a la estimulación ovárica con distintos esquemas en mujeres que ingresaron a programas de fertilización asistida, correlacionando el desarrollo folicular y las concentraciones en suero de estradiol, con el número y calidad de los ovocitos obtenidos. Se analizaron 49 pacientes que fueron divididas de acuerdo al esquema de estimulación fue seguida día a día por medio de determinaciones de estradiol y mediciones foliculares por ultrasonido. con los tres esquemas se recuperaron 205 ovocitos siendo maduros 179,9 inmaduros y 17 atrésicos, no existiendo diferencia significativa entre los métodos de estimulación utilizados.