Estrogens in seminal plasma of human and animal species: identification and quantitative estimation by gas chromatography-mass spectrometry associated with stable isotope dilution.

The research article describes the identification and quantification of estrogens in the seminal plasma of humans and various animal species, such as bulls, boars, and stallions. The process involves gas chromatography-mass spectrometry associated with stable isotope dilution.

Identification and Quantification of Estrogens

• The researchers aimed to identify and quantify specific types of estrogens, namely Estrone, 2-methoxyestrone and estradiol-17 beta, in seminal plasma. Seminal plasma is the fluid part of semen, which provides a fertile medium for sperm.
• The study uses high-resolution gas chromatography associated with selective monitoring of characteristic ions of suitable derivatives. Gas chromatography is an analytical method for identifying and separating components in a mixture, while monitoring of characteristic ions aids in the identification of specific compounds.

Isotope Dilution Method

• Quantitative estimations were performed by the isotope dilution method with deuterated analogues. Isotope dilution is a technique in which isotopically enriched standards (“spike” solutions) are added to samples and the isotopic composition of the “mixed” sample-spike solution analyzed to determine the concentration of the element of interest.
• The researchers used deuterated analogues, which are essentially the same compounds but with one or more hydrogen atoms replaced by deuterium, a heavier isotope of hydrogen. In the case of the study, the labelled and unlabelled compounds were trimethylsilyl ethers.

Concentration Reporting and Statistical Evaluation

• The researchers reported concentrations of both unconjugated and total estrogens. Unconjugated estrogens are those that do not combine with other substances to be carried in the bloodstream, while total estrogens would include both the conjugated (combined) and unconjugated types.
• The study also reports on the statistical evaluation of the accuracy and precision of their results. Accuracy refers to how close the experimental values are to the true or accepted value, while precision refers to how close repeated measurements are to each other.