Detection of exogenous hydrocortisone in horse urine by gas chromatography-combustion-carbon isotope ratio mass spectrometry.

The study proposes a new method for identifying the illegal use of hydrocortisone in horse racing by examining differences in carbon isotope ratios in horse urine.

Introduction to the Research

• The research deals with a critical issue in equine sports – the illegal doping of horses. This is often done to enhance performance, but it compromises the integrity of the sport and harms the animals’ welfare.
• One of the substances often misused is hydrocortisone, a steroid hormone released by the body. It’s given illegally as it could reduce stress and inflammation, making the horse perform better under intense conditions.
• The researchers have developed a method of detecting the presence of this exogenous (originating from outside the body) hydrocortisone in horse urine by using gas chromatography-combustion-isotope ratio mass spectrometry.

Process and Findings

• Gas chromatography-combustion-isotope ratio mass spectrometry is a testing method that involves converting a sample into different gases, separating them, and then comparing the amounts of isotopes (forms of an element with similar properties but different atomic masses).
• In this research, the hydrocortisone found in the horse’s urine was converted into a bismethylenedioxy derivative that has good gas chromatographic properties and brings an additional carbon contribution of only two carbon atoms. This means it doesn’t alter the sample significantly, making the results more reliable.
• The main premise behind this method is that synthetic hydrocortisone has a different carbon-13 (¹³C) abundance than that of naturally-occurring hydrocortisone in a horse’s urine. Therefore, by comparing the isotope ratios, the researchers can distinguish between the natural and synthetic hydrocortisone. They found that the difference between the level of ¹³C in exogenous and endogenous (originating from within the body) hydrocortisone is significant enough to be discernible.
• The proposed technique can thus accurately detect the illegal use of hydrocortisone in equine sports.