A fully automated method to quantitate total carbon dioxide in equine plasma by headspace GCMS.

This research investigates a new method of measuring total plasma carbon dioxide in racehorses using headspace gas chromatography mass spectrometry (HSGCMS), as a response to the discontinued manufacture and support of the traditional ion selective electrode (ISE) instruments. The results show that the HSGCMS method not only meets but also significantly improves the accuracy of the earlier ISE methods, indicating its suitability for regulating the use of alkalinising agents in horse racing.

Introduction

• The study was conducted in response to the need for an alternative technique to measure total plasma carbon dioxide (TCO) in racehorses, given the discontinuation of the manufacture and support of Ion Selective Electrode (ISE) instruments, which were the traditional tools for such measurements.
• The misuse of alkalinising agents in horse racing for boosting athletic performance led to the adoption of TCO thresholds in horse racing regulations, hence the need for accurate measurements of TCO.

Methodology

• The alternative technique investigated was the headspace gas chromatography mass spectrometry (HSGCMS) with fully automated sample preparation.
• The sample preparation involved aspirating plasma from sealed vacutainer tubes for treatment and headspace injection into a GCMS using a Gerstel robot.
• The new method was cross validated against a Beckman Unicel DxC®600, following the cross-validation protocol stipulated by the Association of Official Racing Chemists (AORC).

Results and Discussion

• The HSGCMS technique achieved an accuracy of 99.8%, a within-run relative standard deviation of 0.22% and interday reproducibility of 0.04 mM, indicating significant improvements over the ISE method.
• A population study was also conducted to ensure that the plasma TCO threshold, established with the ISE methodology, did not change with the application of the HSGCMS method. The average concentrations and standard deviations for the two methods were almost the same, giving further credence to the HSGCMS approach.

Conclusion

• From the results obtained, the study concludes that the fully automated HSGCMS technique is a suitable alternative for the measurement of equine plasma TCO, fulfilling the requirement for systematic regulation of the use of alkalinising agents in horse racing.