A recent trend in the use of high resolution accurate mass screening (HRAMS) for 
doping control testing in both human and animal sports has emerged due to 
significant improvement in high resolution mass spectrometry in terms of 
sensitivity, mass accuracy, mass resolution, and mass stability. A number of 
HRAMS methods have been reported for the detection of multi-drug residues in 
human or equine urine. As blood has become a common matrix for doping control 
analysis, especially in equine sports, a sensitive, fast and wide coverage 
screening method for detecting a large number of drugs in equine blood samples 
would be desirable. This paper presents the development of a liquid 
chromatography-high resolution mass spectrometry (LC-HRMS) screening method for 
equine plasma samples to cover over 320 prohibited substances in a single 
analytical run. Plasma samples were diluted and processed by solid-phase 
extraction. The extracts were then analyzed with LC-HRMS in full-scan positive 
electrospray ionization mode. A mass resolution of 60 000 was employed. 
Benzyldimethylphenylammonium was used as an internal lock mass. Drug targets 
were identified by retention time and accurate mass, with a mass tolerance 
window of ±3 ppm. Over 320 drug targets could be detected in a 13-min run. 
Validation data including sensitivity, specificity, extraction recovery and 
precision are presented. As the method employs full-scan mass spectrometry, an 
unlimited number of drug targets can theoretically be incorporated. Moreover, 
the HRAMS data acquired can be re-processed retrospectively to search for drugs 
which have not been targeted at the time of analysis.