Temperature and time after urine collection affect the detection of phenethylamine, a substance prohibited in sports

2-Phenylethylamine (phenethylamine) and its derivatives are stimulant drugs, which are prohibited in sports because of their potential performance-enhancing properties. If phenethylamine is detected in an athlete's urine, the athlete may be subjected to serious sanctions, such as disqualification for both domestic and international competitions. Given the serious consequences athletes face for phenethylamine detection, great care should be taken to avoid false positive tests. In forensic medicine, it is widely known that phenethylamine is produced by putrefactive bacteria in autopsy urine samples; it is possible that this process could also occur in an athlete's urine sample without proper storage. In this study, human urine samples were stored at −20, 4, or 22°C for 14 days, and phenethylamine in the samples was quantitatively analyzed using ultra-high-performance liquid chromatography–tandem mass spectrometry. No phenethylamine was detected in urine samples stored at −20°C throughout 14-day period. Nevertheless, phenethylamine was detected after 6 days in these samples stored at 4°C and after only 1 day in samples stored at 22°C. Additionally, the concentration of phenethylamine in these samples increased each day after detection. These results suggest that urine samples should be stored immediately at −20°C after collection when testing athletes for phenethylamine, especially if the sample must be stored for extended period before testing.