For the sake of clarity on the urine sampling that day; Mayweather gave a PARTIAL urine sample before the IV infusion and much later he gave a PARTIAL urine sample after the IV infusion.
The 2 partial urine samples weren't tested individually but combined and the resulting urine was the one that was tested.
USADA’s Detailed Correction to: Can Boxing Trust USADA?
"... Mr. Mayweather provided PARTIAL urine samples to USADA BOTH PRIOR TO AND FOLLOWING the infusion. The urine provided by Mr. Mayweather on
May 1, 2015, was subsequently tested and has been reported by the
World Anti-Doping Agency accredited laboratory as negative. "
The 2 partial urine samples weren't tested individually but combined and the resulting urine was the one that was tested.
USADA’s Detailed Correction to: Can Boxing Trust USADA?
"... Mr. Mayweather provided PARTIAL urine samples to USADA BOTH PRIOR TO AND FOLLOWING the infusion. The urine provided by Mr. Mayweather on
May 1, 2015, was subsequently tested and has been reported by the
World Anti-Doping Agency accredited laboratory as negative. "
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