4-hydroxy xylazine/Creatinine:MRto:Pt:Urine:Qn:Confirm
4-hydroxy xylazine/creatinine:mrto:pt:urine:qn:confirm
4-hydroxy Xylazine/Creatinine [Mass Ratio] in Urine by Confirmatory method
4-hydroxy xylazine/creatinine [mass ratio] in urine by confirmatory method