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