Using 3-mercaptopropionic acid(MPA) as surface modifiers,Mn doped ZnS quantum dots with stable and good optical properties were synthesized via water phase method.In phosphate-buffered saline solution,the addition of promethazine could obviously quench the room temperature phosphorescence of MPA-capped Mn-doped ZnS quantum dots.Thus,a new method for the detection of promethazine was established.The quenched phosphorescence intensity(ΔRTP) was linearly proportional to concentration of promethazine.The linear ranges of promethazine were 3.2-32 μmol/L and 32-160 μmol/L,with correlation coefficients of 0.998 and 0.999,respectively.The limit of detection for the method was 0.553 μmol/L.This method was used to detect promethazine in human serum and urine samples with satisfactory results,and the recoveries ranged from 96.4%to 103.1%.