As shown in Fig. 7 inset, there was a good linear relationship between the fluorescence quenching ratio (F0-F)/F0(F0 is thefluorescence intensity of Cd2+–8 mmol/L ATP–S2 mixed
system, and F is the fluorescence intensity of Cd2+–8 mmol/L ATP–S2 with addition of various concentration of ALP incubatingfor 30 min) and the ALP concentrations in the concentration range
from 0.42 to 12.6 nU/mL.