In the acid medium,nitrite can diazotize with p-nitroaniline（PNA）and then couple with diethyl malonate（DM） in basic medium to produce an azo compound,which has the maximum absorption at 496 nm and a molar absorptivity(ε496) of 1.7×104L·mol-1·cm-1.A new spectrophotometric approach for nitrite determination was established on such basis with a detection limit of 1.7×10-7 mol/L.Beer’s law was obeyed in the concentration range of 0.05μg/mL-0.80 μg/mL for sodium nitrite.The proposed method has been applied for the determination of nitrite in vegetables,and the results are satisfactory.
