[Multi-wavelength negative absorption fading spectrophotometry to determine trace nitrite and it's mechanism]

Using negative absorption rectifyingtechniquie, the authors investigated spectra of the reaction of nitrite with acridine yellow in 1.0 mol x dm(-3) (1 dm = 10 cm = 0.1 m) hydrochloric medium. The authors established the new dynamics method of mensuratiog trace nitrous acid radical by the negative absorption undertint spectrophotometry at multi-wavelengths, based on the linear relation between the negative absorbance value or the AT value of absorbance sum and the nitrous acid radical concetration in a certain range. The linear range was 7.2 x 10(-6) -3.6 x 10(-4) mol x dm(-3), RSD was 1.06%-3.12%, and CV (recovery) was 98.00%-100.20%. In application to the determination of nitrite in environmental water sample, satisfactory result was abtained with high accuracy, better selectivity and common ions ceasing to effect measuring. According to the change in the absorption peak value in the reactive system,the liquor acidity, the different order for added reagent, liquor temperature, reactive time, acid kind etc., the authors believe that the reaction of acridine yellow with mitrite is diazotization-coupling, under the condition of feasible pH value, temperature, and additive order of midium.