Catalytic-Kinetic Photometric Determination of Nitrite in Pickles with Micro-Wave Assisted Sample Digestion

Sample of pickles was digested with dil.H3PO4 and H2O2 in PTFE vessel and heated in a microwave oven at 400 W for 2 min and 500 W for 4 min.The sample solution obtained was diluted to 100 mL in a volumetric flask and used for photometric determination.In dil.H3PO4 medium,the oxidative color-fading reaction of arsenazo Ⅰ with KBrO3 solution was catalyzed by the presence of NO-2.Difference of values of absorbances (ΔA) measured (at 510 nm) in the colored solutions with (A) and without (A0) the presence of nitrite were directly proportional to the concentrations of NO-2 in the range within 50 μg·L-1 with a detection limit of 0.82 μg·L-1.The proposed method was used in the analysis of 3 pickle samples,giving values of RSD (n=6) less than 2% and values of recovery in the range of 98.0%-102.0%.