微波消解试样-催化动力学光度法测定腌菜中亚硝酸根
Catalytic-Kinetic Photometric Determination of Nitrite in Pickles with Micro-Wave Assisted Sample Digestion
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摘要: 腌菜试样用稀磷酸及过氧化氢置于PTFE罐中,在微波炉先后在400 W及500 W消解2 min及4 min,所得试样溶液于100 mL容量瓶中定容供光度测定.在稀磷酸介质中偶氮胂Ⅰ溶液与溴酸钾溶液的氧化褪色反应因亚硝酸根的存在而催化加速.有及没有亚硝酸根存在的两份相同试液的吸光度A及A0之差ΔA与亚硝酸根质量浓度在50 μg·L-1以内呈线性关系,其检出限为0.82 μg·L-1.用此方法分析3件腌菜试样,测定结果的相对标准偏差(n=6)均小于2%.以此样品为基体,加入亚硝酸根标准溶液进行回收试验,测得的回收率在98.0%~102.0%之间.Abstract: 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%.