催化光度法同时测定肉制品中亚硝酸根和硝酸根

WTMULTANEOUS DETERMINATION OF NITRITE AND NITRATE IN MEAT PRODUCTS BY CATALYTIC SPECTROPHOTOMETRY

依据NO-2能催化溶解氧氧化Fe2+为Fe3+,利用生成硫氰酸铁而间接测定NO-2;再用锌粉还原NO-3为NO-2,由测得的NO-2总昨而计算出NO-3含量,建立了同时测定肉制品中亚硝酸根和硝酸根的催化光度法.线性范围为1.5～5.0μgNO-2/25mL.NO-3的还原率为99.2%,测定结果的相对标准偏差小于2.1%,平均加标回收率为99.1%～101.9%.摩尔吸收系数7.66×104L·mol-1·cm-1.

Nitrite can catalyze oxidation of Fe2^＋ to Fe^3＋ by dissolved oxygen. So the nitrite can be indirectly determined by the thiocyanaate spectrophotometry. Nitrate was reduced to nitrite by zinc powder. The content of nitrate was calculated out from determined total amount of nitrite. A catalytic spectrophotometry for simultaneous determination of nitrite and nitrate in meat products has been developed. The linear range of nitrite was 1.5-5.0μg/25mL. The reduction efficiency of nitrate was 99.2%. RSD＇ s of determination results（n=6） were less than 2.1%. The recoveries of standard addition of samples were 99.1%-101.9%. The molar absorbtivity was 7.66×10^4L·mol^-1·cm^-1.