提出了用离子色谱法测定鱼粉中亚硝酸盐的含量,鱼粉样品用热水(70~80 ℃)及氢氧化钠溶液处理.将溶液的酸度调节至pH为9,置于控温在70~80 ℃的水浴中加热15 min,冷却后,移入冰箱中冷却至0~4 ℃使脂肪凝固,用快速滤纸过滤,除去大部分脂肪、蛋白质和不溶残渣,所得滤液先后通过用C18小柱和On Guard ⅡAg/H保护柱净化,流出液自动进样进行离子色谱测定.测定中采用Dionex Ion Pac AS11柱和不同浓度的氢氧化钾溶液作梯度淋洗,用抑制电导检测进行定量,测得的峰面积值与亚硝酸盐的质量浓度在0.01~20.0 mg·kg-1范围呈线性关系,方法的检出限(3S/N)为2.68 μg·L-1.

An IC method for determination of nitrite (NO-2) in fishmeal was proposed.Sample of fishmeal was treated with hot water (70-80 ℃) and NaOH solution,the mixture was adjusted to pH 9 and heated in a water bath controlled at 70-80 ℃ for 15 min.Fat in the sample was solidified by cooling to 0-4 ℃ in a refrigerator and removed togather with the protein and insoluble rosidues by filtration.The filtrate collected was passed through the C18 micro column and the On Guard ⅡAg/H column successively.The eluate obtained was introduced automatically into the instrument,and its NO-2 content was determined by IC under the optimized analytical conditions.The Dionex Ion Pac AS11 column and gradient elution with KOH solution of different concentrations were adopted in the separation of NO-2-ion,and suppressed conductivity detector was used in the determination.Linear relationship between values of peak area and concentration of NO-2-ion was obtained in the range of 0.01-20.0 mg·kg-1,and the detection limit (3S/N) found was 2.68 μg·L-1.