IC Determination of Nitrite in Fishmeal

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.