Meat and Meat Products Chapter 39.p.8 39.1.2.1
AOAC Official Method 973.31 Nitrites in Cured Meat
Codex-Adopted-AOAC- Method
A.Reagen and Apparatus
(a) NED reagent-Dissolve 0,2 gr N-(1-naphthyl) ethylenediamine 2HCl in 150 ml 15% (v/v) CH3COOH. Filter, if necessary and store in glass - stoppered brown glass bottle.
(b) Sulfanilamide reagent – Dissolve 0,5 gr sulfanilamide in 150 mL 15% CH3COOH
(v/v).Filter, if necessary and store in glass - stoppered brown glass bottle.
(c) Nitrite Standart Solution - (1) Stock Solution – 1000 ppm (µg/mL) NaNO2. Dissolve 1000
gr NaNO2 in H2O and dilute to 1 L. (2) Intermediete solution - 100 (µg/mL) NaNO2. Dilute 100
mL stock solution to 1 L with H2O. (3) Working solution – 1 µg/mL NaNO2. Dilute 10 mL
intermediate solution to 1 L with H2O.
(d) Filter paper - Tes for nitrite contamination by analyzing 3-4 sheets at random , through out box. Filter Ca 40 mL H2O through each sheet. Add 4 mL sulfanilamide reagent, mix, let stand
mix, add 4 mL NED reagent, mix and wait 15 minutes. If any sheets are positive, discard entire box.
B.Determination
Weigh 5 gr finely comminuted and thoroughly mixed tes sample into 50 mL beaker. Add ca 40 mL H2 O heated to 80o C. Mix thoroughly with glass rod, taking care to break up all lumps and
transfer to 500 mL volumetric flask. Thoroughly wash beaker and rot out with successive
portions of the hot H2 O, adding all washing to flask. Add enough hot H2 O to bring volume to ca
300 mL transfer flask to steam bath, and let stand 2 hours, shaking occasionally. Cool to room temperature, dilute to volume with H2 O, and remix.
Filter, if turbidity remains after filtration, sentrifuging will usually clear the solution. Add 2,5 ml sulfanilamide reagent to aliquot containing 5 – 50 µg NaNO2 in 50 mL volumetric flask and mix.
After 5 minutes , add 2,5 ml NED reagent, mix, dilute to volume , mix and let colour develop 15 min. Transfer portion of solution to photometer cell and determine at 540 nm against blank of ƛ
45 mL H2 O, 2,5 mL sulfanilamide reagen and 2,5 mL NED reagen.
Determine nitrit present by comparison with standart curve prepared as follows. Add 10, 20, 30, and 40 ml nitrate working standard solution to 50 ml volumetric flask. Add 2,5 ml sulfanilamide reagent, mix and proceed as above is straight line to 1 µg/mL NaNO2 in final solution
Reference JAOAC 56,922 (1973), 60,594 (1972) Revisied March 1997
Adopted as Codex Reference Method (Type II) for nitrite and potassium and / or sodium salts in canned corned beef and lunche on meat
