Application of flow injection analysis to determine protein-bound nitrite in meat products

The development and application of a methodology based on flow injection analysis (FIA) for the determination of protein-bound nitrite (PBN) in meat products was studied. Since the FIA methodology used for measuring residual nitrite was not appropriate for determining PBN (even at a concentration of 15.9 mg of PBN/kg) in meat products, the procedure was modified and then studied for residual nitrites and PBN. Ammonium chloride (A), which is used conventionally (the original FIA method), was replaced by different carriers (the modified FIA method): B (buffer 7); C (buffer 7.5); D (buffer 8); E (NaOH 0.5 M) and F (NaOH 1 M). Carriers B and C provided the lowest limits of quantification of residual nitrite, lower than that obtained using the original FIA method. The method for determining PBN in several meat products (frankfurter and dry sausages) was validated by comparing it with the method usually used. The results obtained indicate that the modified FIA method (with carriers B and C) can be used as a simple, easy, fast, accurate and precise methodology for quantifying residual nitrite and PBN in meat products.