Page 153 - Analytical method for food addtives

9

E249–50: Nitrites

9.1 Introduction
The major food groups contributing to dietary intake of nitrites are cured, dried
meat products 50 mg/kg (various meat products 100 mg/kg; cured bacon 175 mg/
kg) – residual amounts. The acceptable daily intake (ADI) for nitrites, expressed as
sodium nitrite, is 0.1 mg/kg body weight.

9.2 Methods of analysis

Many of the traditional methods for the determination of nitrite rely on variations
of the Greiss diazotisation procedure, in which an azo dye is produced by coupling
a diazonium salt with an aromatic amine or phenol. The diazo compound is usually
formed with sulphanilic acid or sulphanilamide and the coupling agent is N-1-
1
naphthylethylene diamine (NED). These methods involve colorimetric
determination. 2–11 Methods that have been developed more recently include
spectroscopic determination after enzymatic reduction, 12–14 ion-exchange chroma-
tography (IC), 15–18 flow analysis (FA), 19–20 differential pulse voltammetry (DPV) 21
22
and capillary electrophoresis (CE). A summary of these methods is given in Table
9.1, together with the matrices for which the methods are applicable. If statistical
parameters for these methods were available these have been summarised in Table
9.2. Some of these methods are AOAC Official Methods of Analysis, two
3–5
methods have been accepted as a European Standard 10,14 and three as International
Standards. 2,19,20
There are three AOAC Official Methods for the determination of nitrite in
foods: