EN ISO 20541:2008

Foreword
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents
6 Apparatus
7 Sampling
8 Preparation of test sample
   8.1 Dried milk, dried whey and milk
        protein concentrates
   8.2 Caseins and caseinates
   8.3 Cheese
   8.4 Whey cheese
9 Procedure
   9.1 Preparation of the test portion
   9.2 Removal of fat and protein
   9.3 Reagent blank test
   9.4 Determination
   9.5 Calibration
10 Calculation and expression of results
   10.1 Nitrite (matrix blank) content
   10.2 Total nitrite/nitrate content
   10.3 Nitrate content
11 Precision
   11.1 Interlaboratory testing
   11.2 Repeatability
   11.3 Reproducibility
12 Test report
Annex A (informative) - Interlaboratory trials
Bibliography

ISO 20541|IDF 197:2008 specifies a method for the determination of the nitrate content of milk and milk products by molecular-absorption spectrometry after Griess reaction (preceded by enzymatic reduction).The method is, in particular, applicable to whole, partly skimmed, skimmed and dried milk, hard, semi-hard and soft cheeses, processed cheese, whey cheese, caseins, caseinates, dried whey and milk protein concentrates.The method can be used at contents corresponding to a measured concentration in the sample solution (with blank subtracted) of more than 0,2 mg/l.