EN 12497:2005

Foreword
1 Scope
2 Normative references
3 Principle
4 Reagents
   4.1 General
   4.2 Nitric acid (HNO[3]), 65% (d = 1.42)
        4.2.1 Nitric acid (4.2), diluted 1:1 (V/V) with water
        4.2.2 Nitric acid (4.2), diluted to 1.5% (V/V) with water
   4.3 Potassium permanganate (KMno[4]), 5% aqueous solution (m/V)
   4.4 Mercury, stock solution, 1000 mg/l
Sulphuric acid (H[2]SO[4]), (d = 1,84)
   4.6 Potassium dichromate (K[2]Cr[2]O[7]), 50 g/l in
        sulphuric acid solution
   4.7 Hydroxylammonium chloride (HONH[3]Cl), 20 g/l aqueous
        solution
   4.8 Reducing solutions
        4.8.1 Tin (2) chloride (SnCl[2] . 2H[2]O), 50 g/l
              in 10% hydroxhloric acid (4.9.1)
        4.8.2 Sodium tetrahydroborate (NaBH[4]), 0.2 g/l in 0.05%
              sodium hydroxide solution (4.10)
   4.9 Hydrochloric acid (HCl), 36% (d = 1.19)
        4.9.1 Hydrochloric acid (4.9) (HCl), diluted 10% (V/V)
   4.10 Sodium hydroxide (NaOH), 0.05% aqueous solution (m/V)
5 Apparatus
   5.1 General
   5.2 General laboratory equipment
   5.3 Volumetric flasks, 100 ml
   5.4 Analytical balance, accuracy 0,1 mg
   5.5 Pipettes from 100 [mu]l to 10 ml, glass or plastics,
        (high density polyethylene/polypropylene)
   5.6 Atomic absorption spectrometer with an appropriate
        detection system and sensitivity
6 Preparation of sample
7 Procedure
   7.1 General
   7.2 Preparation of reference solution
   7.3 Determination of mercury
        7.3 1 General
        7.3.2 Standard additions
   7.4 Determination of blank value
8 Expression of results
9 Precision
10 Test report

This European Standard is one in a series of Standards for the determination of heavy metals in an aqueous extract of paper and paperboard intended for contact with food. This European Standard specifies the test method for the determination of mercury in an aqueous extract.It is applicable to paper and board with extractable mercury content exceeding 0,06 mg per kg.NOTE 1The above limit of determination is 5 times below than the actual limit existing today or proposed in Europe.NOTE 2Mercury content levels below 0,06 mg per kg can be measured by this European Standard if very sensitive equipment is available and if all other laboratory conditions fulfil the requirements for trace element analysis.