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