BS EN ISO 12846-2012 pdf download.Water quality – Determination of mercury一Method using atomic absorption spectrometry (AAS) with and without enrichment.
For all aqueous samples, prepare a field blank and analyse as required. Use the same type of container and the same quantity of all reagents as were used in the sample collection. Treat the field blank like a sample.
If waste waters are to be analysed, see 7.4 with regard to the pre-treatment of samples.
6 Determination of mercury after tin(ll) chloride reduction and enrichment by amalgamation
6.1 Reagents and standards
Reagents and water can contain mercury as an impurity. For high sensitivity, use ultra-pure reagents or those with a particularly low mercury content compared to the lowest analyte concentration.
6.1.1 Water, with a purity fulfilling the requirements for grade 1, as specified in Iso 3696 for all sample preparations and dilutions.
6.1.2 Potassium bromate solution, c(KBrO3) 0,033 3 molll.
Dissolve 1,39 g of potassium bromate in 250 ml of water (6.1.1). Potassium bromate can be purified, if necessary, by heating in a muffle furnace overnight at 250 °C ± 20 °C.
The solution is stable for about 1 month.
6.1.3 Potassium bromide solution, c(KBr) = 0,2 molll.
Dissolve 5,95 g of potassium bromide in 250 ml of water (6.1.1). Potassium bromide can be purified, if necessary, by heating in a muffle furnace overnight at 300 C ± 20 °C.
The solution is stable for about 1 month.
6.1.4 Potassium bromidelpotassium bromate reagent.
Mix equal volumes of potassium bromate (6.1.2) and potassium bromide solution (6.1.3). A total volume of 200 ml will allow digestion for 100 samples.
NOTE Pre-mixed ampoules for potassium bromate/bromide stock solution are commercially available. This reagent has been found to contain negligible mercury concentrations.
The reagent can remain stable for several days and up to several weeks. This point shall be checked. The solution should be colourless.
6.1.5 Hydroxylammonlum chloride solution, p(NH4CIOH) = 120 g/l.
Dissolve 6,0 g of hydroxylammonium chloride in water (6.1.1) in a 50 ml volumetric flask and make up to volume.
This solution may be purified by the addition of 1,0 ml of SnCI2 solution (6.1.8) and purging overnight at 500 mI/mm with Hg-free N2. Flow injection systems may require less 5nCl2 for purification of the solution.
The solution is stable for about 1 month.
NOTE An ascorbic acid solution (L-ascorbic acid, 100 g/l) is also permissible. It is up to the user of this International Standard to demonstrate the fitness for purpose of this reduction procedure.BS EN ISO 12846 pdf download.