EN 15841:2009 – Ambient air quality — Standard method for determination of arsenic, cadmium, lead and nickel in atmospheric deposition

5 5.1 Apparatus and reagents Reagents
5.1.1 Ultrapure water distilled or deionised It is recommended that the water used should be obtained from a water purification system that delivers ultrapure water having a resistivity of 1 8,2 MΩ ·cm or greater at 25 °C.
5.1.2 Nitric acid (HNO 3 ), concentrated Density about 1 ,42 g/ml, mass fraction about 70 %, high purity grade (concentration stated by the manufacturer or supplier < 0,005 mg/l for As, Cd, Ni and Pb (typical concentrations are generally ten times lower)), sub-boiled before use if necessary. WARNING — Concentrated nitric acid is corrosive and oxidising, and nitric acid fumes are irritants. Avoid exposure by contact with the skin or eyes, or by inhalation of fumes. Carry out the work in a fume cupboard. Use suitable personal protective equipment (including suitable gloves, face shield or safety glasses, etc.) when working with the concentrated or dilute nitric acid. 5.1.3 Nitric acid for cleaning purposes (2 % by volume) Add approximately 800 ml of ultrapure water to a 1 l acid cleaned volumetric flask. Carefully add 20 ml of concentrated nitric acid to the flask and swirl to mix. Allow to cool, dilute to 1 l with ultrapure water and mix thoroughly. 5.1.4 Nitric acid for filtration purposes (1 % by volume) Add approximately 900 ml of ultrapure water to a 1 l acid cleaned volumetric flask. Carefully add 1 0 ml of concentrated nitric acid (5.1 .2) to the flask and swirl to mix. Allow to cool, dilute to 1 l with ultrapure water and mix thoroughly. 5.1.5 Hydrogen peroxide (H 2 O 2 ), mass fraction about 30 % High purity grade (concentration stated by the manufacture or supplier < 0,005 mg/l for As, Cd, Ni and Pb (typical concentration are generally ten times lower)). 5.2 5.2.1 Sampling equipment General Depending on site characteristics (6.1 ), three different types of collectors can be used to measure deposition of arsenic, cadmium, nickel and lead: wet-only (3.1 .22), bulk (3.1 .3) and Bergerhoff collector (3.1 .2). The two first types of collectors are bottle+funnel combinations while the latter is an open bucket. The choice of which sampler to use is discussed in 6.1 . 5.2.2 General requirements for sampling equipment Collectors shall have a cylindrical vertical section of sufficient height to avoid sampling losses resulting from splashing. See Annex A for illustrations of the samplers used in the field trial. The diameter for the opening area and the volume of the collector need to be selected to be of appropriate size to collect all the precipitation for the required sampling duration. Typical sampling periods vary between one week and one month. The funnel area shall be large enough to provide sufficient sample for chemical analysis at a minimum precipitation height of 1 mm per week. In order for the sample not to be contaminated from the ground during heavy rain, the height of the opening through which precipitation enters the sampler (i.e., the collection orifice) shall be at least 1 ,5 m above ground. For areas that receive high snowfall accumulations, the sampler may be raised onto a platform above the snow [4]. No parts of the collector that are in contact with the sample shall be made of metal. All parts should be easily cleaned. The collector and all surfaces in contact with the samples should be inert for the analytes measured, for example high density polyethylene. EN 15841:2009 – Ambient air quality — Standard method for determination of arsenic, cadmium, lead and nickel in atmospheric deposition