CERTIFIED REFERENCE MATERIALS (CRM-408 AND CRM-409) FOR QUALITY-CONTROL OF MAIN COMPONENTS (AMMONIUM, CALCIUM, HYDRONIUM, MAGNESIUM, NITRATE, POTASSIUM, SODIUM AND SULFATE) IN SIMULATED RAIN WATER

Analyses of rainwater are routinely performed by a number of organisations to monitor the contribution from rainwater to the component occurrences in the environment and the acidification of the environment. To control the quality of such determinations, the Community Bureau of Reference (BCR) has organised a certification campaign to produce two simulated rainwater reference materials (CRM 408, low mineral content and CRM 409, high mineral content). The materials were carefully prepared (addition of pro analysis and supra pure reagents with the mentioned elements to silica-free deionised water) and its homogeneity and long-term stability were verified. The materials were certified for their contents of ammonium (106 mumol/kg) (CRM 409), calcium (7.68 and 15.5 mumol/kg), chloride (67.3 and 113 mumol/kg), hydronium (16.6 and 48.0 mumol/kg), magnesium (6.14 and 12.3 mumol/kg), nitrate (20.1 and 78.1 mumol/kg), potassium (4.25 mumol/kg) (CRM 409), sodium (42.0 and 82.9 mumol/kg) and sulphate (10.5 and 53.2 mumol/kg). Indicative values (not certified) are given for ammonium and potassium in CRM 408. This paper presents the certification work performed, as well as the analytical work for the certification of the contents of relevant species.