Tin Win

Reference Materials in Environmental Studies

Over the last few decades the character of chemical analytical investigations has changed significantly. Due to automatization and computerization in chemical measuring technology, an extensive amount of physical and chemical analysis data has been obtained in a relatively short time. These data have to be evaluated for soundness by means of statistical procedures because the results obtained may be used for decisions with weighty consequences.

Final report on CCQM-K47: Volatile organic compounds in methanol

At the October 2005 CCQM Organic Analysis Working Group Meeting (IRMM, Belgium), the decision was made to proceed with a Key Comparison study (CCQM-K47) addressing the calibration function for the determination of volatile organic compounds (VOCs) used for water quality monitoring. This was coordinated by CENAM and NIST. Benzene, o-xylene, m-xylene and p-xylene were chosen as representative VOCs. The solvent of choice was methanol. Key Comparison CCQM-K47 demonstrated the capabilities of participating NMIs to identify and measure the four target VOCs in a calibration solution using GC-based methods. The measurement challenges in CCQM-K47, such as avoiding volatility loss, achieving adequate chromatographic resolution and isolating potential interferences, are typical of those required for value-assigning volatile reference materials. Participants achieving comparable measurements for all four VOCs in this Key Comparison should be capable of providing reference materials and measurements for VOCs in solutions when present at concentration levels greater than 10 ?g/g. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Analytik von Mineralölkohlenwasserstoffen: Die Problematik der Probenaufbereitung

ZusammenfassungBei der Bestimmung von Mineralölkohlenwasserstoffen (MKW) in Wasser und Boden werden sowohl IR- als auch GC/FID-Verfahren (DEV H-18, ISO/TR 11046, NEN 5733) angewendet. Unabhängig von der Meßmethode werden in diesen Normen unterschiedliche Probenaufbereitungen vorgeschrieben. Als Adsorbentien kommen Aluminiumoxid, Kieselgel und Magnesiumsilicat (Florisil®) zur Anwendung.Der Beitrag beschreibt anhand von ausgewählten Substanzen die Problematik der Probenaufbereitung bei der Analytik von Mineralölkohlenwasserstoffen. Es werden Untersuchungen zu der Art des Adsorbens, des Extraktmediums, der clean-up-Technik und des Extrakt/Adsorbens-Verhältnisses vorgestellt. Es wird gezeigt, daß die Probenaufbereitung zu einer signifikanten Einflußgröße bei der MKW-Bestimmung gezählt werden muß. Die aus der Probenaufbereitung resultierenden Fehlerquellen sowie die Möglichkeiten zu deren Vermeidung werden dargestellt.Ein Extraktionsmittel für Böden wird vorgestellt, das einfach zu handhaben ist und den Anforderungen der Probenaufbereitung optimal angepaßt werden kann.AbstractFor the determination of mineral oil hydrocarbons in water and soil, IR-as well as GC/FID-methods (DEV H-18, ISO/TR 11046, NEN 5733) are used. Independent of the measurement method, different clean-up procedures are prescribed in these standard methods. Aluminium oxide, silica gel and magnesium silicate (Florisil®) are used as adsorbents.This article describes the problems of clean-up occurring in mineral oil analysis using selected substances. Tests concerning the type of adsorbent, extract medium, clean-up-technique and extract/adsorbent-ratio are presented. It will be shown that the clean-up procedure has to be counted as a significant factor of influence in the determination of mineral oil hydrocarbons. The sources of errors resulting from clean-up as well as the possibilities to avoid them are presented.An extraction solvent for soils which is simple to handle and optimally adjustable to the requirements of the clean-up procedure is presented.