Partner und Internationale Organisationen
(Englisch)
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Anorganisch-Chemisches Institut, Univ. Münster, coordinator (D), Swedish National Institute for Working Life, Umea, (S), Sigma-Aldrich Chemie, SUPELCO, Deisenhofen (D),
Institut für Analytische Chemie, Insbruck (A), Institut für Analytische Chemie, Leipzig (D), Miljo-Kemi, Galten, (D) Aero-Laser GmbH, Garmisch-Partenkirchen (D), VITO, Mol (B)
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Abstract
(Englisch)
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For the quality and comparability of determination of aldehyde compounds, an European inter-laboratory comparison for the sampling and analysis of aldehydes was organized in 1999-2000, using facility at VITO (Vlaamse Instelling voor Technologisch Oderzoek, Mol, Belgium) within the framework of the CEC contract SMT4-CT97-2190. The 2 exercises (14-17 June 1999 and 7-9 June 2000) included 6 rounds, including 5 priority analytes: formaldehyde, acrolein, glutaraldehyde, acetaldehyde and acetone at the range of 0.5 to 150 ppb. The aim of the exercises was to assess chemical interference caused by ozone, nitrogen dioxide and ammonia when using different techniques for sampling and analysis. Twenty participants from different European laboratories took part in the exercise. The measurement methods used by the majority of the participants were based on pumped sampling on silica cartridges and glass fibre filters, coated with 2,4-dinitrophenyl hydrazine (DNPH). It was observed that for formaldehyde, and in some cases for acetaldehyde, the majority of the method-laboratory combinations complied with an overall uncertainty of 30%. The results for acrolein, however, indicated a systematic negative bias, often larger than 50% of the true value, caused by the decomposition of the acrolein DNPH derivative in the presence of excess acid and excess DNPH. The results obtained for glutaraldehyde were not encouraging for a majority of the participants: one of the factors that affected the performance of laboratories was the poor storage stability of the glutaraldehyde hydrazone on the sampling media, and another one was decomposition products of the acrolein hydrazone can overlap with the glutaraldehyde hydrazone peaks in HPLC chromatograms. Our active sampling techniques were: liquid impinger, DNPH impregnated cartridges, DNPH impregnated filter (home made), and 2-HMP coated XAD-2 tubes. Analytical methods were HPLC with UV detector for all DNPH based samples and GC-MS for 2-HMP samples. Recovery studies were carried out in our laboratory using controlled dynamic permeation generation of formaldehyde and acrolein. The experimental amounts of aldehyde were compared to the exact concentration of generated atmosphere and recoveries were determined. The overall recoveries were excellent: 96.6% for formaldehyde (n=6) and 99.2% for acrolein (n=6) by GC method and recoveries of HPLC methods were 100% for all aldehydes. Blank values were determined on three samples of each method, and if necessary, blank values were subtracted from the sample. Reproducible results were found in all 6 rounds of this sampling exercise. Since the 2-HMP coated on XAD-2 tubes give only one peak of acrolein oxazolidine-derivatives by GC techniques, this method is finally ready to acrolein sampling in field situation. For other aldehydes, DNPH based samplers combined with HPLC are the methods of choice. In contrast to conventional quality control schemes, this project particularly focuses attention on the sampling and identification step. The intention is for each participant to determine the observed value of the delivered standard atmosphere using the sampling method of his own choice.In conclusion, inter-laboratory comparison for the sampling and analysis of aldehydes organized by VITO was a very good opportunity for the laboratory to check all sampling devices and to assure quality control in the survey.
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