Fast sample preparation involving MASE and coupled column normal phase liquid chromatography for the rapid trace...

A new approach has been developed and tested for the urgent analysis of dioxins in samples of air-dust filters originating from catastrophe emissions. The procedure consists of a fast extraction of the sample with microwave solvent extraction (MASE) and acetone as solvent followed by a fast cleanup of the extract with normal phase coupled column liquid chromatography (LC/LC). The multi-dimensional LC/LC system employs a 50 mm x4.6 mm i.d. column packed with 3mum silica and a 150 mm x4.6 mm i.d. column packed with 5mum PYE as the first and second analytical column, respectively. Iso-hexane is used on both columns to perform cleanup and dichloromethane to perform efficient back-flush elution of the compounds from the second column. The obtained polarity-based separation in the first dimension and molecular-structure based separation in the second dimension provides a fast and powerful cleanup. Validation was done by analysing samples of homemade RIVM air-dust with aged residues (n=8, spiking level about 15pgmg(-1) per compound) of dioxins/furans and samples of reference Urban Dust SRM 1649a (n=4) with both the new approach and the existing conventional procedure and were instrumentally analyzed with capillary gas chromatography and high resolution mass spectrometric detection (GC/HRMS). In comparison to the existing conventional procedure, the new approach reduces sample processing from several days to several hours per sample. As regards the aged-residue air-dust samples, the new method shows a good accuracy, precision and high selectivity providing a performance in good agreement with the existing procedure. In SRM air-dust, the concentration of a few compounds obtained by the new method was below (10-50%) the certified value.