Comparison on the analysis of mineral oil in sediment by gas chromatography and infrared spectrometry
Vergelijking bepaling minerale olie in sediment met gaschromatografie en infraroodspectrometrie
26 May 2012, PDF |
18 pages |
de Jong APJM, van der Heeft E, Visser T
RIVM Report 609021008
A comparitive study has been carried out on the analysis of mineral oil in sediment and water samples by gas chromatography (GC) and infrared spectrometry (IR) according to the current standard methods NEN 5733 and 6675. In an application to sediment samples, results obtained with GC analysis were found to be about 20% higher compared to the IR method (range +6 to +32%). Causes for these differences were not found. Additionally, modifications to improve the performance of the NEN-procedures were investigated. Changes comprised (1) repeated removal of co-extracted dissolved organic carbon (DOC) ; (2) the use of pentaine instead of Freon-113 as extraction solvent and (3) alkaline aqueous washing (back-extraction) of extracts to remove small to medium size acidic co-extractants. However, results obtained were not essentially different from those obtained with the standard method. Based on that, the following conclusions were drawn: (1) the present standard procedures can be considered as reliable methods for the analysis of mineral oil in water en sediment samples, (2) the performance of the GC and IR method is comparable in applications above the determination limit of the latter (0.2-.5 mg/kg) ; (3) improvement of the current standards cannot be achieved with relative simple means; (4) pentane is an acceptable alternative for Freon-113 and other halogenated hydrocarbons in case these solvents are banned for analytical use.