Evaluation of Short-term Physical Weathering of a Heavy Fuel Oil by use of Time Warping and PCA

摘要

Effects of evaporation and dissolution on the chemical composition of a heavy fuel oil were studied in laboratory experiments designed to separate these physical weathering processes. The in vitro evaporation test lasted 7 days and the in vitro dissolution test lasted 14 days. Data from chromatograms of m/z 105 that includes the homologue series of alkyltoluenes, which are affected by both evaporation and dissolution, were analysed using a hyphenated analytical method comprising gas chromatography - mass spectrometry with selected ion monitoring (GC-MS/SIM), data preprocessing by correlation optimised warping (COW), and principal component analysis (PCA). The PCA model using two principal components was capable of resolving the individual effects of evaporation and dissolution, showing clear time dependence. The preprocessing method used was however not able to completely resolve the effects of the in vitro weathering processes from the variability inherent in the analytical procedure.