Figure 7
Variation in benzocarbazole [a]/[c] isomer ratios in outlet oil samples, determined from peak heights in m/z 217 mass chromatograms of the SPE DCM fraction. The values are normalised to the value in the original oil. The benzocarbazoles were completely depleted in the first three oil samples collected, and subsequent samples to ca. 160 ml showed statistically significant depletion of benzo[a]carbazole relative to benzo[c]carbazole compared to later eluted oils. The horizontal dotted line is the reference (injected) oil value at 1.0.