“…Although this technique may exhibit a high degree of chromatographic resolution, especially when capillary columns are used, certain isomeric pairs may still prove difficult to separate (4-7). This tends to limit the usefulness of GC/MS due to the inability of a mass spectrometer to routinely distinguish between structural PAH isomers (4,8). The problem is especially severe when a questionable peak is composed of a mixture of such isomers.…”