The 2011 version of the…

The 2011 version of the draft guidance included the following description in Appendix III. However it is missing from the draft 2013 version. Does this paragraph still apply? If not, is a definition of F1 and F2 fractions forthcoming? "Unfortunately, CCME (2001) does not prescribe methods for how GC/MS analysis should be performed since it is a soil method involving fractionation and GC/FID analysis. CCME (2001) defines F1 as the total area summation between the apex of the hexane and decane peaks, and F2 as between the apex of the decane and hexadecane peaks. The BTEX and naphthalene peak areas are removed from the total area summations for each fraction. The F1 is calibrated against toluene response generally obtained as a full scan GC/MS peak. The F2 is typically calculated against decane response as a full scan GC/MS peak. This is a slight deviation from CCME (2001), which indicates the average of the decane and hexadecane response should be used; however, laboratories find it is difficult to generate and maintain a known vapour concentration of hexadecane. Therefore the response of decane only is often used to calibrate for the F2 fraction. For the aliphatic/aromatic subfractions, one option is identify the peaks as being aliphatic and aromatic peaks within their respective carbon number ranges. Aliphatic subfractions are quantified against the full mass spectra response of n-hexane; aromatics against toluene. While CCME (2001) clearly defines the F1 and F2 fractions, no such guidelines exist for subfractions. This has lead to variable and uncertain definitions, for example, the C6-C8 aliphatic fraction is referenced as either C6-C8 or >C6-C8. The first implies including the n-hexane peak in the area summation. The second implies excluding n-hexane. The n-hexane peak should be included in the analysis considering it has a relatively high toxicity."

[Original Comment ID: 160827]