How do I convert peak areas into toluene equivalents?

A calibration with toluene should first be carried out (typically a five-point calibration is acceptable), to obtain a gradient and intercept for the calibration line. For best results, the spread of standard concentrations should encompass the expected analyte concentration.

You can then use the peak area of your compound to obtain the mass in toluene equivalents, here given in units of nanograms (ng):

To relate this to the mass of our sample we can then divide by the mass of sample analysed: