Correction factor, f_sub, introduced in Eq. (4) due to different emitting areas arising from the sublimation temperature. The shaded area shows where most of the species considered in this work fall on this graph (sublimation temperatures between 55 K and 125 K).The abundance ratios of these species with respect to methanol are found by multiplying their column density ratios with respect to methanol by a factor of between 0.1 and 2.