Figure 8: Two-dimensional separation of Coffee - 1DCN/2DC18 with heart-cut segments from CN phase on C18 separation (cut times 1.6-2.4 minutes). Both dimensions ran at a 20%min-1 gradient, from 100% water to 100% methanol at 2 mLmin-1 the held for 4 minutes and returned to initial conditions in 1 minute (yellow circle indicates caffeine peak).