4.2. Caffeine content
Although syringe barrel columns were used for caffeine SPE, the method can be adapted to SPE cartridges as long as proper sorbent mass is chosen improving the automation of the method. The mobile phase for caffeine determination contains a component that adsorbs at 270nm, triethylamine, that appears in the chromatogram as a system peak (Srbek et al., 2005). This peak did not interfere with caffeine peak in our chromatographic system. The results obtained with the proposed method are in agreement with references. Robusta coffee contains higher levels of caffeine and chlorogenic et al. (2005), caffeine content (dry matter basis of green coffee bean) varies markedly between species and within species. C. canephora (robusta coffee), C. brevipes and C. stenophylla are the coffee species with the highest caffeine content, while C. pseudozanguebariae and C. humblotiana are almost caffeine-free.