| Abstract: | The caffeine content of 124 products, including coffee, coffee-based beverages, energy drinks, tea, colas, yoghurt and chocolate, were determined using RP-HPLC with UV detection after solid-phase extraction. Highest concentrations of caffeine were found for coffee prepared from pads (755?mg?l?1) and regular filtered coffee (659?mg?l?1). The total caffeine content of coffee and chocolate-based beverages was between 15?mg?l?1 in chocolate milk and 448?mg?l?1 in canned ice coffee. For energy drinks the caffeine content varied in a range from 266 to 340?mg?l?1. Caffeine concentrations in tea and ice teas were between 13 and 183?mg?l?1. Coffee-flavoured yoghurts ranged from 33 to 48?mg?kg?1. The caffeine concentration in chocolate and chocolate bars was between 17?mg?kg?1 in whole milk chocolate and 551?mg?kg?1 in a chocolate with coffee filling. A caffeine assessment tool was developed and validated by a 3-day dietary record (r 2?=?0.817, p?<?0.01) using these analytical data and caffeine saliva concentrations (r 2?=?0.427, p?<?0.01). |
