Determination of the caffeine contents of various food items within the Austrian market and validation of a caffeine assessment tool (CAT)

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 (r²= 0.817, p < 0.01) using these analytical data and caffeine saliva concentrations (r²= 0.427, p < 0.01).