Spectrophotometric determination of caffeine in coffee products: collaborative study.

An ultraviolet (UV) spectrophotometric method for determining caffeine in regular and decaffeinated coffee products has been studied collaboratively. Nine laboratories participated in this study which compares the proposed UV method with the official AOAC micro Bailey-Andrew method. Caffeine content was determined on as-is basis on 8 samples of green, roasted, and soluble coffees. The coefficients of variation for the proposed method ranged from 2.02 to 6.98% for the 8 samples studied. The results agreed well with those from the Bailey-Andrew Method. The method was adopted as official first action.