Continuous flow autoanalyzer for the sequential determination of total sugars, colorant and caffeine contents in soft drinks

A novel autoanalyzer for sequential determination of total sugars, class IV caramel and caffeine contents in soft drinks is described for the first time. The multiparametric autoanalyzer is based on the on-line coupling of a continuous solid-phase extraction unit with two detectors in series: UV-vis and evaporative light scattering (ELSD) detectors. Caffeine is selectively retained on the sorbent column and the other components are sequentially determined in the effluent. Caffeine was further eluted with an acetonitrile stream and the signal registered in the ELSD. The proposed autoanalyzer is a useful tool for the determination of these macrocomponents in the selected matrices on account of the high level of capital, basic and productivity-related analytical properties it provides. The method was validated through the use of spiked samples and applied to the analysis of more than 20 different soft drink samples (regular, diet, caffeine-free, energy drinks) with satisfactory results.