Determination of calcium, magnesium, sodium and potassium in wines by FIA using an automatic zone sampling system

In this paper, an automatic flow injection system based on the zone sampling technique for the determination of calcium and magnesium in wines by atomic absorption spectrometry, and sodium and potassium by flame photometry, is described. A reproducible cleavage of a portion of the injected sample plug was achieved by using two computer-controlled rotatory valves. The developed methodology yielded up to a 2000-fold dilution, without a significant decrease in the sampling rate, which was never lower than 90 determinations per h for any of the species analyzed. The quality of the results obtained with the automatic system for several types of wines was evaluated by comparison with those obtained with the reference methods. A relative standard deviation of less than 3% was achieved for all the samples (n = 15) and species analyzed.