HPLC Analysis of Citric and Tartaric Acids in Fruit Nectars and Juices

The aim of this study was to estimate a level of citric and tartaric acids in fruit nectars (n = 17) and juices (n = 13) available on the Croatian market. For analysis reverse-phase HPLC with UV/Vis detector set at 214 nm was used. Mobile phase was phosphate buffer (50 mM, pH = 2.80) at flow rate 0.5 mL [min.sup.-1]. The method was linear ([r.sup.2] = 0.9999). LoD was 0.01 g [L.sup.-1], LoQ was 0.03 g [L.sup.-1] and the intra-day along with the inter-day variability were up to 3 %. The level of citric and tartaric acids in fruit nectars ranged from 1.26 to 4.42 g [L.sup.-1] and 0.68 to 0.86 g [L.sup.-1], respectively, and in fruit juices ranged from 3.03 to 7.67 g [L.sup.-1] and 3.09 to 4.68 g [L.sup.-1], respectively. A higher level of citric acid in fruit juices than in fruit nectars was detected (p < 0.05; MannWhitney U test). Six fruit juices contained a higher level of citric acid allowed by EU regulation implying the importance of monitoring concentrations of both acids in food products. Keywords: citric acid, tartaric acid, fruit juices, monitoring, green chemistry, Croatian market.