Simultaneous Analysis of Nitrates and Major Organic Acids in Spinach Using Capillary Electrophoresis

Abstract

It is necessary to decrease the concentrations of nitrate and oxalate in spinach for human health. This analytical method was developed to simultaneously determine nitrate, oxalate and other major organic acids in spinach using capillary electrophoresis. The essence of the analytical conditions were as follows; the electrolyte used was a mixture of methanol and buffer (pH 5.6, 10 mM 2, 6-pyridinedicarboxylic acid, 5 mM ethylendiamine-tetraacetic acid disodium salt and 0.5 mM cetyltrimethylammonium bromide) at a ratio of 8:92 (V/V) and non-absorbing analytes were detected indirectly at 275 nm. The time needed for the analysis of one sample was 15 min. It was possible to separate nitrate, oxalate, malate, citrate and succinate from the spinach extract. This method could be applicable to tomatoes and other vegetables.