The development, evaluation and application of a simple and low-cost graphite carbon electrode for
the direct determination of citrate in food samples are described here. The electrode exhibits a linear
response with a slope of −29.0 ± 1.0 mV decade−1 in a concentration range of 0.07–7.0 mmol L−1 in
0.1 mol L−1 KCl/1.0 mmol L−1 phosphate buffer solution with a limit of detection of 3.0 mol L−1. The electrode
is easily constructed at a relatively low cost and has a fast time response (within 120 s) with no
significant changes in its performance characteristics. The performance of the graphite sensor was tested
to determine citrate in beverage samples (juices and an isotonic drink), and the results were validated
against a reference procedure. The proposed method is quick, inexpensive, selective and sensitive, and
is based entirely on conventional instrumentation.