Simultaneous determination of potassium, sodium, calcium, and magnesium in virgin olive oils by capillary electrophoresis with capacitively coupled contactless conductivity detection

Abstract

Analysis of trace elements in virgin olive oil (VOO) is important for nutritional information, geographical characterization, and adulteration detection. In this study, Na⁺, K⁺, Ca²⁺, and Mg²⁺ in VOO were extracted to an aqueous solution with the aid of ultrasound energy, which was analyzed by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C⁴D). The metal ions were separated in less than 3 min with good peak resolutions. The CE-C⁴D method exhibited good linearity, with coefficients of determination (R²) ranging from 0.9978 to 0.9995. The limits of quantification for Na⁺, K⁺, Ca²⁺, and Mg²⁺ were 0.029, 0.029, 0.033, and 0.044 mg kg⁻¹, respectively. The results of the recovery tests at three concentration levels ranged from 80.5% to 119.6% with a relative standard deviation of 0.6 to 18.1%. The proposed CE-C⁴D method was successfully applied for determination of the target analytes in five commercial samples of VOO.