Determination of calcium, magnesium, sodium, and potassium in foodstuffs by using a microsampling flame atomic absorption spectrometric method after closed-vessel microwave digestion: method validation.

摘要

A validation process in compliance with the NF/EN ISO/IEC 17025 standard is described for determination of the macrominerals Ca, Mg, Na and K in foods by microsampling with flame AAS after closed-vessel microwave digestion. The French Standards Commission (Agence Francaise de Normalisation) standards NF V03-110, NF EN V03-115 and XP T-90-210 were used to evaluate the method. The method was validated via analysis of the 1322 food samples included in the second French Total Diet Study (TDS). Several performance criteria (linearity, LOQ, specificity, trueness, precision under repeatability conditions and intermediate precision reproducibility) were evaluated. Furthermore, the method was monitored by several internal quality controls. The LOQ values obtained (25, 5, 8.3 and 8.3 mg/kg for Ca, Mg, Na and K, respectively) were in compliance with the needs of the TDS. The method provided accurate results as demonstrated by a repeatability CV (CVr) of <7% and a reproducibility CV (CVR) of <12% for all the elements. Results suggest that this method could be used in the laboratory for the routine determination of these 4 elements in foods with acceptable analytical performance.