Determination of metals and metalloids in traces in honey: Evaluation of different sample preparation methods and assay techniques

Abstract

Literature reports several protocols for assaying metals and metalloids in foodstuffs. This study aimed to identify the most effective combination of sample preparation methods and three atomic spectroscopy instruments for quantifying trace elements in honey. We show that instrumental LODs demonstrated that FAAS is not sensitive enough to control the most toxic elements in honey, at a level complying with European recommendations (e.g., 0.1 mg kg−1 for Pb). This technique should only be used to assay oligo-elements present at higher concentrations in honey such as Zn. The use of extraction methods for sample preparation protocols was excluded due to their incompatibility with the matrix (liquid-liquid extraction) or the low recovery rates achieved (e.g., 0% for As, 48% for Cd, or only 70% for Mn) with solid-phase extraction. The construction of simplified accuracy profiles objectively confirmed that the dilution factor, inherent to the sample preparation, is critical for the choice of the method, especially with ICP-OES measurements. Finally, calcination of the sample followed by an ICP-OES analysis or a simple dissolution in diluted hydrogen peroxide followed by GFAAS analysis were put forward and validated.