Determination of trace elements in agglomerated cork stoppers using inductively...

• Author(s): Gueifão, Sandra ; Nascimento, Ana Cláudia ; André, Catarina ; Coelho, Inês ; Castanheira, Isabel
• Date: 2011
• Persistent ID: http://hdl.handle.net/10400.18/426
• Origin: Repositório Científico do Instituto Nacional de Saúde
• Subject(s): Cork Stoppers; ICP-MS; Trace Elements; Microwave Digestion; Dry Ashing; Segurança Alimentar
• Document Type: Conference Object
• Language: English

Description

Quercus Suber L. is a native species of the Mediterranean region yielding a thick bark, known as cork, used mainly in the production of wine stoppers. The levels of trace elements are an important component of quality, safety and origin of the agglomerated corks stoppers in contact with food. In the present work the concentration of the following elements was determined: Chromium (Cr), Nickel (Ni), Arsenic (As), Cadmium (Cd), Selenium (Se), Lead (Pb), Iron (Fe), Zinc (Zn), Copper (Cu) and Manganese (Mn). Since almost no published work can be found on this subject it was necessary to study all stages of the process. Sampling was made by the producer who sent representative bagged samples to the laboratory. Subsequently it was necessary to have a reliable sample preparation method before the analysis. To do so the sample preparation step was optimized by employing and comparing two distinct methods to destroy the organic matrix: dry ashing and microwave digestion. Afterwards samples were analysed by two different techniques, trace elements were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and the remaining ones by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Both techniques enable the quantification of elements with ICP-MS allowing lower detection limits (ppb and/or ppt) than ICP-OES (ppm) in a complex matrix such as agglomerated cork stoppers. Several elements were found in the sample. These elements may originate from the cork or by contamination of the manufacturing process of agglomerated cork stoppers. Microwave digestion proved to be the best sample preparation method since the results from reproducibility and repeatability were better than the ones obtained from dry ashing.