Abstract
Laboratories dealing with the analysis of food of animal origin have to face the shortage of both appropriate certified reference materials and pertinent proficiency tests (PTs). Therefore, internal quality control (IQC) materials have to be prepared in-house. The combination matrix/analytes/concentration, as well as the physical state, is a key issue. The European Union Reference Laboratory for Chemical Elements in Food of Animal Origin (EURL-CEFAO), within its activity as PT provider, has set a procedure to prepare test items of liquid milk spiked with arsenic, cadmium and lead at adequate values of concentration. This work describes in detail the steps of this procedure. Homogeneity and stability of the PT test items thus prepared were evaluated by the EURL-CEFAO using a sensitive and accurate method accredited according to ISO/IEC 17025. The analyte concentrations in spiked milk were found stable up to 18 months which is of particular interest for cadmium due to the low value of spiking (roughly 5 μg/kg). The outcome proves that the procedure used to prepare liquid milk spiked with chemical elements is suitable to produce in-house reference materials stable enough for analytical purposes. Furthermore, this procedure is easy to perform and can be applied by routine laboratories to produce samples for their IQC.
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References
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This manuscript has been produced with the financial support of the SANCO 2005/Food SAFETY/003-Residues Program of the European Commission.
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The contents of this manuscript are the sole responsibility of the author and can in no way be taken to reflect the views of the European Commission.
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Ciprotti, M., Sorbo, A., Orlandini, S. et al. Preparation of liquid milk for proficiency test and internal quality control for chemical elements in food. Accred Qual Assur 18, 333–339 (2013). https://doi.org/10.1007/s00769-013-0994-7
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DOI: https://doi.org/10.1007/s00769-013-0994-7