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Development and validation of a WD‐XRF method for quantitative trace analysis: Application in the food industry
Author(s) -
Gazulla María Fernanda,
Rodrigo Marta,
Ventura María Jesús,
Orduña Mónica,
Andreu Cristina
Publication year - 2020
Publication title -
x‐ray spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.447
H-Index - 45
eISSN - 1097-4539
pISSN - 0049-8246
DOI - 10.1002/xrs.3215
Subject(s) - certified reference materials , analyte , sample preparation , matrix (chemical analysis) , calibration , environmental science , environmental chemistry , sample (material) , analytical procedures , chemistry , calibration curve , process engineering , detection limit , biochemical engineering , chromatography , mathematics , engineering , statistics
Kaolins, clays, sepiolites, nitrates, carbonates, and so forth are commonly used in the food industry, either as additives or technological contributories in fining and bleaching processes. These materials must be thoroughly controlled as they can contain some heavy metals that must be in very low concentration as they are toxic to humans. Methods using ICP‐OES, AAS, and ICP‐MS for the determination of trace elements are quite tedious and time‐consuming, due to the necessity of a previous sample treatment to extract the analyte in an aqueous matrix, and non‐ecological as this sample treatment implies the use of acids and thermal processes. A robust WD‐XRF method for accurate quantitative determination of Pb, Cd, Ni, Cr, Hg, and As was developed, reaching the following detection limits: 1 mg·kg −1 for Pb and Cd, 2 mg·kg −1 for Cr and As, and 3 mg·kg −1 for Ni and Hg. For that, a thorough study for the optimisation of the sample preparation was undertaken, studying different kind of binders for pellet preparation, as well as the optimisation of the measurement conditions to be able to reach the requirements stated in food regulation. Besides, an exhaustive search of reference materials was also conducted in order to be able to construct appropriate calibration curves. The methodology was validated both by analysing certified reference materials different from the ones used for calibration and by the use of different analytical techniques to get independent results.