Determination of total mercury in nuts at ultratrace level

• Published in: Analytica chimica acta Vol. 838; pp. 13 - 19
• Main Authors: Silva, Maria José da, Paim, Ana Paula S., Pimentel, Maria Fernanda, Cervera, M. Luisa, Guardia, Miguel de la
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2014
• Subjects: Anacardium; Arachis hypogaea; Calibration; Coal; Extraction; Flour; Fluorescence; Gold amalgamation; Juglans; Limit of Detection; Mercury (metal); Mercury - analysis; Mercury determination; Nut; Nuts; Nuts - chemistry; Oryza sativa; Prunus dulcis; Pyrolysis; Sample defatting; Spectrometry, Fluorescence - methods; Brazil; Spain; Mercury determination; Nut; Gold amalgamation; Sample defatting
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2014.06.049

[Display omitted] •Direct analysis of Hg in nuts has been improved by a previous fat removal.•Comparison of cold vapour atomic fluorescence and direct analysis of Hg in nuts.•Mercury content in tree nuts was determined. Total mercury, at μgkg−1 level, was determined in different types of nuts (cashew nut, Brazil nuts, almond, pistachio, peanut, walnut) using a direct mercury analyser after previous sample defatting and by cold vapour atomic fluorescence spectrometry. There is not enough sensitivity in the second approach to determine Hg in previously digested samples due to the strong matrix effect. Mercury levels in 25 edible nut samples from Brazil and Spain were found in the range from 0.6 to 2.7μgkg−1 by using the pyrolysis of sample after the extraction of the nut fat. The accuracy of the proposed method was confirmed by analysing certified reference materials of Coal Fly Ash-NIST SRM 1633b, Fucus-IAEA 140 and three unpolished Rice Flour NIES-10. The observed results were in good agreement with the certified values. The recoveries of different amounts of mercury added to nut samples ranged from 94 to 101%. RSD values corresponding to three measurements varied between 2.0 and 14% and the limit of detection and quantification of the method were 0.08 and 0.3μgkg−1, respectively.