title: Determination of total mercury in nuts at ultratrace level.
abstract: Total mercury, at μg kg(-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 2.7μg kg(-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 0.3μg kg(-1), respectively.
authors: Departamento de Química - Universidade Federal Rural de Pernambuco, Rue Dom Manoel de Medeiros s/n. Dois irmãos, 52171-900 Recife, PE, Brazil. Electronic address: maryquimica@yahoo.com.br.
authors: Maria José
authors: MJ
authors: da  Silva
authors: Departamento de Química Fundamental - Universidade Federal de Pernambuco, Cidade Universitária, 50740-550 Recife, PE, Brazil.
authors: Ana Paula S
authors: AP
authors: Paim
authors: Departamento de Engenharia Química - Universidade Federal de Pernambuco, Recife, PE, Brazil.
authors: Maria Fernanda
authors: MF
authors: Pimentel
authors: Department of Analytical Chemistry, Research Building, University of Valencia, 50th Dr. Moliner Street, E-46100 Burjassot, Valencia, Spain.
authors: M Luisa
authors: ML
authors: Cervera
authors: Department of Analytical Chemistry, Research Building, University of Valencia, 50th Dr. Moliner Street, E-46100 Burjassot, Valencia, Spain.
authors: Miguel
authors: M
authors: de la  Guardia
mesh_terms: D002138:Calibration; D057230:Limit of Detection; D008628:Mercury / Q000032:analysis*; D009754:Nuts / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D008628:Mercury
keywords: Gold amalgamation; Mercury determination; Nut; Sample defatting