title: Determination of mercury in rice by cold vapor atomic fluorescence spectrometry after microwave-assisted digestion.
abstract: A cold vapor atomic fluorescence spectrometry method (CV-AFS) has been developed for the determination of Hg in rice samples at a few ngg(-1) concentration level. The method is based on the previous digestion of samples in a microwave oven with HNO(3) and H(2)O(2) followed by dilution with water containing KBr/KBrO(3) and hydroxylamine and reduction with SnCl(2) in HCl using external calibration. The matrix interferences and the effect of nitrogen oxide vapors have been evaluated and the method validated using a certified reference material. The limit of detection of the method was 0.9ngg(-1) with a recovery percentage of 95+/-4% at an added concentration of 5ngg(-1). The concentration level of Hg found in 24 natural rice samples from different origin ranged between 1.3 and 7.8ngg(-1).
authors.affiliation: Department of Analytical Chemistry, Edificio de Investigación, University of Valencia, 50 Dr. Moliner Street, E-46100 Burjassot, Valencia, Spain.
authors.forename: Maria José
authors.initials: MJ
authors.lastname: da Silva
authors.forename: Ana Paula S
authors.initials: AP
authors.lastname: Paim
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Pimentel
authors.forename: M Luisa
authors.initials: ML
authors.lastname: Cervera
authors.forename: Miguel
authors.initials: M
authors.lastname: de la Guardia
mesh_terms: D003080:Cold Temperature; D005740:Gases / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D008628:Mercury / Q000032:analysis*; D008872:Microwaves; D017942:Nitric Acid / Q000737:chemistry; D012275:Oryza / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D017971:Tin Compounds / Q000737:chemistry
chemical_list: D005740:Gases; D017971:Tin Compounds; C023599:stannous chloride; D017942:Nitric Acid; D006861:Hydrogen Peroxide; D008628:Mercury