title: Determination of total mercury and methylmercury in biological samples by photochemical vapor generation.
abstract: Cold vapor atomic absorption spectrometry (CV-AAS) based on photochemical reduction by exposure to UV radiation is described for the determination of methylmercury and total mercury in biological samples. Two approaches were investigated: (a) tissues were digested in either formic acid or tetramethylammonium hydroxide (TMAH), and total mercury was determined following reduction of both species by exposure of the solution to UV irradiation; (b) tissues were solubilized in TMAH, diluted to a final concentration of 0.125% m/v TMAH by addition of 10% v/v acetic acid and CH(3)Hg(+) was selectively quantitated, or the initial digests were diluted to 0.125% m/v TMAH by addition of deionized water, adjusted to pH 0.3 by addition of HCl and CH(3)Hg(+) was selectively quantitated. For each case, the optimum conditions for photochemical vapor generation (photo-CVG) were investigated. The photochemical reduction efficiency was estimated to be approximately 95% by comparing the response with traditional SnCl(2) chemical reduction. The method was validated by analysis of several biological Certified Reference Materials, DORM-1, DORM-2, DOLT-2 and DOLT-3, using calibration against aqueous solutions of Hg(2+); results showed good agreement with the certified values for total and methylmercury in all cases. Limits of detection of 6 ng/g for total mercury using formic acid, 8 ng/g for total mercury and 10 ng/g for methylmercury using TMAH were obtained. The proposed methodology is sensitive, simple and inexpensive, and promotes "green" chemistry. The potential for application to other sample types and analytes is evident.
authors.affiliation: Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
authors.forename: Mariana A
authors.initials: MA
authors.lastname: Vieira
authors.forename: Anderson S
authors.initials: AS
authors.lastname: Ribeiro
authors.forename: Adilson J
authors.initials: AJ
authors.lastname: Curtius
authors.forename: Ralph E
authors.initials: RE
authors.lastname: Sturgeon
mesh_terms: D000818:Animals; D004785:Environmental Pollutants / Q000032:analysis* / Q000737:chemistry; D005399:Fishes; D005506:Food Contamination / Q000032:analysis*; D005561:Formates / Q000737:chemistry; D005740:Gases; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D010777:Photochemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012680:Sensitivity and Specificity; D012995:Solubility; D013054:Spectrophotometry, Atomic / Q000379:methods; D013997:Time Factors; D017971:Tin Compounds / Q000737:chemistry; D014466:Ultraviolet Rays; D014835:Volatilization
chemical_list: D004785:Environmental Pollutants; D005561:Formates; D005740:Gases; D008767:Methylmercury Compounds; D000644:Quaternary Ammonium Compounds; D017971:Tin Compounds; C030544:formic acid; C023599:stannous chloride; D008628:Mercury; C027917:tetramethylammonium