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Isotope dilution SPME GC/MS for the determination of methylmercury in tuna fish samples
Author(s) -
Centineo Giuseppe,
González Elisa Blanco,
García Alonso J. Ignacio,
SanzMedel Alfredo
Publication year - 2006
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.960
Subject(s) - chemistry , methylmercury , isotope dilution , mercury (programming language) , certified reference materials , isotope , chromatography , environmental chemistry , detection limit , analytical chemistry (journal) , mass spectrometry , bioaccumulation , physics , quantum mechanics , computer science , programming language
The development of a rapid, precise and accurate analytical method for the determination of methylmercury in tuna fish samples is described. The method is based on the use of isotope dilution GC/MS with electron impact ionization, a widespread technique in routine testing laboratories. A certified spike containing 202 Hg‐enriched methylmercury was used for the isotope dilution of the samples. After extraction of the methylmercury from the sample, methylmercury was propylated using sodium tetrapropyl borate in SPME vials and the analytes were sampled from the headspace for 15 min. For isotope measurements, the molecular ion (MePrHg + ) was used in the SIM mode. Five molecular ions were monitored, corresponding to the 198 Hg, 199 Hg, 200 Hg, 201 Hg and 202 Hg isotopes. The detection at masses corresponding to 198 Hg was used to correct for m + 1 contributions of 13 C from the organic groups attached to the mercury atom on the 199 Hg, 200 Hg, 201 Hg and 202 Hg masses with simple mathematical equations, and the concentration of methylmercury was calculated on the basis of the corrected 200 Hg/ 202 Hg isotope ratio. The 202 Hg‐enriched methylmercury spike was applied, with satisfactory results, to the determination of methylmercury in the certified reference material BCR 464. The method was successfully applied to the determination of methylmercury in tuna fish samples, and the obtained results were included in the CCQM‐P39 interlaboratory exercise, organized by the Institute for Reference Materials and Measurements (IRMM, Geel, Belgium) with excellent agreement between our results and the average obtained by the other participants. Copyright © 2005 John Wiley & Sons, Ltd.