Blank correction considerations for isotope dilution and reverse isotope dilution calibration: Determination of methylmercury in fish tissue
- 1 July 2005
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of Analytical Atomic Spectrometry
- Vol. 20 (8), 724-729
- https://doi.org/10.1039/b505545h
Abstract
A mathematical approach to the accurate correction of the blank when applying isotope dilution (ID) and reverse ID is presented. The manner in which blank correction is undertaken is critical to the quality of the final results. Direct subtraction of a procedural blank from the gross analyte concentration is only valid when the blank contributes to the primary ID process and not to the reverse ID process. When the blank contributes to both processes, typically only a fraction of this blank concentration should be subtracted. The approach developed here was illustrated and validated by the determination of MeHg in tuna fish using ID and reverse ID SPME GC-ICP-MS and an enriched Me198Hg spike. Despite a 150-fold higher blank (equivalent to 7% of the analyte concentration in the sample) arising from use of a 1 M NaOAc/HOAc buffer solution compared to that obtained with use of a 0.5 M NH4OAc/HOAc buffer, final concentrations of 19.90 ± 0.34 and 19.88 ± 0.10 μmol kg−1 (one standard deviation, n = 3) respectively, were derived. These data are in good agreement with the assigned value of 19.91 ± 0.82 μmol kg−1 (as 95% confidence interval, derived from an international intercomparison exercise). The methodology was also applied to the determination of a 50-fold lower concentration of MeHg in a salmon fish. A method detection limit (3SD) of 0.9 nmol kg−1 based on processing of a 0.40 g subsample was obtained.Keywords
This publication has 7 references indexed in Scilit:
- The high-accuracy analysis of lead in wine by exact-matching isotope dilution mass spectrometry using ICP-MSJournal of Analytical Atomic Spectrometry, 2005
- High‐yield synthesis of milligram amounts of isotopically enriched methylmercury (CH3198HgCl)Applied Organometallic Chemistry, 2004
- Comparison of sector field- and quadrupole-ICP-MS for the determination of DBT and TBT in sediment following GC separationJournal of Analytical Atomic Spectrometry, 2003
- Determination of methylmercury in fish tissues by isotope dilution SPME-GC-ICP-MSJournal of Analytical Atomic Spectrometry, 2003
- Improvement in measurement precision with SPME by use of isotope dilution mass spectrometry and its application to the determination of tributyltin in sediment using SPME GC-ICP-MSJournal of Analytical Atomic Spectrometry, 2002
- Evaluation of detector dead time calculation models for ICP-MSJournal of Analytical Atomic Spectrometry, 2001
- Determination of methylmercury in fish and river water samples using in situ sodium tetraethylborate derivatization following by solid-phase microextraction and gas chromatography-mass spectrometryJournal of Chromatography A, 1995