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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 

Application of isotope dilution to the determination of methylmercury in fish tissue by solid-phase microextraction gas chromatography-mass spectrometry.

Species-specific isotope dilution (ID) calibration using solid-phase microextraction (SPME) in combination with gas chromatography-mass spectrometry (GC-MS) for separation and detection of methylmercury (MeHg) in fish tissue is described. Samples were digested with methanolic potassium hydroxide. Analytes were propylated and headspace sampled with a polydimethylsiloxane-coated SPME fused-silica fiber. ID analysis was performed using a laboratory-synthesized 198Hg-enriched methylmercury (Me 198Hg) spike. Using selective ion monitoring (SIM) mode, the intensities of Me 202HgPr+ at m/z 260 and Me 198HgPr+ at m/z 256 were used to calculate the m/z ratio at 260/256, which was used to quantify MeHg in NRCC CRM DORM-2 fish tissue. A MeHg concentration of 4.336 +/- 0.091 microg g(-1) (one standard deviation, n = 4) as Hg was obtained in DORM-2, in good agreement with the certified value of 4.47 +/- 0.32 microg g(-1) (95% confidence interval). A concentration of 4.58 +/- 0.31 microg g(-1) was determined by standard additions calibration using ethylmercury (EtHg) as an internal standard. The three-fold improvement in the precision of measured MeHg concentrations using ID highlights its superiority in providing more precise results compared to the method of standard additions. A method detection limit (3 S.D.) of 0.037 microg g(-1) was estimated based on a 0.25 g subsample of DORM-2.[1]

References

  1. Application of isotope dilution to the determination of methylmercury in fish tissue by solid-phase microextraction gas chromatography-mass spectrometry. Yang, L., Colombini, V., Maxwell, P., Mester, Z., Sturgeon, R.E. Journal of chromatography. A. (2003) [Pubmed]
 
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