Species specific isotope dilution for the accurate and SI traceable determination of arsenobetaine and methylmercury in cuttlefish and prawn.

Methods based on species specific isotope dilution were developed for the accurate and SI traceable determination of arsenobetaine (AsBet) and methylmercury (MeHg) in prawn and cuttlefish tissues by LC-MS/MS and SPME GC-ICPMS. Quantitation of AsBet and MeHg were achieved by using a C-enriched AsBet spike (NRC CRM CBET-1) and an enriched spike of MeHg (NRC CRM EMMS-1), respectively, wherein analyte mass fractions in enriched spikes were determined by reverse isotope dilution using natural abundance AsBet and MeHg primary standards. Purity of these primary standards were characterized by quantitative H-NMR with the use of NIST SRM 350b benzoic acid as a primary calibrator, ensuring the final measurement results traceable to SI.

Determination of arsenobetaine in fish tissue by species specific isotope dilution LC-LTQ-Orbitrap-MS and standard addition LC-ICPMS.

An accurate and precise method for the determination of arsenobetaine (AsB, (CH(3))(3)(+)AsCH(2)COO(-)) in fish samples using exact matching species specific isotope dilution (ID) liquid chromatography LTQ-Orbitrap mass spectrometry (LC-LTQ-Orbitrap-MS) and standard addition LC inductively coupled plasma mass spectrometry (LC-ICPMS) is described. Samples were extracted by sonication for 30 min with high purity deionized water. An in-house synthesized (13)C enriched AsB spike was used for species specific ID analysis whereas natural abundance AsB, synthesized and characterized by quantitative (1)H NMR (nuclear magnetic resonance spectroscopy), was used for reverse ID and standard addition LC-ICPMS.

Headspace single-drop microextration for the detection of organotin compounds.

The performance of single-drop microextraction (SDME), coupled with gas chromatography/mass spectrometry, was assessed for the determination of tributyltin compounds in water and solid samples. Experimental parameters impacting the performance of SDME, such as microextraction solvent and sampling and stirring time, were investigated. Analytical results obtained by SDME were compared with those generated by conventional solid phase microextraction (SPME) and liquid-liquid extraction (LLE) for the determination of TBT in PACS-2 sediment certified reference material (CRM).

Certification of a new selenized yeast reference material (SELM-1) for methionine, selenomethinone and total selenium content and its use in an intercomparison exercise for quantifying these analytes.

A new selenized yeast reference material (SELM-1) produced by the Institute for National Measurement Standards, National Research Council of Canada (INMS, NRC) certified for total selenium (2,059+/-64 mg kg(-1)), methionine (Met, 5,758+/-277 mg kg(-1)) and selenomethionine (SeMet, 3,431+/-157 mg kg(-1)) content is described. The +/-value represents an expanded uncertainty with a coverage factor of 2. SeMet and Met amount contents were established following a methanesulfonic acid digestion of the yeast using GC-MS and LC-MS quantitation.

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.

Improvement of measurement precision of SPME-GC/MS determination of tributyltin using isotope dilution calibration.

A unique approach was developed to improve the precision of quantification of tributyltin (TBT) in sedimentsby solid phase microextraction (SPME) using isotope dilution GC/MS. The precision of the analytical technique was initially evaluated using standard calibration solutions. In selective ion monitoring (SIM) mode, the relative standard deviation (RSD) obtained for TBT based on peak area response was 18% (n = 11).