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Results of an international intercomparison study (CCQM-P86) to assess the analytical capabilities of national metrology institutes (NMIs) and selected expert laboratories worldwide to accurately quantitate the mass fraction of selenomethionine (SeMet) and total Se in pharmaceutical tablets of selenised-yeast supplements (produced by Pharma Nord, Denmark) are presented. The study, jointly coordinated by LGC Ltd., UK, and the Institute for National Measurement Standards, National Research Council of Canada (NRCC), was conducted under the auspices of the Comité Consultatif pour la Quantité de Matière (CCQM) Inorganic Analysis Working Group and involved 15 laboratories (from 12 countries), of which ten were NMIs. Apart from a protocol for determination of moisture content and the provision of the certified reference material (CRM) SELM-1 to be used as the quality control sample, no sample preparation/extraction method was prescribed. A variety of approaches was thus used, including single-step and multiple-step enzymatic hydrolysis, enzymatic probe sonication and hydrolysis with methanesulfonic acid for SeMet, as well as microwave-assisted acid digestion and enzymatic probe sonication for total Se. For total Se, detection techniques included inductively coupled plasma (ICP) mass spectrometry (MS) with external calibration, standard additions or isotope dilution MS (IDMS), inductively coupled plasma optical emission spectrometry , flame atomic absorption spectrometry and instrumental neutron activation analysis. For determination of SeMet in the tablets, five NMIs and three academic/institute laboratories (of a total of five) relied upon measurements using IDMS. For species-specific IDMS measurements, an isotopically enriched standard of SeMet (76Se-enriched SeMet) was made available. A novel aspect of this study relies on the approach used to distinguish any errors which arise during analysis of a SeMet calibration solution from those which occur during analysis of the matrix. To help those participants undertaking SeMet analysis to do this, a blind sample in the form of a standard solution of natural abundance SeMet in 0.1 M HCl (with an expected value of 956 mg kg(-1) SeMet) was provided. Both high-performance liquid chromatography (HPLC)-ICP-MS or gas chromatography (GC)-ICP-MS and GC-MS techniques were used for quantitation of SeMet. Several advances in analytical methods for determination of SeMet were identified, including the combined use of double IDMS with HPLC-ICP-MS following extraction with methanesulfonic acid and simplified two-step enzymatic hydrolysis with protease/lipase/driselase followed by HPLC-ICP-IDMS, both using a species-specific IDMS approach. Overall, satisfactory agreement amongst participants was achieved; results averaged 337.6 mg kg(-1) (n = 13, with a standard deviation of 9.7 mg kg(-1)) and 561.5 mg kg(-1) (n = 11, with a standard deviation of 44.3 mg kg(-1)) with median values of 337.6 and 575.0 mg kg(-1) for total Se and SeMet, respectively. Recovery of SeMet from SELM-1 averaged 95...

Background: Joint-replacement surgery has revolutionized the treatment of osteoarthritis and is still the most effective therapy. A recent clinical trend reintroducing metal-on-metal bearing surfaces has in turn stimulated a requirement for accurate measurement of the concentrations of relevant metals in both pre- and postoperative patients. Thus, there is a need for cost-effective, multielement methods for trace metal analysis in whole blood to monitor possible increases in wear metal concentrations. Methods: A method was developed to allow routine analysis of whole blood samples for molybdenum, cobalt, chromium, and nickel. Sample preparation consisted of a simple 1:10 dilution of whole blood with a solution of 10 mL/L Triton X-100, 0.0002 mol/L EDTA, and 0.01 mol/L ammonium hydroxide. Final determination was performed by a double-focusing magnetic sector inductively coupled plasma mass spectrometer operated in medium-resolution mode (resolution, 3400). Online addition of rhodium was used for internal standardization. Results: Detection limits in whole blood were 0.06 μg/L for chromium, cobalt, and molybdenum and 0.30 μg/L for nickel. Base concentrations of 0.22, 0.17, 0.62, and 0.99 μg/L for chromium, cobalt, molybdenum, and nickel, respectively, in whole blood have been found. Polyatomic interferences on all four elements have been shown to be resolved from the analyte masses by use of a resolution of >3000. Conclusions: The simple, rapid method of sample preparation is effective in minimizing potential contamination and enables 60 samples (run time, 8 h) to be analyzed before cleaning the instrument is necessary. A resolution >3000 was sufficient to separate polyatomic interferences from the masses of interest. The method was used to analyze a large number of blood samples taken from primary patients awaiting total hip arthroplasty. The method is sensitive enough to provide base concentrations for chromium, cobalt, and molybdenum in whole blood. The results for nickel were compromised by high signals for blank samples.

An on-line solid phase extraction method has been developed for the determination of 238U and 232Th biological certified reference material using inductively coupled plasma mass spectrometry (ICP-MS ). Absolute detection limits were 2.7 pg and 3.1 pg for the determination of 238U and 232Th respectively, both being blank limited. The result for the determination of 238U in NASS-4 Open Ocean Sea Water was 2.13±0.28 ng ml−1 compared with a certified value of 2.68±0.12 ng ml−1. The results for the determination of 238U in SLRS-3 River Water was 0.043±0.002 ng ml−1 compared with an indicative value of 0.045 ng ml−1. Results for the determination of 238U and 232Th in NIST 1575 Pine Needles were 14.6±3.4 ng g−1 and 28.3±4.5 ng g−1 respectively compared with certified values of 20±4 ng g−1 and 37±3 ng g−1, using a dry and wet ashing sample preparation method. Results for the determination of 238U and 232Th in NIST 1566a oyster tissue were 121±21 ng g−1 and 29±8 ng g−1 for 238U and 232Th compared to certified and indicative values of 132±12 ng g−1 and 40 ng g−1, using the same method. When a lithium metaborate fusion method was used, results for 238U and 232Th were 23.3±2.0 ng g−1 and 36.2±5.6 ng g−1 respectively in NIST 1575 Pine Needles. The application of electrothermal vaporisation ICP-MS ( ETV-ICP-MS) to NASS-4 Open Ocean Sea Water gave 2.81±0.54 ng ml−1 and SLRS-3 River Water 0.045±0.004 ng ml−1 for 238U. When the fused NIST 1575 samples were analysed using ETV-ICP-MS, results for 238U and 232Th were 19.5±1.7 ng g−1 and 38.8±2.2 ng g−1 respectively. Absolute detection limits for ETV-ICP-MS were 30 fg and 9 fg for 238U and 232Th respectively, both being blank limited. cluded that results for the determination of 239Pu in urine were

The development of a novel procedure for the accurate determination of selenium in serum using electrothermal vaporisation inductively coupled plasma mass spectrometry (ETV-ICP-MS) is described. The proposed method eliminates the need for a lengthy sample digestion procedure (a requirement with many methods for the analysis of biological samples), utilising a simple 1+19 dilution of the serum with 1% nitric acid. Many of the interferences normally associated with the determination of selenium by ICP-MS are successfully eliminated with careful optimisation of the ETV temperature program and modifier system. Analytical characteristics for 74Se, 77Se, 78Se and 82Se are reported, including detection limits (3s blank) of approximately 0.1 ng g−1 for 77Se and 82Se. Short-and longterm reproducibility data between 4.7 and 4.9% and 3.2 and 3.8% (RSD) for 77Se and 82Se, respectively, are shown. The accuracy of the method, which included Te as an internal standard, was demonstrated with the analysis of three internal quality control samples and the certified reference material NIST SRM 1598 (bovine serum). Results within 10% of the target value were achieved for three of the four isotopes studied, with slightly worse results for 78Se owing to the large interference from argon adduct ions on this isotope. Preliminary work involving the addition of nitrogen to the argon aerosol carrier gas was successful in reducing the ArAr interference at m/z 78. levels of components such as sodium and organic compounds,