Total selenium and selenomethionine in pharmaceutical yeast tablets: Assessment of the state-of-the-art of measurement capabilities through international intercomparison study CCQM-P86

Authors: GOENAGA-INFANATE, H - LGC LIMITED; STURGEON, R - NATL RES COUNCIL CANADA; TURNER, J - LGC LIMITED; HEARN, R - LGC LIMITED; SARGENT, M - LGC LIMITED; MAXWELL, P - NATL RES COUNCIL CANADA; YANG, L - NATL RES COUNCIL CANADA; BARZEV, A - CSIR-NATL METROLOGY LAB; PEDRERO, Z - UNIV MADRID; CAMARA, C - UNIV MADRID; HUERTA, D - UNIV OVIEDO; FERNANDEZ SANCHEZ, M.L. - UNIV OVIEDO; SANZMEDEL, A - UNIV OVIEDO; EMESE, K - CORVINUS UNIV BUDAPEST; FODOR, P - CORVINUS UNIV BUDAPEST; Wolf, Wayne; Goldschmidt, Robert; VACCHINA, V - GROUP BIO-INORGANIC ANALY

Submitted to: Analytical and Bioanalytical Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2008
Publication Date: 2/15/2008
Citation: Goenaga-Infanate, H., Sturgeon, R., Turner, J., Hearn, R., Sargent, M., Maxwell, P., Yang, L., Barzev, A., Pedrero, Z., Camara, C., Huerta, D., Fernandez Sanchez, M., Sanzmedel, A., Emese, K., Fodor, P., Wolf, W.R., Goldschmidt, R.J., Vacchina, V. 2008. Total selenium and selenomethionine in pharmaceutical yeast tablets: Assessment of the state-of-the-art of measurement capabilities through international intercomparison study CCQM-P86. Analytical and Bioanalytical Chemistry. 390:629-642.

Interpretive Summary: Under the auspices of the Comite Consultatif pour la Quantite de Matiere (CCQM) Inorganic Analysis Working Group, an international intercomparison study (CCQM-P86) involving 15 laboratories (from 12 countries) was conducted to assess the worldwide analytical capabilities to accurately quantitate the content of selenomethionine (SeMet) and total selenium (Se) in pharmaceutical tablets of selenised yeast supplements. A variety of approaches were used to measure SeMet and total Se. A novel aspect of this study relies on the approach used to distinguish any errors that arise during analysis of a SeMet calibration solution from errors which occur during analysis of the matrix. Results averaged 337.6 ± 9.7 mg kg-1 (n = 13, median = 337.6) for total Se and 561.5 ± 44.3 mg kg-1 (n = 11, median = 575.0 mg kg-1) for SeMet. Recovery of SeMet from a Certified Reference Material SELM-1 averaged 95.0 ± 7.2% (n = 9) of the certified value. The ability of laboratories worldwide to deliver accurate results for total Se and SeMet in materials such as Se-yeast tablets with ±10 % uncertainty was demonstrated. The problems addressed in achieving accurate quantitation of SeMet in this product are representative of those encountered with a wide range of organometallic species in a number of common matrices. This information will be used by public and private sector labs involved with analyzing yeast supplements.

Technical Abstract: Under the auspices of the Comite Consultatif pour la Quantite de Matiere (CCQM) Inorganic Analysis Working Group, an international intercomparison study (CCQM-P86) involving 15 labs(12 countries) was conducted to assess the worldwide analytical capabilities to accurately quantitate the content of selenomethionine (SeMet) and total selenium (Se) in pharmaceutical tablets of selenised yeast supplements. For determination of SeMet, 8 labs relied upon measurements using isotope dilution mass spectrometry (IDMS) utilizing an isotopically enriched 76SeMet. Several advances in analytical methodology for determination of SeMet were identified, including the combined use of double IDMS with high performance liquid chromotography- inductively coupled plasma-mass spectrometry HPLC-ICP-MS following extraction with methane sulfonic acid and a simplified enzymatic hydrolysis with protease/lipase/driselase followed by HPLC-ICP-IDMS. Results averaged 337.6 ± 9.7 mg kg-1 (n = 13, median = 337.6) for total Se and 561.5 ± 44.3 mg kg-1 (n = 11, median = 575.0 mg kg-1) for SeMet. Recovery of SeMet from a Certified Reference Material SELM-1 averaged 95.0 ± 7.2% (n = 9) of the certified value. The ability of labs worldwide to deliver accurate results for total Se and SeMet in materials such as Se-yeast tablets with ±10 % uncertainty was demonstrated. The problems addressed in achieving accurate quantitation of SeMet in this product are representative of those encountered with a wide range of organometallic species in a number of common matrices.