Kensaku Okamoto

Analysis of serum elements and the contaminations from devices used for serum preparation by inductively coupled plasma mass spectrometry

Two different samples of serum were prepared from a blood specimen by using two types of serum-separation tubes. Each serum sample was diluted by 100 times with deionized and sub-boiling distilled water. Thirty-six elements in the serum and exudate, from devices used for the serum preparation, were determined by inductively coupled plasma mass spectrometry (ICP-MS). From the comparison of elemental concentrations in two groups of 11 serum samples, it was found that the exudate from serum-separation tubes, as well as from disposable stainless steel needles, had serious effects on the elemental concentrations in the serum. Means for the concentrations of Li, Co, Ga, Cd, Sn, Sb, Ba, La, and Ce in the two serum groups were statistically different from each other. The concentrations of Cr, Mn, Fe, and Mo in both groups were apparently higher than those reported in the literature, suggesting contamination from the disposable stainless steel needle and spectral interferences due to molecular species produced in the argon plasma.

Preparation and certification of rice flour-unpolished reference material.

Rice flour-unpolished reference material was prepared from unpolished rice collected from three locations in Japan. This reference material is certified for elemental composition and consists of three samples containing low-level (0.023 microgram/g), medium-level (0.32 microgram/g) and high-level (1.82 micrograms/g) of Cd. The unpolished rice was pulverized, oven-dried, homogenized and finally packaged into 1000 glass bottles. The prepared material satisfied the homogeneity criteria for a reference material. Collaborative analytical studies on the elemental composition of the rice flour-unpolished reference material were conducted using various analytical techniques which lead to the certification. Stable isotope dilution/ICP-MS was successfully applied to the accurate determination of Cu, Zn, Mo and Cd in the reference material. Certified values are provided for Ca, Cd, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Rb and Zn, based on results of determinations by at least three independent analytical techniques. Reference values are reported for Al, As, Br, Cl, Co, Cr, Hg, Se and Sr. The elemental compositions of the three rice flour-unpolished samples are very similar, except for Cd, and are considered typical of Japanese unpolished rice.

Preparation and certification of tea leaves reference material

SummaryTea leaves reference material was prepared and certified for elemental composition. Japanese green tea leaves were ground, sieved to pass a 80-mesh screen, blended and bottled. The prepared material satisfied the homogeneity criteria for a reference material. Trace element analysis of the material was carried out by flame and graphite furnace atomic absorption and inductively coupled plasma atomic emission spectrometry.Certification of the material was performed using the data obtained by various analytical techniques and certified values are provided for Al, Ca, Cd, Cu, K, Mg, Mn, Na, Ni, Pb and Zn. The elemental composition of the tea leaves reference material is considered typical of Japanese green tea leaves.

Preparation and certification of sargasso seaweed reference material

Abstract Sargasso seaweed reference material was prepared from whole bodies of Sargassum felvellum obtained from an unpolluted area in Japan. The sargasso samples were washed, freeze-dried, pulverized, sieved to pass a 80-mesh screen and finally homogenized. The prepared material satisfied the homogeneity criteria for a reference material. Collaborative studies on the elemental analysis of the sargasso reference material were performed using various analytical techniques. Certified values are provided for Ag, As, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Pb, Rb, Sr, V and Zn, based on results of determinations by at least three independent analytical techniques. Reference values are reported for Al, Br, Cl, Cr, Cs, Hg, I, P, S, Sb, Sc, Se, Ti and U. The sargasso certified reference material contains high levels of alkali metals, alkaline earth metals, I, Br, As and U, while the concentration of trace elements may be considered to be at the lower end of the range of reported values for marine brown algae. The sargasso sample will be of practical use in marine and environmental sciences as a certified reference material having an elemental composition close to background levels.

Role of Reference Materials for Validation of Analytical Data in Trace Element Analysis of Biological Materials

Analytical quality assurance is essential to obtain meaningful results in trace element analysis of biological materials. The incorporation of appropriate reference materials in the scheme of analysis is the most convenient, cost-effective mechanism by which to assess and maintain analytical data quality. The National Institute for Environmental Studies (NIES) has issued a variety of biological and environmental reference materials to serve the needs of scientists engaged in trace element analysis of these types of samples. In this paper the preparation and trace element analysis of NIES “human” reference materials - Freeze-dried Human Serum and Human Hair — and NIES food reference material - Rice Flour-Unpolished - are described.