Preparation and characteristics of standard reference samples of fibrous minerals for biological experiments

Standard reference samples of fibrous minerals to be used for in vitro and in vivo (injection) biological experiments were prepared. Ten samples were selected from among the fibrous minerals currently used in industry: man-made mineral fibers (MMMF); glass wool (GW1), rock wool (RW1), micro glass fiber (MG1), refractory ceramic fibers (RF1, RF2), and mullite fibers (RF3), whiskers; potassium titanate (PT1), silicon carbide (SC1) and rutile (TlO2)(TO1), and a natural fibrous mineral; wollastonite (WO1). The MMMF samples were prepared by using the size-selective press method. The whisker samples and WO1 were all commercial products. The prepared samples were examined by X-ray diffraction and X-ray fluorescence analyses, and no impurities were identified in any of the samples at a level of 1%, although WO1 was found to have about 5% calcite and a trace amount of quartz (< 1%). The fiber sizes were measured by TEM. The geometric-mean length (micron), width (micron) and SD (in parenthesis) are: GW1 20.0 (2.58), 0.88 (3.10); RW1 16.5 (2.51), 1.80 (2.32); MG1 3.0 (2.22), 0.24 (2.35); RF1 12.0 (2.36), 0.77 (2.53); RF2 11.0 (1.96), 1.10 (2.00); RF3 11.0 (1.75), 2.40 (1.37); PT1 6.0 (2.04), 0.35 (1.51); SC1 6.40 (2.45), 0.30 (1.58); TO1 2.1 (2.00), 0.14 (1.53); WO1 10.5 (2.03), 1.00 (1.72). We concluded that these prepared fiber samples can be safely used for biological experiments. Sample sets containing about one gram of each sample known as JFM standard reference samples are provided by the Japan Fibrous Material Research Association (JFMRA).