<?xml version="1.0" encoding='utf-8'?>
<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN" "http://www.wapforum.org/DTD/wml_1.1.xml">
<wml>
<card id="card1" title="Certified reference materials - Page 13 - Wikipedia">
<p>
<a accesskey="1" href="page.php?w=Certified_reference_materials&amp;p=12">1.Previous</a><br />
<a accesskey="3" href="page.php?w=Certified_reference_materials&amp;p=14">3.Next</a>
</p>
<p>remaining impurities. This is often done by commercial producers. Natural matrix CRMs (often shortened to 'matrix CRMs') contain an <a href="page.php?w=analyte">analyte</a> or analytes in a natural sample (for, example, lead in fish tissue). These are typically produced by homogenization of a naturally occurring material followed by measurement of each analyte. Due to the difficulty in production and value assignment, these are usually produced by national or transnational metrology institutes like <a href="page.php?w=NIST">NIST</a> (USA), <a href="page.php?w=Bundesanstalt_f%C3%BCr_Materialforschung_und_-pr%C3%BCfung">BAM</a></p><p>
<a accesskey="1" href="page.php?w=Certified_reference_materials&amp;p=12">1.Previous</a><br />
<a accesskey="3" href="page.php?w=Certified_reference_materials&amp;p=14">3.Next</a>
</p>

<do type="prev" label="Search">
        <go href="search.wml"/>
</do>

</card>
</wml>
