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Multiple quality control steps are observed when preparing our high purity ICP standards and ICP-MS standards. We begin with the purification of the starting materials. This purification is time consuming, but the final, high purity product is our goal. Stoichiometry is controlled during this process, allowing for the streamlining of the standardization checks later on. The purified product is then checked for trace impurities by ICP-MS. Typically, each starting material has a purity between 99.998% to 99.9999%. Other ingredients include high purity acids and ASTM Type I water (18 megaohm). Our glassware is pre-cleaned and pipets, burets and flasks are class A certified and re-tested with documentation. Our semi-micro mettler balance is calibrated regularly with NIST weights. Each batch of stock standard is carefully tested and recorded with lot number, test results via classical wet chemistry, standards used, and standardized to a tolerance of +/-0.3% of specified value. A final check is done by Inductively Coupled Plasma DIRECTLY against the NIST standard reference material. These results are transferred to our certificate sent with each standard. Most standards have a guaranteed shelf life of 18 months from the order date, with the exception of a few elements which have a guaranteed shelf life of one year from the order date.
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