Chemical Stability and Compatibility - Starting material for ICP sulfur (S) standards
Can you tell me what compound you use for the 1000 ug/mL sulfur ICP standard? The standard I have right now uses ammonium sulfate, and it appears to be coming out of solution when it prep it with my diluent, 190 proof ethanol, at or above about 15 ug/mL.
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We have two stock 1000 ug/mL sulfur ICP standards: CGS1 is made from sulfuric acid, and CGMSA1 is made from methanesulfonic acid (MSA). This, plus additional information about the starting materials, is provided in Section 2.0 of the respective Certificates of Analysis. The MSA formulation is useful when measuring Ba or Pb in addition to S, as it prevents the formation of insoluble Ba and Pb sulfates. |