Sulfur analysis in an ICP instrument
I have a question regarding sulfur analysis in an ICP instrument we have. We need to analyze H2S in a vapor phase, and we think we can capture the H2S as Na2S in a NaOH solution. Previously we ordered your sulfate standard.
My question: can we accurately measure sulfur concentration with a sulfide (S2-) analyte using a sulfate (SO42-) standard? Will the alkaline matrix of the analyte and the acidic matrix of the standards lead to an untenable error?
Using a sulfate standard for any sulfur compound is acceptable provided that the standards and samples are both pH>7. Many sulfur compounds have a large enough vapor pressure to give a higher nebulization efficiency and thereby a false high signal. Also beware that sulfide will slowly air oxidize to elemental sulfur in basic media which is not a problem so long as the elemental sulfur does not drop out of solution. Analyze the samples ASAP. Please feel free to call with any questions.
Serving you in chemistry,
Paul R. Gaines, Ph.D.
CEO of Inorganic Ventures & Fellow Chemist
DISCLAIMER: Advice offered by the chemists at Inorganic Ventures is intended for the individual posing the question. Feel free to contact us to verify whether these suggestions apply to your unique circumstances.