Trace Impurity Measurements

I have some questions about trace impurities reported on the certificate of analysis for 1000ug/mL and 10000ug/mL Al solutions

  1. The impurity values are reported with 4 to 6 significant figures for most analytes – how do you get such accurate values?
  2. Are the less than (<) values IDL, MDL or RL – how to assign the same or different impurity values for 1000ug/mL and 10000ug/mL Al solutions, respectively, that are directly reported from analytical results (with/without correction), scientific judgment or computer generated?
  3. Calibration standards and their concentration used for impurity analysis?
  4. How long to complete impurity analysis and report of each product
  1. This is a result of our software system.  The DL is only accurate to one significant figure.
  2. They are generated by the analyst and are a function of the spectra – rarely do we get DLs that are as low as IDLs.
  3. Concentrations vary from 4 ppb to 1 ppm and the techniques used are calibration curve for OES and standard additions for MS.
  4. It takes about 1 day/ product because data are gathered by both OES and MS and then the data and spectra are interpreted by a trace analyst.  Some simple spectral systems are quicker and the more complex spectral chemical systems can take longer

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.