Measurement and Results - High magnesium (Mg) ICP-OES results

The matrices and final concentrations of the diluted standards should be appropriate, and we see no potential issues with these preparations. With regard to the analytical details, we also monitor emission lines for Mg in the 279 nm range, and have found that the 279.553 nm line is less affected by interference than other Mg emission lines (particularly the 279.880 line). If you obtain the same results on multiple Mg lines, then the more likely issue is Mg contamination, though this issue typically is not a concern in the 10-50 ppm range. We have observed Mg contamination from HDPE labware, but it’s usually only an issue at less than 100-500 ppb. As you do not mention any concerns with blanks, etc., at this point we think a careful examination of the spectra, and confirmation using multiple Mg emission lines, is the best approach to determining if you’re observing a measurement issue, or a real Mg contamination.