I am analyzing a series of solutions that contain Ni, Fe, and/or Cu using an Agilent MP-AES.
The solutions were prepared from stripping plated metals from carbon fiber. I have determined the expected weight % metals gravimetrically from the fiber before and after stripping. The analysis solutions are matrix matched to the respective standards.
I obtain expected results when analyzing solutions containing Ni and Iron (i.e. the results from the AES correlate well with the % metals recovery and the measured Ni and Fe concentration are within the expected range of the plating solutions).
The results are significantly lower than expected when analyzing solutions containing Ni, Fe, and Cu. The measured concentration of all elements from the AES are significantly lower than the gravimetric % metals recovery.
I would be interested in ideas on how to reconcile the differences between the gravimetric analysis and the AES results.