Most of you are aware that we have at Perkin Elmer Graphite Furnace Atomic Absorption (GFAA) system with Zeeman background correction. The reason we purchased the system is so that we would have an alternate technique available to us when we suspected that the results from ICPMS were questionable. This occurs when a sample matrix causes enhancement or suppression of the signal or when potential interferences exist in the sample for elements without interference free isotopes. So far our experience has shown that approximately 95% of the time when we encounter problems, GFAA confirms our ICPMS results. The two notable exceptions are Cr in an organic matrix and Ni in a Ca matrix. Therefore, ICPMS is by far our most reliable technique for metals analysis and the technique of choice. Typically, GFAA has a working range for most elements in the 1-100 ug/L range whereas ICPMS can be applied to 0.01-1000 ug/L (extended up to 100 mg/L in the analog detection mode). ICPMS also gives data for several isotopes at the same time, and matrix effects are easily monitored with internal standards in every sample. In the case of Cr in the presence of >100 ppm carbon and Ni in the presence of >100 ppm Ca, alternative isotopes exist for ICPMS but may have interferences and are not reliable. In these cases, GFAA has given us reliable data which is usually less than the values from ICPMS which are biased high from C and Ca interferences. Click here for photos of our GFAA and ICPMS.

ICPMS is by far our most reliable technique for metals analysis and the technique of choice. GFAA is the preferred alternative for Cr in an organic matrix and Ni in a calcium matrix.

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