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Geochemistry / Assay

Assay Overview

Assays are used to determine as accurately as possible the “true value” of a commodity or commodities in question.  Accuracy is typically in the 1-3% range as long as the analyte is greater than 100 times the detection limit of the method.  For some elements more difficult to analyze, this may stretch to 5%. Analyses can be purely instrumental (INAA or DNC) or can be produced by chemical treatment such as fusion or acid digestion with final analyses commonly by AA, XRF, ICP, ICP/MS, titration or gravimetric methods. Usually higher levels of dilution and use of internal standards minimize matrix effects and all dilutions are done either volumetrically or gravimetrically to ensure minimal error. The higher dilution, however, has an effect on lower detection limits by causing them to rise but extends the upper range to much higher levels. All analytical instruments have a linear dynamic range where the response of the analyte is purely linear. If the linear range is exceeded, the accuracy can suffer greatly. 

Not all elements respond equally well to all methods. It is important that the lab being used have as large a variety of analytical technologies available so analysis are “not forced” as a result of the lab having only minimal analytical technology. Having a wide variety of technologies allows the lab to verify “analytical technology bias”. It is possible to get some multi-element assays (e.g major oxides, base metal suites, REE- P2O5-Nb2O5- Y2O3-ZrO2-U3O8-ThO2, PGE, W-Mo-In and Au-Ag), but generally the suite is much reduced from those of geochemical packages. This type of analysis also includes a higher level of repeats and certified international reference materials so it becomes readily apparent as to what the precision and accuracy of the analyses are. Assays are also typically higher in cost than geochemical analyses.

Activation Laboratories Ltd. | 41 Bittern Street, Ancaster, Ontario, L9G 4V5, Canada | TF: +1.888.228.5227
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