It is also standard scientific practice to get several replicates of the data. If these are internally consistent you may be confident that you have measured something accurately and reproducibly. You also need to boil the material up in concentrated acid with hydrogen peroxide to get the minerals you intend to measure into a solution that can be sucked into a delicate scientific instrument. You can't just lay a billet of wood on the lab bench and expect the machines to deliver results. We used two instruments - a Flame Emission Spectrophotometer (FES) for Lithium, Li; Sodium Na and Potassium K and an Atomic Absorbance Spectrophotometer (AAS) for Iron Fe: Copper Cu and Zinc Zn.
I would have preferred to get replicates in triplicate but the microwave digester can only take 10 samples at once. We finished up comparing a number of different variables but with only two replications (less than ideal) of each condition: (two species) x (two samples each) x (two locations) x (two digestion methods) = 16 samples. We can conclude from this very preliminary study that Li and Na are essentially the same in all samples although Na is about 10x more common in plant tissue than Li. The same for copper, although one sample seemed to be anomalously high as if someone had buried a cache of pennies under that tree. Hmmmm, must get metal detector. Iron, Zinc and Potassium, contrariwise, seem to show a consistent pattern with high values alternating with low:
Not totally - the results are sufficiently intriguing that we can take this forward next year perhaps with a final year project student. And we need not measure Copper, Lithium or Sodium in future, there is no signal there.