A major concern about the samples was that they were not acidified following collection. Over time, the strontium in the samples could have possibly been taken up by the polyethylene walls of the collection bottles. Because of the consistency of concentrations of strontium in the samples, this concern should not be of paramount importance in later studies. The unspiked IC samples from Hubbard Brook are more reliable for isotopic composition analysis than the samples from the ID set. While concentrations of strontium cannot be determined without the spike, the isotopic ratios that IC analysis yields are still valuable.
Regression analysis yields an adjusted curve that illustrates the relationship effectively.