Fig. 3

Separation of Ba from isobaric interferents La and Ce during elution of 2 N HNO₃. The y-axis is the signal intensity (in counts per second by SF-ICP-MS) per mL of each column cut, recalculated to reflect the total element signal rather than just the measured isotope. The La and Ce signals are multiplied by the factors shown on the curves; if plotted at their actual intensities, the curves would be barely distinguishable above baseline. The La/Ba and Ce/Ba of the volcanic silicate sample (a) prior to loading was ~ 0.014 and ~ 0.033, respectively, while La and Ce were added to the produced water sample (b) prior to loading to generate high La/Ba and Ce/Ba ratios of ~ 0.67