Updated Rhodamine Dilution
I fixed the graph for the serial dilution of Rhodamine that I did last week and removed all absorbency values that were greater than 1.08 AU. The graph looks much more linear now with an R^2 value of .9517
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What is the absorbance wavelength you are measuring?
The wavelength is measured at 530nm. I checked online and it said that the maximum absobtion of rhodamine is about 530nm.
This looks OK, but I’m still surprised that the data points are not tighter to the line (lower variance). This is close to an ideal system, so I would suggest trying to perfect your technique to get this rock-solid before advancing to more complicated experiments. If you try to measure the same sample multiple times, does the value jump up/down around the line? If so, maybe an averaging is needed?
If you think this is good enough for your purposes, that’s fine too, but you want to make sure that this measurement error is not a significant contributor to the overall experimental error. You should also consider the range of absorbance values that you will typically be using, and confirm accuracy in that regime.
I ran two measurements for each sample and then averaged the two measurements. I’ll run the experiment again on Monday and see if I can get a better fit.
How close were the two measurements for each sample? If each set of two is tight, then the variability is not in the measurement, but the prep. Once you isolate the source of variability, you will probably be able to get nice looking data with a few tweaks of procedure. Even if the variability is outside of your control, it’s still important to understand it for experimental design.