Hello!
In my experiment concerning fluorescence polarization measurements of fluorescein, the following were the P-Values that I obtained:
[Conc (nmol/l), P-Value]: [0.1 nmol/l, 0.08], [2 nmol/l, 0.25], [5 nmol/l, 0.24], [10 nmol/l, 0.26]
I don't know what is the reason behind the low P-Value for the concentration of 0.1 nmol/l. I know that the P-Value should be a constant (independent of fluorescein concentration). Since these were repeated measurements, there wasn't any significant standard deviation either. Please advice regarding this.
EDIT: There were 5 sets of measurements, and rel. standard deviation was 1.9%
How are you defining P-Value?
How many repeated measurements?
Significant standard deviation?
Thanks for the reponse !
NOTE: I've added a little more info in the question regarding the number of repeated measurements and standard deviation.
@Seetharaman
Each concentration was measured 5 times?
Each concentration had a rel SD of 1.9%?
How are defining P-value? Why should it be the same for each concentration?
@Joseph
- Yes, each concentration was measured 5 times.
- Yes, the relative standard deviation for all concentration was ~1.9%
- P-Value is expressed as
P = (I_parallel - I_ perpendicular)/(I_parallel + I_ perpendicular)
Since every concentration shows a proportionate rise in the intensities, the intensity vs concentration plot is linear. Hence, if you substitute these values to the P-Value expression, it is a constant for all concentations.
An explanation could be a contaminant in the solvent or an instrument problem that is important at the lowest concentration. Have you tried making a new solution? Have you tried concentrations intermediate to 0.1 and 2?