It is the experimental standard deviation of at least three degradation test (replicates)

Yes, the percent error can be calculated through standard deviation by replicating the data at least 3 times (generally 5 times), it can be found out with the help of the origin software.

Soumya Ranjan Mishra thank you for your information. I have a photodegradation experiment by selecting SnO2-based nanoparticles. for SnO2 nanoparticles, I repeated the experiments more than 10 times. However, for doping with different metals and composite with Cu2O and rGO I only did one time because I optimized and obtained a promising result for pure SnO2. Therefore, is it possible to find the percent error without repeating the experiment for doped and composite?

Regards!