Parameter Polynomial regression Linear regression
Concentration range(ng/spot) 500 -1200 500 -1200
x2 -coefficient -0.0001 -
x-coefficient 4.509 2.890
y-intercept 1,819 2,464
r2 0.999 0.993
Table1: Linear and polynomial regression equations obtained from the TLC densitometric method for diclofenac sodium.