S. No Drug Wavelength (nm) Linearity range (mMole) Regression equation Correlation coefficient
1 Lef 243.6 0.01-.055 Y=0.429x - 4E-05 0.998
Diclo 258.4 0.09-0.18 Y=0.294x - 0.001 0.984
2 Lef 246.1 0.01-0.055 Y= 0.449x + 8E-05 0.995
Flur 258.2 0.06-0.15 Y=0.440x - 0.002 0.984
3 Lef 248.1 0.01-0.055 Y=0.488x - 0.000 0.983
Ibu 231.4 0.01-0.08 Y=1.036x + 0.025 0.995
4 Lef 253.2 0.01-0.055 Y= 0.244x + 7E-06 0.997
Mef 231.4 0.02-0.065 Y=1.561x - 0.023 0.999
Lef=leflunomide, Flur=flurbiprofen, Ibu=ibuprofen, Mef=mefanamic acid, Diclo=diclofenac sodium
Table 6: Regression analysis of leflunomide and NSAIDs at pH 9 by first order derivative spectrophotometry.