In an attempt to build univariate c

In an attempt to build univariate calibration models for aminophylline solutions, the region in the vicinity of the 564 cm−1 theophylline line was used. Although the regression curves obtained were characterised by higher R2 values than for diclofenac sodium solutions: 0.949 based on band area and 0.939 based on band intensity, the RSEP errors of 8.9% for both models were unacceptably high (Table 2).