In order to obtain maximum sensitivity, it is optimal to detect
each compound at its maximum absorbance wavelength. The
UV–vis spectra of the compounds are shown in Fig. 1. It can be
anticipated that a small peak would be obtained for BA if the detection
wavelength was fixed at 275 nm. On the other hand, small
peaks for BA and CA would be obtained if the detection wavelength
was set at 235 nm. The maximum peak for BA could be obtained if
the detector was set at 225 nm where peak intensities for BA, SA
and CA were the same. Therefore, 225 nm was selected as a suitable
detection wavelength. In order to verify this prediction, a standard
mixture of BA, SA and CA was injected into the HPLC column
at maximum absorption wavelengths of 235 and 225 nm separately.
As shown in Fig. 2(a), it is evident that the peaks of BA
and CA were too small when the detector was set at 235 nm.
However, in Fig. 2(b), all peaks were of satisfactory intensity when
the detector was set at 225 nm.