Derivative and graphical procedures for correction of irrelevant UV spectrophotometric absorption in changeable matrixes.

The application of direct zero-order UV spectrophotometric and graphical or derivative background correction methods to selected pharmaceutical preparations shows their relative advantages in different situations. The assay of the active components in a changeable matrix is a problem with formulations having a limited shelflife. Although the standard three-point correction procedures can provide accurate data, there are practical problems if the irrelevant absorption band is such that only the derivative approach gives enough resolving power for reliable qualitative and quantitative determinations.