Derived UV–Vis Absorbance Spectra for Facile Analysis of Optically Dense Samples

The UV–vis absorption bands of optically dense samples are broad, overlapped, saturated, nonlinear, and have minor peaks suppressed; often, the minor peaks are representative of the analytically noteworthy lowest-energy electronic transitions (S0 to S1). Conventional UV–vis methods limit the accurate analysis of optically dense samples. This study introduces the use of derived UV–vis absorbance spectra (AD = A × 10–A) as a tool for the facile analysis of highly absorbing optically dense samples in their original form, without any pretreatment or alteration. The derived UV–vis absorbance spectrum (AD) is obtained by multiplying the function 10–A with the absorbance data (A) of the sample. The AD spectral profile rises in the interval 0.001 < A < 0.434 due to the increasing function A, then decreases in the interval 0.434 < A < ∞ due to the function 10–A. A maximum is obtained at 0.16 in the AD spectrum, representing an absorbance of 0.434. The AD spectra amplify obscured spectral features, behave well in the linear regime of the Lambert–Beer law, suppress noise- and saturation-dominated regions of the original absorbance spectra, and eliminate the need for dilution (which may introduce errors) or for specialized cuvettes with reduced path lengths. Especially, the AD peak at 0.16, corresponding to a 0.434 absorbance value, serves as a robust and quantifiable spectral descriptor.