with fairly low concentrations, and measuring samples at the absorption maxima of the species spectra.The importance of reference cell samples makes double-beam spectrophotometers commonplace, and even are necessary for certain applications, even though detector drift is an increasingly lesser source of error with improved instrumentation and other technological advances. Another improvement for spectral analysis of samples is the use of photodiode array detectors, allowing the amount of time to measure the entire spectrum of a sample to be taken in orders of magnitudes faster, without sacrificing much resolution or accuracy inwavelength selection.There are a variety of other factors that must be considered with regard to the application at hand. Significant spectral resolution is lost in aqueous samples, as opposed to the same parameters of instrumentation using gas-phase samples. However, the ubiquity and ease-of-use with liquid samples make it a much more common, and more affordable, option. Furthermore, this widespread use of UV-Vis spectrophotometry has led to a plethora of data published available in addition to available compendia of a myriad of compound classes. Such a degree of prevalence and universality is certainly one of UV-Vis spectrophotometry’s greatest assets.Along with this straightforward manner of measurement using UV-Vis spectrophotometry, most modern instrumentation programs allow for derivative analysis of sample spectra. Utilizing this technique allows users to expand the limits of instrumentation beyond the basic constraints of Beer’s Law, which can only be applied under rather idealistic parameters, while many real-life samples rarely fit all such conditions. First derivative spectra provides a simple means locating local absorbance and transmittance extrema, located at wavelength where the derivative absorbance value equal zero. Likewise, one of the things offered by second derivative spectra is a means to create Beer’s Law obedient functions that are more resistant to inaccuracies caused by errors present across all samples, such as interferents that create absorption shoulders. Further derivative spectroscopy have similar robustness features that serve to enhance the range of UV-Vis applications.