Horiba Spectrofluorometer

Analysts interested in determining what compounds are present in a sample or quantifying known compounds like dissolved organic matter or dyes based on fluorescence should consider using a spectrofluorometer. Spectrofluorometers measure the fluorescence of molecules after being exposed to and absorb light. When molecules absorb light, the electrons become excited from their ground state into an excited state (excitation). Shortly after becoming excited, the electrons move back to the ground state giving off energy in the form of fluorescence (emission). The spectrofluorometer in the laboratory is used for both broad spectrum scans and selective scans. A broad spectrum scan is generally used for qualitative data to gain a better understanding of what compounds are in a sample, however concentrations can be calculated using Matlab software. A broad spectrum scan shows the spectrum of a sample over a range of wavelengths, e.g. 200-600nm. Each peak in the spectrum represents a different compound or group of compounds fluorescing at similar wavelengths. A selective scan is used for quantitative analyses. In a selective scan, the user chooses a specific wavelength(s) at the peak of a curve where the highest absorbance value of an analyte occurs. If only one analyte is known to fluoresce at a specific wavelength, the concentration of the sample can be determined by analyzing a set of standards and plotting them against each standard’s fluorescence creating a linear fit. The sample’s concentration is then determined by plugging its fluorescence into the linear fit formula.