Methods for Obtaining Correction Factors for Fluorescence Spectra as Determined with Aminco-Bowman Spectrophotofluorometer

Beam-splitter and cell-window errors in fluorescence spectrometry

Fluorescence excitation spectra should be corrected for distortions caused by spectral variations in the transmittance/reflectance ratio of the beam splitter and by variations in the transmittance of cell windows. The polarization of the excitation beam may cause a large uncertainty in the beam-splitter correction, but this source of error can be eliminated by using angles of incidence of 15 degrees , or less, at the beam splitter. The small distortions due to the transmittances of the sample-cell and quantum-counter entrance windows can be made to cancel one another it the angle of incidence at the quantum counter is also 15 degrees or smaller.

Standardization of fluorescence spectra and the calibration of spectrofluorimeters

A technique is proposed that can be used to calibrate the amplitude of fluorescence spectra so that spectra reported by different laboratories can be compared quantitatively. The technique is based upon the scattering of light by a solution of polystyrene. In order to compare quantitatively data obtained from different spectrofluorimeters, these terms are defined: the spectrofluorimetric sensitivity, the noise-equivalent concentration, and the fluorophotometric reproducibility. The author shows how these quantities can be measured with the polystyrene standard.

Fluorescence quantum yield measurements: vitamin B6 compounds

Quantum yields for pyridoxal, pyridoxamine, and pyridoxamine-5-phosphate at 25 degrees C in neutral aqueous solution were 0.048, 0.11, and 0.14, respectively. The fluorescence efficiencies were highly temperaturedependent, and the compounds were extremely sensitive to light. There were marked discrepancies between the values obtained in this study for quantum yield and fluorescence polarization of pyridoxamine-5-phosphate and the values recently reported by others.

Apparent Concentration Quenching of Morphine Fluorescence

Fundamental fluorescence equations were examined. Deviations from the theoretical were observed by varying the light path length to determine effects on "apparent" fluorescence. It was found that the decrease in emission of morphine solutions with the increase in concentration was caused by absorption effects that prevented excitation of the whole system.