Quantitative Photoacoustic Spectroscopy: Determination of Fluorescein and Bromocresol Green Adsorbed on Modified Silica Gel Samples

Abstract

A series of standards was prepared by mixing the fluorescein or bromocresol green adsorbed on silica gel modified with N,N-diethylaminopro-pyltriethoxysilane with varying amounts of unmodified silica. Photoacoustic magnitude and phase values were obtained at their respective absorption maxima, 470 and 600 nm. Calibration graphs were prepared by combining the magnitude and phase into the response function. Two-component samples were prepared by mixing the different ratios of the standard samples. The concentration of the dyes in the two-component samples was determined by referring to the respective calibration graphs and solving a pair of simultaneous equations. The relative error in the determination ranged from −5.6% to 5.1% for fluorescein and −16.8% to 38% for bromocresol green when compared to their concentration determined by spectrophotometry.

Molecular Photoacoustic Contrast Agents: Design Principles & Applications

“…In some cases, however, it is merely used as a fluorescent probe to compliment alternative PAI studies . In the 1980s, PAS was used to determine the concentration of 20 adsorbed onto silica gel and demonstrate the advantage of this nondestructive method for quantitative analysis . McDonald et al .…”

Functional group analysis

“…Fluorescein and bromcresol green absorbed on modified silica gel were determined by use of photoacoustic spectroscopy. The relative errors ranged from -5.6% to 5.1% for fluorescein and from -16.8% to 38% for bromcresol green (273).…”