Spectrophotometric determination of gallium(III) with phenylfluorone in the presence of hexadecylpyridinium bromide and pyridine

Phenylfluorone reacts with gallium in the presence of hexadecylpyridinium bromide and pyridine to form a water-soluble chelate with an absorption maximum at 570 nm and constant absorbance in the pH range 4.0-5.5. At this wavelength, Beer's law is obeyed up to 4.3 x 10(-6)M gallium. The sensitivity is very high and the molar absorptivity is 1.48 x 10(5) 1.mole(-1).cm(-1). The chelate has been utilized in the determination of gallium at the mug level. The ratio of gallium to phenylfluorone in the complex is 1:2.