Analysis of Phosphoric Acid Content in Popular Carbonated Drinks
Chemistry and Biochemistry
Letter to the Editor
A polemic in response to Lozano-Calero et al. (S. J. Chem. Educ. 1996, 73, 1173-1174) is presented. The study by Lozano-Calero et al. indicates that the color of cola beverages interferes in the colorimetric detn. of phosphoric acid, in that only clear colas can be analyzed. However, in a sep. study by Rodgers and Koether, they detd. that colored soft drinks absorb below 650 nm while the absorbance measurement for the anal. of phosphoric acid is made at 830 nm. Rodgers and Koether further detd. that the required 20-fold diln. is not to dil. the color but merely to place the sample within the calibration range of the anal.