Date of Publication


Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Biochemistry

Subject Categories

Biochemistry, Biophysics, and Structural Biology


College of Science



Thesis Advisor

Laurenzo D.V. Alba

Defense Panel Member

Eric R. Punzalan
Lourdes P. Guidote


The salicylate method is an established method used to quantify ammonia in a sample. The method involves the addition of a salicylate catalyst solution, an alkaline citrate solution, and an alkaline hypochlorite solution. All of which are involved in the Berthelot reaction that produces an indophenol-like dye, which can be quantitatively measured using a spectrophotometer. Giner-Sanz et al. (2020) has determined that iron interferes with the salicylate method, inhibiting the accurate measurement of ammonia. Thus, this study determined the effect of other transition metals to the salicylate method employed. Through a series of experiments, the study was able to determine that manganese, in the form of Mn2+, dramatically decreased the visible peak at 650 nm. With an R2 = 0.989, the TAN with Mn2+ standard is a good representation of the effect of Mn2+ to the indophenol reaction in the salicylate method. In addition, calculating for the equation at which the changes in absorbance is determined by the concentration of Mn2+ the Beer law has been used and the molar absorptivity was calculated at 27.7 mM-1 cm-1. In conclusion, the effect of Mn2+ can be quantified using the Beer’s law equation, and as such could be employed to determine the specific absorbance of TAN, in the presence of Mn2+ at predetermined concentration. While the salicylate method is used to determine the concentration of ammonia, the effect of Mn2+ was found to decrease the indophenol as the concentration of the metal increased, just like the known effect of Fe3+.

Abstract Format







Salicylates; Ammonia; Indophenol

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Available for download on Saturday, August 24, 2024