Viability of API testing kit for ammonium measurment

• In Event: Poster Presentation and Judging for: Biomedical; Cell & Molecular Biology; Chemistry & Biochemistry; Marine Science; Systematics & Evolutionary Biology.
  In Poster Session: Chemistry & Biochemistry Poster Session

Abstract

Monitoring ammonium levels is important in aquaculture. While plants are able to use ammonium for growth, very small quantities are toxic to a wide range of animals. Unfortunately, mainstream methods of testing ammonium are expensive and involve cumbersome equipment. The purpose of this experiment was to determine whether the inexpensive API ammonium testing kit, typically sold for hobbyists, is a viable option for testing ammonium concentration in water.
A test was devised to measure the accuracy of color absorbance (675 and 700nm) at varying parts per million of ammonia and at varying time intervals of 2, 5, 7.5, 10, and 60 minutes after reagents were mixed. From 0 ppm to 16 ppm, absorbance at 700 nm follows a strong linear relationship, with an R2-squared value of 0.9963. Above 16 ppm, the absorbance peak shifted from 700 nm to 675 nm. It was also found that the company instructions to allow 5 minutes to elapse before color measurement is an underestimate, and at least 7.5 minutes should pass before absorption is measured.
The research found that the API ammonium testing kit is a viable option for measuring ammonium levels in water. The linear relationship given by absorbance peaks allows for accurate measurement of ammonium levels, the reagents used are stable in solution and can be used in the microliter range, allowing the kit to be used for many more tests. Thus, use of the API ammonium testing kit could decrease the cost of measuring ammonium levels in water substantially.

Author

• Sonal V Jha, University of Texas Rio Grande Valley