Open-Source Photometric System for Enzymatic Nitrate Quantification

PLoS One. 2015 Aug 5;10(8):e0134989. doi: 10.1371/journal.pone.0134989. eCollection 2015.


Nitrate, the most oxidized form of nitrogen, is regulated to protect people and animals from harmful levels as there is a large over abundance due to anthropogenic factors. Widespread field testing for nitrate could begin to address the nitrate pollution problem, however, the Cadmium Reduction Method, the leading certified method to detect and quantify nitrate, demands the use of a toxic heavy metal. An alternative, the recently proposed Environmental Protection Agency Nitrate Reductase Nitrate-Nitrogen Analysis Method, eliminates this problem but requires an expensive proprietary spectrophotometer. The development of an inexpensive portable, handheld photometer will greatly expedite field nitrate analysis to combat pollution. To accomplish this goal, a methodology for the design, development, and technical validation of an improved open-source water testing platform capable of performing Nitrate Reductase Nitrate-Nitrogen Analysis Method. This approach is evaluated for its potential to i) eliminate the need for toxic chemicals in water testing for nitrate and nitrite, ii) reduce the cost of equipment to perform this method for measurement for water quality, and iii) make the method easier to carryout in the field. The device is able to perform as well as commercial proprietary systems for less than 15% of the cost for materials. This allows for greater access to the technology and the new, safer nitrate testing technique.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calibration / standards
  • Environmental Monitoring / instrumentation
  • Environmental Monitoring / methods*
  • Environmental Monitoring / standards
  • Nitrate Reductase / metabolism*
  • Nitrates / analysis*
  • Nitrates / metabolism
  • Photometry / instrumentation
  • Photometry / methods*
  • Photometry / standards
  • Reference Standards
  • Reproducibility of Results
  • Water Pollutants, Chemical / analysis
  • Water Pollutants, Chemical / metabolism


  • Nitrates
  • Water Pollutants, Chemical
  • Nitrate Reductase

Grants and funding

This research was supported by the National Science Foundation (NSF STTR Phase I Grant #IIP-1417061). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.