On-Line Analyzer for Nitrate, Nitrite, Ammonia, pH and Dissolved Oxygen

Period of Performance: 01/01/1997 - 12/31/1997


Phase 1 SBIR

Recipient Firm

Northwest Instrument Systems,
3100 George Washington Way
Richland, WA 99352
Principal Investigator


This project will develop an on-line analyzer instrument for rapid automated sequential analysis of water samples for nitrate nitrogen, nitrite nitrogen, ammonia, pH, and dissolved oxygen. These common chemical constituents and characteristics are essential to the management of aquacultural production facilities. These parameters must be measured frequently and accurately to maintain the health of fish crops. Existing test methods are typically labor- intensive or prohibitively expensive. The proposed device will allow aquacultural operators to produce reliable, calibrated analyses with an unattended instrument that requires little routine maintenance. The analyzer will utilize proven colorimetry analytical methods for nitrogen compounds and dissolved oxygen and solid state ion-selection field effect transistor for pH measurement. The system will incorporate automated initial and continuing calibration using modular reagent cartridges. The instrument will generate very small volumes of waste solutions (e.g., one to five ml per sample). The analyzer will be capable of collecting and analyzing water samples on a user-selected schedule and will have data logging capability. Phase 1 of this proposal will proof-test the miniaturized components of the instrument and demonstrate the feasibility of collection of water samples from an aquatic water source and the analysis of multiple analytes using this device, using conventional analytical method validation procedures to establish accuracy, precision, representativeness, and comparability. A prototype portable instrument has been demonstrated for field analysis of a single analyte. Phase 2 of this work will produce a fully-functional instrument that can be integrated into a control or alarm system for installation in a production facility.