Publication Abstract

Project ME4117 – Development and Improvement of Analytical Methods for Marine Monitoring. 4.3 – Assessment of a commercially available nitrate/nitrite biosensor – Phase 1: laboratory testing

Project ME4117 – Development and Improvement of Analytical Methods for Marine Monitoring. 4.3 – Assessment of a commercially available nitrate/nitrite biosensor – Phase 1: laboratory testing

S. Kröger

Two different types of biosensor from Unisense were tested, a NOx- sensor responding to both nitrate and nitrite and a sensor with exclusive nitrite (NO2-) sensitivity. Due to differences in the bacteria employed in the construction of these sensors, the NOx- sensor did not perform very satisfactory (short life time, frequent operational problems), while the nitrite sensor gave very good results. Consequently most tests were carried out using the nitrite sensor and it was concluded that this sensor shows real promise for field use. From communications with the manufacturer an improvement in the NOx- sensor performance due to replacement of the bacteria strain with a new superior isolate is expected. Assuming these improvements can be confirmed in future tests, the use of both types of sensors in parallel appears desirable, thus obtaining nitrite readings directly and nitrate measurements from the differential in the signal between both sensors. A note of caution still has to be made: use of these sensors requires significant appreciation of the nature of the measurements made, the susceptibility of the sensors to environmental influences (temperature, solution composition) and life history factors (bacteria starved, shocked or nutrient saturated, permeability of the membrane). Providing sufficient allowances for these factors are made and calibration/performance checks included with measurements at regular intervals, we consider their performance promising enough to undergo phase II, the field testing, of the devices.

S. Kröger

Cefas Technical Report