An accurate and stable nitrate-selective electrode for the in situ determination of nitrate in agricultural drainage waters.
A field evaluation of a novel nitrate-ion selective electrode (ISE) was undertaken by continuous immersion over a period of 5 months in agricultural drainage weirs. The nitrate sensor N,N,N-triallyl leucine betaine was covalently attached to polystyrene-block-polybutadiene-block-polystyrene (SBS) using a free radical initiated co-polymerisation, to produce a rubbery membrane which was incorporated into a commercially available electrode body. A measurement unit was constructed comprising the nitrate-ISEs, a reference electrode and a temperature probe connected through a pre-amplifier to a data-logger and battery supply. A temperature correction algorithm was developed to accomodate the temperature changes encountered in the drainage weirs. The nitrate results obtained with the ISEs at hourly intervals compared very favourably (R2 = 0.99) with those obtained with laboratory automated chemical determinations made on contemporaneous samples of drainage in a concentration range 0.47-16 ppm nitrate-N. The ISEs did not require re-calibration and no deterioration in performance or fouling of the membrane surface was observed over four months of deployment.
Le Goff
Thierry
T
Department of Environmental Sciences, University of Plymouth, Drake Circus, UK.
Braven
Jim
J
Ebdon
Les
L
Chilcottt
Neil P
NP
Scholefield
David
D
Wood
John W
JW
D004566:Electrodes; D009566:Nitrates / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D009566:Nitrates; D014874:Water Pollutants, Chemical