TROLL 9500 Operator's Manual - Geotech Environmental Equipment

Section 17: NitratePotential InterferencesThe following table shows concentrations of possible interfering ionsthat cause 10% error at various levels of NO 3 – .Ion 100 ppm NO 3–10 ppm NO 3–1 ppm NO 3–ClO–40.01 0.001 0.0001I – 0.5 0.05 0.005ClO–35 0.5 0.05CN – 10 1 0.1Br – 70 7 0.7NO–270 7 0.7HS – 100 10 1HCO–31000 100 10CO2–32000 200 20Cl – 3000 300 30H 2PO–45000 500 50HPO 42–5000 500 50PO3–45000 500 50AcO – 20,000 2000 200F – 60,000 6000 600SO2–4100,000 10,000 1000Sensor Care and HandlingSensor RemovalPosition the yoke of the sensor removal tool at the pointwhere the sensor meets the sensor block and pry thesensor upward.Avoid touching the membrane at the tip of thesensor. Contaminants on the membrane canchange its properties and affect measurements.sensorremovaltoolIf film buildup is visible on the membrane, rinse under a gentle streamof clean water, or swish gently in a mild detergent solution, rinse wellwith clean water, and shake to dry.To avoid depletion of the reference solution, do not allow the sensor tosoak in pure water for more than a few minutes at a time.The electrode is not customer-refillable.StorageStore the sensor immersed in 14 or 140 ppm N solution, dependingon usage requirements, rather than dry or in DI water.ReferencesEaton, A.D., L.S. Clesceri, E.W. Rice, and A.E. Greenberg, eds.,Standard Methods for the Examination of Water and Wastewater,21st edition, Washington, D.C.: American Public Health Association,American Water Works Association, and Water EnvironmentFederation, 2005. Section 4500-NO 3–D. Nitrate Electrode Method.EPA, Methods for Chemical Analysis of Water and Wastes,EPA/600/4-79-020, revised March 1983. Method 350.3, Nitrogen,Ammonia, Potentiometric, Ion Selective Electrode. Approved at 40CFR Part 136.Rundle, Chris C., A Beginners Guide to Ion-Selective ElectrodeMeasurements. Nico2000 Ltd., London, UK. On the web at www.nico2000.netMaintenance/Inspection/CleaningAs long as extreme pH and high organic solvent content is avoided,the sensor should last for several months at room temperature.Eventually some of the components will leach out, and this will affectthe response (detection limit and scope), but this can be compensatedthrough calibration.TROLL 9500 Operator’s Manual 1200095110 rev. 007 01/09