Nitrato NO3

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  • NOOrion 9307, Orion 9707 ionplus

    Orion NitrateElectrode



    Analyze Detect Measure Control

  • AQUAfast, Cahn, EZ Flash, Ionalyzer, ionplus, KNIpHE, No Cal, ORION, perpHect, PerpHecT, PerpHecTion, pHISA, pHix, pHuture, Pure Water, Sage, Sensing the Future, SensorLink, ROSS Ultra, Sure-Flow, TEA Analyzer, Titrator PLUS, TURBO2 and Wine Master are registered trademarks of Thermo Electron Corporation.

    1-888-pHAX-ION, A+, All in One, Aplus, AQUAsnap, AssuredAccuracy, AUTO-BAR, AUTO-CAL, AUTO DISPENSER, Auto-ID, AUTO-LOG, AUTO-READ, AUTO-STIR, Auto-Test, BOD AutoEZ, Cable-Free, CERTI-CAL, CISA, DataCOLLECT, DataPLUS, digital LogR, DirectCal, DuraProbe, Environmental Product Authority, Extra Easy/Extra Value, FAST QC, Flash Titration, Flash Titrator, GAP, GLPcal, GLPcheck, GLPdoc, ISEasy, KAP, LabConnect, LogR, Low Maintenance Triode, Minimum Stir Requirement, MSR, NISS, One-Touch, One-Touch Calibration, One-Touch Measurement, Optimum Results, Pentrode, pHuture MMS, pHuture Pentrode, pHuture Quatrode, pHuture Triode, Quatrode, QuiKcheK, rf link, ROSS, ROSS Resolution, SAOB, Smart CheK, Stacked, Stat Face, The Enhanced Lab, ThermaSense, Triode, TRIUMpH, Unbreakable pH, Universal Access are trademarks of Thermo.

    Guaranteed Success and The Technical Edge are service marks of Thermo.

    PerpHecT meters are protected by U.S. patent 6,168,707.

    PerpHecT ROSS are protected by U.S. patent 6,168,707.

    ORION Series A meters and 900A printer are protected by U.S. patents 5,108,578, 5,198,093 and German patents D334,208 and D346,753.

    Sure-Flow electrodes are protected by European Patent 278,979 and Canadian Patent 1,286,720.

    ionplus electrodes and Optimum Results solutions are protected by US Patent 5,830,338.

    ROSS Ultra electrodes have patents pending.

    ORION ORP Standard is protected by US Patent 6,350,367.

    ORION Series A conductivity meters are protected by US Patent 5,872,454.

    Copyright 2003, Thermo Electron Corporation. All rights reserved. Question everything, and Analyze.Detect.Measure.Control are trademarks of Thermo Electron Corporation.

    The specifications, descriptions, drawings, ordering information and part numbers within this document are subject to change without notice.

    This publication supersedes all previous publications on this subject.

  • GENERAL INFORMATION 1Introduction 1Required Equipment 2Required Solutions 3

    BEFORE USING THE ELECTRODE 5Electrode Assembly and Preparation 5

    Orion 9307 Nitrate Half Cell Electrode 5Orion 90-02 Double Junction Reference Electrode 5Orion 9707 ionplus Nitrate Combination Electrode 6

    Checking Electrode Operation (Slope) 10

    Recommendations for Optimum Results 13Units of Measurement 13Sample Requirements 13Important ISE Measurement Techniques 14

    Roadway to ionplus Success! 16Guide to measuring techniques 16

    MEASUREMENT PROCEDURES 18Direct Measurement 18Small Volume Direct Measurement 24Low-Level Measurements By Direct Measurement 29Known Addition 34


    TROUBLESHOOTING 46Troubleshooting Checklist 46Troubleshooting Guide 50Assistance 53

    ELECTRODE CHARACTERISTICS 54Electrode Response 54Limits of Detection 54Reproducibility 54Temperature Effects 54Interferences 56Electrode Life 57Theory of Operation 59





    The Orion 9307 and Orion 9707 ionplus Nitrate Electrodes measurenitrate in aqueous solutions simply, accurately, and economically.

    The Orion 9707 ionplus Nitrate Electrode offers additional benefitsfrom its Sure-Flow combination reference design. With thiselectrode, a separate reference electrode is unnecessary, making itconvenient to use with small sample volumes. The free-flowing Sure-Flow junction assures stable, drift-free potentials. Whenmeasuring dirty samples that would clog conventional electrodejunctions, the Sure-Flow junction can be cleaned by pressing theelectrode cap.

    General analytical procedures, required solutions, electrodecharacteristics, and electrode theory are discussed in this manual.Operator instructions for Orion meters are outlined in the individualmeters instruction manual.

    Consult Orions Technical Service Chemists for assistance and troubleshooting advice. Please refer to Troubleshooting forinformation on contacting Orion.

  • 2Required Equipment

    MeterISE meters, such as Orion EA 940, 920A, 720A, 710A, or 290A,offering direct concentration readout for specific ions are the easiestto use. If unavailable, use a pH/mV meter with readability to 0.1 mV,such as Orion 420A, 520A, or 525A.

    Reference Electrode Orion No.

    For use with Orion 9307:Orion 90-02 Double Junction Reference Electrode 900200

    For use with Orion 9707:No separate reference electrode required NA

    ionplus Stirring Accessory or Stir Bars, and Magnetic Stirrer Stir bar or ionplus stirring accessory, Orion 900060 which slidesover the electrode body, to mix solution. Micro stir bars arerecommended for small volume measurements.

    Graph Paper 4 cycle semi-logarithmic paper for preparing calibration curves (for use with digital pH/mV laboratory meters).

  • 3Required Solutions

    Distilled or Deionized WaterTo prepare all solutions and standards.

    Reference Electrode Filling SolutionRequired for a complete measuring system.

    Filling Solution Orion No.

    For Orion 9707 & Outer chamber of Orion 90-02:Optimum Results F Filling Solution 900046

    NOTE: Do not use the outer filling solution shipped with the reference electrode.

    For Orion 90-02:Inner Chamber Filling Solution 900002

    Nitrate Stock Calibration StandardsTo prepare daily calibration solutions.

    Standards Orion No.

    0.1 M Nitrate Concentration Standard 920706

    1000 ppm as N Standard 920707

    100 ppm as N Standard 930707

    Ionic Strength Adjustor (ISA) Orion 930711To adjust ionic strength of samples and standards.

    Nitrate Interference Suppressor Solution Orion 930710For removal of a variety of interfering anions, including chloride ion,present in samples such as drinking water, wastewaters, and soils.See Interferences.

    Preservative Solution Customer PreparedPrepare a 1 M boric acid preservative solution by dissolving 6.2 greagent-grade boric acid in 100 mL boiling water. Let cool. Add 1 mLpreservative solution to 100 mL of all standards and samples to prevent biological degradation of the solutions.

  • 4


    Electrode Assembly and Preparation

    Orion 9307 Nitrate Half Cell Electrode:

    Remove the sensing module from the vial. Make sure the rubberelectrode washer on the sensing module is in place. See Figure 1.Screw the sensing module into the electrode body until finger tight. Toensure electrical continuity, shake down the electrode like a clinicalthermometer. Rinse the nitrate electrode with distilled water, then soakin Nitrate Standard, 100 ppm (or 10 -2 M) for 1 to 2 hours prior toinitial use. Do not immerse the electrode past the rubber electrodewasher. See Figure 1.

    Orion 90-02 Double Junction Reference Electrode:

    Required for use with Orion 9307 Nitrate Half Cell Electrode. Noassembly is required. Fill the reference electrode according toinstructions in the reference electrode instruction manual, using Orion900002 Filling Solution in the inner chamber. Use Optimum Results F,Orion 900046, instead of the Outer Chamber Filling Solution providedwith the electrode. Do not use the outer chamber filling solutionshipped with the 90-02 reference electrode because it will interferewith your nitrate measurements.

    Figure 1Orion 9307 Electrode Assembly

    electrode body


    sensing module

    sensing membrane

  • 6outer body sleeve



    inner stem

    reference pellet

    fill hole

    sensing module

    sensing membrane

    Orion 9707 ionplus Nitrate Combination Electrode:

    This electrode consists of two parts, the sensing module and theelectrode handle. See Figure 2. The assembly is different than otherOrion electrodes.

    Be careful not to touch the sensing membrane or reference pellet during assembly!


    Figure 2Orion 9707 ionplus Nitrate Combination Electrode

  • 76

    Grasp the outer body sleeve, do nottouch the sensing membrane. Withyour other hand, pull on the cableand gently screw the cap onto theinner stem. Stop when an oppositeforce is felt. Do not over tighten orcontinue to turn the cap! The capwill not completely stop! If the innerbody turns at all, the cap is too tight.Remove the cap and reassemble.


    Take the outer body sleeve, with thefill hole end towards the cap, andgently push the inner stem throughthe outer body.


    Slide the outer body sleeve, spring,and cap down the elctrode cable untilthe outer body sleeve is beyond theinner stem.


    With one hand, grasp the middle ofthe inner stem without touching thereference pellet. With your otherhand, screw the sensing moduleonto the stem until it stops and themodule is flush against the stem.Then tighten an additional one-quarter turn and stop. Do notcontinue to tighten. The moduleshould be firmly attached to the stem.


    Remove the sensing module fromthe vial. Make sure both o-rings are in place. Take the handle fromthe box.


    Holding the electrode cable, slide theouter body, spring and cap over theinner stem.

  • 87

    Hold the electrode with one hand.Press on the top of the cap with yourthumb to make sure the electrodehas a smooth flushing motion andreseats back onto the module.


    Fill the outer body withOp