HI 4113 NITRATE COMBINATION SENSOR HANDLE HI 4000-50 Instruction Manual HI 4013 HI 4113 Half-cell Combination Nitrate Ion Selective Electrode 1
HI 4013 Nitrate Half-cell HI 4113 Nitrate Combination Electrode I. Introduction: The Hanna HI 4013 and HI 4113 are ion selective electrodes designed for the measurement of nitrate ions in aqueous solutions. They utilize a replaceable sensing module that contains an organic polymer membrane that is sensitive to nitrate ions. The HI 4013 is a half-cell electrode that requires a separate reference. The HI 4113 is a combination ion selective electrode. IIII.
III. Theory of Operation Operation:: The HI 4013 and HI 4113 nitrate electrodes are potentiometric devices used for the rapid determination of free nitrate ions in water, emulsified foods and plant samples. The electrode functions as a sensor or ionic conductor. The HI 4013 requires a separate reference electrode to complete its electrolytic circuit. The HI 4113 is a combination electrode with a Ag/AgCl reference electrode with gel stabilized Cl electrolyte in it’s inner chamber.
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V. Equipment required: • The HI 4013 requires the Hanna HI 5315 Double junction reference electrode with HI 7078 as external electrolyte. • Hanna HI 4222 pH/ISE/mV meter or other suitable ion or pH/mV meter (Note: log/linear graph paper is useful if an ISE (ion) meter is not available). • Hanna HI 180 magnetic stirrer or equivalent with magnetic stirring bars (Note: Isolate beakers from stirrer motor heat by placing insulating material such as foam or cork between them).
O-Ring • • • • • • • • • • Due to shipping or storage the internal solution inside the PVC modules may have developed an air pocket near the membrane. Gently shaking the sensor down (like the old style mercury thermometer) will place the internal solution next to the membrane. Presoaking the Nitrate sensor in a 10-2 M standard without ISA for at least half-hour before calibration will help to optimize the sensor response.
Additional HI 4113 guidelines • Remove the protective plastic wrap that covers the ceramic junction before assembling sensor for the first time. • Add reference HI 7078 fill solution to bottom of fill hole or empty and refill fill solution daily before using. • During measurement always operate electrode with the fill hole open. • During normal use, fill solution will slowly drain out of the tapered cone junction at the lower portion of the electrode.
SENSOR HANDLE HI 4000-50 3. Holding the assembled electrode at the cable end, shake the sensor to ensure internal fill solution that may have separated during shipping is in contact with inner membrane surface. 4. Prepare HI 5315 reference electrode by filling electrolyte reservoir with HI 7078 fill solution. 5. Place sensor and reference electrodes into electrode holder and connect cable connectors to meter. 6. Soak the Nitrate electrodes membrane in a Nitrate containing standard (0.
Deionized Water Remove Parafilm Install sensing module 4. Rinse inner stem with deionized water making certain to wet o-ring found on the inner stem. 5. Reassemble electrode by gently pushing the inner assembly into the outer body, sliding spring down cable, and screwing cap into place. 6. Remove fill hole cover and o-ring on fill hole spout. Using the dropper pipette provided, add a few drops HI 7078 fill solution to the electrode.
HI 4113 E NITRAT TION NA COMBI 7. Holding the body of the electrode gently press upper cap with your thumb. This permits the fill solution to drain out of the body. Release cap and verify electrode returns to its original position. (You may need to gently assist for this to occur). 8. Tighten the electrode cap onto the body and fill electrode body until fill solution volume is just below fill hole. 9.
stabilized. This value should be less than the previous value noted (more negative). • Determine the difference between the two mV values. An acceptable value for this slope is 56 ± 4 mV (20-25°C) X. Corrective action • Verify module has been screwed into sensor handle or inner stem. • Verify Parafilm® seal has been removed from ceramic junction (HI 4113 or HI 5315 reference). • Verify fill solution has been added to reference chamber.
2. Unscrew upper cap and slide down cable toward connector. 3. Move spring and outer body down cable also. 4. Dry off inner stem and module with a soft tissue. 5. Hold inner stem and unscrew module and replace with a new one. (HI 4113-51). 6. Reassemble electrode (see section VII), and refill with electrolyte. Soak new membrane in nitrate solution without ISA to condition before calibration. XI. Direct Calibration and Measurement This method is a simple procedure for measuring many samples.
Procedure: Follow sections VIII and IX to prepare electrodes for measurement. 1) Follow section VI to prepare standards/ solution. Standards should bracket and fall within the range of interest. Standards and solutions should be at the same temperature. • 2 mL of HI 4013-00 is added to 100 mL of both samples and standards. OR • 10 mL of ISISA are added to 50 mL both samples or standards. Add stir bar and mix before taking measurements. 2) Follow section VII; General Guidelines to optimize test set-up.
XII. Other Measurement TTechniques echniques Known addition An unknown concentration can be determined by adding a known volume and concentration of NO3 - standard to the sample. mV values are noted before and after the addition of standard (∆E). An ideal sensor slope can be used in the equation but actual determined slopes at the temperature of measurement should be used if known (S). This method is preprogrammed in the Hanna HI 4222 pH/ISE/mV meter, which simplifies the method greatly.
XIII XIII. pH and Interferents HI 4013/ HI4113 Nitrate electrodes can operate over a pH range of 3 to 8 but better results are found if pH is kept constant throughout calibration and test. Sulfuric acid or NaOH can be used for pH adjustment or use ISISA to surpress interferences and buffer pH. Limiting the length of time of exposure to samples containing interferences will prolong useful life of your electrode.
MAN4113 08/11 WARRANTY Hanna Instruments Ion Selective Electrodes are warranted to be free of defects in material and workmanship for 6 months from date of purchase when used for their intended purpose and maintained according to instructions. If they fail to work when first used contact your dealer immediately. Damage due to accidents, misuse, misapplication, tampering or lack of prescribed maintenance is not covered.
