HI 4103 CADMIUM COMBINATION CADMIUM HI 4003 Instruction Manual HI 4003 HI 4103 Half-cell Combination Cadmium Ion Selective Electrode 1
HI 4003 Cadmium Half-cell HI 4103 Cadmium Combination Electrode I. Introduction: The Hanna HI 4003 and HI 4103 are ion selective electrodes designed for the measurement of cadmium ions in aqueous solutions. The HI 4003 is a solid state half-cell sensor that requires a separate reference. The HI 4103 is a combination ion selective electrode. IIII. Specifications Type: Solid State electrode with a Cadmium sulfide/ silver sulfide membrane. + Cadmium (Cd 2+) Ion(s) measured: 0.1 M to 1X 10-7 M 11,200 to 0.
III. Theory of Operation Operation:: The HI 4103 or HI 4103 cadmium electrodes are potentiometric devices used for the rapid determination of free cadmium ions in samples and as a detector for the titration of cadmium with EDTA. Cadmium sensors are “electrodes of the third kind” because they detect cations which also form low-solubility salts with sulfide anions that also form lowsolubility salts with silver. The electrode functions as a sensor or ionic conductor.
IV.
V. Equipment required: • Hanna HI 5315 Double Junction Reference Electrode with HI 7072 Fill Solution for use with HI 4003 halfcell. • 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 TFE coated stirring bars (HI 731320). Note: isolate beakers from stirrer motor heat by placing insulating material such as foam or cork between them.
VII VII. General Guidelines • Concentrated samples (>0.10 M) should be diluted before measurement. Multiply the final result by the corresponding dilution factor. • Calibration standards and sample solutions should have the same ionic strength. • For high ionic strength samples, use standard addition or titration methods. • Calibration standards and sample solutions should be at same temperature. • The magnetic stirrer may generate heat.
• Gas bubbles may form from solution out-gassing due to temperature change. Gently tap body of sensor to dislodge them from sensing membrane. HI 4003 • Remove protective cover from sensor tip. HI 4103 • Remove the protective plastic wrap that covers the ceramic junction before assembling sensor for the first time. • HI 7072 reference fill solution should be added daily to electrolyte reservoir before electrode use. • During measurement always operate electrode with the fill hole open.
Deionized Water VIII. Electrode Preparation HI 4003 1. Remove protective cover from sensor tip. 2. Prepare reference electrode by filling outer electrolyte reservoir with HI 7072. 3. Place sensor and reference electrodes into electrode holder and connect cable connectors to meter. HI 4103 1. Unwrap plastic film seal found over ceramic junction on inner stem and discard. This is only used for shipping and long term storage. 2.
HI 4103 M IU CADM ATION IN COMB 6. 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). 7. Tighten the electrode cap onto the body and fill electrode body until fill solution volume is just below fill hole. 8. Position electrode in a Hanna HI 76404 electrode holder (or equivalent) and connect plug to meter.
IX. • • • • • • • Quick Check of Electrode Slope Connect sensors to pH/mV/ISE meter Place meter in mV mode. Place 100 mL of deionized water into a beaker with stir bar and 2 mL of HI 4000-00 ISA. Add stir bar and place on magnetic stirrer. Place electrodes into prepared sample. Add 1 mL of the stock standard HI 4003-01 (or .01 M or .001 M standard by dilution) to the beaker. Record the mV value when reading has stabilized.
appear on polishing strip move the paper slightly and continue polishing. • If the membrane is damaged, the response becomes extremely sluggish, or the slope of the electrode has decreased significantly, and procedures above have not helped, the sensor should be replaced. XI. Direct Calibration and Measurement This method is a simple procedure for measuring many samples.
1) 2) 3) 4) 5) Procedure Follow sections VIII and IX to prepare sensors for measurement. Follow section VI to prepare standards / solution. Standards should bracket and fall within the range of interest. Two mL HI 4000-00 ISA is added to 100 mL of both samples and standards. Add stir bar and mix before taking measurements. Follow section VII; General Guidelines to optimize test set-up. During calibration it is best to start with lower concentration samples first.
This technique is called Known Addition. The method can use an ideal sensor slope, but actual determined slopes at the temperature of measurement should be used if known. The volume and concentration of the added standard must cause a mV change of at least 8 mV. This method is preprogrammed in the Hanna HI 4222 pH/ISE/mV meter, which simplifies the method greatly. The method works well for samples with high ionic strengths.
the free ions from the measurement pool. Cd2+ + EDTA <—>Cd-EDTA The EDTA reacts with the cadmium ion forming a complex. The EDTA also can react with a host of other metals. Working at a pH between 4 and 6 optimizes the pH of the Cd-EDTA complex, and also discourages complexing with other ions that form stable complexes at high pH. Consult a comprehensive Analytical Chemistry Treatise for techniques concerning your particular interferent.
XIII. pH XIII.pH HI 4103 and HI 4003 electrodes may be used in solutions with values between 4.5 and 7.5 pH. Samples above pH 7.5 may form Cd(OH)2. Adjust these samples with nitric acid. XIV. SStorage torage and Care of the HI 4003 and HI 4103 sensors The HI 4003 and HI 4103 sensor can be stored in very dilute standards (<10-3M) for short periods of time. The HI 4003 should be stored dry with it’s protective cap on for longer periods.
MAN4103 02/07 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.
