Instruction Manual Calcium Electrode EUTECH INSTRUMENTS PTE LTD.
Calcium Electrode Instruction Manual TABLE OF CONTENTS GENERAL INSTRUCTIONS .......................................................................................................... 3 Introduction ..............................................................................................................................................3 Required Equipment.................................................................................................................................
Instruction Manual Calcium Electrode EUTECH INSTRUMENTS PTE LTD. CALCIUM ELECTRODE INSTRUCTION MANUAL GENERAL INSTRUCTIONS Introduction Eutech Instruments Calcium Ion Electrode is used to measure calcium ions in aqueous solutions quickly, simply, accurately, and economically. Required Equipment 1. A pH/mV meter or an ion meter, either line operated or portable. 2. Semi-logarithmic 4-cycle graph paper for preparing calibration curves when using the meter in the mV mode. 3. A magnetic stirrer. 4.
Calcium Electrode Instruction Manual flask gently to dissolve the solid. Fill to the mark with distilled water, cap, and upend several times to mix the solution. 6. EDTA titrant, 1M stock solution, for the titration of calcium. To prepare this titrant, add 37.2 grams of reagent grade Na2EDTA.2H2O, ethylenediaminetetraacetic acid dihydrate, disodium salt, to a 100 ml volumetric flask, add about 75 ml of distilled water, and swirl the flask gently to dissolve the solid.
Instruction Manual Calcium Electrode Electrode Slope Check (with ion meter) (Check electrodes each day) 1. Prepare standard calcium solutions whose concentrations vary by tenfold. Use either the 0.1M Ca+2, 1,000 ppm Ca+2, or the 100 ppm Ca+2 (as calcium carbonate) standard stock solutions. Use the serial dilution method for this preparation. 2. To a 150 ml beaker, add 100 ml of the lower value standard and 2 ml of ISA. Place the beaker on the magnetic stirrer and begin stirring at a constant rate.
Calcium Electrode Instruction Manual Dilute concentrated samples (over 0.1M) before measurement. Recalibrate every few hours for routine measurement. Sample Requirements All samples and standards must be aqueous and not contain organics which can dissolve in the membrane or extract out the liquid ion exchanger. The temperature of the standard solutions and of the sample solutions should be the same and below 40oC. About a 2% error will be introduced for a 1oC difference in temperature.
Instruction Manual Calcium Electrode 3. Place the mid-range solution (1.0X10-3M or 10 ppm) in a 150 ml beaker on the magnetic stirrer and begin stirring. After rinsing the electrodes with distilled water, blot dry, and immerse the electrode tips in the solution. When the reading has stabilized, record the mV value. 4. Place the most concentrated solution (1.0X10-2M or 100 ppm) in a 150 ml beaker on the magnetic stirrer and begin stirring.
Calcium Electrode 7. Instruction Manual The calibration should be checked every two hours. Assuming no change in ambient temperature, place the electrode tips in the mid-range standard. After the reading has stabilized, compare it to the original reading recorded in Step 3 above. A reading differing by more than 0.5 mV or a change in the ambient temperature will necessitate the repetition of Steps 2-5 above. A new calibration curve should be prepared daily.
Instruction Manual Calcium Electrode 1. Dilute 10 ml of the 0.1M standard to 1,000 ml to prepare a 1.0x10-3M standard solution for measurements in moles per liter. Dilute 10 ml of the 1,000 ppm or 1 ml of the 100 ppm standard to 1,000 ml to prepare a 10 ppm standard solution for measurements in ppm. 2. Soak the calcium electrode for at least 1 hour in 1.0x10-3M or 100 ppm calcium standard solution. 3. To a 150 ml beaker, add 100 ml of distilled water.
Calcium Electrode Instruction Manual The progressive and quantitative addition of a reagent to a measured sample until neither active species (reagent or sample) is in excess. Ion selective electrodes are excellent endpoint detectors since they are not influenced by solution color or turbidity. Though titration is more time consuming than direct measurement, it is about 10 times more accurate.
Instruction Manual MCa Calcium Electrode +2 VtMt = ——— VCa+2 where MCa+2 Vt Mt VCa+2 = concentration of calcium ion in the unknown (moles/liter) = volume of EDTA added at endpoint = EDTA concentration (moles/liter) = volume of unknown sample ELECTRODE CHARACTERISTICS Reproducibility Electrode measurements reproducible to ±4% can be obtained if the electrode is calibrated every hour. Factors such as temperature fluctuations, drift, and noise limit reproducibility.
Calcium Electrode Instruction Manual Interferences (ppm) 1,000 ppm CaCO3 +2 Mg 2.43X105 6.53X105 Zn+2 Ba+2 9.60X105 K+1 1.56X105 Na+1 4.60X104 Ni+2 2.94X104 Cu+2 2.54X104 Fe+2 1.11X104 Sr+2 5.20X103 H+1 1.4 pH +2 Hg 8.0X103 2.0X101 Pb+2 100 ppm CaCO3 2.43X104 6.53X104 9.60X104 1.56X104 4.60X103 2.94X103 2.54X103 1.11X103 5.20X102 2.4 pH 8.0X102 2.0 10 ppm CaCO3 2.43X103 6.53X103 9.60X103 1.56X103 4.60X102 2.94X102 2.54X102 1.11X102 5.20X101 3.4 pH 8.0X101 2.
Instruction Manual Calcium Electrode Electrode Response Plotting the mV potential against the calcium concentration on semi-logarithmic paper results in a straight line with a slope of about 27 mV per decade (Refer to Figure 1). The time needed to reach 99% of the stable electrode potential reading, the electrode response time, varies from one minute or less for calcium concentration above 1.0x10-4M to several minutes near the detection limit. (Refer to Figure 3.
Calcium Electrode Instruction Manual Electrode Storage The calcium electrodes may be stored for short periods of time in 1.0X10-2M calcium standard. For longer storage (longer than two weeks), rinse and dry the calcium membrane and cover the tip with any protective cap shipped with the electrodes. The reference portion of the combination electrode (or the outer chamber of the reference electrode) should be drained of filling solution, if refillable, and the rubber insert placed over the filling hole.
Instruction Manual Calcium Electrode Solutions other than this may be used as ISA's as long as ions that they contain do not interfere with the electrode's response to calcium ions. The reference electrode must also be considered. When two solutions of different composition are brought into contact with one another, liquid junction potentials arise. Millivolt potentials occur from the inter-diffusion of ions into the two solutions.
Calcium Electrode 5. Instruction Manual If another electrode is not available for test purposes, or if the electrode in use is suspect, review the instruction manual and be sure to: - Clean and rinse the electrodes thoroughly. - Prepare the electrodes properly. - Use the proper filling solution. - Adjust the pH of the solution according to the method being used for the analysis. - Measure correctly and accurately. - Review TROUBLESHOOTING HINTS.
Instruction Manual Calcium Electrode TROUBLESHOOTING HINTS Symptom Out of Range Reading Noisy or Unstable Readings (readings continuously or randomly changing "Incorrect Answer" (but calibration curve is good) Possible Causes defective meter Next Step check meter with shorting strap (see meter instruction manual) defective electrode check electrode operation electrodes not plugged in properly unplug electrodes and reset reference electrode not filled be sure reference electrode is filled air bu
Calcium Electrode Instruction Manual between samples Drift (reading slowly changing in one direction) Low Slope or No Slope samples and standards at different temperatures allow solutions to come to room temperature before measurement electrode exposed to interferences soak electrode in calcium standard incorrect reference filling solution use recommended filling solution incorrect pH adjust to pH 3-10 with NaOH or HCl standards contaminated or incorrectly made prepare fresh standards defecti
Instruction Manual Calcium Electrode SPECIFICATIONS Concentration Range: 1M to 5x10-6M pH Range: 3 to 10 Temperature Range: 0o to 40 oC Resistance: 100 Mohms Reproducibility: ±4% Samples: Aqueous solutions only; no organic solvents Size: 110 mm length; 12 mm diameter; 1 m cable length Storage: Store in dilute calcium standard ORDERING INFORMATION CODE NO. DESCRIPTION EC-CAL-03 Calcium Electrode, epoxy body combination EC-SCS-CA1-BT Calcium Standard, 0.