Instruction Manual Silver/Silver Sulfide Electrode EUTECH INSTRUMENTS PTE LTD.
Silver/Silver Sulfide Electrode Instruction Manual TABLE OF CONTENTS GENERAL INSTRUCTIONS .......................................................................................................... 3 Introduction................................................................................................................................................................ 3 Required Equipment......................................................................................................................
Instruction Manual Silver/Silver Sulfide Electrode EUTECH INSTRUMENTS PTE LTD. SILVER/SULFIDE ION ELECTRODE INSTRUCTION MANUAL GENERAL INSTRUCTIONS Introduction Eutech Silver/Sulfide Ion Electrode is used to measure silver and sulfide ions in aqueous solutions quickly, simply, accurately, and economically. The two ions are virtually never present in solution together, owing to the extreme insolubility of silver sulfide.
Silver/Silver Sulfide Electrode Instruction Manual times to mix the solution. Store the solution in a brown bottle, tightly capped, in a dark place. 4. Eutech Silver Standard, 1,000 ppm as Ag+, Code no. EC-SCS-SS2-BT. To prepare this solution from your own laboratory stock, dry reagent-grade, pulverized silver nitrate in a laboratory oven for one hour at 150oC. Quantitatively transfer 1.57 grams of the dried silver nitrate to a 1 liter volumetric flask containing about 500 ml of distilled water.
Instruction Manual Silver/Silver Sulfide Electrode GENERAL PREPARATION Electrode Preparation Remove the rubber caps covering the electrode tips and the rubber insert covering the filling hole of the reference electrode. Fill the combination electrode or the reference electrode with the filling solution shipped with the electrode to a level just below the fill hole. No preparation is required for a sealed reference electrode.
Silver/Silver Sulfide Electrode Instruction Manual Electrode Slope Check (with ion meter) (Check electrodes each day) Using silver standards: 1. Prepare standard silver solutions whose concentrations vary by tenfold. Use either the 0.1M AgNO3 or 1,000 ppm 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 a magnetic stirrer and begin stirring at a constant rate.
Instruction Manual 7. Silver/Silver Sulfide Electrode Read the electrode slope according the meter manufacturer's instructions. Correct electrode operation is indicated by a slope of 90-100%. See the TROUBLESHOOTING section if the slope is not within this range. MEASUREMENT Measuring Hints All samples and standards should be at the same temperature for precise measurement. A difference of 1 oC in temperature will result in about a 2% measurement error.
Silver/Silver Sulfide Electrode Instruction Manual Mercury cannot be present in silver samples. Since HgS and Hg2S are insoluble, no mercury will be present in sulfide samples. Other interference should be absent. If they are present, use the procedures found in the Interference and Electrode Response sections to remove them.
Instruction Manual 5. Silver/Silver Sulfide Electrode Using the semi-logarithmic graph paper, plot the mV reading (linear axis) against concentration (log axis). Extrapolate the curve down to about 2.0X10-6M or 0.2 ppm. A typical calibration curve can be found in Figure 2. A calibration curve is constructed on semi-logarithmic paper when using a pH/mV meter in the millivolt mode. The measured electrode potential in mV (linear axis) is plotted against the standard concentration (log axis).
Silver/Silver Sulfide Electrode 2. 3. Instruction Manual Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate. Assure that the meter is in the concentration mode. Lower the electrode tips into the solution. 4. Adjust the meter to the concentration of the silver standard and fix the value in the memory according to the meter manufacturer's instructions after stabilization of the reading. 5. Rinse the electrodes with distilled water and blot dry. 6.
Instruction Manual Silver/Silver Sulfide Electrode 4. Place the most concentrated sulfide standard 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 reading. 5. Using the semi-logarithmic graph paper, plot the mV reading (linear axis) against concentration (log axis). A typical calibration curve can be found in Figure 1.
Silver/Silver Sulfide Electrode Instruction Manual standard into individual 150 ml beakers and add 25 ml of SAOB and 25 ml of distilled water to each. 2. 3. Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate. Assure that the meter is in the concentration mode. Lower the electrode tips into the solution. 4.
Instruction Manual Silver/Silver Sulfide Electrode 2. Dilute 1 ml of 0.1M standard to 1 liter to prepare a 1.0X10-4M solution for measurements in moles per liter. Prepare a 10 ppm standard solution by diluting 1 ml of the 1,000 ppm standard to 100 ml of solution for measurements in ppm. Standards should be prepared fresh daily. 3. Add 1 ml of low level ISA to a 100 ml volumetric flask and fill to the mark with distilled water.
Silver/Silver Sulfide Electrode Instruction Manual Titration of Sulfide The minimum sulfide sample concentration for this method is 1.0X10-5M. The titrant to be used is a lead perchlorate standard solution. 1. Using Eutech Lead Perchlorate Solution, 0.1M, Code No. EC-SCS-PB1-BT, prepare a lead titrant that is about 10-20 times as concentrated as the expected sample concentration by dilution. 2. Dilute 25 ml of the sample with 25 ml of SAOB in a 150 ml beaker.
Instruction Manual Silver/Silver Sulfide Electrode The minimum silver sample concentration for this method is about 1.0X10-4M. For halides, it is 1.0X10-4M. Data gathered by titration of less concentrated samples can be plotted using the Gran's Plot technique. (See the chloride titration that follows.) 1. Using Eutech Sodium Chloride Solution, 0.1M NaCl, Code No. NA0AS01, for silver titration, or the 0.
Silver/Silver Sulfide Electrode Instruction Manual 5. Add 1 ml of titrant and record the mV reading after stabilization. Repeat this operation four more times. 6. Using Gran's Plot paper, plot the values as follows: a) The horizontal axis is the volume axis. Each major division is equal to 1 ml of titrant used. b) The vertical axis is the mV axis. Each major division is equal to 5 mV. The axis should be scaled so that the mV value obtained after 5 ml of titrant added is near the top of the graph. 7.
Instruction Manual Silver/Silver Sulfide Electrode 17
Silver/Silver Sulfide Electrode Instruction Manual ELECTRODE CHARACTERISTICS Reproducibility Electrode measurements reproducible to ±2% can be obtained if the electrode is calibrated every hour. Factors like temperature fluctuations, drift, and noise limit reproducibility. Reproducibility is independent of concentration within the electrode's operating range. Interference A surface layer of silver metal may be formed by strongly reducing solutions.
Instruction Manual Silver/Silver Sulfide Electrode 50 32.1 64.1 If changes in temperature occur, the electrodes should be re-calibrated. The temperature range for Eutech Silver/Sulfide Ion Combination Electrode is 0o-80oC, provided that temperature equilibrium has occurred. If the temperature varies substantially from room temperature, equilibrium times up to one hour are recommended.
Silver/Silver Sulfide Electrode Instruction Manual 5. If using jeweller's rouge, place a cotton ball on the table top and flatten it using the bottom of a beaker. 6. Put 1-2 drops of distilled or deionized water in the center of the cotton pad. 7. Add a small amount of jeweller's rouge to the damp cotton. 8. Continue with Steps 3 and 4 above. Limits of Detection The upper limit of detection in pure silver nitrate solutions is 1M.
Instruction Manual Silver/Silver Sulfide Electrode ELECTRODE THEORY Electrode Operation The silver/sulfide electrode is composed of a silver sulfide crystal membrane bonded into an epoxy or glass body. When an electrode potential develops across the membrane, the membrane is in contact with a solution containing sulfide or silver ions and is capable of measuring free sulfide or silver ions. This electrode potential is measured against a constant reference potential, using a pH/mV meter or an ion meter.
Silver/Silver Sulfide Electrode Instruction Manual The composition of the liquid junction filling solution in the reference electrode is most important. The speed with which the positive and negative ions in the filling solutions diffuse into the sample should be as nearly equal as possible, that is, the filling solution should be equitransferent. No junction potential can result if the rate of which positive and negative charge carried into the sample solution is equal.
Instruction Manual Silver/Silver Sulfide Electrode - Clean and rinse the electrodes thoroughly. - Prepare the electrodes properly. - Use the proper filling solution. - Adjust the pH and the ionic strength of the solution by the use of the proper ISA. - Measure correctly and accurately. - Review TROUBLESHOOTING HINTS. Standards and Reagents Whenever problems arise with the measuring procedure that has been used successfully in the past, be sure to check the standard and reagent solutions.
Silver/Silver Sulfide Electrode Instruction Manual TROUBLESHOOTING HINTS Symptom Out of Range Reading Noisy or Unstable Readings (readings continuously or rapidly changing) Drift (reading slowly changing in one direction) 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 fi
Instruction Manual Low Slope or No Slope "Incorrect Answer" (but calibration Silver/Silver Sulfide Electrode standards contaminated or incorrectly made prepare fresh standards ISA not used use recommended ISA standard used as ISA use ISA electrode exposed to complexing agents check section entitled air bubble on membrane remove bubble by re-dipping probe incorrect scaling of semi-log paper plot millivolts on the linear axis.
Silver/Silver Sulfide Electrode Instruction Manual SPECIFICATIONS Concentration Range: 1M to 1.0X10-7M sulfide (32,000 to 0.003 ppm) 1M to 1.0X10-7M silver (108,000 to 0.01 ppm) pH Range: 2 to 12 Temperature Range: 0o-80oC Resistance: <1 Mohm Reproducibility: +/- 2% Samples: Aqueous solutions only; no organic solvents Size: 110 mm length; 12 mm diameter; 1 m cable length Storage: Store in silver or sulfide solution ORDERING INFORMATION CODE NO.
