pH Electrodes Instruction Sheet Models 601100, 601500 and 60120B Electrode Specifications Model number Description Dimensions Construction material Measuring range Temp. range Reference junction Reference type Isopotential point Precision Connector Cable length Storage container 601100 Flat surface combination pH electrode with gelled reference solution 15 x 115 mm Polymer housing, flat glass bulb 0 to 14.0 pH units o 0-80 C Teflon Ag/AgCl (silver silver chloride) ~7.0 pH 0.02 pH units BNC 1 meter (39”) Bottle 60120B Mini combination pH electrode with sealed gelled reference filling solution and detachable bulb guard 10 x 126 mm Polymer housing, glass bulb 0 to 14.0 pH units o 0-80 C Ceramic Ag/AgCl (silver silver chloride) ~7.0 pH 0.02 pH units BNC 1 meter (39”) Cap General Electrode Procedure 1. 2. 3. 4. 5. To avoid damage to the electrode when removing it from or inserting it into the soaking bottle; a) Unscrew the bottle cap. b) Remove the electrode and cap from the bottle. c) Slide the cap off the electrode. d) Reverse this procedure when storing the electrode. Rinse the electrode with deionized or distilled water. Carefully shake electrode to ensure that any air bubbles in the bulb or lower stem of the electrode are dislodged upwards. Blot electrode with tissue. Connect electrode to pH meter and follow the pH meter manufacturer’s instruction for calibration. Before Measurement 1. Generally, the sample should be aqueous and fall within the range 0 – 14 pH 2. Always use fresh buffers for calibration. Choose buffers that are no more than 3 pH units apart. 3. To obtain the maximum precision, always buffer as close as possible to the expected measured value. 4. Between measurements, rinse electrodes with distilled water and then with the next solution to be measured. 5. Stir all buffers and samples. 6. Avoid rubbing or wiping electrode bulb in order to reduce the chance of error due to polarization. pH Calibration and Measurement Refer to the owner’s guide from the manufacturer of the pH meter being used for detailed information regarding calibration and temperature compensation procedures. Two-Buffer Calibration (for high precision measurements) 1. Set up the pH meter according to the manufacturer’s instruction manual. o 2. Ensure that all buffers are at the same temperature (+/- 2 C.) If samples are at varying temperatures, temperature compensation is recommended. (See pH meter instruction manual.) 3. Select two buffers that bracket the expected pH value. The first should be near the electrode isopotential point (pH 7) and the second near the expected pH of the sample. (e.g., pH 4 or 10.) 4. Rinse the electrode first with distilled water and then with pH 7 buffer. Place the electrode in the pH 7 buffer. 5. Wait for a stable pH 7 reading. Set the pH meter to the pH value of the buffer at its measured temperature. 6. Rinse the electrode first with distilled water and then with the second buffer. Place the electrode in the second buffer. 7. Wait for a stable display. Set the pH meter to the pH value of the buffer at its measured temperature. 8. Calibration is complete. Proceed to pH measurement Single-Buffer Calibration (for lower precision measurements) 1. Set up the pH meter according to the manufacturer’s instruction manual. 2. Choose a buffer that has a value close to the expected pH of the sample. 3. Rinse the electrode first in distilled water and then in the buffer being used for calibration. Place the electrode in the buffer. 4. 5. 601500 General-purpose combination pH electrode with sealed gelled reference filling solution and detachable bulb guard 12.5 x 155 mm Polymer housing, glass bulb 0 to 14.0 pH units o 0-80 C Ceramic Ag/AgCl (silver silver chloride) ~7.0 pH 0.02 pH units BNC 1 meter (39”) Bottle Wait for a stable display. Set the pH meter to the pH value of the buffer at its measured temperature. Proceed to pH measurement pH Measurement 1. Calibrate the electrode as described in previous section. 2. Rinse the electrode with distilled water and then with the sample solution. 3. Place the electrode in the sample. 4. Stir the sample. 5. When the reading is stable, record the pH value. Electrode Storage and Maintenance Electrode Storage 1. Electrodes 601100 and 601500 Store in the soaking bottle. The soaking solution should be 22.4g KCl dissolved in 100ml pH4 buffer solution or 25g KCl dissolved in 100ml pure water. 2. Electrode 60120B Store with wetting cap kept damp with pH4 buffer or, alternatively, store in a soaking solution. Electrode Maintenance 3. Inspect the electrode for scratches, cracks, salt crystal build-up, or membrane/junction deposits. 4. Rinse off any salt build-up with distilled water, and remove any membrane/junction deposits as directed in cleaning procedures below. 5. Drain the reference chamber, flush it with fresh filling solution and refill the chamber Cleaning Procedures Soak in mild detergent or dilute 0.1M HCl for 30 minutes Electrode Reconditioning If the electrode has been allowed to dry for any period of time it may require reconditioning. Soak the electrode in a pH 4 buffer solution for at least 20 minutes. Depending on the dryness of the reference junction, this reconditioning process may require up to a 24 hour soaking period in order to obtain accurate pH readings. Warranty EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects in parts and workmanship for one year from date of shipment (a six month limited warranty applies on sensors and cables). If it should become necessary to return the instrument for service during or beyond the warranty period, contact the Customer Service Department at (781) 890-7440 ext. 210 for authorization or visit our website at www.extech.com (click on ‘Contact Extech’ and go to ‘Service Department’ to request an RA number). A Return Authorization (RA) number must be issued before any product is returned to Extech. The sender is responsible for shipping charges, freight, insurance and proper packaging to prevent damage in transit. This warranty does not apply to defects resulting from action of the user such as misuse, improper wiring, operation outside of specification, improper maintenance or repair, or unauthorized modification. Extech specifically disclaims any implied warranties or merchantability or fitness for a specific purpose and will not be liable for any direct, indirect, incidental or consequential damages. Extech's total liability is limited to repair or replacement of the product. The warranty set forth above is inclusive and no other warranty, whether written or oral, is expressed or implied. 601XXX V1.3 11/01