this solution. Vernier sells 500 mL bottles of pH Storage Solution (order code
PH-SS), or you can prepare additional storage solution by adding 10 g of solid
potassium chloride (KCl) to 100 mL of pH 4 buffer solution. Vernier sells a
pH Buffer Capsule kit (PH-BUFCAP) that includes a buffer solution preservative.
Storing the electrode in this solution contributes to electrode longevity and retains
electrode response time when the unit is placed back into service.
If the electrode is inadvertently stored dry for a short period of time, immerse the
tip in the pH 4 buffer/KCl storage solution for a minimum of 8 hours prior to use.
If the readings are still not accurate after calibration or if the response is slow, try
shocking the sensor as described in the Troubleshooting section.
How the Sensor Works
The pH amplifier inside the handle is a circuit that allows the standard
combination pH electrode to be monitored by a lab interface. The cable from the
pH amplifier ends in a BTA plug.
The pH Sensor produces a voltage of approximately 1.75 volts in a pH 7 buffer.
The voltage increases by about 0.25 volts for every pH number decrease. The
voltage decreases by about 0.25 volts/pH number as the pH increases.
The Vernier gel-filled pH Sensor is designed to make measurements in the pH
range of 0 to 14. The gel-filled reference half cell is sealed; it cannot be refilled.
The pH Sensor is designed to be used in aqueous solutions. The polycarbonate
body of the sensor can be damaged by many organic solvents. In addition, do not
use the sensor in solutions containing: perchlorates, silver ions, sulfide ions,
biological samples with high concentrations of proteins, or Tris buffered solutions.
Do not use the sensor with hydrofluoric acid or in acid or base solutions with a
concentration greater than 1.0 molar.
Troubleshooting
When testing a pH Sensor, it is best to measure a buffer solution because it is
easier to determine if the sensor is reading correctly. Do not test your sensor by
measuring distilled water. Distilled water can have a pH reading in the range of
5.5–7.0, due to varying amounts of dissolved carbon dioxide. Furthermore, due to
a lack of ions, the pH values reported with the sensor in distilled water will be
erratic.
If your pH Sensor is reading differently from the pH of a buffer solution (e.g., reads
6.7 in a buffer 7), you may simply need to calibrate the sensor. See the Calibration
section for more information.
Examine the glass bulb. If it is broken, pH readings will be incorrect.
If your readings are off by several pH values, the pH readings do not change when
moved from one buffer solution to a buffer solution of different pH, the sensor was
stored dry for an extended period of time, or the sensor’s response seems slow, the
problem may be more serious. A method called “shocking” can be used to revive
pH electrodes. To shock your pH Sensor, perform the following:
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1. Soak the pH Electrode for 4–8 hours in an HCl solution of 0.1 M–0.5 M.
2. Rinse off the electrode and soak the tip in freshly prepared long term storage
solution (recipe above) for 30–60 minutes.
3. Rinse the electrode and test it with buffer solutions of known pH.
Occasionally, mold will grow in the pH 4 buffer/storage solution. Mold will not
harm the electrode and can easily be removed using a mild detergent solution.
Mold growth in the storage solution can be inhibited by adding a buffer
preservative.
For additional troubleshooting and FAQs, see
www.vernier.com/til/1361
Repair Information
If you have watched the related product video(s), followed the troubleshooting
steps, and are still having trouble with your pH Sensor, contact Vernier Technical
Support at [email protected] or call 888-837-6437. Support specialists will
work with you to determine if the unit needs to be sent in for repair. At that time,
a Return Merchandise Authorization (RMA) number will be issued and
instructions will be communicated on how to return the unit for repair.
Accessories/Replacements
Item
Order Code
Electrode Storage Solution, 500 mL
PH-SS
pH Buffer Capsules (3×10) kit
PH-BUFCAP
Storage Solution Bottles, pkg of 5
BTL
Warranty
Vernier warrants this product to be free from defects in materials and workmanship
for a period of five years from the date of shipment to the customer. This warranty
does not cover damage to the product caused by abuse or improper use. This
warranty covers educational institutions only. Additionally, the warranty does not
cover accidental breakage of the glass bulb of the pH Sensor.
Vernier Software & Technology
13979 SW Millikan Way • Beaverton, OR 97005-2886
Toll Free (888) 837-6437 • (503) 277-2299 • FAX (503) 277-2440
[email protected] • www.vernier.com
Rev. 2/8/16
Logger
Pro,
Logger Lite, Vernier LabQuest 2, LabQuest Mini, and other marks shown are our trademarks or
registered trademarks in the United States.
All other marks not owned by us that appear herein are the property of their respective owners, who may or may
not be affiliated with, connected to, or sponsored by us.
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