Home Page Hydroponic Supplies Sitemap         Cleaning and Reconditioning Electrodes Back to Tips & Techniques Cleaning and Reconditioning pH Testr Series Electrodes Often, the OAKTON pH Testr's are used in applications which require regular cleaning of the electrode or reference. These applications involve very hard waters (i.e. those with high scale content), dirty samples like soil slurries, viscous materials or samples with high oil and protein content. As with any procedure involving strong chemicals, please wear appropriate clothes and goggles, and provide adequate ventilation. We do not recommend these procedures for persons unfamiliar with or unable to use safe techniques involving these chemicals: Detergents HCI (Hydrochloric Acid) NaOH (Sodium Hydroxide) Method 1 Soak the electrode in a 0.1 molar concentration of HCI (hydrochloric acid) for one hour, then rinse the electrode with deionized or distilled water. This should remove any organic protein from the glass electrode and the surface of the reference electrode. Method 2 Soak the electrode in a 3.8 or 4.0 molar KCI (potassium chloride) solution heated to 50°C for one hour. Allow the KCI solution to cool down to room temperature, then rinse the electrode with deionized or distilled water. This will open and clear the reference electrode of all contaminants. Method 3 Soak the electrode in a 4.01 pH buffer solution, heated to 50°C for one hour. Allow the buffer to cool down to room temperature, then rinse the electrode with deionized or distilled water. This should open and clear the reference electrode. Method 4 After each use, rinse the electrode in 0.5 N or 1% HCI . Soak in 1% HCI solution overnight. If you have a build-up of oil or protein contaminants, try soaking the electrode in a warm detergent and water solution. Degreasing dishwashing detergents or stain removing pre wash pretreatment's are ideal for this: any brand will do. An overnight soak may be needed if build-up is heavy. Then rinse the pH Testr in deionized or distilled water and soak for 1 hour in 1% HCI. Rinse the pH Testr in deionized or distilled water and check in buffers. If the pH Testr calibrates to buffers it can be used in tests. When the pH Testr cannot be calibrated even after attempts to clean it, it must be replaced. Method 5 For protein removal soak the electrode in contact lens enzymatic cleaner solution overnight. The enzymes will remove proteins from glass and plastic. pH Tester Economies It is a common practice to replace electrodes regularly especially in more troublesome applications. Since pH Testr's cost about the same or less than a typical general purpose pH electrode, it is also common practice to replace them on a regular bash when working in 1roublesome applications. Consider regular replacement of pH Testr's where metal ions are present; where organic materials such as oils, proteins, solvents, and polymers am present; when used in viscous samples like paint, and when used in slurries such as soil and sludge. Low Battery Message On rare occasions, an Oakton Testr may seem to be defective because the display fades, does not come on at all, or the "E1 " auto diagnosis error message for low battery condition appears even when the batteries are new. Since most OAKTON Testr's have an automatic shut off feature to conserve batteries, these problems are not necessarily the result of low batteries. Instead they may be the result of poor electrical contact with the Testr that results from oily, waxy, or dirty coatings on the batteries. To correct this, use a pencil eraser or screw driver blade to rub or scrape these coatings off the batteries and the contacts. Reinstall the batteries and try operating the Testr again. This procedure will, in many cases, help customers keep Testr's working and reduce the number of customer returns. pH Testr Care The OAKTON pH Testr is a low-cost, exciting innovation for pH testing. It can do the work of hundreds of rolls of pH paper when cared for properly. Frequently a low cost, pocket-sized device will be abused because the user is not aware of its limits of application or durability. This is a problem common to many portable electronic devices. Keep in mind that the more careful the treatment, the longer the life of the pH Testr. Here are some basic DO'S and DONT'S: DO NOT: DO NOT submerse, spray, or otherwise waterlog your pH Testr. DO NOT immerse at or above the colored band. DO NOT drop, hit, or cause physical shock to your pH Testr. The electronic instrumentation and glass sensing bulbs are delicate. DO NOT touch anything solid to the glass bulb electrode or it will break. DO NOT throw away the instruction sheet or protective box that comes with your pH Testr, because there is useful information listed for reference purposes. DO: DO calibrate your pH Testr in a pH buffer solution once a week or at any time you suspect a problem with the readings. This is the surest way to check the operation of the pH Testr. If the Testr calibrates at a pH other than 7 your pH Testr probably works. DO change the batteries if you cannot calibrate and/or if the reading fades or is suspect. Low batteries are the pH Testr's most common ailment. DO store the pH Testr with tap water, or electrode storage solution soaked in a piece of sponge or paper in the cap to prevent the dehydration of the electrode and premature failure of the pH Testr. This procedure also speeds up the response time of the pH Testr. DO store your pH Testr in an area where the temperature is within 32 and 122 degrees F. Extreme temperatures will damage the electronics. DO consult your distributor concerning applications involving harsh chemicals or solvents and viscous samples to determine the suitability of the pH Testr. If you are concerned about treatment other than the points mentioned above, please remember the following: the pH Testr is a digital electronic instrument that has a delicate and exposed glass electrode. It is designed to give six months or more of reliable service following the care and use guidelines on the instruction sheet and box and in this Tech Tip Bulletin