Research Instruments Success Through Innovation


Products - Environmental Monitors

pH Meter

pH Meter 3 with probe and holder

Building on the success and popularity of our pH Meter, RI now offers a new compact version, the pH Meter 3.

Smaller, lighter and with an improved digital probe, it allows you to read and record media pH in real-time inside any popular incubator, including benchtop models. The large colour screen guides you quickly through the calibration and use of the meter.

With the pH Meter 3 you can see exactly what is happening to the media during culture to better inform lab protocols and optimise conditions. The pH Meter is suitable for various laboratory surveys and is compatible with standard media equilibration practises. The amount of data storage has been increased from 300 to 65,000 log points per log file, with the capacity for multiple files, in anticipation of transfer to your PC and our dedicated software, using adaptable graphs to display pH and the temperature over time. Details can also be archived, reported to other software programs and printed for lab records.

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Key benefits


New pH Meter readings with excellent calibration response and repeatability


Suitable for use with all popular incubators including benchtop versions


IVF culture dish design and improved robust probe

Increased data storage capacity

New LCD display and user interface

Language options

English, French, German, Dutch and Spanish available


Why use the RI pH Meter?

Measuring the pH of culture media accurately is extremely difficult because the pH of media droplets under oil shifts above 7.4 within just 2mins 30 seconds of removal from the incubator. So the likelihood is, if measuring the pH of media outside of the incubator, that you are measuring artefact pH Levels.

The RI pH Meter 3 provides accurate, real-time analysis of media pH within the incubator using its unique custom IVF pH probe. The probe fits into all incubators and allows embryologists to measure the effect of CO2 concentration and other factors on the pH in the media. No more guesswork or assumptions when trying to deliver the correct pH for the media being used.

How is it used?

A media droplet is made up in the pH probe well and placed in the incubator. The thin ribbon cable can be passed out through a sample port or through the incubator door. The pH meter will then measure and display the pH in real-time.

How does it work?

The probe has a semiconductor sensor at the tip. The probe is placed in the 4 well shaped holder. This holder has a well where the media sample is placed. The probe also contains a sensor that measures the temperature of the sample and compensates the pH reading accordingly.

Software trend analysis

The meter has on board memory for datalogging. Test results stored by the pH meter may be easily downloaded to a personal computer for analysis and printing. With the auto archiving feature, the software is very easy to use.

pH Meter 3 Specs

  pH Meter Brochure (311.6 KiB, 0 hits)

  Environmental Monitoring Brochure (170.2 KiB, 2,042 hits)

  RI Product Catalogue (6.2 MB, 1,255 hits)

  MSDS pH 4 - 2013 (41.3 KiB, 0 hits)

  MSDS pH7 - 2013 (41.3 KiB, 0 hits)

  MSDS pH 10 - 2013 (46.4 KiB, 0 hits)

Q: How much media is actually required to be placed in the probe?

A: 0.5 to 1ml of media is required.

Q: Is there any special way of making up the media in the probe?

A: No, make the media drop the same way as your other dishes. You must ensure that the media covers the sensor at the tip of the probe.

Q: When should I place the probe in the incubator?

A: You should place the probe in the incubator at the same time as your dishes.

Q: How long is the warranty period?

A: The pH Meter main unit has 12 months warranty. The probe has 6 months warranty.

Q: How quickly does the probe equilibrate?

A: The probe has a very fast response. Typically less than 2 seconds. The probe holder is designed to be placed into the incubator and mimic the gas transfer between the incubator and the media. If it is put into the incubator at the same time as the culture dish it will, in effect, give a live reading of the pH in the culture dish.

Q: Can I use the pH meter to adjust the CO2 on my incubator?

A: CO2 levels will influence pH, but the relationship between the two is not a simple one. pH is also influenced by temperature, pressure and medium chemistry. See; Pool, T., 2004. Optimizing pH in clinical embryology. Clinical Embryologist, 7(3), pp.1–17. Available at:

Q: How do I calibrate the unit?

A: Use the calibration buffers provided by RI. The full calibration procedure is described in the user manual.

Q: How often does the probe need calibration?

A: Check with pH7.00 buffer daily. If the reading is incorrect then perform a recalibration. Calibration should also be done each time the meter is switched off and back on, whenever a new probe is connected, or whenever the calibration reminder on the meter appears.

Q: How long does a probe last?

A: The probe is relatively robust and should last for at least a year with correct maintenance.

Q: How do I clean my probe?

A: Soak briefly in a lab detergent such as 7X and rinse with purified water. Use the soft bristled brush supplied to clean the probe and rinse again with purified water. Follow this with a soak in potassium chloride solution. See the User Manual for full instructions.

Q: How long can you continuously monitor media pH in an incubator with IVF media and protein before you have to clean the probe?

A: We currently recommend a maximum recording length of 24 hours. The probes naturally exhibit a small upwards drift in pH. Within 24 hours this drift should be no more than 0.14pH, and can be corrected for with the built in Drift Compensation feature.

Q: Does the concentration of protein affect how often the probe needs to be cleaned and the life of the probe?

A: Proteins tend to adhere to the probe surface, hence higher concentrations will require more regular cleaning.

Q: How can I measure the pH of several incubators in succession?

A: We don’t recommend that you measure in succession because each measurement should take 24 hours and if the measurements were done too quickly the accuracy is compromised. We suggest that upon acquiring the pH Meter you measure, following the instructions in the manual, each incubator in the lab. When you are satisfied that all the incubators are working with sufficient uniformity the pH Meter should only be employed when there is a change to the conditions. This means that when there is a new batch of media or CO2 then a reading can be taken from any of the incubators and that reading should be representative of all the other incubators.