Dear colleagues
we are working with ISFET measurement technology to detect NO3-, H2PO4 and K+ as well as pH.
I am looking for a comprehensive publication with the subject: conditioning of ion sensitive ISFET. So, how is the ionophore optimally conditioned or made sensitive to the corresponding ion. Is there any indication for different approach when different concentrations are to be analyzed?
Who has researched different conditioning procedures and published the results?
Many thanks and best regards from Osnabrück / Germany, Stefan
We are also working with ion-selective membranes for soil samples. We have found the following procedure to be effective for calibration before measuring in soil, reducing cross-sensitivity to other ions:
Recalibration of the sensor after few samples may be required, in case the diviation gets higher.
This procedure has been successful for us in reducing cross-sensitivity and obtaining accurate measurements. We hope you find it helpful for your work as well.
Best regards, Mohamed Bourouah
Hello Mohamed,
Thanks for your reply and explaining your procedure for calibration and measurement. How you do it is a different procedure for us; we will discuss it internally. Thanks again.
What do you do before calibration and measurement; how and what do you do when conditioning the ISFET membrane/ionophores?
There are different indications in the literature, e.g. before using the ISFET electrode condition the ionophores with a 1mMol/l solution for several hours. Another indication from the literature is to condition with a 10 mMol/l solution.
It is also important to consider the duration of the conditioning.
How do you prepare the ionophore/membrane? How do you condition the ionophores?
Many thanks and best regards from Osnabrück, Stefan
Hello Stefan,
I wanted to share with you that we are using ion-selective electrodes from Van London, available at http://www.vl-pc.com/default/index.cfm/ion-selective/laboratory/ise-potassium/. According to the data sheets provided by Van London, they recommend immersing the electrode in deionized water for thirty minutes prior to its first usage or after long-term storage. Once this procedure is followed, the electrode is ready for use. We have been using this procedure and it has been successful for us.
In most cases, the ionophore used in ion-selective electrodes is similar to the ISFET ionophore. However, it's worth noting that different sensor providers may have their own conditioning recommendations. For example, Hach sensors suggest conditioning the sensors in a low concentration solution, typically around 10ppm, for a duration of 10-30 minutes(https://support.hach.com/myhach/s/article/KA-en-US-TE6932-1009127?language=en_US).
Please feel free to contact me if you have any additional questions
Best Regards, Mohamed
Hello Mohamed
Thank you for your reply. I have read the instruction manual. You are using ISE (Van London ISE-Electrode) with wet reference electrode. Conditioning/sensitization of the Van London ISE-Electrode is probably not necessary.
Hach ISE electrodes are to be conditioned with the lowest calibration solution in the calibration set.
I find it very interesting that are now 2 very different notes on conditioning.
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