Find out more about protocols and guidelines for everyday pH monitoring

Site Standardization

What is site standardization?

This procedure is like an initial calibration that is done with CO2 or temperature sensors in incubators. At the time of installation, each TrakPod must be “initialized” to the exact physical environment of your lab so that it will report the correct pH. There are several factors that can impact the displayed pH reading which are corrected for with site standardization. Primarily these are 1) the type of media used, 2) the CO2 concentration and 3) elevation conditions at the clinic. For cabinet incubator installations, additional considerations are proper fixture installation on the incubator shelf and whether or not the fiber optic cable on the TrakPod is compressed and/or bent as part of the installation. TrakStation site standardization is not used initially to help the clinic find the right CO2 settings to get a desired pH. Site standardization is customizing the Trakpod pH calculation and pH read to the incubator conditions using a comparison pH sample under the same conditions. Once the TrakStation is installed the real value comes from maintaining optimal conditions.

Why is site standardization so important?

Site Standardization is done when you first install the TrakStation pH monitoring system.  It is used to correct for three key variables: Media type, Elevation, and Fiber optic installations.  Each of these three components has a measurable impact on the pH readings collected using the TrakStation pH monitoring system, but they are easily corrected for with the site standardization protocol.

Why do I use 3 sensors for site standardization?

We recommend three sensors to achieve an average pH value. Each sensor can have slight differences in pH with a tolerance expected of ±0.05 pH units. Using the average of three sensors avoids the possibility that the TrakPod value will be offset from one sensor that read at the high or low range of the pH tolerance.

What are the references that should be used for site standardization?

BCSI has three choices in reference pH samples:

1. BEST OPTION- Read a pH sample using a blood gas analyzer (BGA)

2. GOOD OPTION: Read a pH measurement using a pH meter.

3. OK OPTION: Use the pH information from the media certificate of compliance and match the CO2 value and/or correct for elevation.

Options 1 and 2 are most recommended by BCSI.

What are the limitations of using the certificate of compliance as a reference?

The certificate of compliance (COC) is the least preferred reference for media site standardization, and should only be used if no other direct pH measurements exist. When using the COC, several key assumptions are made: 1. You have duplicated the incubator environmental conditions that the media manufacturer used during their pH measurements 2. The media in the sv2 sensor cups has fully equilibrated to the levels expected for the CO2 and temperature. The best option for site standardization is to make a direct measurement from another media sample, in the same incubator, using a reference pH measurement tool.

What if a lab doesn’t have a reference pH and they don’t want to use the CoA from the media?

Alternative references can be brought into a clinic: Sometimes the media manufacturer is willing to send out application specialists to do pH measurements for the clinic. If you are unsure about your current pH read capabilities or do not know your preferences for a reference pH, please contact support@safesens.com prior to installation to determine the optimal method. We are happy to assist you in meeting the lab’s reference pH preferences.

What if the initial readings from site standardization show a lot of variance?

The pH system is accurate to ±0.05 pH units – sensor readings can range from say 7.14 to 7.24 and be within expected tolerances. Ultimately what to do depends on what type of variance is seen. Often when three sensors are used there will be two that agree closely and one that is different. In this case, read the two that closely agree twice each and average those four readings. If the different sensor is high, it most likely has not equilibrated well in the CO2 environment. Sometimes a bubble of air that is temporarily present in the sensor can prevent or slow the equilibration process. If all three (3) sensors are very different from each other then it is advisable to start over with new sensors. Pay attention to the filling of the media and oil and be careful about bubbles. These factors make differences in the actual pH within the sensor cups.

If the sensor cups weren’t in long enough to equilibrate can we still do site standardization?

It is best to wait the full twenty-four (24) hours before doing the site standardization procedure. If you take the sensor pH readings prior to equilibration you may artificially be reading a pH that is too high because the sensor has not fully equilibrated. A full 24 hour equilibration time period will result in a smoother site standardization. If time does not allow the full 24 hours, you may need to make adjustments post installation.

How large of a pH offset value is OK?

If the offset value is greater than 1.0 pH units, something is likely wrong with the system. Make sure to run a QC test and repeat the site standardization measurements. Set the offset value so that data displayed will be saved for later data review. Afterwards, please download the data and contact us at support@safesens.com for further assistance.

Can we use the sensors from site standardization in the first test?

Yes. If the site has multiple incubators, you can set up three (3) for the site standardization, measure them in the first incubator and move them quickly to the next incubator and measure them there on site standardization also. When completed put one (1) sensor on each TrakPod and start the first week of pH monitoring.

Everyday Testing

What should I do for pH monitoring if my lab changes media in cycle?

Several options exist for pH monitoring:
1. You can monitor each media and confirm that the environmental impact for that media remains optimal.

OR

2. Two (2) TrakPods can be used to monitor each media type.

OR

3. Lastly, two (2) sensors can be prepared – one with each media and the sensors can be exchanged when the embryos are moved to the next media (this can be difficult to time when embryos have different starting times).

How long does it take to set up the system prior to each cycle?

The day before each cycle starts, it takes 1-2 minutes to prepare a sensor with media and begin the overnight equilibration.  Another 1-2 minutes are needed to run a QC test at the start of the cycle followed by starting the pH test with the newly equilibrated sensor.

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How long does equilibration take?

Sensor setup is done with un-equilibrated media and oil.  The sensor is then placed in the incubator overnight so it is properly equilibrated and ready for monitoring the next day (16 to 24 hours later).  This allows time for the sensor wetting between two (2) and four (4) hours and also for CO2 adsorption into media approximately twelve (12) hours.image002

How do I correct the certificate of compliance to be the right pH level for my lab that uses a different CO2 concentration?

BCSI has an excel worksheet that performs the calculation based on bicarbonate media equilibrations against CO2, elevation or pressure. It is provided here as well as on the USB flash drive with the TrakStation.

How can we mimic the oil level used in our culture dishes using the sv2 sensor?

The recommended volume of 100 μL of media should not be changed as this is needed to cover the fluorescent membrane. Oil layers for humid incubators should be at least 50 μL. For dry incubators they should be 150 μL. The smaller oil layer will allow the pH sensor to respond to CO2 changes with a pH change more quickly. But users may increase their oil volume up to the 150 μL if they desire.

If a sensor was filled incorrectly can it be rinsed with a correct media and then used?

Sensors cannot be reused after they have been filled and used for a pH monitoring. We do not have data to support pH accuracy when you rinse out one media and replace it with a different one. As a result, we recommend using a new sensor.

Does the system include an alarm feature to notify laboratory staff if the pH changes?

Yes- users can easily set a predetermined range and email alerts will be sent in the event the pH moves out of set range.  To enable this feature, the TrakStation must be connected to the internet.

What is the drift correction about and how does it work?

Each time the TrakPod takes a fluorescent pH measurement, there is a small effect on the sensor that creates a decrease in pH over time. This effect is well understood and is linear. The Drift Correction compensates for this effect during pH monitoring and is based on how long a pH test has run to calculate for small fluorescent changes.

Data Collection and Analysis FAQs

Get answers to common questions on how to retrieve and visualize pH data collected using your TrakStation pH monitoring technology

Can I save the data?

Yes, data can be exported into a CSV file to a USB drive or over a network connection.

Can I see trends of pH readings from the TrakPods?

Yes each TrakPod detail screen show recent pH data.  This can also be exported and plotted in spreadsheet tools.

How do I remotely access the TrakStation?

If your TrakStation is network connected, it is possible to access all the controls of the TrakStation from a separate computer that is on the same network. Please follow instructions here: https://www.safesens.com/trakstation-users-manual/menu-functions/.

If the lab already has a PC, can we use that as a TrakStation?

In 2017 we released a software-only version that allows almost any Windows PC running 8.0, 8.1 or 10 to emulate TrakStation software. All features and functions are available. Please contact Customer Support at support@safesens.com for availability.

Can we set the TrakStation up so we get emailed the data automatically?

This is a feature we plan to enable in a future software release. If the TrakStation is connected to a WiFi network, you can have the user email data directly. Or, if no network connection exists, the user can download the data to a USB storage device and email those files from a lab PC. A list of TrakStation supported USB storage devices is located on the website at https://www.safesens.com/ivm/usb-drive-support/.

If you are unsure about the network connection a lab may have, please inform the lab before installation they may need to contact their IT department and determine how to connect to a network if they do not know how to do so. We are happy to reach out and discuss options to successfully install the system with a network connection when given information prior to installation.

How frequently are pH data points collected?

The TrakStation measures pH data every 30 minutes for 7 days as the standard interval.  pH data collection is also possible for research applications using 1-minute data collection for 3 days.

I have a question that was not covered in the FAQ. What now?

Great! Please email support@safesens.com with your question and we will be happy to provide an answer for you. Please let us know in your message that you could not find your question in the FAQ sections, and we will add it to our website in order to assist other customers in the future.