back to Manual - Perfusion Circuit

 

Refractometers are used in cryonics to measure the concentration of cryoprotective agents (CPAs) during perfusion. 

 

Inline refractometers are described on the DAQ Refractometer page.

 

Digital Handheld Refractometer

Atago model PAL-alpha

Clean the prism of the digital handheld refractometer with distilled water and wipes.  Place a few drops of liquid to be analyzed on the prism and wait for the temperature of the prism and the liquid to equalize.  It uses built-in temperature compensation, which is not very accurate for our situation, so always ensure that the temperature showing is within a few degrees of 20 deg C.  Record the Brix, which will later be converted to Percent Concentration Needed to Vitrify (%CNV).

 

Concentration Conversions

Conversions from Brix to %CNV are handled through lookup tables.  The lookup table is determined upon startup in the Startup window.

 

Software

The Perfusion Monitor Software has a section for concentration at the bottom middle.

 

 

Click the "Handheld Readings" button to manually enter a reading from the handheld refractometer.

 

 

Click Add Reading or double click on an existing reading

 

 

The %CNV box is not editable, but is instead calculated automatically based on the Brix reading and interpolation from the lookup conversion tables.  Change the time to match when the sample was obtained rather than the current time.  The time is automatically set to 3 minutes ago as a first guess.

 

While the inline refractometer values are recorded in realtime in the main text output file, the handheld measurements above are handled differently.  For technical reasons, because the readings are entered after the fact, the values must be recorded to a separate text file.  The data in the grid above is saved to file every time the grid window is closed.  It is possible to go directly to the file on the hard drive to see and verify that this is happening.  The file will be read-only as long as the software is running to prevent a lock situation.

 

Both the inline refractometers and the handheld refractometer natively measure Brix, so all measurements in the software are stored as Brix.  The measurements are then converted to % Concentration Needed to Vitrify (%CNV) for display on the graph.  The primary digital display to the right of the concentration graph is the inline arterial value.