Solid Phase Microextraction Sampling: A Probe-based Technique for Sample Extraction from Graft Tissues

Start by preparing a preconditioning mixture composed of 1 to 1 methanol and water. Pipette 1 milliliter of the solution into each 2-milliliter glass vial and place one probe in each vial. Agitate the vials on a vortex agitator at 1,200 rpm for 1 hour. Then, rinse the probes with LC-MS grade water and sterilize them according to the standard surgical sterilization protocol or in sterile processing department.

When ready to extract the sample, open the sterile packaging and insert two probes directly into the kidney cortex for 10 minutes per time point, making sure that the entire length of the coating is covered by the tissue matrix. Make sure to keep track of the time of sampling for each probe. Retract the probe by pulling it out from the tissue and immediately rinse the coating with LC-MS grade water to remove any remaining blood, making sure to rinse away from the surgical site.

To transport the probes, place them in separate vials and close them. Then, place the vials in a box filled with dry ice or liquid nitrogen. Store the samples at negative 80 degrees Celsius or immediately proceed with desorption.

Prepare a desorption solution composed of acetonitrile and water for metabolomic analysis and another composed of isopropanol and methanol for lipidomic analysis. Add 100 microliters of the solution to inserts in the 2-milliliter labeled vials and place one probe in each vial. Agitate the vials at 1,200 rpm for 2 hours. Then, remove the probes from the vials and proceed with LC-MS analysis.