Table 1.
General procedure to prepare contrast agent (CA) concentrates for DNP.
| Step | Operation | Duration (min) | Comments |
|---|---|---|---|
| 1 | Take CA and trityl radical out of the freezer/fridge | 5 | Consider storing conditions and shelf life of agents |
| 2 | Wait until CA and radical are melted | 20 | Keep the vials in a warm place. Avoid the direct sunlight |
| 3 | Add desired amount of CA to the vial (e.g. 1.3 g) | 2 | e.g. Eppendorf vial |
| 4 | Add deionized water and glycerol in sufficient quantities (e.g. 0.5 g each) | 2 | Use scales to measure glycerol |
| Check for the glassy matrix by dropping 5 µL of the solution in liquid nitrogen | |||
| 5 | Put desired amount of radical in a vial (e.g. ~ 50 mg) | 2 | |
| 6 | Mix CA and radical | 10 | Using spatula or ultrasonic mixer e.g |
| 7 | Divide in ca. 250 µL aliquots | 5 | Using pipet, Eppendorf vial |
| 8 | Put mixtures in freezer | 1 | e.g. − 20 °C |
| 9 | Warm up one vial, retrieve desired amount of concentrate, freeze remaining aliquot | 15 |