3.3.1. JH extraction
Transfer the entire acetonitrile sample into a 12 x 75 mm disposable glass test tube, but avoid transferring debris that may have accumulated during storage.
2. Add 1 ml of 0.9 % NaCl.
3. Add 1 ml of hexane.
4. Vortex thoroughly for 10 s.
5. Keep vials on ice for 30 min.
6. Centrifuge for 5 min at low speed for complete phase separation.
7. Transfer the hexane phase (upper layer) to a new 12 x 75 mm glass test tube.
8. Repeat steps 2 to 7 twice, each time adding 1 ml of hexane to the acetonitrile/saline phase.
9. Pool the hexane phases of each extraction step.
10. Evaporate hexane to dryness by vacuum centrifugation or under an N2-stream.
11. Re-dissolve JH in 40 µl of toluene containing 0.5% propanediol .
12. Transfer liquid to a RIA glass vial (disposable 6-8 x 40-50 mm test tubes).
13. Wash the extraction vial with another 40 µl of toluene/propanediol.
14. Add to RIA vial (step 12).