We've just acquired a new freeze-dryer that allow us to perform freeze-drying with two steps and with accuracy on the level of vacuum and temperature to be used. I have been used to use old machines, that did not allow such an accuracy to freeze-dry the samples before isotopic analyses. So I'm wondering if some of you would be kind to share the protocol (ie time, temperature and pressure) they use to perform two-steps freeze-drying ?

Thanks in advance for your help !