What is the effect of temperature during cryotrapping?
It depends on the temperature regime you of your cryo-trap.  If you are trapping in the temperature range from dry ice to water ice then you must be sure any significant water vapor in you sample has been removed.  If you are using liquid nitrogen, there is some danger of condensing oxygen.  This can be mitigated by using the enough-warmer-that-this-doesn't-happen-with-air liquid argon.