Hello everyone! I'm a graduate student at the University of Virginia beginning a project on Oxygen-18 and deuterium in rain water. I'm building a rain collector that allows for collection at 5 minute increments for 12 hours and I am worried about the possibility of sample fractionation. I read a paper suggesting the creation of a dodecane bi-layer when analyzing for oxygen, but I am unsure how this would effect deuterium results. Does anyone know of a reference or have an opinion of using such a technique when analyzing for deuterium? Due to field constraints, refrigeration really isn't an option and I was curious if anyone had ever run into this problem before or had a good solution to fractionation in the field. Thanks!, Isabella Angelini University of Virginia [log in to unmask]