Essential Practical NMR of Organic Chemistry by S.A. Richards and J.C. Hollerton - ISBN 978-0-470-71092-0
is a practical starter for this topic.
Chapter 2.4 / page 18 to 21 has to do with your question.
They do even more, ... their filtration vessel is pasteur pipette, filled up first with a cotton wool plug, some "Hyflo" (R) layer and on top of this a layer with anhydrous Na2SO4.
... extra drying, and adsorbing unwanted particles from your deuterated solution (solvent and suspended material)
Be also aware, cotton can also keep unwanted material on its surface and can react with your solvents, ... you can use here glass wool instead!
Please read the whole article and also the whole book. ;-)
answered Sep 12 '16 at 03:15