Justin's example might be perfect, but without knowing the rule you are using it is hard to tell. The rule might be to drop all leading digits and spaces, or it might be to start at "Assay". And on the other end, the rule might be to drop two final space delimited numbers, or all but the last digit or everything after the last digit connected to a word. And these are just some possible rules. Once you know the rule, making a regex to follow it becomes easier.
If you are puzzling over Justin's example, read it like this:
( ... )+ means match what is inside the parens one or more times
[a-z]+ means match one or more letters
\d? means match one or zero digits
\s means match a space
Each 'word' matched by the parens includes an optional trailing digit and a required trailing space, even the last word. Justin used the trim function to remove the final space from the result. If your data might not have a space after the last word, the last word won't be included.
Craige