In-line filter Vs filter at end of sampling probe [Dissolution / BCS / IVIVC]
Please I need an explanation on what is the difference between an in-line filter and filter at end of sampling probe.
I saw a dissolution methodology which stated thus:
"...tablet was placed into a dissolution medium and then 5ml of dissolution was withdrawn at the stipulated time and immediately filtered through a syringe filter."
This methodology was queried by seasoned regulators. They requested that the filters should be in-line or at the end of the sampling probe or both.
What do they mean by that statement? Isn't that syringe filter considered as an in-filter? What do they mean by filter at end of sampling probe? What's the difference between an in-line filter and a filter at end of sampling probe?
I will really appreciate an assistance with this puzzle.