In an embodiment, an optical system comprises an optical cell having an interior fluid chamber defined by an interior surface of a housing, a process inlet disposed in the housing and in fluid communication with the interior fluid chamber, and a process outlet disposed in the housing and in fluid communication with the interior fluid chamber, wherein the process inlet and process outlet facilitate the flow of a fluid through the interior fluid chamber. A sampling outlet can be disposed in the housing and in fluid communication with the interior fluid chamber. A first bi-directional pump can be in fluid communication with the sampling outlet and a first storage vessel and can be configured to withdraw a first sample of the fluid via the sampling outlet and to cause the first sample to flow into the first storage vessel.