A process comprising: carbonylating at least one member selected from the group consisting of methanol, dimethyl ether, and methyl acetate in the presence of 0.1 to less than 14 wt.% water, a rhodium catalyst, methyl iodide and lithium iodide, to form a reaction medium comprising acetic acid in a reactor; separating the reaction medium into a liquid recycle stream and a vapor product stream; separating the vapor product stream in up to 2 distillation columns in a primary purification train to produce a crude acid product comprising acetic acid comprising lithium cations; contacting the crude acetic acid product with a cationic exchanger in the acid form within a first treatment device to produce an intermediate acid product; and contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin having acid cation exchange sites within a second treatment device to produce a purified acetic acid, the first treatment device, the second treatment device, or both comprising an inner chamber bound by a plurality of sides radially arranged about a central axis; an inlet end in fluid communication with, and longitudinally separated from, an outlet end through the inner chamber; a plurality of sampling ports disposed through at least one of the sides, each comprising: a first open flow path between a sample inlet located within the inner chamber and a flow control element operable between an open position and a closed position located external to the inner chamber; and a second flow path comprising a porous element disposed between the sample inlet and a second flow control element operable between an open position and a closed position located external to the inner chamber. carbonylating at least one member selected from the group consisting of methanol, dimethyl ether, and methyl acetate in the presence of 0.1 to less than 14 wt.% water, a rhodium catalyst, methyl iodide and lithium iodide, to form a reaction medium comprising acetic acid in a reactor; separating the reaction medium into a liquid recycle stream and a vapor product stream; separating the vapor product stream in up to 2 distillation columns in a primary purification train to produce a crude acid product comprising acetic acid comprising lithium cations; contacting the crude acetic acid product with a cationic exchanger in the acid form within a first treatment device to produce an intermediate acid product; and contacting the intermediate acetic acid product with a metal-exchanged ion exchange resin having acid cation exchange sites within a second treatment device to produce a purified acetic acid, the first treatment device, the second treatment device, or both comprising an inner chamber bound by a plurality of sides radially arranged about a central axis; an inlet end in fluid communication with, and longitudinally separated from, an outlet end through the inner chamber; a plurality of sampling ports disposed through at least one of the sides, each comprising: a first open flow path between a sample inlet located within the inner chamber and a flow control element operable between an open position and a closed position located external to the inner chamber; and a second flow path comprising a porous element disposed between the sample inlet and a second flow control element operable between an open position and a closed position located external to the inner chamber. a first open flow path between a sample inlet located within the inner chamber and a flow control element operable between an open position and a closed position located external to the inner chamber; and a second flow path comprising a porous element disposed between the sample inlet and a second flow control element operable between an open position and a closed position located external to the inner chamber.