A reagent preparation and dispensing device includes a body having a reaction chamber for a reagent and a solution reservoir for a solution. The solution reservoir is isolated from the reaction chamber. A plunger is movably coupled with the body. Movement of the plunger from a starting position to a seated position pushes the solution into the reaction chamber. A dispensing path extends from the reaction chamber out of the body. The dispensing path is configured to dispense a reagent mixture formed from the solution and the reagent. A vent path extends from the reaction chamber, the vent path vents reaction chamber gas displaced by the addition of the solution to the reaction chamber throughout movement of the plunger from the starting position to the seated position.