If you prepare two separate solutions of Fehling's A and Fehling's B, what is the shelf life likely to be? Will the effectiveness of the solution diminish over time? The literature recommends preparing these solutions separately and storing them in rubber stoppered bottles. I assume this means that atmospheric air will affect the solution. My thought is that carbon dioxide will dissolve in the solution and form an acid, which would lead to a false positive result later in the Fehling's reagent test for carbohydrates.