As helpful as iron is to me initially, it really interferes as I try to progress my samples. This means one removal step isn’t quite enough. This brings me to my first column. What is a column? Well, in chemistry terms it is a physical structure used to separate substances or elements from each other. As seen here, my iron removal columns are rather small (maybe 5 inches tall) plastic tubes that narrow at the base of the reservoir (upper section) and again near the very base. These plastic columns are loaded with resin, the resin changes based on the goal of the column. The resin is key, it reacts in a predictable way with different elements and we can control that reaction based on the eluent, or fluid, we pass through the column. In this case, as long as we add only hydrochloric acid the resin will hold on to the iron (that is why there is a bright yellow layer near the top of the resin) and will let the rare earths pass through (a “clean” sample). If we added nitric acid, the iron would be released but that’s not what we want!