The present invention provides a method for preparing DMF for sucralose production, including, e.g., isolating DMF from a composition comprising DMF, water, and methanol, using a single-tower rectification system. In various embodiments of the present invention, the composition, after the removal of water and methanol, may be further dried/dehydrated, such as, by using a dehydration agent and/or filtration. The resulting substantially pure DMF may comprise at least about 98-99% DMF. The present invention further provides a method of preparing a composition comprising anhydrous sucrose for sucralose production, which may comprise mixing regular sucrose with a water-containing DMF composition, and drying the resulting sucrose-DMF composition. Also provided is a single-tower separation system for isolating DMF from a composition comprising DMF, water, and methanol.