BACKGROUND Both polymerase chain reaction (PCR) purification kits and DNA gel extraction kits have been widely used for DNA purification in laboratories worldwide. However, the uses of these kits are costly and produce laboratory wastes that have negative impacts on the environment; it is important to develop a novel method to overcome these drawbacks. RESULTS Here we demonstrate that a saturated sodium iodide solution and a laboratory-made washing buffer can replace the buffers in PCR purification and gel extraction kits for DNA purification and do not affect DNA purification capacity. These two buffers can be utilized to purify DNA along with the columns recycled from PCR purification and DNA gel extraction kits and can maintain DNA purification capacity that is comparable to that of commercial kits. For small-sized DNA fragments, the buffers developed in this study are even more efficient compared to commercially available buffers from PCR purification and DNA gel extraction kits. The quality of DNA purified with these two buffers can meet the requirements of gene cloning. CONCLUSIONS This study provides a two-buffer method that is used for both PCR product purification and DNA gel extraction. This method is simple, of low cost and beneficial to numerous laboratories worldwide. (c) 2019 Society of Chemical Industry