Method for preparing deionized formamide

The invention provides a method for preparing deionized formamide, which comprises the following steps: (1) formamide and ion exchange resin are mixed to obtain a mixture; (2) the mixture obtained from the step (1) is uniformly mixed, then the mixture is passed through a filter for removing ion exchange resin, collecting a filtrate to obtain the deionized formamide. The water content of deionized formamide prepared by the above scheme is below 1.8%, the conductivity of formamide is substantially lower than 100 muS/cm, the repeatability between batches is good and the stability under the room temperature is good, so that deionized formamide is capable of satisfying the application requirement. The detection results of capillary electrophoresis present that the internal standard peak type is sharp, the resolution is good, no non-specificity impurity peak generation, the sampling volume of DNA fragments is uniform, the distribution of peak height is normal, thereby the detection results present that the conductivity of deionized formamide conforms to the treating requirement of capillary electrophoresis samples.