Methods for purification of messenger RNA

A method of large scale purification of mRNA, comprising steps of:

• providing a solution comprising at least 250 mg of in vitro synthesized mRNA;
• adding one or more agents that promote precipitation of the mRNA, thereby obtaining a slurry;
• stirring the slurry in an agitated filter dryer at a speed between 50 revolutions per minute RPM and 500 revolutions per minute underpressure to the slurry and/or a vacuum to the slurry sufficient to direct the slurry's mother liquor through the filter, thereby obtaining a precipitate-containing composition;
• and
• washing the precipitate-containing composition with stiffing and under pressure, thereby yielding a purified mRNA precipitate,
• wherein the purified mRNA has reduced impurity of enzyme reagents used in in vitro synthesis as compared to the otherwise same mRNA purified by tangential flow filtration and has an integrity greater than about 95% determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis with silver staining.