Acid guanidinium thiocyanate-phenol-chloroform extraction (abbreviated AGPC) is a liquid–liquid extraction technique in biochemistry. It is widely used in molecular biology for isolating RNA (as well as DNA and protein in some cases). This method may take longer than a column-based system such as the silica-based purification, but has higher purity and the advantage of high recovery of RNA: an RNA column is typically unsuitable for purification of short (<200 nucleotides) RNA species, such as siRNA, miRNA, gRNA and tRNA.
It was originally devised by Piotr Chomczynski and Nicoletta Sacchi, who published their protocol in 1987. The reagent is sold by Sigma-Aldrich by the name TRI Reagent; by Invitrogen under the name TRIzol; by Bioline as Trisure; and by Tel-Test as STAT-60.