Nat. Protoc. 10, 681–700 (2015); doi:10.1038/nprot.2015.031; published online 2 April 2015; corrected after print 27 May 2015

In the version of this article initially published, the text detailing the HPLC elution protocol in the Equipment Setup section (a 2-min column pre-equilibration in 9:1 A:B (vol/vol); sample injection; 2-min wash with 100% A; 14-min linear gradient to 100% B; and 15-min post-run column equilibration) was incorrect and has been changed to read: a 2-min column preequilibration in 9:1 A:B (vol/vol); sample injection; 2-min wash with 100% A; 12-min linear gradient to 100% B; and 1-min post-run column equilibration. The error has been corrected in the HTML and PDF versions of the article.