小中大

求助！关于marker residue ！！谢谢谢谢！

tulathromycin residues were converted to the marker residue by acid-catalyzed hydrolysis with 2N hydrochloric acid at 60 C.
1，这个marker residue 要怎样能够得到？！
2，这里所说的加入2N 盐酸，要怎么加入！？
谢谢各位大神了