For example, the retention of neutral compounds in reversed-phase chromatography systems is independent of the pH of the mobile phase; acidic compounds will increase their retention as the state tends to be neutral when the pH tends to be acidic (the pH becomes lower, especially lower than the pka value of the compound); and Basic compounds tend to be more retained as the mobile phase pH tends to be basic (the pH becomes higher, especially above the compound’s pka value) as the state tends to be neutral.
However, if the pH of the mobile phase is adjusted too low, the column efficiency will be reduced, the resolution will be reduced, the peak shape will be affected, and the column life will be shortened. Today we’re talking about a column that maintains its stability and longevity in acidic mobile phase conditions, the Welch LP series of columns.
The C18 column is widely used and has “magnificent powers”. The LP-C18 chromatographic column in the Welch Ultisil® series adopts a unique silica gel surface treatment and stationary phase bonding process. The barrier protection technology enables better decomposition performance, stability and longer service life under acidic mobile phase conditions. LP is the abbreviation of “Low pH”. In addition to being tolerant to lower pH mobile phases, LP-C18 also has good peak shape and resolution under 100% aqueous mobile phase conditions.
In addition to LP-C18, LP-AQ, LP-C8, LP-C3, LP-CN and UHPLC LP-C18 are members of the large family of Ultisil® LP series, all of which are characterized by low pH tolerance. Among them, LP-AQ is also a C18 column, its tolerance to aqueous phase can reach 100%, but it will have different selectivity from LP-C18. The retention performance of C8 and C3 on the analyte is weaker than that of C18, and the carbon content has a great influence on the separation effect and the retention of the main components. When the analyte is too strongly or too weakly retained on a C18 column, then a CN column may be an alternative. The existence of Welch UHPLC LP-C18 chromatographic column makes the ultra-high performance liquid chromatography mode not a problem under low pH chromatographic conditions.