Improving Peak Shapes Affected by Sample Solvents in UHPLC Systems

User Benefits

- Peaks broadened by sample solvents in UHPLC systems can be improved. - Peak shapes can be improved using the “co-injection” automatic pretreatment function.

Introduction

Ultra high performance liquid chromatography (UHPLC) enables high speed and high separation analysis by using a UHPLC column packed with particles about 2 μm in size. UHPLC columns have an internal diameter that is narrower than general-purpose high performance liquid chromatography (HPLC) columns, which results in less diffusion of sample components within the column. However, because peak shapes are affected by diffusion that occurs throughout the system, including the column, using an HPLC system for analysis prevents the full benefit from UHPLC column performance capabilities to be obtained, due to system diffusion in areas other than the column. Therefore, a UHPLC system commonly employs tubing with an inner diameter of 0.1 mm or less. On the other hand, the use of the UHPLC system which employs tubing with smaller inner diameter is prone to be affected with inadequate mixing of the sample solvent and mobile phase. Consequently, the peak shape may be broadened when using a sample solvent with a higher elution strength than the mobile phase. That phenomenon can occur in cases (1) and (2) below. (1) When analysis is performed in a UHPLC system using HPLC analytical conditions. (2) When large volumes are injected and there is a large difference between the elution strength of the mobile phase and sample solvents. This article introduces a case where peak shape was improved by using the automatic pretreatment function (co-injection) of autosamplers in Nexera series when peak broadening occurs in cases (1) and (2) above.

October 26, 2022 GMT