abstract

Abstract

The ExionLC 2.0 system is a flexible and robust UHPLC system that is suitable for today’s challenging LC-MS workflows. With high autosampler precision and accuracy and low carryover, excellent linearity of injection is demonstrated. High retention time precision enables large scale time scheduled quantitative assays.

introduction

Introduction

An important aspect of a successful mass spectrometry (MS) experiment is combining it with some form of high-quality upfront sample separation. In majority of cases, this is achieved using liquid chromatography (LC). As the sensitivity, speed and selectivity of mass spectrometers continually improves, faster, more powerful LC-MS workflows are achievable. LC-MS users also desire workflows with reduced sample preparation. They require detection levels to be attainable with less sample injected onto the LC-MS system. This puts pressure on the LC system to be able to handle increasingly complex matrices and provide good injection reproducibility for sub-5 µL volumes. In addition, more sensitive MS instruments with detection capabilities at lower levels have requirements for even lower carryover on the LC system, to reduce the risk of false positive results.

In this technical note, the key performance attributes of the SCIEX ExionLC 2.0 system were investigated, specifically the injection linearity and precision. Injection routines were also investigated to assess the system carryover with the various approaches. As is typical, flow rate precision and resulting retention time reproducibility was studied. Either a SCIEX Triple Quad 5500 system or the integrated optional ExionLC 2.0 diode array detector HS were used for detection, depending on the specific test performed.

Figure 1. Retention time precision. Overlaid extracted ion chromatograms of select compounds from 100 repeat injections of the same standard solution of forensic drug compounds using the ExionLC 2.0 system. Typical retention time stability achieved is <0.3% RSD.

image-top

Key features of the ExionLC 2.0 system

• High-pressure, dual, serial piston pump rated to 860 bar at flow rates of 0.001 to 2 mL/min for maximum flexibility
• Precise and stable solvent flow delivering less than 0.3% RSD retention time variation
• Accurate and precise quantification results with injection linear coefficient of determination performance (r²) > 0.999 and precision <1% coefficient of variation for injection volumes from 0.5 to 50 µL for most compounds studied; 0.5 to 25 µL for all compounds
• Multiple wash solutions and extended needle wash capabilities to minimize carryover and reduce the false positive rate and the need for repeat extractions and re-injections
• Ability to accommodate a wide range of UHPLC columns for fast separations and high throughput
• Achieve high peak resolution and capacity at lower pressures using fused core columns with particles in the 2-3 µm range.