Since its inception, high-performance liquid chromatography (HPLC) has undergone technological enhancements in all aspects, whether that’s improvements in detectors, better accuracy and precision or new column chemistries. Since the millennium, most of the advances have been centred on performing faster separations through the advent of UHPLC (ultra-high-performance liquid chromatography) complemented by smaller column particles and diameters. That’s not to say that other enhancements have not been made in the areas of robustness, reliability and detection sensitivity. All of these developments have given rise to increases in productivity, but what actually is productivity?
Productivity means different things to different people, but in general for liquid chromatography, it has many beneficial outcomes, such as higher throughput, reduced cost per sample, greater return-on-investment (ROI) for high-value instrument purchases (not just the HPLC instrument, but ancillary equipment such as mass spectrometers) and basically a faster route from sample to knowledge. Where is the future for HPLC? Will it all be focused on productivity?
My belief is that the future for HPLC is focused around productivity. Technology enhancements, whether that is offering more pump pressure, reducing column particle sizes and diameters, or simply offering better system performance and robustness, all increase productivity. They will increase throughput and drive down cost per sample. Productivity is king and there is a new solution out there that can really enhance productivity.
Three Workflows. Two Flow-Paths. One Integrated Solution.
This new step-change for HPLC productivity comes in the form of the Thermo Scientific™ Vanquish™ Duo UHPLC systems. These systems build off the Vanquish UHPLC platform by incorporating new modules (i.e. dual gradient pump and a unique dual autosampler) to offer three workflows that increase productivity in a single system: dual LC, tandem LC or LC-MS and Inverse Gradients.
Dual LC – by combining a dual gradient pump and a dual autosampler you basically achieve two systems (and two flow-paths) in one instrument. This allows you to run two samples in parallel or two different applications in parallel, doubling throughput or obtaining more information from a single sample respectively
Tandem LC or LC-MS – how long does your detector sit idle waiting for the next time it is required to collect data? From our research it is frequently over 30% of the time. Tandem LC or LC-MS uses two individual pumps, e.g. a dual gradient pump (no need for a dual autosampler here), and two columns. Whilst you are performing your analytical run on one column using one pump, the other column can be re-conditioned on the second pump. You then simply switch the column used for the next sample. In this way, the detector does not sit idle waiting for the column to be re-conditioned before the next run begins. This not only saves time, but also maximises the utilisation and return-on-investment of your detector.
Inverse Gradient – to maximise productivity it is important to detect all components in your sample, however not all detectors offer a uniform response. For example, analytes lacking a chromophore cannot be detected by UV. The Charged Aerosol Detector (CAD) is a near-universal detector that negates this issue and also allows you to obtain quantitative information without the use of reference standards. However, the signal intensity varies as the solvent composition changes over a gradient which leads to lower quantitative accuracy. Using a dual gradient pump it is possible to perform an Inverse Gradient on the second pump to match the analytical gradient. The two gradients then combine before the CAD so that it receives a constant solvent composition which greatly improves uniformity of response for quantitation.
This demonstrates that in one single system you can increase productivity in three different ways. I envisage that over the next decade HPLC will continue to evolve, with productivity being at the centre of all developments and enhancements, whether that is in hardware, software or columns and chemistries.