Greening LC

As we all do our part to combat climate change and protect the environment, every aspect of life should be considered to some extent – including our jobs. For those in science careers, not only should we be considering the materials we use and how they are produced, but also the full life cycle – transport and disposal included. Together, we can bring about colossal change through many small efforts. 

Many researchers are focused on developing greener approaches to sample preparation, primarily through the use of alternative solvents with lower toxicity and lower carbon footprint. And I have also heard of efforts to recycle metals in consumables (column hardware, tubing, and so on), but this may not be an option available to all chromatographers.

The overall development of compact instrumentation for traditional LC-UV analysis has greatly improved the sustainability of chromatography. There have been similar efforts in the area of MS, but there are a number of significant challenges to overcome in making compact MS instruments. Further efforts to reduce the overall size, power consumption, and consumable needs of a complete LC-MS system would greatly enhance the ways in which this technique could be applied…

To further improve the sustainability of liquid chromatography (LC), we can develop faster methods, which reduces the time instruments spend in full power mode. But we can likely have the biggest impact by considering solvent consumption – and that’s arguably the most easily addressed. In my view, we need to more actively make the shift to smaller column diameters, which allows instruments to be operated at lower flow rates, consuming less mobile phase and generating less waste.

In our lab, we’ve been exploring the potential of translating the typical small molecule analytical methods used within the pharmaceutical industry down to the capillary scale. We’re currently exploring similar experiments on biopharmaceutical compounds. In fact, many of our projects involve advancing the use of capillary scale LC columns in a broad range of application areas. We typically employ columns in the 0.150–0.300 mm diameter range, which brings the flow rates down 100–1000 times lower than typical analytical scale columns in the 2.1–4.6 mm diameter range. With this decrease in flow rate comes a reduction in the need for mobile phase – as well as the carbon footprint of shipping and the generated chemical waste. For cases where there is no access to capillary scale instrumentation, we have also started exploring the use of 1.5 mm diameter columns – which are useful in generating results that are comparable to typical 2.1 mm diameter columns but at half the flow rate. 

Capillary LC has long been seen as a tool primarily for biomedical researchers conducting LC-MS analysis on very complex samples. I am hoping that our work, and that of others investigating similar topics in the field, can demonstrate that there are many routine LC applications that can be performed with smaller diameter columns. We all just need to make the effort.