Green Chromatography Reaches New Peaksby Ashley Glowinski, Assistant Managing Editor
Designed for HPLC and UHPLC applications, the PerkinElmer Flexar SQ 300 MS is a fast and accurate analytical system that enables labs and workflows to be more efficient and productive. | Over the past few years, “going green” has become less of a novelty and more of a mainstay for companies across the board. The field of chromatography is no exception. Smaller, faster, micro-scale instruments, along with solvent-saving techniques, is helping to drive the eco-friendly movement in analytical chemistry.
Besides the environmental benefits that come from inheriting greener technologies, the push for sustainability has also been triggered by economic conditions and material shortages. Methods that use less solvent generate less waste and reduce the expensive process of hazardous waste removal. Additionally, smaller, solvent-saving, sensitive instruments require less overall runtime, further adding to a lab’s energy efficiency.
In addition to reducing costs, the “importance of sustainability was particularly brought home last year by the worldwide shortage of acetonitrile, a by-product of acrylonitrile production,” says Mark Upton, Liquid Chromatography product specialist, UK and Ireland at PerkinElmer.
It was this acetonitrile shortage chromatographers faced in 2008 and early 2009 that pushed scientists toward ultra high performance liquid chromatography (UHPLC) for reducing solvent consumption and to also look for alternative, less toxic solvents such as methanol and ethanol to run their chromatography methods.
The combination of these economic and material factors has opened the door for greener chromatography techniques in a variety of ways.
Same system, greener benefits
“We actually find ourselves today in a very interesting time for green chromatography solutions because there are new technologies available that are system-type independent,” says Jeremy Bierman, brand manager for Phenomenex. “Whether you have an HPLC or a UHPLC system, there are new media types out there that allow you to achieve performance benefits and solvent savings, regardless of which one of those systems you’re using.”
Eksigent Technologies, for example, a company that focuses mainly on HPLC, is seeking ways to reduce size while retaining performance.
“New developments such as pumping technologies provide splitless nano-LC gradients at nano-LC flow rates, which contribute to savings and use less solvent,” says David Neyer, VP and co-founder of Eksigent. “Other focuses, such as UV-absorbance flow cells, result in higher sensitivity and smaller volumes, which add to greener techniques.”
Alternative eco-friendly methods
Newer technologies not only increase energy efficiency in the lab using current methods, but also allow chromatographers to adopt alternative methods.
“In the last five years, developments in sub-2 micron particles combined with the instrumentation to handle the resultant higher backpressures and the narrower peaks generated, have resulted in increasing adoption of UHPLC,” says PerkinElmer’s Upton.
Also new on the scene are core-shell particle columns, that allow for shorter columns with greater efficiency, which enables faster analyses and less solvent consumption, regardless of the system.
“These core-shell columns provide performance increases at pressures compatible with regular HPLC systems,” adds Bierman. “Now people don’t have to upgrade or invest in new high-pressure systems; they can take advantage of these green benefits on the current systems they’re using.”
“Kinetex core-shell particles are not a fully porous,” continues Bierman. “Compounds only have to diffuse into and out of the porous shell, which allows for an increased rate of mass transfer and the benefits that come with ultra-high efficiency.”
As instrumentation and column technologies give HPLC and UHPLC a facelift, there is also growing interest in methods such as supercritical fluid chromatography (SFC).
“In a typical HPLC or UHPLC you can expect to see 50 percent of your mobile phase being made up of environmentally hazardous organics,” explains Bierman. “With SFC, 90 percent of your mobile phase is liquid carbon dioxide with 10 percent organic modifier, so you’re significantly decreasing the amount of hazardous organic.”
Once atmospheric pressure is reached with SFC, the liquid carbon dioxide turns to gas and evaporates.
While the general green pull has been to reduce solvents used in LC methods, gas chromatography (GC) is naturally green, according to Upton.
“However, GC has a sustainability issue since the predominant gas used is helium, of which there is a limited supply and will become scarce and more expensive,” says Upton, adding that there is movement to hydrogen as a carrier gas for GC although this often requires some method development.
Switch to savings
As companies seek greener chemistry technologies, they are helping individual chromatographers make the switch in their own lab.
PerkinElmer offers customers method transfer calculations, including solvent saver calculations, according to Upton. The company also provides guidelines for converting to UHPLC and the practicalities involved with this method available for free on their website.
Phenologics from Phenomenex is a convenient method development service available that “works with our customers to develop or optimize methods to reach their goals,” says Bierman.
In addition to these services, companies have also “greened” their instrumentation offerings to make the switch to sustainable methods easier for users.
Eksigent’s Neyer says, “By introducing instruments with nano- and micro-flow rates and shorter columns, users see significant cost and environmental savings.”
Recently, Eksigent introduced the ExpressLC-Ultra, a microscale HPLC system that allows the use of sub-2 micron particle columns. In addition to a UV detection system, the system enables solvent savings as well as reduced sample requirements and frictional heating.
From small to fast, “the PerkinElmer Flexar range of LC modules enables the easy transition from conventional to fast to UHPLC, resulting in much faster analyses and up to 90 percent or more, solvent savings,” says Upton. “The ability of these modules to run at pressures of 18,000 psi and up to 5 mL/min also enables use of more viscous solvents such as methanol and ethanol rather than acetonitrile.”
Adopting new column technology such as the Phenomenex Kinetex core-shell columns “really gives a new life to systems,” says Bierman. “Helping customers continue to use their existing instruments reduces what goes into the landfill.”
New environmental wave
So what’s the next step for green chromatography?
“More microfabrication, such as lab-on-a-chip devices will emerge in the future,” says Eksigent’s Neyer.
Neyer also believes detection technology such as microelectronics and LEDs for optical electronics will make further contributions to greener chemistry.
Upton agrees. “Further miniaturization of LC to capillary LC and nano-LC, especially in conjunction with MS, is likely,” he says, adding that sample preparation improvements may also have a greener effect.
Overall, as more become aware of the benefits of methods using SFC, UHPLC and core-shell columns, “the market for these will increase and we’ll see more resources available,” says Bierman.
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