Closing the Consumption Gap: Making GC More Accessible

Gas chromatography users agree on at least two things: that GC is a mature technology, and that the performance and features of instrumentation largely meet the application requirements for which GC is routinely deployed. Often heard among users is that there is a gap between the rich features and performance and their ability to actually access and leverage these. This so-called “consumption gap” between function and usability¹ ultimately limits results.

Conversations with hundreds of GC users and lab managers around the world revealed several things. First, eliminating the consumption gap was an important opportunity to make a substantial improvement on a technique even as mature as GC. Second, global expansion over the past 20 years exacerbated the gap. Practically, it was not possible to replicate the deep chromatographic expertise resident at a corporate center of excellence, among all the disparate points of GC use scattering about the globe.

Finally, a demographic shift, experienced throughout many industries, was at play. Many users once scholastically trained in chromatography, with decades of experience, were now retiring and being replaced by a new generation who, unfortunately, were not formally trained in GC per se, but instead, in general science or even liberal arts. This leaves them at a disadvantage when faced with operating a complex, highly functional instrument, especially when their wide-ranging duties often preclude them from the continuous focus normally required to develop a deep domain expertise.

It was easy to conclude that in order to advance the GC technique, one shouldn’t focus significant effort on expanding functionality and increasing GC performance. Instead, driving a more successful outcome for the user, and ultimately for the business enterprise the user serves, should be top priority. This meant that making GC much easier to learn, use and maintain was critical to achieve meaningful innovation. It also meant that innovations that drive productivity improvements should also be highly prioritized. These were the driving forces behind the development of the Agilent Intuvo 9000 GC System.

A New Approach to GC

The maturity of GC represented a significant challenge. Over the past 50 years, the approach to the technique has been interactively refined, and the huge investment in application methods along with the supporting supplies and consumables was a significant cost few practitioners would be willing to walk away from. It was clear those innovations that mattered most would have to coexist within the GC lab ecosystem in place.

Naturally, lab managers strive for consistent, reliable delivery of on-time results We were told repeatedly that a top cause of unplanned downtime, and a major difficulty encountered in GC, was leaks due to improperly fitted connections in the GC flow path. Nuts and ferrules used to make traditional connections in GC were cumbersome and error-prone for many users. Inadvertent over tightening of the connection usually led to crushing the ferrule, causing leaks. Eliminating them altogether was thus identified as a key innovation target.

Figure 1 – A torque wrench applies 1.2 Nm of torque to ensure each click-and-run connection is made correctly, leak-free. Audible and tactical feedback of the torque wrench click, along with automatic leak checking, assures the operator that the connection was indeed made properly.

This led Agilent to develop direct face seal connection technology, where an audible and tactile click of a torque wrench provides feedback and certainty to the user that the connection was made properly. A torque wrench (Figure 1) ensures that an exact amount of force is applied to the connection, no matter how many times the wrench is turned. Also included was an automatic hands-free leak-check function that can be performed autonomously throughout a sample batch to provide continuous assurance that the system is operating leak-free.

The fused-silica capillary GC column, introduced by Agilent over 35 years ago, was, a core technology, with proven value that could not be dispensed with. But the time for a much more streamlined format had come. Driving this new format was the design of a new approach to heating the GC itself. Conventional convective air-bath ovens have been effective for years and its use will likely continue. However, they consume a great deal of space and power and are relatively slow. Motivated by the need for speed and efficiency, Agilent designers turned to direct conductive heating technology.

Figure 2 – A planar heater coupled to a planar column exhibits optimum thermal performance for GC

The format of a solid planar heater coupled to a planar column winding was found to give optimum thermal performance for GC (Figure 2). A thin composite silicon-based heating structure was designed to temperature program the column at a rate as fast as 250 °C/minute. Likewise, a planar column format ensured direct intimate contact of the column with the heater. This immediately made ultrafast GC methods accessible.

Throughput not only depends on how fast the column can be heated, but also on how fast it can be cooled back down to be ready for the next analytical run. Rapid cooling was accomplished with turbo-axial fan technology, which has recently been used in varied applications, from rapid hand-drying to cooling server farms. Directing air at over 200 km/hr across the column and its thin heating element allows significantly faster cooling rates and improved cycle times.

Figure 3 – Intuvo Flow Chips can be installed easily with click-and-run connections, to assemble GC flow paths. Mass spectrometer connection flow chip is illustrated. The Smart Key attached to the Flow Chip automatically informs Intuvo of its configuration.

Implementing direct column heating mandated direct heating for the remainder of the GC flow path. This opened the door to wide implementation of microfluidic technology and the development of plug-and play flow path components. Intuvo Flow Chips (Figure 3), fitted with “click-and-run” connections, were designed to be easily installed to assemble back flush or splitter flow paths, for example. One obvious benefit of this design is consistency of flow path component dimensions and structure. Unlike conventional flow paths, with arbitrary dimensions arising from variability among individual operators, Intuvo flow paths can be assembled with reproducible dimensions in every lab, providing consistent analytical behavior and results among operators and labs across the globe. This level of consistency is of great benefit to global organizations in particular that need to compare results from site to site and minimize site-specific bias.

Figure 4 – The flow channel in every Intuvo Flow Chip has a high-purity silica base chemically treated with Intuvo Ultra Inert surface.

The development of inert flow paths is well established in GC. A third generation of deactivation chemistry, called Intuvo Ultra Inert, was implemented. At the heart of each Intuvo Flow Chip is a flow channel (Figure 4) with dimensions consistent with conventional capillary GC. Each Flow Chip channel has a chemically bonded high-purity silica base, further chemically treated with an Ultra Inert surface. This produces an inert flow path analogous to what an analyte would encounter in a conventional fused-silica GC capillary. The level of freedom from activity^2,3 ensures high performance for applications involving active compounds such as pesticides, and environmental contaminants.

The Guard Chip is a disposable flow chip (Figure 5) that fits in between the inlet and the column. It acts as a retention gap, protecting the column from unwanted high-molecular-weight contaminants that could otherwise deposit on the head of the column. Clipping a portion of the column off is typically done to remediate this contamination, but the process takes time and skill to perform. Column clipping has other problems as well; continuously shortening the column ultimately degrades its performance and shortens its useful life. Moreover, clipping usually results in a shift in chromatographic retention times, which must be adjusted almost every time the column is clipped.

Figure 5 – Intuvo’s disposable Guard Chip acts as a retention gap and can be installed in a few minutes. It protects the column from contamination eliminating the need to clip the column and adjust retention times.

In comparison, replacing the Guard Chip is an easy task that takes only a few minutes, because it is also fitted with click-and-run direct connections. More importantly, changing the Guard Chip does not shift retention times the way clipping does, saving considerable time. Finally, the column remains the same length the day it was installed through to the day it is retired.

Closing the consumption gap

Intuvo was designed as an “Internet of Things” (IOT) appliance, amenable to remote access. It has a home page that provides a full suite of user documentation and support materials that can be searched to aid in learning, use and troubleshooting. A high-fidelity glass color touch display fitted on Intuvo provides an operating interface that users recognize as an intuitive app on a smart device. This interface (Figure 6) not only provides extensive status, real-time data and graphical step-by-step maintenance procedures, but can stream videos to a tablet, phone or laptop.

Figure 6 – The Intuvo color touch interface is recognized by users as an intuitive app on a smart device. It provides extensive status and real-time data, as well as a full suite of user assistance on learning, maintenance and troubleshooting.

Modern electronic architecture allows many more parameters to be measured, including voltages, flows and duty cycles, to qualify Intuvo’s operating status and to simplify troubleshooting, even remotely. This provides secure access to Intuvo’s status, to expertise that may be remote to a given installation, allowing the system to be up and running again more quickly.

Memory chips were also utilized to build in Smart Key devices attached to Intuvo Flow Chips and the Intuvo column (see Figure 3). Plugging in the Smart Key to Intuvo, when installing the chip or column, informs Intuvo of exactly how it is configured. This speeds up method setup, because Intuvo now knows about the relevant dimensions, flows, pressures and other operating conditions necessary for optimized operation of that specific configuration. Intuvo not only automatically knows about the column, phase and dimensions it has installed, but the column’s Smart Key also keeps an accurate record of use history of the column, which can help optimize column deployment.

All of this smart technology closes the consumption gap of GC, making powerful technology and functionality much more accessible to the user. This ensures that more successful use of GC is enabled, that the lab is made more productive and that results can be delivered more reliably, as unplanned downtime is reduced. Closing the consumption gap is a major trans formative step for GC that is sure to drive much better outcomes for users and the enterprises they serve.

References

1. Wood, J.B.; Hewlin, T. et al. B4B. TSIA Books, 2013.
2. Veeneman, R. and Stevens, J. Multiresidue Pesticide Analysis with the Agilent Intuvo 9000 and Agilent 7000 Series Mass Spectrometer, 5991-7216EN, Agilent Technologies, 2016.
3. Giardina, M. Analysis of Semivolatile Organic Compounds Using the Agilent Intuvo 9000 Gas Chromatograph, 5991-7256EN, Agilent Technologies, 2016.