Instrument Used: Nexera UC
We interviewed Mr. Kotake from Chugai Pharmaceutical Co., Ltd. about the Nexera UC supercritical fluid extraction (SFE)/supercritical fluid chromatography (SFC) system.
He gave us his opinions about its usefulness by comparing SFC and UHPLC and suggested new ways to use SFE systems in drug discovery research.
Medicinal Chemistry Research Department, Research Division,
Chugai Pharmaceutical Co., Ltd.
Please tell us how you became interested in SFC technology and what made you decide to use the system.
This experience put the thought into your head that the SFC system would also perform on the different compounds as well, didn’t it?
Do you have any other ideas about the benefits of SFC?
Do you mean that a combination of the normal phase column and SFC provides results that are different from normal phase LC?
SFC gave similar retention times for the compounds that have weak and strong retentions in the reversed-phase mode.
After using an SFC system for six months, what do you think of its usability and the theory behind it as compared to an LC?
This is an encouraging message to LC users who hesitate to use an SFC system. Can you think of any negative points about the SFC as compared to the LC and GC?
In other words, when you have more options, optimization is more difficult.
SFE technology has been available for a long time. SFE has some benefits compared to general liquid extraction. For example, SFE consumes less solvent, the extraction step takes less time, and there is no need to concentrate samples because solvents evaporate after extraction. We connected SFE and SFC systems online to fully automate the processes from an extraction through chromatography, enabling multi-sample processing.
We believe the system provides excellent features. For example, it can perform processes from extraction to MS analysis in a completely closed condition when analyzing metabolites from dried blood spot (DBS) card or analyzing residual pesticides in vegetables. It can also analyze unstable samples that would degrade in the extraction process without any modification.
What kind of applications do you want to challenge using the SFE system?
When we saw the online SFE system, we first thought of how we would use it to purify synthetic compounds. As with LC systems, we often hear about the troublesome steps in the purification procedure; which solvent should be used to dissolve the samples, how well they are dissolved, how sample solvents negatively affect chromatogram, and how precipitation occurs because of the solubility difference between the mobile phase and the sample solvents, which causes clogging or stops the instrument from operating. We thought using an online SFE as a sample introduction device into a preparative SFC system would be good because only extracted and dissolved compounds would be loaded on the column. Therefore, there is no need to consider the sample solvent and the risk of clogging. In SFE, the loading amount can be controlled by the extraction time instead of the injection volume. This aspect allows the compounds that have poor solubility into CO2 increasing in the loading amount by extending the extraction time. Additionally, we might also be able to collect the entire amount of the target compound by repeating the extraction process. For these reasons, I expect that we will be able to use the SFE system without worrying about any problems related to sample solvents. I did a search about this idea and found several reports in other countries as well.
In contrast, there is another case that the remaining compound on the residue after the extraction can be the pure product. It would be interesting if we could place a crude material in an SFE vessel and wash it with CO2 to obtain a purified product in a dry condition when the vessel is open.
Shimadzu develops SFE systems to extract and analyze target compounds. But you are thinking about washing target compounds instead of extracting them, which means that you extract impurities and then purify the remaining portion?
Of course, the purification performance should depend on the solubility of the target component and other impurities to CO2. I mean, all "extraction", "clean-up", and "purification" functions are essential for the truly variable purification platform. I hope that Shimadzu will develop this type of system.
Thank you very much for very good comments and suggestions.
Would you tell us why you chose Shimadzu’s Nexera UC instead of other similar products?
The final deciding factor was that an LC and an SFC can be utilized in the same platform with the Nexera UC. We hesitated to purchase a dedicated SFC system only to discover that it would be useless for our purpose. I also feel that switching back and forth between an LC and an SFC is desirable, as the combination of this technique with an MS detector would become more common in the near future. Two individual systems of LC and SFC simply require double the space. Additionally, I think it would be a big burden to change the systems and piping again to connect an MS system to an LC system at certain times, and to an SFC system at others.
We also appreciate the mobile phase blending function. The current standard modifier is 10 mM ammonium formate methanol solution. We blend methanol and 100 mM ammonium formate methanol solution by a ratio of 9:1. We are using the instrument for a wide range of purposes because the measurement can be performed on an LC without changing configuration settings.
Is the operating rate of the instrument high?
The system you purchased can perform regular LC, SFC, and on-line SFE. Which of these do you use the most?
What do you think about SFE usability? Is it different from existing chromatographs?
Thank you for sharing your opinion. We will try to make improvements, including a better extraction vessel.
Does the Nexera UC have any outstanding features?
You mean that the reproducibility is better than your first worry, don’t you? The basic structure of the pump is the same as that of regular LC. The only difference is the pump head that delivers CO2. Feeding back the temperature on the pump head helps to provide the good reproducibility. The other key technology is reducing the pressure fluctuation on the back pressure regulator (BPR). It influences the reproducibility. There is almost no pressure variation in Shimadzu's BPR, which also contributes to excellent reproducibility.
Indeed. The influence of the refractive index is more significant in an SFC because the pressure-resistant cells are used. Shimadzu LabSolutions has a function to compensate the chromatogram by subtracting what is obtained in the region with no absorption. Noise can be reduced in the same way. Of course, we’d like to plan to develop the detector cell with a lower refractive index to make the system provide a S/N ratio as good as that of LC.
What do you think about the software? Would you tell us your impression about the method scouting?
What do you think about Shimadzu's support system?
Thank you for the compliment. Could you share your opinions about Shimadzu overall and any requests to us?
It is beneficial to share our views with a Japanese company like Shimadzu because the voices of chromatography users in Japan can influence product development. I believe our opinions led to the development of excellent add-on software such as method scouting, OpenSolution, and SharedBrowser as well as the improvement of measurement and analysis usability with LabSolutions. The unique analytical technologies such as iPDeA and iDReC can be available for the data files acquired in the past, just by updating to the later version. The new peak detection algorithm of iPReC Finder provides better peak integration that looks like the person does it manually. It results in fewer data processing steps with higher satisfaction. I had the opportunity to observe the development work of iPReC Finder. It was clear that the experienced development personnel were devoted to creating the best system so that the users do not have to configure settings each time. I was moved by their devotion and the younger development personnel's motivation and enthusiasm. I also feel that we currently communicate well with the staff in charge of the instrument development.
However, I am concerned that an attitude that satisfies customers' requests too much can be a negative aspect as well. For example, when two users have similar but different needs or they have needs that conflict with each other, you may add two similar functions to fulfill both needs. Fulfilling all of those requests may be difficult; adding new functions and new windows to software, or sometimes completely novel platforms or software, should be considered. Satisfying specific requests from users with a powerful voice or company-specific problems should not take priority over more general requests from users with a smaller voice. I hope Shimadzu fairly considers the requests of all users and clearly shows its direction while closely listening to users' opinions.
Thank you very much. Do you have any other requests?
You mean an SFE system as an autosampler?
I understand your requests. Thank you so much for your important ideas.
Comments About the Interview
The three-in-one system adopted by Chugai Pharmaceutical can be used as SFC, UHPLC, and SFE units. We will support customers continuously in order to help them use our systems for various purposes and develop products that satisfy customers' requests.