The Third Wave of Chromatography

The request from Associate Professor Bamba provided a great opportunity for Shimadzu to get involved in SFC.
Development started right away but, of course, progress was not straightforward. The biggest problem was the valves used to control pressure. For SFC, even slight pressure variations in the chamber filled with supercritical fluid can affect the state of the separation. The accurate functioning of the valves that control that pressure serves as a key factor in separation analysis. The SFC system faced issues for a long time due to sample components dissolved in the supercritical fluid crystallizing near the valve outlet as a result of pressure drop. This caused blockages, which resulted in pressure instability. Remembering his days as a student researching supercritical fluids, Yasuhiro Funada, now an engineer for LC instruments at Shimadzu Corporation recalled: "We spent just as much time troubleshooting as performing experiments."
Not only was the large volume of the needle valves used prior to this project preventing pressure stability, which generated pressure fluctuations, but the structure of the valves also made it easier for precipitated components to become clogged. Therefore, a valve with a smaller volume and completely new structure was required. Initially, Iwata contacted valve manufacturers outside of Japan, but not one said they could make the part.
Iwata therefore declared: "If that is the case, let's make it ourselves," and asked Shimadzu's Technology Research Laboratory to develop a valve. Hiroomi Goto, a third-year employee, was assigned to the project.
In order to acquire accurate data and increase reliability, we needed to create a valve with a smaller volume and produce constant pressure without clogging. To accomplish this mission, Goto and his research team produced many sketches.

After a number of meetings, Goto said to Iwata, "We have thought of all sorts of things, but I think a ball valve design is the most achievable. We have experience using ball valves as a check valve for LC applications, so it probably won't require a long development time."
However, Iwata gave an unexpected response.
"That's fine, but what about that other idea? Even if it takes longer to develop, would you please at least try it?"
The "other idea" that he was referring to was a type of valve called a diaphragm valve. The design is similar to a pair of pliers pinching a hose, so there is no extra volume involved, whether or not pressure is applied. Goto got the idea from the adjustment knob on the IV tube used at the hospital where his daughter was receiving treatment. The simplicity of the "pinch and release" design was perfect for an SFC valve. Though there was no assurance of it working, success would mean that an ideal and completely new valve structure would be achieved.
Once the valve was nearly finished, two sample valves were taken to Osaka University for testing. The results showed that the ball valve design also reduced pressure fluctuations, but that the diaphragm design provided even better performance. In fact, the pressure fluctuations dropped to one tenth the level of the existing product.
Associate Professor Bamba expressed his joy by saying: "Who would have thought that we could achieve such a great result in only one year!"
As if to validate the result after the valve design was basically decided, the SFC development project was selected as a Program for the Development of Systems and Technology for Advanced Measurement and Analysis, sponsored by the Japan Science and Technology Agency (JST). That accelerated the development process and, in 2013, the first prototype system was completed. This was followed by the development of an integrated analysis system that included SFE capability, which resulted in completion of a prototype close to the final product in 2014. When trial operations were performed, the dramatically superior performance of the system surprised even those involved in its development.