Analytical scientists working in many sectors have long expressed the need for increasingly fast chromatographic separations. The pharmaceutical industry, for example, has a growing demand for high- throughput methodologies in order to accelerate the discovery and development of new chemical entities.(1) Analytical toxicology laboratories require fast, robust methods for routine analysis of many clinical and forensic samples.(2) In biomedical research, in-depth proteomic and metabolomic studies of complex biological systems will continue to advance with rapid separation-based techniques.(3) Progress in these areas and others has advanced in parallel with improvements to LC column technology, especially as it relates to smaller packing materials, over the past several decades.(4) Arguably the most impactful result of the steady reduction in the size of chromatographic stationary phase supports is faster LC, run at higher mobile phase velocities without the significant losses in efficiency that are observed on columns packed with larger diameter particles. Both the use of smaller particles and higher mobile phase velocities require higher pressures than achievable with traditional HPLC instruments (400 bar limit), which necessitated the development of ultrahigh pressure liquid chromatography (UHPLC) instrumentation (1000 - 1500 bar limit). It has been over 20 years since the first demonstration of capillary UHPLC (5-7) and over 15 years since the release of the first commercial UHPLC platform.(8) Since that time, there has been a sharp increase in the use of UHPLC for analytical separations, with continuing trends toward higher speed and higher performance. This review focuses on recent advances that have led to unprecedented increases in method throughput for LC separations, especially as they relate to new developments in instrumentation and column technologies. In general, the descriptions of 'high -through put' and 'ultrafast' LC have been defined in the context and limits of enabling technologies and thus continue to evolve. Defining metrics can include individual sample analysis time, full method cycle time, and general daily productivity. Although many papers make claims to fall under the ultrafast/high-throughput regime, the focus in this review is on separations that span the time scale from subsecond to an upper range of 1 - 2 min. The main emphasis of this review is on work that has been conducted since early 2017, although some older results are discussed for context or significance to a specific topic. Chromatographic theory, as it relates to column and particle design for separations performed at very high mobile phase velocities, is described. In addition, the practical instrumentation and hardware requirements needed to achieve higher throughput for both analytical scale and microscale techniques are discussed. Finally, specific modes of chromatography facilitating ultrafast separations and common application areas employing these techniques are detailed.

Kato, K., Shinoda, T., Nagao, R., Akimoto, S., Suzuki, T., Dohmae, N., Chen, M., Allakhverdiev, S.I., Shen, J.-R., f Akita, F., Miyazaki, N., Tomo, T., 2020. Structural basis for the adaptation and function of chlorophyll in photosystem I. Nature Communications 11, 238.

https://doi.org/10.1038/s41467-019-13898-5 Chlorophylls (Chl) play pivotal roles in energy capture, transfer and charge separation in photosynthesis. f Among Chls functioning in oxygenic photosynthesis, Chl is the most red-shifted type first found in a Halomicronema hongdechloris f cyanobacterium . The location and function of Chl in photosystems are not H. hongdechloris clear. Here we analyzed the high-resolution structures of photosystem I (PSI) core from grown under white or far-red light by cryo-electron microscopy. The structure showed that, far-red PSI binds 83 a f f Chl and 7 Chl , and Chl are associated at the periphery of PSI but not in the electron transfer chain. The f appearance of Chl is well correlated with the expression of PSI genes induced under far-red light. These f results indicate that Chl functions to harvest the far-red light and enhance uphill energy transfer, and changes f in the gene sequences are essential for the binding of Chl .

Katsuta, N., Matsumoto, G.I., Hase, Y., Tayasu, I., Haraguchi, T.F., Tani, E., Shichi, K., Murakami, T., Naito, S., Nakagawa, M., Hasegawa, H., Kawakami, S.-i., 2019. Siberian permafrost thawing accelerated at the Bølling/Allerød and Preboreal Warm periods during the last deglaciation. Geophysical Research Letters 46, 13961-13971.

https://doi.org/10.1029/2019GL084726