A high-capacity stationary phase for the separation of fullerenes was prepared by immobilizing 3-[(pentabromobenzyl)oxy]propylsilyl (PBB) groups onto silica surfaces. The stationary phase was developed by a reciprocal approach. This was possible by finding the structure of solvents that provided high solubilities as well as high eluent strength for chromatographic elution of fullerenes. The increased solubility and increased eluent strength for Ceo seen with solvents containing heavy heteroatoms suggested the preferential interaction of Ceo with such solvent molecules. The stationary phases containing sulfur, chlorine, or bromine in fact resulted in longer retention of fullerenes. The PBB silica showed high retentivity with excellent efficiency for fullerenes, permitting the use of solvents providing high solubilities, such as carbon disulfide and 1,2,4-trichlorobenzene for gramscale separations with ordinary HPLC equipment HPLC is an indispensable technique for the purification of fullerenes, although a very convenient method was reported recently for the isolation of Cm using calixarene.2 This is because HPLC can provide a means to separate fullerenes of various sizes through C9o or larger.3 The packing materials for HPLC currently employed, however, possess relatively low capacities, allowing only small-scale separations. An exception is the low-efficiency charcoal column that was used to achieve rough separations of C6o and C70•4Considerable effort has been made to prepare high-capacity HPLC packing materials for fullerene separation. Stationary phases with electron acceptors,5 electron donors,56•6 and aromatic groups shaped to fit fullerene surfaces63•7 showed a greater capacity than conventional ones including inorganic adsorbents,8 octadecylsilyl (Ci«) silica,3b d e•9 or poly (styrene-co-divinylbenzene) beads.10 In the chromatographic separation utilizing fullerene-* Nacaiai Tesque, Inc.

Messenger ribonucleic acids (mRNAs) have been used in vaccines for various diseases and are attracting attention as a new pharmaceutical paradigm. The purification of mRNAs is necessary because various impurities, such as template DNAs and transcription enzymes, remain in the crude product after mRNA synthesis. Among the various purification methods, reversed-phase high-performance liquid chromatography (RP-HPLC) is currently attracting attention. Herein, we optimized the pore size of the packing materials, the mobile phase composition, and the temperature of the process; we also evaluated changes in the separation patterns of RNA strands of various lengths via RP-HPLC. Additionally, single-stranded (50–1000 nucleotides in length) and double-stranded (80–500 base pairs in length) RNAs were separated while their non-denatured states were maintained by performing the analysis at 60 °C using triethylammonium acetate as the mobile phase and octadecyl-based RNA-RP1 with super-wide pores (> 30 nm) as the column. Furthermore, impurities in a long-stranded RNA of several thousand nucleotides synthesized by in vitro transcription were successfully separated using an RNA-RP1 column. The columns used in this study are expected to separate various RNA strands and the impurities contained in them. Graphical abstract

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The retention behavior of a wide variety of stationary phases was compared in supercritical fluid chromatography (SFC) and normal-phase high-performance liquid chromatography (NP-HPLC). We also attempted to elucidate the retention behavior in SFC by investigating the selectivity of the different stationary phases. SFC separation conditions with polar stationary phases, such as silica gel (SL) and diol (Diol) phases, operate via adsorptions that include hydrophilic and ionic interactions similar to those in NP-HPLC. Moreover, non-polar stationary phases, such as pentabromophenyl (PBr), pyrenylethyl (PYE), and octadecyl (C18), could be used despite the non-polar mobile phase conditions, because the dispersion and π-π interactions were stronger in SFC than in HPLC. These results reflect the selectivity of the stationary phase and its retention factor, thus providing useful information for the selection of appropriate stationary phases for particular analytes.

We developed a system to separate and identify racemised and isomerised aspartic acid (Asp) residues in amyloid β by labeling with an original chiral resolution labeling reagent, 1-fluoro-2,4-dinitrophenyl-5-D-leucine-N,N-dimethylethylenediamine-amide (D-FDLDA). The...