One-pot synthesis of a new high vinyl content hybrid silica monolith dedicated to nanoliquid chromatography: Liquid Chromatography

Chromatographic separation of peptides and proteins for characterization of proteomes

Characterization of proteomes aims to comprehensively characterize proteins in cells or tissues via two main strategies: (1) bottom-up strategy based on the separation and identification of enzymatic peptides; (2) top-down strategy based on the separation and identification of intact proteins. However, it is challenged by the high complexity of proteomes. Consequently, the improvements in peptide and protein separation technologies for simplifying the sample should be critical. In this feature article, separation columns for peptide and protein separation were introduced, and peptide separation technologies for bottom-up proteomic analysis as well as protein separation technologies for top-down proteomic analysis were summarized. The achievement, recent development, limitation and future trends are discussed. Besides, the outlook on challenges and future directions of chromatographic separation in the field of proteomics was also presented.

Advancements in the preparation and application of monolithic silica columns for efficient separation in liquid chromatography

Fast and efficient separation remains a big challenge in high performance liquid chromatography (HPLC). The need for higher efficiency and resolution in separation is constantly in demand. To achieve that, columns developed are rapidly moving towards having smaller particle sizes and internal diameters (i.d.). However, these parameters will lead to high back-pressure in the system and will burden the pumps of the HPLC instrument. To address this limitation, monolithic columns, especially silica-based monolithic columns have been introduced. These columns are being widely investigated for fast and efficient separation of a wide range of molecules. The present article describes the current methods developed to enhance the column efficiency of particle packed columns and how silica monolithic columns can act as an alternative in overcoming the low permeability of particle packed columns. The fundamental processes behind the fabrication of the monolith including the starting materials and the silica sol-gel process will be discussed. Different monolith derivatization and end-capping processes will be further elaborated and followed by highlights of the performance such monolithic columns in key applications in different fields with various types of matrices.

Pipette tip micro-solid phase extraction (octyl-functionalized hybrid silica monolith) and ultra-high-performance liquid chromatography-tandem mass spectrometry to determine cannabidiol and tetrahydrocannabinol in plasma samples

This manuscript describes the development of an innovative method to determine cannabinoids (cannabidiol and tetrahydrocannabinol) in human plasma samples by pipette tip micro-solid phase extraction and liquid chromatography-mass spectrometry/mass spectromtery. An octyl-functionalized hybrid silica monolith, which had been synthesized and characterized, was used as a selective stationary phase. The octyl-functionalized hybrid silica monoliths presented high permeability and adequate mechanical strength. The micro-solid phase extraction variables (sample pH, draw-eject cycles, solvent for phase clean-up, and desorption conditions) were investigated to improve not only the selectivity but also the sorption capacity. The method was linear at concentrations ranging from the lower limit of quantification (10.00 ng/mL) to the upper limit of quantification (150.0 ng/mL). The lack of fit and homoscedasticity tests, as well as the determination coefficients (r² greater than 0.995), certified that linearity was adequate. The precision assays presented coefficient of variation values lower than 15%, and the accuracy tests provided relative error values ranging from 3.2 to 14%. Neither significant carry-over nor matrix effects were detected. Therefore, the pipette tip micro-solid phase extraction/liquid chromatography-mass spectrometry/mass spectrometry method has demonstrated to be adequate to determine cannabidiol and tetrahydrocannabinol simultaneously in plasma samples for therapeutic drug monitoring of patients undergoing treatment with cannabinoids.

Nano liquid chromatography columns

Nano liquid chromatography (nanoLC), with columns having an inner diameter (ID) of ≤100 μm, can provide enhanced sensitivity and enable analysis of limited samples.

A facile AuNPs@aptamer-modified mercaptosiloxane-based hybrid affinity monolith with an unusually high coverage density of aptamer for on-column selective extraction of ochratoxin A

A convenient and high-performance AuNPs@aptamer-modified mercaptosiloxane-based hybrid affinity monolithic column with an unusually high coverage density of aptamers was facilely prepared and used for on-column selective recognition of ochratoxin A (OTA). Due to the high surface-to-volume ratio of AuNPs, the robust conjugation of Au-SH and large specific surface area of hybrid-silica monolith, high coverage density of 5'-SH-aptamers up to 3494 pmol μL-1 was achieved, which was 2.5-10 folds higher than that of other previously reported affinity monoliths modified with AuNPs@Apt. Using OTA as the model analyte, the highly selective recognition of OTA was carried out via online coupling with HPLC, and the cross-reactivity towards analogues, such as OTB and aflatoxin B1, was weak. High recovery yields of OTA were achieved at more than 92% (n = 3) even when OTB was added at a high concentration level up to 50 ng mL-1. For sample analysis, efficient discrimination of OTA was successfully obtained with a sensitive detection limit of 25 pg mL-1. The recoveries of OTA with different fortified levels were achieved at 88.6%-94.1% and 88.2%-94.3% for beer and wine samples, respectively. This protocol provides a facile approach for fabricating a desirable affinity monolith modified with abundant aptamers for highly selective and sensitive on-column extraction of target analyte OTA.