Effective Separation of Human Milk Glycosides using Carbon Dioxide Supercritical Fluid Chromatography

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2021-2022

The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates is a well-established technique and this review is the 12th update of the original article published in 1999 and brings coverage of the literature to the end of 2022. As with previous review, this review also includes a few papers that describe methods appropriate to analysis by MALDI, such as sample preparation, even though the ionization method is not MALDI. The review follows the same format as previous reviews. It is divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of computer software for structural identification. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other general areas such as medicine, industrial processes, natural products and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. MALDI is still an ideal technique for carbohydrate analysis, particularly in its ability to produce single ions from each analyte and advancements in the technique and range of applications show little sign of diminishing.

Chemical Synthesis of Human Milk Oligosaccharides: para-Lacto-N-hexaose and para-Lacto-N-neohexaose

Human milk oligosaccharides (HMO) have emerged as a very active area of research in glycoscience and nutrition. HMO are involved in the early development of infants and may help to prevent certain diseases. The development of chemical methods for obtaining individual HMO aids the global effort dedicated to understanding the roles of these biomolecules. Reported herein is the chemical synthesis of two common core hexasaccharides found in human milk, i. e. para-lacto-N-hexaose (pLNH) and para-lacto-N-neohexaose (pLNnH). After screening multiple leaving groups and temporary protecting group combinations, a 3+3 convergent coupling strategy was found to work best for obtaining these linear glycans.

First proof-of-concept of UC/HILIC for extending the versatility of the current art of supercritical fluid separation

Supercritical Fluid Chromatography (SFC), a high-throughput separation technique, has been widely applied as a promising routine method in pharmaceutical, pesticides, and metabolome analysis in the same way as conventional liquid chromatography and gas chromatography. Unified chromatography (UC), an advanced version of SFC, which applied gradient elution with mobile phase changing continuously from supercritical to subcritical and to liquid states, can further extend the SFC applications. UC mostly applying the popular mobile phase of 95%:5%/Methanol:Water with additives allows to analyze many hydrophilic compounds. However, many of phosphorylated metabolites or multi carboxylic acids show very poor peak shapes or even can't be eluted under UC conditions, thus hampering the UC's metabolome coverage. In this study, we proposed the first proof-of-concept of UC/HILIC, a novel strategy to extend the current UC metabolome coverage by employing an aqueous gradient right after the UC gradient on a single packed column in a single measurement. The proposed method showed significant improvement regarding the chromatographic performance and metabolome coverage, while still maintaining the precision and high throughput in comparison with conventional UC methods.

Determination of Saccharides in Honey Using Supercritical Fluid Chromatography Coupled with Single Quadrupole Mass Spectrometry

Saccharides are one of the most important biomoleculars in the world, which are responsible for various roles in living organisms. In this work, a combined use of mass spectrometry (MS) together with supercritical fluid chromatography (SFC) was applied for the separation of eight saccharides. A satisfactory separation was achieved within 15 min on a Unitary Diol column using 10 mM ammonium acetate in methanol as mobile phase additive at a temperature of 60°C. Compared to liquid chromatography-MS (LC-MS), the SFC-MS presented faster running time and better selectivity. The SFC-MS was validated and applied to the analysis of three saccharides (fructose, glucose and sucrose) present in different honey samples. The limits of detection (LODs) and limits of quantification (LOQs) of SFC-MS method for fructose, glucose and sucrose were 5.2, 4.5, 7.4 μg/mL and 17.2, 14.9, 24.1 μg/mL, respectively. The relative standard deviations for intrabatch and interbatch precision were <2.5% and the recoveries ranged from 97.6% to 103.1% for three concentration levels. The values of LODs and LOQs using SFC-MS method were lower (1.5-2.4-fold) than using LC-MS method. The results demonstrated the potential of SFC-MS for fast and sensitive determination of saccharides in honey.