Development and validation of HILIC-UHPLC-ELSD methods for determination of sugar alcohols stereoisomers and its application for bioconversion processes of crude glycerin

An HPLC-ESI-QTOF method to analyze polar heteroatomic species in aviation turbine fuel via hydrophilic interaction chromatography

Aviation turbine fuel is a complex mixture of thousands of compounds. An analytical method using hydrophilic interaction liquid chromatography (HILIC) coupled with electrospray ionization and quadrupole time-of-flight mass spectrometry (ESI-QTOF) was developed for the identification of heteroatomic, polar compounds in aviation turbine fuel. Although compounds containing oxygen, nitrogen, and sulfur functional groups are each found at low levels (<0.1 % by mass) in fuels, their presence can generate significant effects on fuel properties. The HILIC-ESI-QTOF method is a combined separation and detection technique that possesses many advantages including a fast and simple sample preparation-requiring no extraction step therefore ensuring no loss of compounds of interest-and the ability to acquire high-fidelity compound data for chemometric analysis of heteroatomic species in aviation turbine fuel. In the development of the method, it was found that the chromatographic conditions and nature of the injection sample had a significant effect on separation efficiency and repeatability. For a sample dataset optimized using a singular aviation turbine fuel, retention time shift was able to be reduced from 0.4 min to 2.0 % relative standard deviation (RSD) to approximately 0.1 min with RSD of 0.4 % using the newly developed method. In addition, a high number of untargeted molecular features (944) and targeted amines (121) were able to be identified when utilizing optimal method conditions. The specific benefits and limitations of utilizing HILIC techniques with HPLC-ESI-QTOF are also discussed herein. This new method is currently being expanded to include analysis of all heteroatoms and is being applied to real fuel sets. The results of these studies are forthcoming.

Erythritol as a Potential Causal Contributor to Cardiometabolic Disease: A Mendelian Randomization Study

People with type 2 diabetes frequently use low-calorie sweeteners to manage glycemia and reduce caloric intake. Use of erythritol, a low-calorie sweetener, has increased recently. Higher circulating concentration associates with major cardiac events and metabolic disease in observational data, prompting some concern. As observational data may be prone to confounding and reverse causality, we undertook bidirectional Mendelian randomization (MR) to investigate potential causal associations between erythritol and coronary artery disease (CAD), BMI, waist-hip-ratio (WHR), and glycemic and renal traits in cohorts of European ancestry. Analyses were undertaken using instruments comprising genome-wide significant variants from three cohorts with erythritol measurement. Across instruments, we did not find supportive evidence that increased erythritol increases CAD (b = -0.033 ± 0.02, P = 0.14; b = 0.46 ± 0.37, P = 0.23). MR indicates erythritol may decrease BMI (b = -0.04 ± 0.018, P = 0.03; b = -0.04 ± 0.0085, P = 1.23 × 10-5; b = -0.083 ± 0.092, P = 0.036), with potential evidence from one instrument of increased BMI adjusted for WHR (b = 0.046 ± 0.022, P = 0.035). No evidence of causal association was found with other traits. In conclusion, we did not find supportive evidence from MR that erythritol increases cardiometabolic disease. These findings await confirmation in well-designed prospective studies.

ARTICLE HIGHLIGHTS

A new ionic liquid bridged periodic mesoporous organosilicas stationary phase for per aqueous liquid chromatography and its application in the detection of biogenic amines

In order to solve the problems of using a large proportion of acetonitrile on the hydrophilic interaction liquid chromatography (HILIC) columns that was not environmentally friendly, and the poor acid and base resistance of traditional bonded silica columns, we reported a novel stationary phase of Au nanoparticles (Au NPs) covalently bonded to ionic liquid (ILs) bridged periodic mesoporous organosilicas (PMO) hydrophilic microspheres (PMO-ILs-Au NPs) for per aqueous liquid chromatography (PALC). The PMO hydrophilic microspheres were prepared by condensation of 1,3-bis(trimethoxysilylpropyl)imidazoliumchloride and 1, 2-Bis (triethoxysilyl) ethane and then modified with Au NPs the surface. The obtained materials were characterized by elemental analysis, FT-IR spectra, scanning electron microscope and transmission electron microscopy. The retention behavior was evaluated by investigating the effect of various chromatographic factors on the retention of different types of solutes. The retention mechanism of the stationary phases in PALC was a mixed type of anion-exchange and hydrophobic interaction. Compared with C₁₈-SiO₂ column, the acid and base resistance of the stationary phase were greatly improved. Compared with the HILIC column and C₁₈ column, some hydrophilic compounds such as six organic acids and eight biogenic amines were baseline separated with the enhanced resolution of the PMO-ILs-Au NPs column under the PALC mode. The efficiency of the new column was significantly higher than that of the HILIC column. Furthermore, the analysis of PALC-triple quadrupole mass spectrometry was developed for simultaneous detection of eight biogenic amines. This method could improve detection efficiency, save reagent and reduce environmental pollution. PALC as a green chromatography analytical method was suitable for the replacement of HILIC.

Rapid Identification of Common Secondary Metabolites of Medicinal Herbs Using High-Performance Liquid Chromatography with Evaporative Light Scattering Detector in Extracts

The discovery and identification of novel natural products of medicinal importance in the herbal medicine industry becomes a challenge. The complexity of this process can be reduced by dereplication strategies. The current study includes a method based on high-performance liquid chromatography (HPLC), using the evaporative light scattering detector (ELSD) to identify the 12 most common secondary metabolites in plant extracts. Twelve compounds including rutin, taxifolin, quercetin, apigenin, kaempferol, betulinic acid, oleanolic acid, betulin, lupeol, stigmasterol, and β-sitosterol were analyzed simultaneously. The polarity of the compounds varied greatly from highly polar (flavonoids) to non-polar (triterpenes and sterols). This method was also tested for HPLC-DAD and HPLC-ESI-MS/MS analysis. Oleanolic acid and ursolic acid could not be separated in HPLC-ELSD analysis but were differentiated using LC-ESI-MS/MS analysis due to different fragment ions. The regression values (R² > 0.996) showed good linearity in the range of 50–1000 µg/mL for all compounds. The range of LOD and LOQ values were 7.76–38.30 µg/mL and 23.52–116.06 µg/mL, respectively. %RSD and % trueness values of inter and intraday studies were mostly <10%. This method was applied on 10 species of medicinal plants. The dereplication strategy has the potential to facilitate and shorten the identification process of common secondary metabolites in complex plant extracts.

Chromatographic characterization of a silica hydride-based amide stationary phase

An amide phase based on a porous silica hydride support material is tested for retention characteristics in both the reversed-phase and aqueous normal-phase modes. A series of retention maps (capacity factor vs. mobile phase composition) were obtained using reference standards of varying analyte sizes, functionalities, and polarities. An assessment of the specific column selectivity is made and classes of compounds are identified that show high potential for effective retention, resolution, and efficiency when using amide functionalized silica hydride columns for reversed-phase and aqueous-normal phase separation. Several practical applications are presented that illustrate the capabilities of this particular column format.

First Determination of Glycidyl Ester Species in Edible Oils by Reverse-Phase Ultra-Performance Liquid Chromatography Coupled with an Evaporative Light-Scattering Detector

In this work, a new ultra-performance liquid chromatograph-evaporative light-scattering detector (UPLC-ELSD) method for quantitation of glycidyl esters (GE) contents in edible oils is presented. The method features complete separation of five GE species within 20 min by a C18 column and gradient elution with a mobile phase consisting of 85% and 2.5% methanol aqueous solutions. The coefficients of regression (R²) were all ≥0.9999 for the linear-quadratic regression curves of GE species in a concentration range of 5~80 μg/mL. The intraday and interday recoveries (%) of GE species in solvent were in a range of 81.3~107.3%, and the intraday and interday coefficients of variation (CVs, %) were all ≤8.6%. The average recovery (%) of GE species spiked in extra-virgin olive oil samples ranged from 88.3~107.8% and the intermediate precision (CV, %) of ≤14% indicated acceptable accuracy and precision. The method exhibited limit of quantification (LOQ) for each GE species (0.6 μg glycidol equivalents/g oil). The method was applied to determine GE concentrations of six commercial oil samples, and total glycidol equivalents were consistent with data obtained by GC-MS method. This UPLC-ELSD method could be adopted for precursory screening and research purposes to improve food safety when MS detectors are unavailable.

On-line two-dimensional liquid chromatography hyphenated to mass spectrometry and ion mobility-mass spectrometry for the separation of carbohydrates from lignocellulosic biomass

Lignocellulosic biomass is a promising resource of renewable energy. Its transformation to ethanol requires efficient pretreatment leading to complex liquid mixtures made of hundreds of oxygenated analytes. A large part of the released compounds belong to the carbohydrates family. To overcome the complexity of such samples, a comprehensive on-line two-dimensional reversed-phase liquid chromatography hyphenated to high-resolution mass spectrometry (RPLC × RPLC-HRMS) was dedicated to the separation of carbohydrates and more specifically oligomers coming from pretreated lignocellulosic biomass. The first part of this study consisted in the optimization of such hyphenation (i.e. selection of stationary phases, mobile phases, sampling time, etc.). Then, the analytical method was applied to an industrial aqueous biomass product coming from the sulfuric acid-based pretreatment of a wheat straw. Around 70 well-resolved chromatographic peaks corresponding to oligomers were obtained. Occupation of the separation space between each chromatographic dimension was estimated to 75%. In the last part of this study, the interest of ion mobility-mass spectrometry in addition to RPLC × RPLC was discussed. Some examples highlighted the additional separation that can bring ion mobility to RPLC × RPLC-IMS-HRMS method. Using this four-dimensional hyphenation method, each analyte was described by two retention times, the collisional cross section and the molecular formula allowing to reach a level of detail never seen for biomass sample compositions.