Polar Compounds Research Articles

Valorization of Spent Hops from Dry Hopping for Bittering of Pilsener Style Beer

In the last decade production of dry hopped beers increased considerably. Dry hopping results in significant amounts of spent hop material (mixture of beer and hop vegetative matter), which is mostly regarded as waste and is discarded. During dry hopping polar (aroma) compounds are extracted into beer, while nonpolar compounds such as humulones largely remain in the spent hops. In this study, spent hops from local craft breweries were collected. They were analyzed towards dry matter (d.m.), surplus beer content, their concentration of humulones, and iso-humulones, and were then used as the sole source of bitterness in the production of Pilsener Style beer. It was found that humulone concentrations in spent hops ranged from 1 to 10.3% dry matter, which corresponds to retention rates of 28 to 94%. Wort and beer samples made from selected spent hop samples were analyzed using a range of physicochemical analyses, along with sensory evaluation of both fresh and aged beers. Beer analysis showed that the targeted bitterness (30 BU) was successfully achieved in most brews. Sensory analysis confirmed the good overall quality of spent hop beers as such and also in comparison with a reference brew using hop pellets. In summary, spent hops can be valorized by substituting hop pellets in the kettle, leading to reduced beer losses, savings on hop pellets, increased sustainability and hence reduction of production costs.

Cork-Activated Carbon as a Sorptive Phase for Microextraction of Emerging Contaminants in Water Samples

A novel strategy for microextraction of emerging contaminants was developed by using cork activated carbon (CAC) as the sorbent phase. Carbonization of the natural phase increased the surface area and the porosity of the material, thus improving the extraction efficiency. Moderately polar compounds, such as ibuprofen and its metabolites, were used as model analytes in water samples. Rotating disk sorptive extraction (RDSE) together with gas chromatography‒mass spectrometry (GC‒MS) were used for extraction and determination of the analytes, respectively. The optimum conditions for the material synthesis were 600 °C, K2CO3 as the activating agent and a mass ratio of 0.8:1 (activating agent:raw material). The optimum values for the RDSE were pH 2, a sample volume of 25 mL and an extraction time of 90 min. The absolute recovery rates for ibuprofen and its metabolites ranged from 19 to 55%, and the relative standard deviations were between 3 and 13%. The proposed method was used to measure the analytes in the influent and effluent from a wastewater treatment plant in Santiago, Chile. The concentrations found for ibuprofen and its metabolites were 0.98–9.8 µg L-1 and 0.8–8.6 µg L-1 in the influent and effluent, respectively. Activation of the cork material enabled the synthesis of a sorbent phase with sorption efficiencies similar to those obtained with the commercial octadecylsilane (C18) phase and superior to that observed for styrene-divinylbenzene (S-DVB). This process is simple and cost-effective.

Ensemble machine learning as a mathematical approach to predict high-voltage electric field-assisted removal of color and oxidative indices from soybean oil using the activated porous electrodes

Porous electrode materials provide a large surface area for electrochemical reactions and facilitate ion transport efficiently. By optimizing the design and properties of porous electrodes, it is possible to enhance the bleaching performance. In this research, three machine learning (ML) algorithms, namely Support Vector Regression, Ridge Regression, and Decision Tree Regression were utilized for predicting the bleaching efficiency under different conditions of HVEF-assisted bleaching (HVEFAB). Subsequently, the outcomes of these models were compared to ensemble models created by combining the algorithms as mentioned earlier using three techniques including bagging, boosting, and stacking. The levels of chlorophyll and carotenoids were reduced as a result of increased voltage, modification in the electrode surface, number of cathode-anode, and the presence of an inert electrolyte. Meanwhile, the reduction of red color and chlorophyll pigments was more significant than yellow color and carotenoid pigments. Moreover, the application of HVEFAB can potentially decrease the levels of polar compounds, such as oxidative compounds on the electrode surface. Based on the MSE, MAE, and R2 metrics, the algorithms' efficacy in forecasting outputs 1 (color index) and 2 (oxidative index) can be ordered as follows: Stacking > Boosting > Bagging > Decision Tree (DT) > Ridge > Support Vector Regression (SVR). The findings demonstrate that integrating these three models, mainly through the stacking technique, substantially improves the accuracy of the predicting model. Particle swarm optimization (PSO) and polynomial regression rather than RSM represented a superior model to predict red color removal.

General characteristics of lavender biomass (Lavandula angustifolia Mill.) before and after industrial distillation

The aim of the present study was to evaluate and compare three types of lavender (Lavandula angustifolia Mill.) biomasses for their content of biologically active substances and potential application. The first one was from unprocessed lavender (L-UNTR22_Z) and the other two were industrial steam-distilled lavender solid residues (L-SD22_Z and L-SD22_M). Ash, protein, polyuronide content and the degree of esterification of the pectic substances in the biomass were investigated. 70% ethanolic extracts of the residues were prepared and their total polyphenol content and antioxidant activity were evaluated by four methods. Individual phenolic acids, flavonoids, polar non-volatile compounds and polar volatile compounds were also determined by chromatographic analyses. The highest degree of esterification (83.9±0.5%) and protein content (8.15±1.6%) were found in L-SD22_Z extract. L-SD22_M extract demonstrated the highest polyphenolic content and antioxidant activity. Six phenolic acids (protocatehuic, syringic, p-coumaric, ferulic, salicylic, and gallic acid) and five flavonoids ((+)-catechin, (-)-epicatechin, rutin, hesperidin, and quercetin) were detected by HPLC analyses. The detail information about amino acids, sugars, organic and phenolic acids, as well as polar volatile compounds was obtained by GC-MS. The results suggested that the lavender (untreated and residual biomass) are a good source of dietary antioxidants and compounds with potent biological activity.

Robust and versatile assembly for emitter positioning, observation, and heating in atmospheric pressure field desorption mass spectrometry.

Atmospheric pressure field desorption (APFD) mass spectrometry (MS) has recently been introduced as a new variant of field desorption (FD) mass spectrometry. The development aimed at providing the basic characteristics of FD-MS in combination with instruments equipped with an atmospheric pressure (AP) interface. Hitherto, APFD has been demonstrated to yield both positive and negative even electron ions of highly polar or ionic compounds as well as to enable the generation of positive molecular ions, M+•, of polycyclic aromatic compounds. The prototype setup for APFD was based on a nano-electrospray ionization (nanoESI) source slightly modified to allow for emitter positioning in front of the AP interface of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer. The entrance electrode of the interface was set to negative or positive high voltage with respect to the emitter at ground potential, thereby permitting the formation of positive or negative ions, respectively. This work describes a custom-built device for quicker and more reproducible sample loading on and positioning of field emitters at the entrance electrode of the atmospheric pressure interface of a mass spectrometer. In addition, the device provides means for observation of the emitter during operation and for resistive emitter heating as employed in traditional FD-MS. Emitter heating both speeds up the desorption of the analytes and allows for the desorption/ionization of analytes of higher molecular weight than without emitter heating. In some cases, the signal-to-noise ratio of APFD mass spectra is improved due to higher ion currents effected by compressing the entire process into shorter periods of spectral acquisition. The new setup enables robust and reliable operation in APFD-MS. Moreover, it has been designed as to allow for use on a range of instruments as it can either be used on an FT-ICR mass spectrometer or in combination with a trapped ion mobility-quadrupole-time-of-flight (TIMS-Q-TOF) instrument.

Electrostatic Repulsion Hydrophilic Interaction Liquid Chromatography (ERLIC) for the Quantitative Analysis of Polyamines

Highly polar low molecular weight organic molecules are still very challenging to analyze by liquid chromatography. Yet, with the steadily increasing application of metabolomics and similar approaches in chemical analysis, separating polar compounds might be even more important. However, almost all established liquid chromatography techniques (i.e., normal and reversed phase, hydrophilic interaction liquid chromatography (HILIC), ion chromatography) struggle with either carry-over, low sensitivity, or a lack of retention. For improving these shortcomings, electrostatic repulsion hydrophilic interaction chromatography (ERLIC) might be an alternative. By combining a HILIC mobile phase, that is highly organic with a low water content, and an ion exchange column, a distinct layer system develops. When the analyte's charge is of the same direction as the stationary phase, retention and elution are determined by two antagonistic forces: electrostatic repulsion and hydrophilicity. One prominent group of challenging polar analytes are the polyamines cadaverine, putrescine, spermidine, and spermine. Carrying charges from +2 to +4 at physiological pH, these compounds are essential cell constituents and found in all living organisms. However, they are still notoriously challenging to analyze via the established liquid chromatography methods. In the present work, an ERLIC tandem mass spectrometry method has been exemplarily developed, optimized, and validated for the quantitative determination of cadaverine, putrescine, spermidine, and spermine. This method enables symmetrical peak shapes and good separation of analytes with different charges while simultaneously selectively detecting the co-eluting diamines by MS/MS. Furthermore, high linearity (R > 0.998) and sensitivity (LODs ≤ 2 ng/mL) have been proven. Thus, ERLIC may be interesting for both targeted and untargeted analysis approaches of highly charged low molecular weight organic molecules.

Bioretention Design Modifications Increase the Simulated Capture of Hydrophobic and Hydrophilic Trace Organic Compounds.

Stormwater rapidly moves trace organic contaminants (TrOCs) from the built environment to the aquatic environment. Bioretention cells reduce loadings of some TrOCs, but they struggle with hydrophilic compounds. Herein, we assessed the potential to enhance TrOC removal via changes in bioretention system design by simulating the fate of seven high-priority stormwater TrOCs (e.g., PFOA, 6PPD-quinone, PAHs) with log KOC values between -1.5 and 6.74 in a bioretention cell. We evaluated eight design and management interventions for three illustrative use cases representing a highway, a residential area, and an airport. We suggest two metrics of performance: mass advected to the sewer network, which poses an acute risk to aquatic ecosystems, and total mass advected from the system, which poses a longer-term risk for persistent compounds. The optimized designs for each use case reduced effluent loadings of all but the most polar compound (PFOA) to <5% of influent mass. Our results suggest that having the largest possible system area allowed bioretention systems to provide benefits during larger events, which improved performance for all compounds. To improve performance for the most hydrophilic TrOCs, an amendment like biochar was necessary; field-scale research is needed to confirm this result. Our results showed that changing the design of bioretention systems can allow them to effectively capture TrOCs with a wide range of physicochemical properties, protecting human health and aquatic species from chemical impacts.

Assessing the potentialities of an easy-to-use sample treatment strategy: Multivariate investigation on “Moka extraction” of typical ingredients from dietary supplements

Mr. Bialetti invented Moka in 1933 and it still represents the most common way to prepare coffee at home. The process through which Mokas extract components from the ground coffee is a solid-liquid extraction which occurs at high pressure and temperature. These features are desirable in simple sample treatment strategies, since they allow good extraction efficiencies in a short time. Herein, for the first time, Moka-pot extraction was considered as an alternative processing protocol to extract polar compounds from dietary supplements. The effect of four experimental variables on extraction efficiency was evaluated through a fractional factorial design of experiments applied to a pooled matrix. In particular, solvent pH and its content of organic modifier, heating temperature and sample mass (reflecting the ratio to the amount of solvent which has to be kept fixed due to practical needs) were considered. The performances of the best conditions were then validated by determining recoveries (between 52 and 134 %, except for acetylsalicylic acid) and matrix effects (resulting always negligible or moderate at 100-fold dilution) of a spiked matrix which did not present any of the target analytes. They were finally applied to real samples, allowing to quantify some compounds, including artificial sweeteners, methylxanthines and taurine. Results were then compared with the quantities declared on the labels and those obtained with a Salt-Assisted Liquid-Liquid Extraction (SALLE), previously developed. Interestingly, the two methods were comparable for most compounds, but Moka extraction allowed to quantify taurine, which was not recovered with the SALLE. This promising result encourages further work to extend the use of the simple Moka device to other analytes and further matrices.

A Review of Recent Progresses on Olive Oil Chemical Profiling, Extraction Technology, Shelf-life, and Quality Control.

Olive oil (OO) is widely recognized as a main component in the Mediterranean diet owing to its unique chemical composition and associated health-promoting properties. This review aimed at providing readers with recent results on OO physicochemical profiling, extraction technology, and quality parameters specified by regulations to ensure authentic products for consumers. Recent research progress on OO adulteration were outlined through a bibliometric analysis mapping using Vosviewer software. As revealed by bibliometric analysis, richness in terms of fatty acids, pigments, polar phenolic compounds, tocopherols, squalene, sterols, and triterpenic compounds justify OO health-promoting properties and increasing demand on its global consumption. OO storage is a critical post-processing operation that must be optimized to avoid oxidation. Owing to its great commercial value on markets, OO is a target to adulteration with other vegetable oils. In this context, different chemometric tools were developed to deal with this problem. To conclude, increasing demand and consumption of OO on the global market is justified by its unique composition. Challenges such as oxidation and adulteration stand out as the main issues affecting the OO market.

Uremic Toxins and Inflammation: Metabolic Pathways Affected in Non-Dialysis-Dependent Stage 5 Chronic Kidney Disease.

Chronic kidney disease (CKD) affects approximately 12% of the global population, posing a significant health threat. Inflammation plays a crucial role in the uremic phenotype of non-dialysis-dependent (NDD) stage 5 CKD, contributing to elevated cardiovascular and overall mortality in affected individuals. This study aimed to explore novel metabolic pathways in this population using semi-targeted metabolomics, which allowed us to quantify numerous metabolites with known identities before data acquisition through an in-house polar compound library. In a prospective observational design with 50 patients, blood samples collected before the initial hemodialysis session underwent liquid chromatography and high-resolution mass spectrometer analysis. Univariate (Mann-Whitney test) and multivariate (logistic regression with LASSO regularization) methods identified metabolomic variables associated with inflammation. Notably, adenosine-5'-phosphosulfate (APS), dimethylglycine, pyruvate, lactate, and 2-ketobutyric acid exhibited significant differences in the presence of inflammation. Cholic acid, homogentisic acid, and 2-phenylpropionic acid displayed opposing patterns. Multivariate analysis indicated increased inflammation risk with certain metabolites (N-Butyrylglycine, dimethylglycine, 2-Oxoisopentanoic acid, and pyruvate), while others (homogentisic acid, 2-Phenylpropionic acid, and 2-Methylglutaric acid) suggested decreased probability. These findings unveil potential inflammation-associated biomarkers related to defective mitochondrial fatty acid beta oxidation and branched-chain amino acid breakdown in NDD stage 5 CKD, shedding light on cellular energy production and offering insights for further clinical validation.

Molecular transformation of petroleum compounds by hydroxyl radicals produced upon oxidation of reduced nontronite

At redox interfaces, the interaction between oxygen and structural Fe(II) in minerals produces hydroxyl radicals (●OH); however, the specific reactivity and mechanisms of oxidation of complex petroleum compounds by ●OH remain poorly understood. This study investigates the interaction mechanisms between ●OH generated from reduced nontronite, an Fe-rich clay mineral (NAu-2), and petroleum compounds by employing a suite of wet chemistry, gas chromatography mass spectrometry and Fourier transform-ion cyclotron resonance-mass spectrometry, as well as theoretical calculations. The results showed that the intrinsic structure, composition, solubility, and adsorption of petroleum molecules onto reduced NAu-2 significantly influenced their reactivity with ●OH. Specifically, the aromatic fraction of a crude oil sample exerted a minimal influence on the oxidation rate of structural Fe(II) in reduced NAu-2, but enhanced the production of ●OH by generating environmentally persistent free radicals. ●OH reacted more with water-soluble dissolved organic matter from oil compared to polar compounds. The newly generated molecules by ●OH exhibited a preference for the insoluble (polar) phase. The oxidation of petroleum hydrocarbons by ●OH was mediated through hydrogen atom abstraction and radical adduct formation, followed by dehydrogenation, hydroxylation, and carboxylation reactions. Consequently, the abundance of oxygen-containing compounds in polar compounds increased. However, specific oxidation pathways differed depending on the nature of petroleum compounds. Our results provide insights that oxidation of petroleum compounds by ●OH is vital for mitigating the negative impacts from hydrocarbon contamination and for evaluating the role of these processes in the carbon cycle in redox-active environments.

Analysis of aromatic carboxylic acid and calcium salt couples with gas chromatography-mass spectrometry: Implications and comparison with in situ measurements at Mars' surface

Aromatic organic salts such as benzoates or phthalates may be widespread degradation products of organic molecules at the surface of Mars. The low volatility of these aromatic carboxylic salts could have compromised their detection through thermal extraction in situ analyses such as those performed by the Viking landers. However, over the years, analytical chemistry laboratories on board current and future Martian surface missions, such as the Sample Analysis at Mars (SAM) instrument suite on board the Curiosity rover and the Mars Organic Molecule Analyzer (MOMA) instrument of the Rosalind Franklin ExoMars rover, respectively, have evolved. These instruments have improved in efficiency to detect refractory and polar organic compounds, which could influence the detection of aromatic organic salts. To evaluate the capability of detecting aromatic organic salts on Mars with in situ instruments, we performed laboratory experiments under Viking, SAM, and MOMA-like Gas Chromatography-Mass Spectrometry (GC–MS) conditions with two carboxylic acid/salt couples: phthalic acid/calcium phthalate and benzoic acid/calcium benzoate. We studied the behavior and signatures of both molecular forms when using pyrolysis and derivatization experiments and the implications of these results in the search for organic molecules on Mars. This study showed that the Viking experiments could not have detected the presence of aromatic carboxylic salts in Martian samples because its maximum pyrolysis temperature was too low (500 °C). However, we showed that calcium benzoate and calcium phthalate, despite their refractory nature, could be identified indirectly through the detection of thermal and derivatized degradation products, both with SAM and MOMA. No conclusive proof of the presence of these aromatic organic salt species have been found in the SAM in situ data but given the right instrumental set-up they could be detected if present. The conclusions of this work raise essential questions on the detectability of refractory molecules, the analytical efficiency of flight instruments, and the interpretation of in situ data.

Unsaturation and polar compounds of vegetable oils affect the properties of sunflower wax‐oleogels

AbstractAlthough it is important to understand the factors affecting the physical properties of oleogels for their application in food products, the effects of the kind of oils and components in them are not well understood. Previous studies on the effects of unsaturation and polar compounds of oils on the properties of oleogels reported inconsistent results, presumably, due to different gelling agents, experimental conditions, and different amounts of minor components in oils. In this study, a systematic study was conducted with 12 vegetable oils with and without polar compounds to understand these effects on the properties of 3% and 7% sunflower wax (SW)‐oleogels. In general, oils with higher unsaturation produced oleogels with lower gel strength. Polar compounds in oil negatively affected the gel strength. Melting and crystallization temperatures increased with increasing unsaturation of oil. The platelet shape of SW crystals was almost identical, regardless of the kind of oil. Solid wax content values were similar across the oleogel samples with 12 different oils. This study enlightens several factors affecting the physical properties of SW‐oleogels.Practical Application: This study provides information about the effects of unsaturation of oil and polar compounds in oil on firmness and melting properties of sunflower wax (SW)‐based oleogels. It was found that the firmness of SW‐oleogel can be significantly different (up to 65%) depending on vegetable oils used, and it decreased with increasing unsaturation of oil. It was also found that the firmness of the oleogel can be increased by up to 36% by removing polar compounds in oil. Solid wax content (SWC) of oleogels did show meaningful correlations with the firmness of SW‐oleogels. All the oleogels examined in this study had very similar shapes and sizes of SW crystals. For practical application, the unsaturation of oil and the polar compound content have to be considered when designing oleogels with desired textural properties.

Gas Extraction Generation of Gas Mixtures of Polar Organic Compounds at the Level of Trace Concentrations

Gas Extraction Generation of Gas Mixtures of Polar Organic Compounds at the Level of Trace Concentrations

Physicochemical Quality and Thermal Stability of Vegetable Oils during Deep-Fat Frying of Potato Chips

Background: Deep-fat frying induces organoleptic and physicochemical changes in both oils and fried products. Excessive use of frying oils accrues decomposition products with potential hazards to human health. Optimizing frying conditions and selecting the best frying oils are needed for better-fried products. Objective: This study was conducted to investigate the physicochemical changes and thermal behavior of vegetable oils (olive, canola, corn, sunflower and soybean oils) during deep-fat frying of potato chips, and determine the optimum conditions required to produce the best quality fried product. Methods: Thermal behavior, organoleptic characteristics, physicochemical properties (color index, viscosity, specific gravity, peroxide value, free fatty acids, total polar compounds), and fatty acid compositions of oils were investigated during the frying process every 8 hours up to 40 hours of heating. Results: Oils showed different quality and thermal stability. The optimum time and temperature for frying were 10 minutes and 180°C. Sensory attributes, physicochemical characteristics and fatty acid composition of oils were markedly affected by heating. Olive oil was the most stable for frying. Total polar compounds of 27% (the rejection point for frying oils) would be reached upon heating olive oil at 180°C for 114 hours. The corresponding times were 45, 43, 30 and 26 hours for canola, corn, sunflower and soybean oils, respectively. Conclusion: Olive oil showed the highest stability and produced the best-fried product, followed by canola oil. Frying time increased with extended heating, and it could be used as a good indicator of oil quality and when it should be discarded.

A Novel Model for Evaluating the Natural Antioxidant Carnosic Acid to Improve the Stability of Rapeseed Oil in the Thermal Degradation.

The quality and stability of oil during thermal processing reflect the reactions in vegetable oil. The deterioration of the oil is close to the viscosity, fatty acid composition (FA), total polar compounds (TPC), etc. Carnosic acid (CA) is the main antioxidant component of rosemary extract; it is a natural and clean-label antioxidant that is allowed to be added to prolong oil processing and storage. To achieve a clear correlation of this situation, a novel stability evaluation model was used to predict the thermal degradation of rapeseed oil (RSO) with CA. The RSO with CA (200 mg/kg, 400 mg/kg, and 700 mg/kg), the tert-Butylhydroquinone (TBHQ, 200 mg/kg), and the fresh RSO (without additives) during thermal processing (180 ± 5 °C) were studied. The temperature dependency of viscosity fits well with the Lioumbas model (R2 ≥ 0.999). The parameter b value in the Lioumbas model showed a decrease linearly with the processing time (tP, R2 ≥ 0.965). The multiple linear regression analysis showed that the accuracy of the model in predicting viscosity was less than ±2 mPa·s-1, and the deviation% was less than ±10% in all the samples. After 32 h of thermal degradation, the addition of 700 mg/kg CA showed the lowest degradation rate (13.84%) of polyunsaturated fatty acids (PUFAs), and the TPC content was 26.00 ± 0.50%. The TPC showed a positive relationship with viscosity (r = 0.99, p < 0.01), tP (r = 0.97, p < 0.01), and effective carbon numbers (ECN, r = 0.84, p < 0.05). In conclusion, this study can make a potential prediction for the stability of RSO.

Unique heterocyclic phenolic compounds from shrimp (Pandalus borealis) and beyond

Shrimps are the most consumed species among crustaceans and are well appreciated for their flavor and high nutritional value. This work investigated the antioxidative compounds of Northern shrimp (Pandalus borealis) and its processing discards (shells and heads) using various solvents and chromatographic techniques as well as mass spectrometry. Ethanol served as the best extraction medium, and the extracts obtained demonstrated strong antioxidant activity in a β-carotene-linoleate emulsion system. The antioxidative compounds of the extract were isolated using a silica gel column chromatography, followed by thin layer chromatography. This led to the identification of two highly polar and two low polarity compounds. These compounds, for the first time, were isolated and purified by using reversed-phase HPLC. Their structures were tentatively elucidated using electrospray mass spectrometry. These unique compounds were heterocyclic phenolic compounds and identified as 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tetrahydropyridin-2-yl) quinoline and 7-(3-butenyl)-2-hydroxy-6-(1,2,5,6-tertahydropyridin-2-yl)-7,8-dihydroquinoline and their isomers. The proposed novel compounds in shrimp provide a reason for their oxidative stability and potential benefits, as well as possibly serving as substrates for the discoloration of shrimp.Graphical

Specific fractionation of ginsenosides based on activated carbon fibers and online fast screening of ginseng extract by mass spectrometry

Ginseng is beneficial in the prevention of many diseases and provides benefits for proper growth and development owing to the presence of various useful bioactive substances of diverse chemical heterogeneity (e.g., triterpenoid saponins, polysaccharides, volatile oils, and amino acids). As a result, understanding the therapeutic advantages of ginseng requires an in-depth compositional evaluation employing a simple and rapid analytical technique.In this work, three types of surface-activated carbon fibers (ACFs) were prepared by gas-phase oxidation, strong acid treatment, and Plasma treatment to obtain CO2-ACFs, acidified-ACFs, and plasma-ACFs, respectively. Three prepared ACFs were compared in terms of their physicochemical characterization (i.e., surface roughness and functional groups). A separation system was built using a column with modified ACFs, followed by mass spectrometry detection to investigate and determine substances of different polarities. Among the three columns, CO2-ACFs showed the optimum separation effect. 13 strong polar compounds (12 amino acids and1 oligosaccharide) and 15 lesser polar compounds (ginsenosides) were separated and identified successfully within 4 min in the ginseng sample. The data obtained by CO2-ACFs-TOF-MS/MS and UHPLC-TOF-MS/MS were compared. Our approach was found to be faster (4 min vs. 36 min) and greener, requiring much less solvent (1 mL vs. 10.8 mL), and power (0.06 vs. 0.6 kWh). The developed methodology can provide a faster, eco-friendly, and more reliable tool for the high-throughput screening of complex natural matrices and the simultaneous evaluation of several compounds in diverse samples.

Colorimetric Readout Based Photoionization Detector for Gas Chromatographs

This paper presents a new scheme for readout of a photoionization detector (PID) that utilizes the ionization luminescence of target gases in helium plasma to generate an output signal. Our signal readout method is based on processing the recorded video and correlating the light peak intensity with the sample injection time and concentration. We successfully demonstrated the feasibility of a colorimetric readout‐based photoionization detector coupled with a gas chromatography column by detecting a mixture of non‐polar compounds (alkanes) and two polar compounds (acetone and ethanol). The detection limit for our first‐generation device was calculated to be ~118 ng for acetone and around 26 ng for ethanol. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Preparation and investigation of two-component silica-modified hydrophobic layer for minimizing retention loss of reversed-phase chromatographic columns using fully aqueous mobile phases

Chromatographers often employ fully aqueous mobile phases to retain highly polar compounds in reversed-phase liquid chromatography (RPLC). However, when the flow rate is interrupted, either accidentally or intentionally, a substantial loss in retention occurs due to the spontaneous dewetting of water from the hydrophobic surface of conventional RPLC-C18 particles. Previous studies have shown that maintaining a low C18 surface coverage (approximately 1.5 μmol/m2) can mitigate water dewetting by increasing chain disorder, facilitating the intercalation of water clusters between the C18-bonded chains, and keeping the mesopores wetted. In this research, we explore the potential and additional benefits of using two-component surface bonding materials (C8/C18 and PhenylHexyl (PhHx)/C18) at a constant and low total surface coverage of 1.51 ± 0.15 μmol/m2. We synthesized seven one- and two-component modified silica particles with a volume average particle size of 5.22 μm and an average mesopore size of 104 Å. The surface coverage was increased from 0 to 0.54, 1.00, and to 1.66 μmol2 for C8 chains and from 0 to 0.52, 0.70, and to 1.65 μmol2 for PhHx ligands. To prevent interactions between water and any unreacted silanols, all seven derivatized particles were heavily endcapped with trimethylsilane (TMS) reagent. The fraction of the surface area remaining in contact with water was determined by measuring the retention times of weakly (thiourea) and strongly (thymine) retained compounds at intervals of 1, 2, 4, 8, 16, 32, and 64 minutes following the cessation of flow. Two distinct column temperatures, 24°C and 60°C, were employed in the experiments. Retention losses were found to be minimized in the presence of a small quantity of C8 chains (less than 40% of the total surface coverage). Additionally, it is essential to consider substantial fractions of PhHx chains, as long as the presence of the PhHx ligand does not significantly impact retention and selectivity. Combining mixed RPLC bondings with a low total surface coverage of approximately 1.5 μmol/m2 emerges as a viable solution for further minimizing retention loss in standard C18-bonded RPLC columns, particularly within the surface coverage range of 2.5-3.0 μmol/m2.