High-performance Ion Chromatography Research Articles

Gastrodin alleviates diabetic peripheral neuropathy by regulating energy homeostasis via activating AMPK and inhibiting MMP9

BackgroundDiabetic peripheral neuropathy (DPN) is a serious complication of diabetes that lacks effective treatment. Gastrodin, the primary bioactive compound derived from Rhizoma Gastrodiae, has a long history in treating epilepsy and various central nervous system disorders. However, its effect on DPN remains uncertain. PurposeThis study aims to explore the therapeutic potential and underlying mechanisms of gastrodin in the treatment of DPN. MethodDPN model rats were induced with streptozotocin (STZ) injection and divided into four groups receiving either gastrodin at two doses (30 and 60 mg kg-1 per day), α-lipoic acid (positive drug, 60 mg kg-1 per day), or placebo. Healthy rats were administrated with placebo. The administrations began eight weeks post-STZ injection and continued for six weeks. Following a comprehensive evaluation of the neuroprotective effects, a systematic pharmacology-based approach was subsequently employed to investigate the underlying mechanism of gastrodin in vivo and in vitro. ResultsGastrodin was demonstrated to effectively enhance peripheral nerve function and reduce pathological damages in DPN rats. Furthermore, gastrodin facilitated the expression of remyelination-related proteins and mitigated oxidative stress in DPN rats. Transcriptomic analysis indicated that the modulation of energy metabolism was pivotal in the neuroprotective effect of gastrodin, corroborated by targeted metabolomic analysis using high-performance ion chromatography coupled with mass spectrometry. Using network pharmacology analysis, 12 potential targets of gastrodin were identified. Among these, matrix metallopeptidase 9 (MMP9) was further validated as the primary target through molecular docking and cellular thermal shift assays. Functional Analysis of the potential targets underscored the pivotal role of AMPK signaling, and gastrodin demonstrated the capability to activate AMPK and inhibit MMP9 in vivo. In vitro studies further found that gastrodin enhanced antioxidant capacity and mitochondrial function of high glucose-cultured rat Schwann cells RSC96 in an AMPK-dependent manner. Inhibition of AMPK hindered the decrease of MMP9 induced by gastrodin in vitro. ConclusionThis study revealed the new role of gastrodin in alleviating DPN by restoring the homeostasis of energy metabolism through activating AMPK and inhibiting MMP9. These findings highlight gastrodin's potential as a novel therapeutic candidate against DPN, and underscores an appealing strategy of regulating energy metabolism for DPN therapy.

Personal Exposure to Sulfuric Acid in the Electroplating Industry: Development and Validation of a Predictive Model.

This study aimed to measure personal exposure to sulfuric acid in the electroplating industry to establish a predictive model and test its validation. We collected indoor air parameters and related information from four electroplating plants. Silica gel sorbents were used to collect air samples using high-performance ion chromatography. We collected air samples from three plants (i.e., Plant B, Plant C, and Plant D) and applied multiple linear regressions to build a predictive model. Eight samples collected from the fourth plant (i.e., Plant A) were used to validate the model. A total of 41 samples were collected with a mean of 25.0 ± 9.8 μg/m3 (range 12.1-51.7 μg/m3) in this study, including Plant A (8 samples, 17.5 ± 2.8 μg/m3, 13.0-22.0 μg/m3), Plant B (11 samples, 36.5 ± 9.7 μg/m3, 23.1-51.7 μg/m3), Plant C (11 samples, 16.4 ± 1.7 μg/m3, 12.1-17.8 μg/m3), and Plant D (11 samples, 27.4 ± 1.7 μg/m3, 24.1-29.9 μg/m3). Plant B was significantly higher in sulfuric acid than the other plants. Workers from the electroplating process plants were exposed to sulfuric acid at 29.0 ± 11.5 μg/m3. The predictive model for personal exposure to sulfuric acid fit the data well (r2 = 0.853; adjusted r2 = 0.837) and had an accuracy of 5.52 μg/m3 (bias ± precision; 4.98 ± 2.38 μg/m3), validated by the personal sampling of the fourth plant. This study observed that sulfuric acid exposure was lower than the permissible exposure level of 1000 μg/m3 in Taiwan and the United States, and only two samples were lower than the European Union standard of 50 μg/m3. The developed model can be applied in epidemiological studies to predict personal exposure to sulfuric acid in plants using electroplating.

Discriminating three lab scale dark chocolate bars from fine Cameroon cocoa hybrids using sensorial evaluation and organic acid content.

Previous studies have shown a correlation between chocolate sensory profile and certain (bio)chemical components. The aim of this study was to examine the sensorial profile and organic acid content of three lab scale chocolate brands produced from different cocoa genotypes. The sensorial evaluation was examined by a team of 12 panelists and evaluation of aroma volatiles was done by means of HS-SPME-GC-MS. On the other hand, organic acids were assessed using a high-performance ion chromatography coupled with an electrochemical detector (HPIC-ED). Results showed a variability in sensorial profile: SCA12×ICS40 chocolate (vanilla/sweet, spicy, and floral), ICS40 × SCA12 chocolate (fruity, bitter, and dry) and SNK16 × T60/887 chocolate (chocolate, honey-like, woody, sweet). Moreover, some aroma volatiles like (2-methyl, 3-methyl, iso) butanal (ICS), terpenes (SCA), and ketones (acetophenone and 2-nonanone) (SNK) allowed to discriminate dark chocolate sample according to their raw cocoa genetic group. Besides, the organic acid content differed from one chocolate brand to another, and it was obtained a high content of oxalic acid and a low lactic acid content which are good indicators of chocolate quality. Results of the current study highly recommend knowing the variety of cocoa beans with high content of some volatiles and high oxalic and low acetic acid and lactic contents to produce high aromatic (special flavor) chocolates.

An up-scaled biotechnological approach for phosphorus-depleted rye bran as animal feed

Side streams from the milling industry offer excellent nutritional properties for animal feed; yet their use is constrained by the elevated phosphorus (P) content, mainly in the form of phytate. Biotechnological P recovery fosters sustainable P management, transforming these streams into P-depleted animal feed through enzymatic hydrolysis. The enzymatic P mobilization not only enables P recovery from milling by-products but also supports the valorization of these streams into P-depleted animal feeds. Our study presents the scalability and applicability of the process and characterizes the resulting P-depleted rye bran as animal feed component. Batch mode investigations were conducted to mobilize P from 100 g to 37.1 kg of rye bran using bioreactors up to 400 L. P reductions of 89% to 92% (reducing from 12.7 gP/kg to 1.41–1.28 gP/kg) were achieved. In addition, High Performance Ion Chromatography (HPIC) analysis showed complete depletion of phytate. The successful recovery of the enzymatically mobilized P from the process wastewater by precipitation as struvite and calcium hydrogen phosphate is presented as well, achieving up to 99% removal efficiency. Our study demonstrates a versatile process that is easily adaptable, allowing for a seamless implementation on a larger scale.Graphical

Split-ring resonator with interdigital Split electrodes as detector for liquid and ion chromatography

The analysis of food and drugs as well as the monitoring of chemical processes and bioreactors by high-performance liquid chromatography and ion chromatography requires universal, cost-effective, and sensitive detectors. Therefore, this work presents a split-ring resonator that detects changes in the electrical and dielectric properties of the eluate from liquid chromatography or ion chromatography by monitoring the amplitude of the transmitted signal using an envelope detector. The used split-ring resonator consists of a simple printed circuit board featuring two microstrip lines. One is formed to a ring with interdigital split electrodes. The interdigital split electrodes forming the sensitive area significantly enhance the sensitivity to changes in relative permittivity, dielectric losses and electrical conductivity of the eluate In addition, the split-ring resonator is a small, inexpensive and easy-to-use detector that uses several dielectric parameters simultaneously for the measurement. Furthermore, the split-ring resonator measures these parameters at a significantly lower frequency than optical detectors and therefore measures different changes in frequency-dependent permittivity. For demonstrating feasibility of a split-ring resonator as a detector for high-performance liquid chromatography and ion chromatography, various anion and cation standards, basic and acidic amino acids, sugars, as well as sugar alcohols were separated and detected. A conductivity detector for ion chromatography and a refractive index detector for high-performance liquid chromatography were used as reference detectors.

Comparison of three methods for collecting interstitial fluid from subcutaneous tissue in mini pigs

Interstitial fluid, owing to its similarity to blood components and higher sensitivity and specificity, finds widespread application in disease diagnosis and tumor marker detection. However, collecting interstitial fluid, particularly from the deep subcutaneous connective tissue, remains challenging.•This study aimed to compare three different collection methods - push-pull perfusion, multi-filament nylon thread implantation, and tissue centrifugation - for collecting interstitial fluid from the subcutaneous connective tissue layer of mini-pigs. High-performance ion chromatography was employed to analyze the conventional cation components in the samples and compare ion composition analysis between the different methods.•Results indicated that while the distribution of conventional cations in the interstitial fluid collected by the three methods was generally consistent, there were slight variations in the detection rates and concentrations of different ions. Hence, suitable collection methods should be selected based on the ions or collection sites of interest.

Integrative omics studies revealed synergistic link between sucrose metabolic isogenes and carbohydrates in poplar roots infected by Fusarium wilt.

Advances in carbohydrate metabolism prompted its essential role in defense priming and sweet immunity during plant-pathogen interactions. Nevertheless, upstream responding enzymes in the sucrose metabolic pathway and associated carbohydrate derivatives underlying fungal pathogen challenges remain to be deciphered in Populus, a model tree species. In silico deduction of genomic features, including phylogenies, exon/intron distributions, cis-regulatory elements, and chromosomal localization, identified 59 enzyme genes (11 families) in the Populus genome. Spatiotemporal expression of the transcriptome and the quantitative real-time PCR revealed a minuscule number of isogenes that were predominantly expressed in roots. Upon the pathogenic Fusarium solani (Fs) exposure, dynamic changes in the transcriptomics atlas and experimental evaluation verified Susy (PtSusy2 and 3), CWI (PtCWI3), VI (PtVI2), HK (PtHK6), FK (PtFK6), and UGPase (PtUGP2) families, displaying promotions in their expressions at 48 and 72h of post-inoculation (hpi). Using the gas chromatography-mass spectrometry (GC-MS)-based non-targeted metabolomics combined with a high-performance ion chromatography system (HPICS), approximately 307 metabolites (13 categories) were annotated that led to the quantification of 46 carbohydrates, showing marked changes between three compared groups. By contrast, some sugars (e.g., sorbitol, L-arabitol, trehalose, and galacturonic acid) exhibited a higher accumulation at 72 hpi than 0 hpi, while levels of α-lactose and glucose decreased, facilitating them as potential signaling molecules. The systematic overview of multi-omics approaches to dissect the effects of Fs infection provides theoretical cues for understanding defense immunity depending on fine-tuned Suc metabolic gene clusters and synergistically linked carbohydrate pools in trees.

The specific molecular signature of dissolved organic matter extracted from different arctic plant species persists after biodegradation

Dissolved organic matter (DOM) is a small but very reactive pool of organic matter (OM) in the environment. Its role is related to its composition, which depends on its source. In soils, vegetation is the main source of DOM, and biodegradation is the main regulating mechanism. This study aims to characterise DOM produced by contrasted arctic vegetation species and their biodegradation products.The water-extractable organic matter (WEOM) was produced from C. stellaris (lichen), E. vaginatum (sedge), A. polifolia (dwarf evergreen shrub) and B. nana (deciduous dwarf shrub). The WEOM were inoculated with a common aerobic heterotrophic soil bacteria (P. aureofaciens) and incubated for 7 days. During the experiment, WEOM was characterised through a wide range of analytical methods (TOC, UV–Vis absorbance, high-performance ion chromatography and HRMS Orbitrap).The results showed bacteria consumed a significantly greater proportion of WEOM produced by C. stellaris than by A. polifolia and B. nana at the end of the experiment (p < 0.05). Furthermore, the number of features in WEOM decreased for C. stellaris and E. vaginatum, whereas it increased for B. nana. These findings shed light on the species-specific biodegradation processes that rely on the initial composition of DOM, specifically influenced by the vegetation's capacity to produce recalcitrant compounds. Furthermore, our results emphasised that even though bacterial activity greatly impacted molecular characteristics, the WEOM produced by different vegetation species maintained their distinct molecular signatures. As a result, it can be inferred that the DOM found in natural environments directly reflects the relevant vegetation cover despite the strong influence of biogeochemical processes on DOM molecular composition. This should be considered when developing models to assess the influence of climate change on vegetation cover composition and its subsequent effects on DOM dynamics in soil and surface waters.

Activated Inositol Phosphate, Substrate for Synthesis of Prostaglandylinositol Cyclic Phosphate (Cyclic PIP)-The Key for the Effectiveness of Inositol-Feeding.

The natural cyclic AMP antagonist, prostaglandylinositol cyclic phosphate (cyclic PIP), is biosynthesized from prostaglandin E (PGE) and activated inositol phosphate (n-Ins-P), which is synthesized by a particulate rat-liver-enzyme from GTP and a precursor named inositol phosphate (pr-Ins-P), whose 5-ring phosphodiester structure is essential for n-Ins-P synthesis. Aortic myocytes, preincubated with [3H] myo-inositol, synthesize after angiotensin II stimulation (30 s) [3H] pr-Ins-P (65% yield), which is converted to [3H] n-Ins-P and [3H] cyclic PIP. Acid-treated (1 min) [3H] pr-Ins-P co-elutes with inositol (1,4)-bisphosphate in high performance ion chromatography, indicating that pr-Ins-P is inositol (1:2-cyclic,4)-bisphosphate. Incubation of [3H]-GTP with unlabeled pr-Ins-P gave [3H]-guanosine-labeled n-Ins-P. Cyclic PIP synthase binds the inositol (1:2-cyclic)-phosphate part of n-Ins-P to PGE and releases the [3H]-labeled guanosine as [3H]-GDP. Thus, n-Ins-P is most likely guanosine diphospho-4-inositol (1:2-cyclic)-phosphate. Inositol feeding helps patients with metabolic conditions related to insulin resistance, but explanations for this finding are missing. Cyclic PIP appears to be the key for explaining the curative effect of inositol supplementation: (1) inositol is a molecular constituent of cyclic PIP; (2) cyclic PIP triggers many of insulin's actions intracellularly; and (3) the synthesis of cyclic PIP is decreased in diabetes as shown in rodents.

Simultaneous determination of six nitroaromatic compounds and three anions in environmental matrices using a liquid chromatography-ion chromatography coupled system

Nitroaromatic compounds are used extensively in various fields such as dyes, pesticides, spices, pharmaceuticals, and explosives. However, the residual raw materials of these compounds accumulate in the environment and pose serious risks to human health. Chronic exposure to low concentrations of nitroaromatic compounds can cause anemia, cancer, and organ damage. Currently, Fenton oxidation and natural bioremediation are the processes most often used to eliminate nitroaromatic compounds from environmental water and soil. According to previous research, the presence of inorganic anions such as chloride, nitrite, and nitrate ions in the environmental matrix exerts an inhibitory effect on the biodegradation of nitroaromatic compounds. Furthermore, high nitrate levels in drinking water can lead to the production of nitrosamine carcinogens, which affect ecological safety and human health, in water bodies. Thus, the simultaneous determination of nitroaromatic compounds and chloride, nitrite, and nitrate ions in environmental soil and water matrices is critical for selecting appropriate nitroaromatic compound degradation methods and monitoring surface water quality. Traditional detection methods require two sample pretreatment steps and two instrumental analytical techniques to determine nitroaromatic compounds and inorganic anions in environmental matrices; moreover, these methods are time consuming, labor intensive, and error prone. Therefore, in this study, a method that combines high performance liquid chromatography (HPLC) and ion chromatography (IC) was developed to simultaneously detect nitroaromatic compounds and anions in environmental matrices. In this method, sample enrichment was achieved through bulk injection and enrichment column collection, which greatly simplified the pretreatment process. The HPLC instrument was connected to the IC instrument using two six-way valves and an enrichment column. The system operation can be divided into four stages: (A) sample loading to the quantitative ring, (B) separation of nitroaromatic compounds and anions, (C) enrichment of anions in an AG20 column, and (D) simultaneous determination of nitroaromatic compounds and anions by HPLC and IC, respectively. The time of the anions flowing out of the C18 column was determined by directly connecting the C18 column to a conductivity detector. Based on the retention times of the anions, the switching time of the six-way valve was optimized to ensure that the anions completely entered the IC column, thereby ensuring the accuracy of the method. During the chromatographic analysis stage, nitroaromatic compounds were separated and analyzed by HPLC system with a mobile phase composed of potassium phosphate buffer (pH 7.0) and acetonitrile (60∶40, v/v) at a flow rate of 1.0 mL/min; in the IC system, the anions were separated and analyzed using a 20 mmol/L sodium hydroxide aqueous solution as the mobile phase under a suppression current of 50 mA. Both anions and nitroaromatic compounds exhibited strong linear correlations within certain concentration ranges, with correlation coefficients greater than 0.993. The recoveries of the nitroaromatic compounds and anions ranged from 88.20% to 105.38% at three spiked levels, with relative standard deviations ranging from 2.0% to 11.5%. The contents of six nitroaromatic compounds and three anions in five surface water and five soil samples were determined using the developed method. Although no nitroaromatic compounds were detected in these samples, the three anions were detected at contents ranging from 0.41 to 55.3 mg/L in surface water samples, and 0.56 to 30.2 mg/kg in soil samples. Methodological validation and actual sample detection demonstrated that the proposed method has a high degree of automation, simple operation, good repeatability, high accuracy, wide applicability, and high sensitivity. Thus, this method is suitable for the rapid determination of chloride, nitrite, nitrate ions and nitroaromatic compounds in soil and water and can be extended to the simultaneous determination of inorganic ions and organic matters in other samples.

Towards a Better Understanding of the Back-Side Illumination Mode on Photocatalytic Metal–Organic Chemical Vapour Deposition Coatings Used for Treating Wastewater Polluted by Pesticides

Pesticides are emerging contaminants that pose various risks to human health and aquatic ecosystems. In this work, diuron was considered as a contaminant model to investigate the influence of the back-side illumination mode (BSI) on the photocatalytic activity of TiO2 coatings grown on Pyrex plates by metal–organic chemical vapour deposition (MOCVD). A photoreactor working in recirculation mode was irradiated at 365 nm with ultraviolet A (UVA) light-emitting diodes in BSI. The degradation of diuron and its transformation products was analysed by high-performance liquid chromatography, ion chromatography, and total organic carbon analysis. The coatings were characterised by X-ray diffraction analysis and scanning electron microscopy. Five coatings containing 3, 7, 10, 12 and 27 mg of TiO2 exhibited different morphology, crystallinity, thickness and photocatalytic activities. The morphology and crystallinity of the coatings had no significant influence on their photocatalytic activity, unlike their mass and thickness. TiO2 contents less than 10 mg limit the photocatalytic activity, whereas those greater than 15 mg are inefficient in the BSI because of their thickness. The maximum efficiency was achieved for coatings of thickness 1.8 and 2 µm with TiO2 contents of 10 and 12 mg, revealing that the photocatalyst thickness controls the photocatalytic efficiency in the BSI.

Phytate degradation in composite wheat/cassava/sorghum bread: Effects of phytase-secreting yeasts and addition of yeast extracts.

Iron deficiency anemia is highly prevalent in developing countries due to the consumption of cereal-based foods rich in phytate that chelates minerals such as iron and zinc making them unavailable for absorption by humans. The aim of the present study was to degrade phytic acid in composite flour (wheat/cassava/sorghum) bread by the addition of phytase-producing yeasts in the baking process to achieve a phytate-to-iron molar ratio <1 and a phytate-to-zinc molar ratio <15, ratios needed to achieve an enhanced absorption by humans. The high-phytase (HP)-producing yeasts were two Saccharomyces cerevisiae (YD80 and BY80) that have been genetically modified by a directed mutagenesis strategy, and Pichia kudriavzevii TY13 isolated from a Tanzanian lactic fermented maize gruel (togwa) and selected as naturally HP yeast. To further improve the phytase production by the yeasts, four different brands of phytase-promoting yeast extracts were added in the baking process. In addition, two yeast varieties were preincubated for 1 h at 30°C to initiate phytase biosynthesis. The phytate content was measured by high-performance ion chromatography (HPIC) and the mineral content by ion chromatography (HPIC). The results showed that all three HP yeasts improved the phytate degradation compared with the composite bread with no added HP yeast. The composite bread with preincubated S. cerevisiae BY80 or P. kudriavzevii TY13 plus Bacto yeast extract resulted in the lowest phytate content (0.08 μmol/g), which means a 99% reduction compared with the phytate content in the composite flour. With added yeast extracts from three of the four yeast extract brands in the baking process, all composite breads had a phytate reduction after 2-h fermentation corresponding to a phytate: iron molar ratio between 1.0 and 0.3 and a phytate: zinc molar ratio <3 suggesting a much-enhanced bioavailability of these minerals.

Dynamic changes and formation of key contributing odorants with amino acids and reducing sugars as precursors in shiitake mushrooms during hot air drying.

The dynamic variations in key contributing odorants, amino acids and reducing sugars in shiitake mushrooms during hot-air drying were determined by gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography-tandem mass (HPLC-MS/MS) and ion chromatography (IC). The potential precursors were explored by the partial least squares-discriminant analysis and Pearson correlation analysis, and Met, Cys, and ribose were considered as the possible precursors of dimethyl trisulfide and lenthionine. The verification experiments in the absence and presence of shiitake mushroom matrix further confirmed that Met and its interaction with ribose both contributed to generating dimethyl trisulfide. The polynomial nonlinear fitting curve could better represent the dose-effect relationships of Met and Met-ribose to produce dimethyl trisulfide with R2 of 0.9579 and 0.9957. Conversely, ribose, Cys or Cys-ribose were verified to be unable to form the key contributing odorants. Collectively, the results provided a method to reveal precursors and generation pathway of odorants.

Smoke toxicity of fire protecting timber treatments

Most fire deaths arise from inhalation of toxic gases. The fire toxicity of untreated plywood, pressure impregnated plywood and surface coated plywood was investigated under a range of fire conditions. Using the steady state tube furnace individual fire stages were replicated, fire effluent sampled, and toxic product yield determined by high performance ion chromatography and spectrophotometry. Despite different phosphorus loadings, both treatments hindered developing fires with less than 50% mass loss during non-flaming oxidative pyrolysis and did not readily undergo steady flaming. During under-ventilated flaming, all samples produced hydrogen cyanide (HCN), and both fire protecting treatments produced phosphoric acid (H3PO4). Assessment of smoke toxicity as fractional effective dose for incapacitation was based on asphyxiants carbon monoxide (CO) and hydrogen cyanide (HCN). This work demonstrates that due to emission of large amounts of CO, the predicted smoke toxicity of impregnated timber is significantly higher than coated timbers when a growing fire reaches the under-ventilated stage. The results have clear implications for those selecting products to ensure fire safety in enclosures such as buildings.

4-Hydroxybenzyl alcohol from Sinapis alba mustard seed meal extract for control of liverwort (Marchantia polymorpha)

Sinapis alba mustard seed meal extract is a by-product of mustard oil extraction, that is used for biodiesel and renewable jet fuel production. Recently, S. alba mustard seed meal has been shown to have herbicidal activity for a range of problematic weeds. The objectives of the present research were 1) to optimize the preparation of S. alba mustard seed meal extract; 2) to explore the applicability of S. alba mustard seed meal extract for control of liverwort, a common pest in ornamental plants greenhouses; and 3) to identify the major herbicidal compound(s) in these extracts. For extraction, methanol content in aqueous solution was optimized between 0% and 100%. Extracts prepared with 0–30% aqueous methanol provided 98–100% control of liverwort after single application and prevented liverwort plants from recovering. Extracts prepared using sequential extraction with 60% methanol provided an additional benefit of low particulate solutions. The efficiency of the produced S. alba mustard seed meal extract was comparable to two commercially available herbicides labeled for liverwort control under greenhouse conditions. Composition of S. alba mustard seed meal extracts was analyzed by high-performance liquid chromatography mass spectrometry and ion chromatography. 4-Hydroxybenzyl alcohol was identified as a main herbicidal compound based on the analysis and using commercially available reference solution. To the best of our knowledge, this is the first report of 4-hydroxybenzyl alcohol herbicidal activity toward nonvascular plants. The high concentrations of 4-hydroxybenzyl alcohol naturally produced from S. alba mustard seed meal, makes it a potential herbicide feedstock material.

Structural characterization and partial properties of dextran produced by Leuconostoc mesenteroides RSG7 from pepino.

Exopolysaccharides (EPSs) produced by lactic acid bacteria possess various bioactivities and potential attractions for scientific exploration and commercial development. An EPS-producing bacterial strain, RSG7, was previously isolated from the pepino and identified as Leuconostoc mesenteroides. Based on the analyses of high-performance size exclusion chromatography, high-performance ion chromatography, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and methylation, the RSG7 EPS was identified as a dextran with a molecular weight of 5.47 × 106 Da and consisted of α-(1→6) glycosidic linkages as backbone and α-(1→2), α-(1→3), α-(1→4), and α-(1→6) glycosidic linkages as side chains. Scanning electron microscopy observed a honeycomb-like porous structure of RSG7 dextran, and this dextran formed aggregations with irregular hill-shaped lumps according to atomic force microscopy analysis. Physical-chemical investigations suggested that RSG7 dextran possessed excellent viscosity at high concentration, low temperature, and high pH; showed a superior emulsifying capacity of tested vegetable oils than that of hydrocarbons; and owned the maximal flocculating activity (10.74 ± 0.23) and flocculating rate (93.46 ± 0.07%) in the suspended solid of activated carbon. In addition, the dextran could coagulate sucrose-supplemented milk and implied potential probiotics in vitro. Together, these results collectively describe a valuable dextran with unique characteristics for exploitation in food applications.

A fast and efficient method for the analysis of α-dicarbonyl compounds in aqueous solutions: Development and application

Among the highly oxygenated species formed in situ in the atmosphere, α-dicarbonyl compounds are the most reactive species, thus contributing to the formation of secondary organic aerosols that affect both air quality and climate. They are ubiquitous in the atmosphere and are easily transferred to the atmospheric aqueous phase due to their high solubility. In addition, α-dicarbonyl compounds are toxic compounds found in food in biochemistry studies as they can be produced endogenously through various pathways and exogenously through the Maillard reaction. In this work, we take advantage of the high reactivity of α-dicarbonyl compounds in alkaline solutions (intramolecular Cannizzaro reaction) to develop an analytical method based on high performance ion chromatography. This fast and efficient method is suitable for glyoxal, methylglyoxal and phenylglyoxal which are detected as glycolate, lactate and mandelate anions respectively, with 100% conversion at pH > 12 and room temperature for exposure times to hydroxide ranging from 5 min to 4 h. Diacetyl is detected as 2,4-dihydroxy-2,4-dimethyl-5-oxohexanoate due to a base-catalysed aldol reaction that occurs before the Cannizzaro reaction. The analytical method is successfully applied to monitor glyoxal consumption during aqueous phase HO∙-oxidation, an atmospherically relevant reaction using concentrations that can be observed in fog and cloud water. The method also reveals potential analytical artifacts that can occur in the use of ion chromatography for α-hydroxy carboxylates measurements in complex matrices due to α-dicarbonyl conversion during the analysis time. An estimation of the artifact is given for each of the studied α-hydroxy carboxylates. Other polyfunctional and pH-sensitive compounds that are potentially present in environmental samples (such as nitrooxycarbonyls) can also be converted into α-hydroxy carboxylates and/or nitrite ions within the HPIC run. This shows the need for complementary analytical measurements when complex matrices are studied.

English

Diet based on whole cereal flours is associated with a high prevalence of iron deficiency anemia and zinc deficiency in low/middle-income countries. Such flours contain high content of phytate that chelates minerals such as iron and zinc, making them unavailable for absorption by humans. To improve the mineral absorption, a phytate:iron molar ratio &lt;1 and a phytate:zinc molar ratio &lt;5 is needed to be achieved. This study aimed to improve the phytate degradation in composite wheat-cassava-whole sorghum flour bread by adding a phytase releasing yeast Pichia kudriavzevii TY13 in baking, preincubated or not, with addition of yeast extract. The phytate and mineral contents were measured by high-performance ion chromatography. Addition of P. kudriavzevii TY13 to the composite flour dough and fermentation for 2 h at room temperature resulted in a 98% phytate degradation. However, the same phytate reduction in the composite bread was achieved after 1 h fermentation at room temperature with addition of preincubated P. kudriavzevii TY13 plus yeast extract. Increasing the fermentation temperature to 30&deg;C, the phytate content was equally low after fermentation for 1 h with P. kudriavzevii TY13 (preincubated or not) plus yeast extract. In conclusion, a faster reduction of phytate in composite bread was obtained by increasing the fermentation temperature, and addition of P. kudriavzevii TY13 (preincubated or not) with added yeast extract. The phytate to iron molar ratio was then 0.2 and the phytate to zinc molar ratio 0.6, which strongly indicates an improved bioavailability of both minerals from such a bread. &nbsp; Key words: Phytate, phytase, Pichia kudriavzevii TY13, yeast extract, wheat flour, cassava flour, sorghum flour, bread making.

Development of Analytical Methods for the Determination of N-Bromosuccinimide in Different Active Pharmaceutical Ingredients by High-Performance Ion Chromatography with Suppressed Conductivity Detection

Product safety is important for medicines. For drugs on the market, it must be demonstrated that the levels of toxic contaminants are below the permitted limits. These impurities are used as reagents or are generated during synthesis. N-bromosuccinimide is used as a brominating agent in the synthesis of some active pharmaceutical ingredients. The determination of N-bromosuccinimide is difficult due to its high reactivity. In this work, a high-performance ion chromatographic method was developed for the determination of N-bromosuccinimide. The ion chromatographic measurement can be performed in two ways, one involves the assay of the resulting bromide ion and the other is via the assay of the 3-carbamoyl propanoic acid ion produced from the succinimide. Both acid ions were analyzed on an anion exchange column by gradient elution with potassium hydroxide eluent and detection was performed by a suppressed conductivity detector. During the method development, the results showed that the measurement of bromide ion was more selective than the measurement of 3-carbamoyl propanoic acid ion. Two different types of active pharmaceutical ingredients (API), i.e., prasugrel and favipiravir, were chosen to test the developed method and sample preparation. For both APIs, sample preparation was performed in a vial and consists of liquid–liquid extraction with an alkaline reagent. Finally, the anion exchange ion chromatography method was validated at the limit value level, and harmonized with the guidelines. For prasugrel, the quantification limits and the accuracy at the limit level are 7.2 ppm and 96.4%, while for favipiravir these are 7.5 ppm and 114.7%, respectively.

Fast and Complete Destruction of the Anti-Cancer Drug Cytarabine from Water by Electrocatalytic Oxidation Using Electro-Fenton Process

The fast and complete removal of the anti-cancer drug cytarabine (CYT) from water was studied, for the first time, by the electro-Fenton process using a BDD anode and carbon felt cathode. A catalytic amount (10−4 M) of ferrous iron was initially added to the solution as catalyst and it was electrochemically regenerated in the process. Complete degradation of 0.1 mM (24.3 mg L−1) CYT was achieved quickly in 15 min at 300 mA constant current electrolysis by hydroxyl radicals (●OH) electrocatalytically generated in the system. Almost complete mineralization (91.14% TOC removal) of the solution was obtained after 4 h of treatment. The mineralization current efficiency (MCE) and energy consumption (EC) during the mineralization process were evaluated. The absolute (second order) rate constant for the hydroxylation reaction of CYT by hydroxyl radicals was assessed by applying the competition kinetics method and found to be 5.35 × 109 M−1 s−1. The formation and evolution of oxidation reaction intermediates, short-chain carboxylic acids and inorganic ions were identified by gas chromatography-mass spectrometry, high performance liquid chromatography and ion chromatography analyses, respectively. Based on the identified intermediate and end-products, a plausible mineralization pathway for the oxidation of CYT by hydroxyl radicals is proposed.