High-pressure Liquid Chromatography Research Articles

DEVELOPMENT AND OPTIMIZATION OF HPLC METHODS FOR THE CHIRAL SEPARATION OF ARYLPYRAZOLE, CHLOROACETANILIDE AND ORGANOCHLORINE PESTICIDES: CASE STUDIES OF BENZOBICYCLON, ACETOCHLOR AND CHLORDANE.

This work is centered on the development and optimization of High-Performance Liquid Chromatographic methods for the separation of chiral pesticides, particularly benzobicyclon, chlordane and acetochlor employing Agilent Technologies Infinity II chiral HPLC system equipped with a UV – 2000 detector. The stereoisomers were successively separated using a standard analytical column of dimensions 250 mm X 4.6 mm. The Cis– stereoisomers of chlordane exhibited partial baseline separation while the Trans – enantiomers were fully separated. Benzobicyclon and acetochlor enantiomers attained full baseline separation under optimized conditions. Chlordane and benzobicyclon were analyzed using normal phase chromatography [NP]c with a mobile phase of 90% Normal hexane and 10% Isopropanol, while acetochlor was analyzed by reverse phase chromatography [RP] c using 70% methanol and 30% water. Benzobicyclon was later spiked into soil sample and subsequently extracted using Environmental Protection Agency (EPA) methods and the extracts were further analyzed with a shorter analytical column of dimensions 75 mm X 4.6 mm. The HPLC separation revealed that the longer column provided more efficient separation for the benzobicyclon stereoisomers than the shorter column as reflected by high separation factors (?). The high recovery rate of the stereoisomers of benzobicyclon and the internal standard from the soil extracts confirmed the effectiveness of the method of extraction and the HPLC system employed.

Residue analysis of premix formulation of fipronil and imidacloprid and its metabolites in hot pepper (Capsicum annum)

A field experiment was conducted during 2018–19 and 2019–20 at Chaudhary Charan Singh Haryana Agricultural University, Hisar, Haryana to assess the dissipation pattern of a ready mix formulation i.e. fipronil and imidacloprid along with their metabolites in fruits of hot pepper (Capsicum annum L.). The Hot pepper variety Kranti was used for the study. Quantitative analysis was done on gas liquid chromatography (GLC) and high pressure liquid chromatography (HPLC) for fipronil and imidacloprid with their metabolites, respectively. At the suggested dose, fipronil residues were lower than 0.01 mg/kg in the studied years. However, in double doses, the total residues of fipronil were detected on the 5th (0.071 mg/kg) and 3rd (0.043 mg/kg) day for the 1st and 2nd year following drench application. Imidacloprid was detected only in the subsequent year’s trial in double doses. Residual leftovers of imidacloprid metabolite (6- CNA) were lower than 0.01 mg/kg (LOQ). No residual leftovers were present in fully ripened red chilli and harvest time samples of soil.

The efficacy of high pressure liquid chromatography (HPLC) in detecting congenital glycosylation disorders (CDG)

Abstract Objectives Congenital disorders of glycosylation (CDG) are a family of rare inherited metabolic disorders. This study aimed to examine the carbohydrate-deficient transferrin (CDT) screening results of 1,328 patients with suspected CDG by using transferrin- high pressure liquid chromatography (Tf- HPLC) method and to evaluate the performance of the method as a reference diagnostic tool. Methods Relative CDT levels (CDT concentrations expressed as percent of total transferrin) were determined in serum samples by HPLC. The method sensitivity, specificity and positive predictive value (PPV) were further calculated. Results Abnormal transferrin isoform profile consistent with CDG Type-I and CDG Type-II were determined in 50 cases; in 44 cases asiolo-Tf (7.63 ± 5.44 %) and disialo-Tf (36.29 ± 9.04 %), in six cases monosialo-Tf (3.95 ± 0.95 %) and trisialo-Tf (25.05 ± 4.46 %) were determined and decreased tetrasialo-Tf (49.75 ± 11.59 %) was identified in all cases. Two cases having abnormal CDT pattern were molecularly diagnosed with hereditary fructose intolerance and galactosemia and 11 cases diagnosed with CDG based on clinical and molecular analysis showed a normal pattern. The sensitivity, specificity and positive predictive values of Tf-HPLC method were 81.96 %, 99% and 96 %, respectively. Conclusions Tf-HPLC is a useful, highly sensitive, cost-advantageous and reliable method for the detection and preliminary diagnosis of CDG for laboratories working with large sample series.

Smartcard: an integrated approach for contaminant monitoring, from field to laboratory.

Effective food safety monitoring requires a multi-step approach from farm to fork, involving different methods, ranging from convenient screening devices to sophisticated laboratory confirmatory testing. However, sample transportation to routine laboratories is time-consuming and expensive. Simplified on-site sampling followed by laboratory analysis offers a potential solution. Dried blood spot (DBS) cards ensure stability and ease of sample transportation and are used in clinical testing. However, the applicability of such an approach could be broader and include the storage of dried extract from more complex (solid) matrices. Therefore, a simplified approach is presented here, using DBS cards for on-site sampling and subsequent laboratory confirmation for food contaminants. To achieve this, an analytical tool (Smartcard) was designed using 3D-printing technology. As a proof of concept, the approach was applied to detect the pesticide fipronil, which is widely used in ornamental flower production to limit pests and on poultry farms. The Smartcard can securely store the sample extracts on a DBS card (dried extract spot (DExS) card), incorporate the lateral flow immunoassay (LFIA) and immediately provide an estimate of contamination levels. After simplified in-syringe extraction of the sample, the LFIA allows direct screening of fipronil (half maximum inhibitory concentration of 6.5µg/l with calibration standards), and the same sample extract can be directly applied to the DExS card for storage and transport to the laboratory, where analyte re-extraction and instrumental analysis is performed using ultra high-pressure liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detecting fipronil down to 0.8µg/kg.

Glucose influence cold tolerance in the fall armyworm, Spodoptera frugiperda via trehalase gene expression

The fall armyworm (FAW), Spodoptera frugiperda is a cold-sensitive species that overwinters in temperate climates without diapause. Overwintering in insects involves rapid cold hardening (RCH), supported by trehalose (TRE), which serves as an intermediate between glycogen (GLY) and glucose (GLU). However, both GLU and TRE help maintain homeostasis under stress. TRE is hydrolyzed by the enzyme trehalase (Treh) into GLU. This study retrieved Sf-Treh1a, Sf-Treh1b, and Sf-Treh2 from the FAW transcriptome analysis. RNA interference (RNAi) targeting these three Treh genes resulted in significant downregulation of mRNA levels and altered survival rates in RNAi-treated FAW larvae following RCH treatment. High-pressure liquid chromatography (HPLC) quantification of TRE and GLU in treated groups suggests that GLU is an essential component of the hemolymph for survival adaptation to cold conditions in S. frugiperda. This study reveals limited cold adaptability of FAW, as evidenced by lower glucose concentration levels. We found that FAW requires alternative molecules, in conjunction with glucose and trehalose for freeze tolerance and survivability. Our study aims to discover the molecular mechanisms that contribute to freeze tolerance in FAW by exploring the roles of trehalose, glucose, and glycogen.

Antibacterial, Herbicidal, and Plant Growth-Promoting Properties of Streptomyces sp. STD57 from the Rhizosphere of Adenophora stricta

Bacterial wilt triggered by the soil-borne pathogenic bacterium Ralstonia solanacearum is one of the most serious diseases in tomato plants, leading to huge economic losses worldwide. Biological control is considered an environmentally friendly and sustainable way to manage soil-borne diseases. In this study, Streptomyces sp. STD57 isolated from the rhizosphere of Adenophora stricta showed strong antibacterial activity against R. solanacearum. Pot experiments showed that strain STD57 exhibited a significant biocontrol effect (81.7%) on tomato bacterial wilt in the greenhouse environment. Furthermore, strain STD57 could inhibit the growth of weeds (Amaranthus retroflexus, Portulaca oleracea, and Echinochloa crusgalli) but promote the growth of crops (wheat, rice, and tomato). The plant growth-promoting substance was identified as indoleacetic acid (IAA) by high-pressure liquid chromatography–mass spectrometry and genome analysis. Coarse separation of the fermented extracts revealed that the antibacterial and herbicidal substances were mainly in the fermentation supernatant and belonged to different products. These findings suggested that strain STD57 may be a potential biocontrol and bioherbicide agent useful in agriculture.

The Ability of Vaping Technology to Deliver an Equivalent Respirable Dose of Beclomethasone Dipropionate Compared to Nebulization

Background/Objectives: This study focuses on the ability of vaping technology to deliver beclomethasone dipropionate compared to nebulization. Methods: An in vitro comparison of aerosol properties in terms of respirable dose with the Glass Twin Impinger and the mass median aerodynamic diameter using the Next Generation Impactor was performed. The respirable dose delivered in a vaping drug delivery system (VDDS) puff as a function of concentration was quantified by high-pressure liquid chromatography coupled with an ultraviolet detector. Results: The mass of drug contained in a single puff of 55 mL of aerosol varied between 0.94 and 1.95 µg for a refill liquid concentration range of 400 to 1600 µg/mL. The analysis of the particle size distribution shows an advantage for a VDDS in producing smaller particles compared to nebulization (1.56 ± 0.05 µm vs. 2.30 ± 0.19 µm). In total, 81 puffs are needed to reach the dose equivalent to nebulized beclomethasone dipropionate under these specific experimental conditions, which corresponds to an aerosol duration of about 4 min (i.e., four times lower than the jet nebulizer) and a patient administration time of about 45 min (i.e., three times higher than the jet nebulizer). Conclusions: The results show the potential of vaping devices as an alternative to nebulizers for the administration of beclomethasone dipropionate in an equivalent respirable dose.

Application of Polydopamine-Based Magnetic Solid-Phase Extraction for Highly Sensitive Determination of Aristolochic Acid I from Traditional Chinese Medicine Samples.

A low cost-effective and simple synthesis method combining magnetic solid-phase extraction (MSPE) and high-pressure liquid chromatography was developed for the analysis of aristolochic acids I (AAI) in traditional Chinese medicine samples. A novel polydopamine (PDA) modified magnetic nanoparticles with one single carbon layer (Fe3O4@1C NPs) via one-pot hydrothermal approach was prepared and then successfully employed to extract AAI for the first time. Dopamine (DA) can form a PDA layer on Fe3O4@1C NPs surface through self-polymerization to form Fe3O4@1C@PDA. As a surface modifier of DA, PDA offered more adsorption sites to AAI due to π-π stacking, hydrogen bonding and electrostatic interactions. The parameters of MSPE were optimized by univariate and multivariate methods (Box-Behnken design) in detail. High degree of linearity was obtained in the range of 0.05-200.0μg/mL. The limits of detection (S/N = 3) and quantification (S/N = 10) were 0.08 and 0.25μg/mL, respectively. The recoveries of AAI in spiked Xiaoqinglong mixture samples were in the range of 86.7 to 108.5% with the relative standard deviation of less than 5.2%. Thus, a fast, convenient, sensitive and eco-friendly method was successfully proposed and became a promising approach for the determination of AAI in herbal plants or its preparation in the manufacturing procedure.

The Role of BAG3 Protein Interactions in Cardiomyopathies.

Bcl-2-associated athanogene 3 (BAG3) plays an important function in cellular protein quality control (PQC) maintaining proteome stability. Mutations in the BAG3 gene result in cardiomyopathies. Due to its roles in cardiomyopathies and the complexity of BAG3-protein interactions, it is important to understand these protein interactions given the importance of the multifunctional cochaperone BAG3 in cardiomyocytes, using an in vitro cardiomyocyte model. The experimental assay was conducted using high pressure liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in the human AC16 cardiomyocyte cell line with BioID technology. Proteins with BAG3-interaction were identified in all the 28 hallmark gene sets enriched in idiopathic cardiomyopathies and/or ischemic disease. Among the 24 hallmark gene sets enriched in both idiopathic cardiomyopathies and ischemic disease, 15 gene sets had at least 3 proteins with BAG3-interaction. This study highlights BAG3 protein interactions, unveiling the key gene sets affected in cardiomyopathies, which help to explain the molecular mechanisms of the cardioprotective effects of BAG3. In addition, this study also highlighted the complexity of proteins with BAG3 interactions, implying unwanted effects of BAG3.

Hydroxyurea Pharmacokinetic Evaluation in Patients with Sickle Cell Disease

Background: Hydroxyurea (HU), also known as hydroxycarbamide, is an oral ribonucleotide reductase inhibitor. In 1999, the United States Food and Drug Administration (FDA) approved HU for the treatment of sickle cell disease (SCD). Since then, it has become the cornerstone in the management of SCD patients, helping to reduce vaso-occlusive crises, acute chest syndrome, the need for blood transfusions, hospitalizations and mortality. There is considerable variability among individuals in HU pharmacokinetic (Pk) parameters that can influence treatment efficacy and toxicity. The objective of this work is part of a clinical study aimed at investigating HU Pk and determining the optimal sampling time to estimate the Area Under the Curve (AUC) in SCD patients. Methods: HU plasma concentration in 80 patients at various time points (2, 4, 6, 24 h) following a 48-h drug washout was quantified using High-Pressure Liquid Chromatography (HPLC) coupled with an ultraviolet (UV) detection method previously described in the literature and adapted to new conditions with partial modifications. Results: The mean HU administered dose was 19.5 ± 5.1 mg/kg (range: 7.7–37.5 mg/kg). The median AUC quantified in plasma patients was 101.3 mg/L/h (Interquartile Range (IQR): 72.5–355.9) and it was not influenced by the weight-based dose. However, there was a strong positive correlation between AUC and Body Mass Index (BMI) as well as dose per Body Surface Area (BSA). Along with a three-point approach for AUC determination present in the literature, we show results obtained from a four-point sampling strategy, which is more useful and effective for better optimizing dose escalation to the maximum tolerated dose (MTD). Moreover, we observed that most patients achieved the maximum HU plasma concentration two hours after drug administration, regardless of age differences. Conclusions: HU treatment, which represents a milestone in the treatment of SCD due to its ability to reduce disease complications and improve patients’ quality of life, requires careful monitoring to optimize the individual dose for saving potential side effects and/or adverse events.

Exploring seed characteristics and performance through advanced physico-chemical techniques

Simple physico-chemical techniques can be used to evaluate the composition, structure, and characteristics of plant seeds to determine their viability, quality, and possible uses in agriculture. Advanced analytical techniques, including thermo gravimetric analysis (TGA), electron paramagnetic resonance (EPR), and high-pressure liquid chromatography (HPLC), provide completely new insights and more precise information. They can be integrated to build up seed quality profiles, with great advantage to assess water content, organic compounds, and inorganic metals without the need to carry out many extraction procedures, as requested by more conventional methods. In this study, seed lots from three different plant species such as Triticum turgidum L. subsp. durum (wheat), Trigonella foenum graecum L. (trigonella or fenugreek), and Atriplex halimus L. (saltbush or sea orach) have been used to test the potential of TGA, EPR, and HPLC to discriminate between seed-specific features. A key finding of this study is that HPLC is essential in Principal Component Analysis (PCA) because various seeds (from the same species or other species) may contain compounds with varying polarity groups. The reported data confirm the efficacy of this approach. These data, fully available for other users, are coherently constructed and provide a proof of concept for future seed quality control studies.

Unveiling connections: bisphenol A and vitamin D dynamics in breast milk among healthy lactating mothers

ABSTRACT Bisphenol A (BPA) has negative impact on human health. This study aims to explore the association between the levels of BPA and 25(OH) vitamin D in breastmilk. BPA exposure and vitamin D sources were recorded on the study form. Breastmilk 25(OH) vitamin D was measured by the competitive enzyme-linked immunosorbent assay method, and BPA was analyzed by fluorescence detector high pressure liquid chromatography technique. Multiple logistic regression analysis were performed for association. Among 70 lactating mothers, the median 25(OH) vitamin D level was 12.6 ng/mL. In 92.9% of breastmilk samples, detectable levels of BPA were found, with a median BPA concentration of 2.56 ng/mL. However, both univariate and multivariate analyses failed to reveal any association between breastmilk BPA and 25(OH) vitamin D levels. This lack of association in healthy lactating mothers, highlighting the need for further research to comprehensively understand the intricate dynamics of these factors.

Screening of Antioxidant Maillard Reaction Products Using HPLC-HRMS and Study of Reaction Conditions for Their Production as Food Preservatives

The Maillard reaction (MR) involves interactions between reducing sugars and amino acids or proteins during heating, producing Maillard reaction products (MRPs) that influence food flavour, aroma, and colour. Some MRPs exhibit antioxidant properties, prompting interest in their potential as natural food preservatives. This study aimed to develop a method for detecting and identifying antioxidant MRPs using high-pressure liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (HRMS). By improving chromatographic conditions, the separation of antioxidant MRPs was optimised using known antioxidant MRPs as reference signals. This work also examined the effects of pH, reaction time, and different sugar–amino acid combinations on the production and composition of antioxidant MRPs. Results indicated that neutral to basic pH facilitated faster reactions, with pH 7 selected as optimal. A library of 50 m/z signals for potential antioxidant MRPs was created, and the best combinations of amino acids and sugars for their production were identified. These findings pave the way for more precise analyses of antioxidant MRPs, with future research focusing on isolating and characterising specific MRPs to understand their structures and mechanisms, ultimately contributing to the development of functional foods with natural antioxidant properties.

Investigating in vitro anticholinergic potential (anti-AChE and anti-BuChE) of Chaenomeles leaves extracts and its phytochemicals including chlorophylls, carotenoids and minerals.

The goal of this work was to evaluate the chemical constitution and health-promoting potential of 12 varieties of Chaenomeles × superba, speciosa and japonica leaves. Carotenoids, chlorophylls, triterpenes, sugars, polyols and acids were analyzed quantitatively and qualitatively using high pressure liquid chromatography (LC) coupled with mass spectrometry (MS), while the mineral profile was determined using atomic absorption spectroscopy (AAS). Moreover, the in vitro anticholinergic potential (inhibition of acetyl-cholinesterase (AChE) and butyryl-cholinesterase (BuChE)) and antioxidant (ABTS, FRAP, ORAC) capacity were evaluated. For the first time in Chaenomeles genotypes 26 carotenoid derivatives and 22 chlorophyll derivatives were identified. Some varieties contained high amounts of carotenoids and chlorophylls (Ch. × superba 'Colour Trail', 'Nicoline', 'Pink Lady', 'Texas Scarlet'), and triterpenes (Ch. speciosa 'Simonii', 'Rubra', and Ch. × superba 'Colour Trail', 'Nicoline') and showed high ORAC antioxidant (Ch. × superba 'Pink Lady' and Ch. speciosa 'Simonii') and anticholinergic (Ch. speciosa species) activity. The studied leaves also contained sugars (3.1 to 16.5mg/100g), organic acids (3.9-8.1g/100g), and minerals (Ca, Cu, Fe, K, Mg, Mn, Na, and Zn). In conclusion, Chaenomeles leaves show potential as a new source for the production of nutraceuticals, as well as for medical and/or cosmetic purposes.

Novel Chiral HPLC Method for Accurate Identification and Quantification of R&S Enantiomers in Ropivacaine on Immobilized Chiral Stationary Phase: Development and Validation

Purpose: Ropivacaine is a widely used local anesthetic for managing postoperative pain, particularly in procedures such as caesarean sections. While historically used as a racemate, its structural similarity to mepivacaine and bupivacaine within the pipecoloxylidide group is notable. Both enantiomers of ropivacaine exhibit similar nerve-blocking properties, but the R enantiomer is associated with increased cardiotoxicity compared to the S-Ropivacaine, like bupivacaine. This study aimed to develop and validate precise and rapid chiral chromatographic techniques for quantifying potential (R&S enantiomers). Methods: We used normal phase chromatography with a (3,5-dimethylphenylcarbamate) immobilized- type polysaccharide stationary phase to quantify R&S enantiomers. The method followed ICH Q2(R1) guidelines, employing CHIRAL ART Amylose-SA for determining S-Ropivacaine enantiomeric purity in pharmaceutical drugs. The validation included accuracy and LOQ (limit of quantification) profiles, with measurement error assessments. Linear regression of accuracy profiles post square root transformations set acceptance limits at ±10%. Results: The method accurately quantified R&S enantiomers, adhering to ICH Q2(R1) guidelines. Validation showed high accuracy and precise LOQ profiles. Measurement error assessments confirmed reliability. Linear regression of accuracy profiles stayed within ±10% acceptance limits, confirming the method's suitability for determining S-Ropivacaine enantiomeric purity. Conclusion: The developed chiral chromatographic method provides an effective means of quantifying the enantiomeric purity of S-Ropivacaine in pharmaceutical drugs. Its adherence to ICH Q2(R1) guidelines ensures reliability and accuracy in measurement. This method enables precise determination of S-Ropivacaine content, which is crucial for optimizing therapeutic outcomes while minimizing the risk of cardiotoxicity associated with the R enantiomer.

Digital model of biochemical reactions in lactic acid bacterial fermentation of simple glucose and biowaste substrates

As concerns about the environmental impacts of biowaste disposal increase, lactic acid bacterial fermentation is becoming increasingly popular. Current academic research is aimed at the process optimization by developing digital bioreactors. The primary focus is to develop a digital model mimicking the biochemical reactions. In the light of this, this paper intended to build a digital model of biochemical reactions during the fermentation process of both glucose and biowaste substrates, including white pasta and organic municipal waste. For this purpose, near-infrared (NIR) and mid-infrared (MIR) spectroscopy techniques were used to collect spectral information during the fermentation process. Next, the samples were analyzed by High Pressure Liquid Chromatography (HPLC) to measure their glucose, fructose, arabinose, xylose, disaccharide, lactic acid, and acetic acid contents. The results showed that learning algorithms trained on MIR spectra accurately estimated the biochemical reactions for both glucose and biowaste substrates. For the glucose substrate, the results showed R-squared of 0.97 and RMSE of 4.69 g/L for glucose, and R-squared of 0.98 and RMSE of 2.74 g/L for lactic acid. In the case of biowaste substrate, estimations included glucose (R-squared = 0.97, RMSE = 4.69 g/L), fructose (R-squared = 0.88, RMSE = 1.47 g/L), arabinose (R-squared = 0.98, RMSE = 0.55 g/L), xylose (R-squared = 0.93, RMSE = 1.11 g/L), disaccharide (R-squared = 0.90, RMSE = 0.55 g/L), total sugar (R-squared = 0.98, RMSE = 3.79 g/L), lactic acid (R-squared = 0.98, RMSE = 2.74 g/L), and acetic acid (R-squared = 0.97, RMSE = 0.36 g/L). Regarding NIR spectral data, the predictive models were accurate when the substrate was glucose, however, they failed to accurately estimate the chemical reactions in the case of biowaste substrate. The findings of this study can be used to fulfill the requirements for a continuous fermentation process with the objective of maximizing lactic acid production.

A General and Scalable Method toward Enantioenriched C2-Substituted Azetidines Using Chiral tert-Butanesulfinamides.

Diverse ranges of chiral nitrogen-containing heterocycles serve as a molecular toolbox for modulating a wide array of biological processes, but enantioenriched production of smaller chiral heterocycles is a bottleneck. There is a lack of general approaches for the stereoselective preparation of chiral 4-membered monocyclic C2-substituted azetidines, where many routes to different substitution types are possible, but no simple and common approach exists. To bridge this gap, inexpensive and widely available chiral tert-butanesulfinamides are harnessed for chiral induction with 1,3-bis-electrophilic 3-chloropropanal, providing a three-step approach to C2-substituted azetidines with aryl, vinyl, allyl, branched alkyl, and linear alkyl substituents. Eleven azetidine products are produced, and the approach is shown to be effective on a gram-scale with a single purification of the protected azetidine product in 44% yield over three steps in an 85:15 diastereomeric ratio. In most cases, the diastereomers are separable using normal phase chromatography, often resulting in previously elusive enantiopure azetidine products. Protected azetidines were shown to undergo rapid and efficient sulfinamide cleavage, producing an azetidine hydrochloride salt that was subjected to derivatization reactions, highlighting the method's applicability to medicinal chemistry approaches.

Determination of adsorption capacity, regeneration ability, and aggregation tendency toward inorganic and organic pollutants of metal-doped carbon–silica composites in multicomponent systems

Abstract The main aim of the study was to develop a method for determining the adsorption capacity, regeneration ability, and aggregation tendency of metal-doped carbon–silica composites (iron-doped, C/Fe/SiO2, and manganese-doped, C/Mn/SiO2) against heavy metals and selected organic substances. The properties of these composites were compared with those of metal-free silica–carbon composite (C/SiO2). Inductively coupled plasma–optical emission spectrometry (ICP–OES) and high-pressure liquid chromatography were used to determine the adsorbed amounts and the desorption degree of organic/inorganic pollutants. Potentiometric titrations and electrophoretic mobility measurements were conducted to understand the mechanisms that were driving adsorption and particle aggregation. The size of the aggregates formed in the systems as well as the stability of the examined suspension were estimated by using ultraviolet-visible spectrophotometry. The performed experiments showed that the selected combination of methods is appropriate to determine the potential of metal-doped carbon–silica composites as adsorbents as well as the ease of their removal with adsorbed contaminants from aqueous solutions by sedimentation.

Behaviour of ionic herbicides in different forestry soils derived from volcanic ash

Background: Weed control has been one of the most significant factors in forest establishment practices that can improve biomass production, and herbicides represent the most effective and convenient way to control weeds. The environmental concern about herbicides in this industry is because the herbicide-treated area is often located near water reservoirs or areas where rivers and creeks originate. This study aimed to determine the adsorption and degradation behaviours of seven ionic herbicides used in forestry production in five Chilean forestry soils and their relation to the leaching and to generate information to validate environmental predictive models. Methods: Adsorption and degradation of ionisable herbicides such as simazine, terbuthylazine, hexazinone, metsulfuron-methyl, indaziflam, flazasulfuron and glyphosate were studied in Andisol, Ultisol, Inceptisol, Entisol and Alfisol forestry soils, to be related to their leaching in 100-cm high and 11-cm diameter soil disturbed lysimeters. Herbicides were quantified using high-pressure liquid chromatography and gas chromatography. Relationships between soil physicochemical properties, herbicide adsorption and degradation, and herbicide leaching were determined. Results: In decreasing order, the herbicides were mobile in Entisol>Alfisol>Ultisol>Inceptisol>Andisol soils. On the other hand, the more leachable herbicides, from high to low, were: hexazinone, metsulfuron-methyl, simazine, glyphosate, terbuthylazine, flazasulfuron and indaziflam. The last two herbicides were not detected below 60 cm soil depth. In general, the maximum soil depth herbicide reached and the percentage mass leached up to 90 cm soil depth were inversely related to soil adsorption (1/Kd), soil porosity, humidity, silt, aluminium, and calcium soil content. Herbicide degradations were generally faster than referential published values. Conclusions: The environmental coefficients of ionic herbicides were more related to soil properties than their physicochemical properties. Persistence of herbicides in soil was smaller than that commonly reported in other studies or international databases and soil adsorption averages were generally higher than international reference values. The stronger relationship between ionic herbicide behaviour and forestry soil properties endorses the requirement to determine the environmental herbicides parameters in situ, avoiding using parameters estimated in other soils.

Major Bitter-Tasting Compounds from the Dichloromethane Fraction of Bitter Gourd (Fruit of Momordica charantia L.) Extract and Their Precursors.

The unripe fruit of the plant Momordica charantia L., commonly known as bitter gourd or bitter melon, is a popular vegetable and medical herb in many parts of the world and is characterized by its strong bitter taste. In our endeavor to decode its bitter taste, the dichloromethane fraction of 75% methanol extract of bitter gourd was found to be intensely bitter. Combining sensory analysis-guided fractionation and newly developed comparative high-pressure liquid chromatography (HPLC) analysis-guided purification led to the isolation of five known compounds including momordicoside L (1), (23E)-3β-O-malonyl-7β,25-dihydroxycucurbita-5,23-dien-19-al (2), 3-O-β-d-allopyranosyl-7β,25-dihydroxycucurbita-5,23(E)-dien-19-al (3), momordicine IV (5), and charantoside B (6) and three new compounds 3-O-β-d-3-ketoglucopyranosly-7β,25-dihydroxycucurbita-5,23(E)-dien-19-al (4), 6'-O-malonylmomordicoside L (7), and 6'-O-malonylmomordicine IV (8) from bitter gourd. Sensory analysis revealed compounds 3-8 had strong bitter taste with their bitter taste recognition thresholds in the range between 3.6 (4) and 13.6 ppm (6) in 3% ethanol. UPLC-MS/MS quantification showed that their concentration in bitter gourd ranged from 16.5 ± 1.3 mg/kg (4) to 214.8 ± 14.0 mg/kg (6) on a dry weight basis. Calculation of the dose-over-threshold (DoT) factor showed that momordicine IV (5) and charantoside B (6) should be considered as bitter principles of bitter gourd. In addition, the study also demonstrated the ubiquity of the isomerization reaction in the side chain of cucurbitane-type triterpenoids. Many isolated compounds were the isomerized products of their natural precursors, and these precursors should be the primary bitterness contributors of fresh fruits. In addition, comparative HPLC analysis-guided purification could be a practical approach for the fast isolation of acid-labile precursors.