Composition Of Carboxylic Acids Research Articles

Year-round observations of stable carbon isotopic composition of carboxylic acids, oxoacids and α-Dicarbonyls in fine aerosols at Tianjin, North China: Implications for origins and aging

To better understand the origins and photochemical processing (aging) of organic aerosols (OA), we studied fine aerosols (PM2.5) collected at urban (Nankai District (ND)) and suburban (Haihe Education Park (HEP)) Tianjin, North China over a one-year period (2018–2019) for stable carbon isotopic composition (δ13C) of water-soluble diacids, oxoacids, α-dicarbonyls and fatty acids. Maleic (M, −18.3 ± 10.9‰ at ND and −23.5 ± 10.2‰ at HEP) and fumaric (F, −22.0 ± 12.1‰ at ND and −22.5 ± 10.5‰ at HEP) acids were found to be most enriched with 13C followed by oxalic acid (C2, −24.7 ± 3.9‰ at ND and −25.9 ± 4.7‰ at HEP) during the campaign. Based on seasonal changes in δ13C of selected marker species: C6 and C9 diacids, phthalic, glyoxylic and pyruvic acids and glyoxal, and their comparison with the source signatures, we found that water-soluble OA in Tianjin were mainly originated from fossil fuel combustion and biomass burning emissions and were subjected for significant aging. The contribution from fossil fuel combustion including coal combustion was high in autumn and winter, especially at ND. Considering the enrichment of 13C in specific species together with linear relations of δ13C of selected species with their concentrations, with mass ratios and with the relative abundance of C2 diacid, we inferred that the photochemical transformations of longer-chain diacids, oxidation of α-dicarbonyls (Gly and mGly), preferably in gas phase, were important in warm period (March–September), whereas the oxidation of Gly, mGly and other precursors in aqueous phase were major in cold period (October–February).

Carboxylic acids in the flowers of Veronica spicata L. and Veronica incana L.

In the Ukrainian flora, species of Veronica L. genus (Plantaginaceae Juss.) are classified into 8 sections. Among the representatives of Pseudolysimachion W. D. J. Koch section in the Kharkiv region, Veronica spicata L. (spike speedwell) and Veronica incana L. (Veronica spicata L. subsp. incana (L.) Walters, silver speedwell) are common. Plants are used for the treatment of upper respiratory tract diseases, malignant neoplasms, gastrointestinal tract and genitourinary system disorders, diabetes mellitus.
 The aim of the research was to study the carboxylic acids of flowers of Veronica spicata L. and Veronica incana L.
 Materials and methods. The objects of the research were flowers of Veronica spicata L. and Veronica incana L., collected in the flowering stage in the Botanical Garden of Karazin University (Kharkiv, Ukraine) in summer 2018. The study of carboxylic acid composition was performed by chromatography-mass spectrometry on a 6890N MSD/DS Agilent Technologies chromatograph with a 5973N mass spectrometric detector. Identification of methyl esters of acids was performed using data from the mass spectrum libraries NIST 05 and Willey 2007 in a combination with programs for the identification of AMDIS and NIST; also, their retention time and the retention times of standard compounds were compared.
 Results. In Veronica incana L. flowers, 37 carboxylic acids were identified and quantified, constituting 1.05 %. In Veronica spicata L. flowers, 32 carboxylic acids were identified and quantified, the total content of which was 2.75 %.
 Conclusions. A higher carboxylic acid content was established in the flowers of Veronica spicata L. The fatty acid composition of Veronica incana L. flowers is characterized by a comparable content of saturated and unsaturated acids, while in Veronica spicata L. flowers, unsaturated fatty acids prevail over saturated fatty acids. The content of aromatic acids in the flowers of studied species was comparable. The characteristic carboxylic acids in the flowers of Veronica incana L. are oxalic, 3-hydroxy-2-methylglutaric, pentadecanoic, heneicosanoic, tricosanic,4-hydroxybenzoic, 4-methoxybenzoic and 3,4-dimethoxybenzoic acids; in the flowers of Veronica spicata L. – 2-hydroxy-3-methylglutaric, α-furanic and homovanillic acids

New Insight into Carboxylic Acid Metabolisms and pH Regulations During Insoluble Phosphate Solubilisation Process by Penicillium oxalicum PSF-4.

Phosphate solubilising fungi (PSF) play an important role in increasing phosphorus (P) bioavailability and the fertility of soil. However, the mechanism by which PSF solubilise insoluble P using carboxylic acid is not fully understood. In this study, Penicillium oxalicum PSF-4 was isolated and shown to have satisfactory solubilisation performance towards tricalcium phosphate (TP) and iron phosphate (IP). In treatments with TP or IP, the soluble P (Psol) concentrations were positively correlated with the carboxyl groups in organic acids but negatively correlated with the pKsp of insoluble P sources and pH. Additionally, the compositions of the organic acids (considering the lowest pKa value for acids with several pKas) were remarkably different between the treatments: oxalic (pKa = 1.27), malic (pKa = 3.46), and formic (pKa = 3.75) acids in TP treatments (maximum 381mg/L); and lactic (pKa = 3.85), gluconic (pKa = 3.86), and citric (pKa = 3.12) acids in IP treatments (maximum 1634mg/L). The addition of H+ without P. oxalicum PSF-4 inoculation markedly improved Psol concentrations. The above results offer new insights that the pKsp of P sources, compositions of carboxylic acids, and pH regulation are the key factors influencing P solubilisation of different insoluble P sources.

Mild oxidative degradation of spent auricularia auricular substrate and molecular composition of carboxylic acids in the resulting soluble portion

Spent auricularia auricular substrate (SAAS) was oxidatively degraded with aqueous hydrogen peroxide (AHPO)/acetic anhydride (AAH) to produce carboxylic acids (CAs) under mild conditions. The results show that up to 53.6% of the organic matter in SAAS was converted to the soluble species (SSs). In total 122 CAs were detected in the SSs by the analysis with a gas chromatograph/mass spectrometer, which can be classified into 29 group components, mainly being aliphatic acids and along with small amount of aromatic acids. Among the aliphatic acids, normal alkanedioic acids are the most abundant. The detected aromatic acids include benzoic acids, phthalic acids, trimellitic acids, pyromellitic acids, and their derivatives. The synergistic oxidation and the released OH, CH 3 COO , and HOO induced by AHPO/AAH play crucial roles in oxidatively degrading SAAS. • SAAS can be degraded to produce CAs, which consists of aliphatic acids and aromatic acids. • Aliphatic acids represent the predominant species, and NADAs are the most abundant. • AHPO/AAH ratio and temperature have impact on the composition and yield of CAs. • OH, CH 3 COO , and HOO play crucial roles in the SAAS oxidative degradation.

Enhanced carboxylic acids production by decreasing hydrogen partial pressure during acidogenic fermentation of glucose

In this study, the effect of reduced hydrogen partial pressure (PH2) on the generation of carboxylic acids from acidogenic fermentation of glucose was investigated. Three strategies were applied to reduce PH2: headspace removal (T1), CO2 sparging (T2) and H2:CO2 (80:20) sparging (T3). Results showed that the production of carboxylic acids in T1-T3 were 10.21, 11.64 and 12.71g/L, respectively, which were 1.04, 1.19 and 1.30-fold of that in the control (T4). The composition of carboxylic acids changed significantly in T3 with enhancement of homoacetogenesis, as more acetate and butyrate were produced comparing to the control. In addition, decreasing PH2 led to more carbon flow to carboxylic acids. Species of Clostridium became dominant in treatment T3, resulting in the shift of metabolic pathways. This study demonstrated that decreasing PH2 could increase the production of carboxylic acids, especially under the strategy of enhancing homoacetogenesis.

Production and Characterization of Energy Materials with Adsorbent Properties by Hydrothermal Processing of Corn Stover with Subcritical H2O

This work aims to investigate the effect of temperature on the process performance of hydrothermal processing (HTC) of corn Stover with subcritical H2O and on the morphology of solid products. The experiments were carried out at 200, 225 and 250 ºC, reaction time of 240 minutes, heating rate of 2.0 ºC/min, and biomass to water ratio of 1:10, using a pilot scale stirred tank reactor (STR) of 5 gallon, operating in batch mode. The process performance analyzed by computing the yields of solid and liquid reaction products (RLP). The aqueous phase (H2O + RLP) was physicochemical analyzed for pH and total carboxylic acids, expressed as total acetic acid content. The chemical compositions of carboxylic acids, furfural, and hydroxymethylfurfural (HMF) in the aqueous phase determined by GC-MS and HPLC. The results showed solid yields ranging from 57.39 to 35.82% (wt.), and liquid reaction products (RLP) yields ranging from 39.53 to 54.59% (wt.). The solid phase products were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The chemically activated (2.0 M NaOH) solid phase energy material obtained by HTC at 250 °C, applied as adsorbent to investigate the capacity and/or efficiency to adsorb acetic acid from 1.0 to 4.0 g/L model solutions at 25 °C. The solid phase yield decreases along with the temperature, showing an inflection region between 200 and 225 °C, whereas a drastic change takes place, while that of liquid phase increases, showing also a drastic change between 200 and 225 °C. The total acetic acid content of aqueous phase varied from 4064 to 5387 mg/L, while the pH from 3.77 to 3.91. The GC analysis identified the presence of volatile carboxylic acids, particularly acetic acid, in concentrations between 4020 and 5040 mg/L. HPLC identified the presence of furfural and hydroxymethylfurfural, whose concentrations decrease exponentially and linearly along with the temperature between 686.7 and 0.0, and 443.9 and 0.0 mg/L, respectively, being both compounds not detectable at 250 °C. The elemental/ultimate analysis of solid products shows that carbon content increases, while the oxygen and hydrogen contents decrease, along with the temperature. The H/C and O/C ratios decrease linearly as process temperature increases, and the high heating value (HHV) of solid reaction products, an energy densified material, changes sharply between 200 and 225 °C, showing an increase with temperature. The SEM, EDX, and XDR indicates a change on the morphology and mineralogical phases present in solid reaction products with temperature, particularly at 250 °C. The activated solid phase has proven to be very selective to adsorb acetic acid, showing that recovery of acetic acid from hydrothermal carbonization/liquefaction aqueous solutions is feasible by using a multistage-stage adsorption process in series.

Insight into the Ligand-Mediated Synthesis of Colloidal CsPbBr3 Perovskite Nanocrystals: The Role of Organic Acid, Base, and Cesium Precursors.

While convenient solution-based procedures have been realized for the synthesis of colloidal perovskite nanocrystals, the impact of surfactant ligands on the shape, size, and surface properties still remains poorly understood, which calls for a more detailed structure-morphology study. Herein we have systematically varied the hydrocarbon chain composition of carboxylic acids and amines to investigate the surface chemistry and the independent impact of acid and amine on the size and shape of perovskite nanocrystals. Solution phase studies on purified nanocrystal samples by (1)H NMR and IR spectroscopies have confirmed the presence of both carboxylate and alkylammonium ligands on surfaces, with the alkylammonium ligand being much more mobile and susceptible to detachment from the nanocrystal surfaces during polar solvent washes. Moreover, the chain length variation of carboxylic acids and amines, ranging from 18 carbons down to two carbons, has shown independent correlation to the size and shape of nanocrystals in addition to the temperature effect. We have additionally demonstrated that employing a more soluble cesium acetate precursor in place of the universally used Cs2CO3 results in enhanced processability without sacrificing optical properties, thus offering a more versatile recipe for perovskite nanocrystal synthesis that allows the use of organic acids and amines bearing chains shorter than eight carbon atoms. Overall our studies have shed light on the influence of ligand chemistry on crystal growth and stabilization of the nanocrystals, which opens the door to functionalizable perovskite nanocrsytals through surface ligand manipulation.

Selective recovery of pyruvic acid from two and three acid aqueous solutions by reactive extraction

Abstract In this study, a multi-stage reactive extraction system is devised for the selective recovery of pyruvic acid (PA) from a multiple-acid solution having a carboxylic acid composition identical to that obtained in microbial fermentation. With single-stage extraction, approximately 40% of the acetic acid (AA) is preferentially and selectively recovered from the aqueous three-acid solution using 0.1 M trioctylamine (TOA) in 1-octanol. Pyruvic acid is the only solute positively affected by an increase in the TOA concentration; however, the purity of the final extract is compromised by co-extracted acids. The distribution coefficient (KD) values obtained in three-acid solutions are lower than those obtained in single-acid solutions, showing the antagonistic effects due to the presence of other acids. However, in two-acid solutions, the presence of lactic acid (LA) at an initial concentration of about 7–20% (0.05–0.15 M) of that of PA (0.75–0.85 M) causes an increase of 33–80% on the KD of the latter. Using 0.6 M TOA in 1-octanol, 92% of initial PA is recovered from the two-acid solution. The competition with the other acid(s) for ion pair formation and its marked hydrophilicity hinders the extraction of LA from multiple acid solutions. Thus, a successful selective separation is achieved for the three acids present in the aqueous phase. A further increase in the initial concentration ratio of LA to PA in two-acid solution results in reduced KD values for the latter. The maximum separation factor of 54.3 is obtained at the lowest acid ratio (AR, 0.19) and highest TOA concentration (0.6 M). Hence, reactive extraction can be successfully employed to selectively recover PA from two and three-acid aqueous solutions.

An enantioselective fluorescence sensing assay for quantitative analysis of chiral carboxylic acids and amino acid derivatives

A chiral 1,8-diacridylnaphthalene-derived fluorosensor exhibiting a C(2)-symmetric cleft designed for stereoselective interactions with hydrogen bond donors has been used for the determination of both concentration and enantiomeric composition of carboxylic acids and amino acid derivatives.

Source and turnover of organic matter in agricultural soils derived from n-alkane/ n-carboxylic acid compositions and C-isotope signatures

Agricultural soils are regarded as one potential sink for atmospheric CO 2 via photosynthetic fixation in plant biomass and subsequent transformation into soil organic matter upon soil diagenesis. The difference in C-isotope signatures of C 3- vs. C 4-plants allows for a natural isotopic labelling of soil organic matter after changes from C 3- to C 4-cropping. In this study, we demonstrate that isotopic shifts are paralleled by molecular signatures of C 3- vs. C 4-crop alkyl lipids. Turnover times vary significantly, based on cropping techniques. For grain-maize cropped soils at steady state average turnover times of 40 years for bulk SOC, 35 years for n-alkanes and 21 years for n-carboxylic acids were determined. Turnover times for silage-maize cropped soil at steady state were on average 250 years for bulk SOC, 60 years for n-alkanes and 49 years for n-carboxylic acids. Turnover times reported here for silage-maize cropped soils may be taken as maximum values only, because they derive from a single trial, which was affected by addition of anthropogenic refractory carbon. Discrimination of input from various plant parts (roots, stems and leaves) based on bulk C-isotopes is not feasible but can easily be achieved using compositions of carboxylic acids, especially the ratio of n-C 24 vs. n-C 22+26 and their respective C-isotope values. This enables delineation of the influence of different cropping techniques, e.g., silage- or grain-maize, on carbon storage in soils. Admixture of external sources of organic matter to the soil organic carbon pool of an urban site in Halle, Germany was identified based on alkyl lipid distributions. Nearby lignite mining was identified as a source for non-crop-derived alkyl lipids, primarily based on the elevated n-C 26-carboxylic acid content and heavier carbon isotopic signatures.

Study on Distribution and Composition of Carboxylic Acids of Bohai Crude Oil in China

This study concerns with distribution, type, and structure of carboxylic acids in the 200–550°C distillates of Bohai crude oil. The acids, isolated by aqueous alcoholic sodium hydroxide, were converted into corresponding methyl esters with BF3 as catalyst. The chemical structure of these carboxylic acids and distribution of their various components in different distillates were studied in detail by IR, VPO, MS, and elemental analysis. The results show that the carboxylic acids in Bohai crude oil are mainly composed of naphthenic acids and branched chain fatty acids, and the content is high in distillates at about 405°C and 505°C. With increase of boiling temperature of distillates, the content of naphthenic acids increases gradually. The ring numbers of naphthenic acids in diesel distillate are mainly 1–3, and those in lubricant distillate are mainly 1–6.

Study on Distribution and Composition of Carboxylic Acids of Bohai Crude Oil in China

This study concerns the distribution, type, and structure of carboxylic acids in the 200–550°C distillates of Bohai crude oil. The acids, isolated by aqueous alcoholic sodium hydroxide, were converted into corresponding methyl esters with BF3 as a catalyst. The chemical structure of these carboxylic acids and distribution of their various components in different distillates were studied in detail by IR, VPO, MS, and elemental analysis. The results show that the carboxylic acids in Bohai crude oil are mainly composed of naphthenic acids and branched chain fatty acids, and the content is high in distillates at about 405 and 505°C. With the increase of boiling temperatures of distillates, the content of naphthenic acids increases gradually. The ring numbers of naphthenic acids in diesel distillate are mainly 1–3, and those in lubricant distillate are mainly 1–6.

Study on Distribution and Composition of Carboxylic Acids of Bohai Crude Oil in China

Study on Distribution and Composition of Carboxylic Acids of Bohai Crude Oil in China

A Method for Forensic Identification of Vegetable Oil Stains—Rapid Analysis of Carboxylic Acids with Methyl Esterification Using Purge-and-Trap Gas Chromatography/Mass Spectrometry

A simple method using purge-and-trap gas chromatography/mass spectrometry (P&T-GC/MS) for forensic examination of oil stains was studied. Carboxylic acids, chosen as target components for discrimination of oil samples, were extracted from stains with ether, methyl esterified by tetramethylammonium hydroxide, and analyzed by P&T-GC/MS. Vegetable oils were discriminated according to their carboxylic acid compositions. Carboxylic acid composition was independent of the substrate material of the stain. Although the carboxylic acid composition of the oil changed on exposure to sunlight, identification of oil was possible for oil stains that had been in the shade, if analysis was made within 20 days.

Influence of biodegradation on crude oil acidity and carboxylic acid composition

Quantitative analysis of separated carboxylic acid fractions of 33 crude oils from the UK, Italy and California, showed that the carboxylic acid fraction is a major factor responsible for the acidity in these oils. It was apparent that biodegradation is the main process that produces high concentrations of carboxylic acids in these crude oils with the extent of biodegradation, as measured from their hydrocarbon compositions, being clearly correlated with their total acid number (TAN). Although probably not important in influencing oil TAN, the distribution of C30–C32 hopanoic acids was also seen to be controlled by biodegradation, increasing in concentration for all but the most biodegraded oils. Hopanoic acids with the 17β(H),21β(H) stereochemistry were found in many of the biodegraded oils, and were thought to be mainly derived from the bacteria that were responsible for the biodegradation of the oil. This may have implications for the timing and mechanisms of the biodegradation involved. The role of C0–C3 alkylphenols in determining oil acidity was investigated and shown not to be a significant factor in the sample set studied. However, a number of undegraded oils, with low carboxylic acid contents were seen to have relatively high acidities, showing that factors other than biodegradation, possibly related to high sulphur content can control oil acidity in certain oil types.

Optimization of the separation of polycarboxylic acids by capillary zone electrophoresis

The optimization of electrolyte systems for the separation and detection of polycarboxylic acids using capillary zone electrophoresis described. A borate buffer in the pH range 9–10 was chosen for the separation. The factors affecting separation selectivity include the addition of complexing reagents, such as alkaline earth metal ions and cyclodextrins, to the carrier electrolyte. A model can be developed that is based on the chemical complexation equilibria and allows the prediction of migration times and optimum carrier electrolyte compositions. Five experiments were found to be sufficient for establishing optimum separation conditions for 18 di- and tricarboxylic acids. UV detection at 185 nm was feasible for both aromatic and aliphatic carboxylic acids. The technique can be applied to the determination of the carboxylic acid composition of alkyd resins and similar technical products.

Carboxylic Acid Composition of Varietal Juices Produced from Fresh and Stored Apples

Juices were produced from 11 apple cultivars from three regions of Ontario before and after storage in 2 years and analyzed for acids. The concentration ranges (mg/L) for fresh and stored apples, respectively, were as follows: malic, 4780-15 730 and 2470-13 390; citric, 263-538 and 321-714; quinic, 10-754 and 10-693; lactic, 10-203 and 17-219; succinic, 2-28 and 1-51; shikimic, 1-25 and 1-26; chlorogenic, 74-85 and 10-80; total, 5770-16 880, and 3330-14 760; titratable acidity, 2700-11 700 and 1500-9300; pH, 3.22-3.90 and 3.29-4.41; malic:citric, 16.0-39.6 and 7.0-26.8; sugar:acid, 10.0-37.7 and 12.3-66.0. Cultivar affected all except succinic and chlorogenic acids. Region and season had only minor influence. Malic, quinic, total, and titratable acids and H + decreased, while citric, lactic, and shikimic acids increased upon storage. Most commercial juices had acid compositions similar to those of the authentic ones, except fumaric acid was present and quinic, shikimic, and succinic acids were frequently absent

Carboxylic Acid Composition of Authentic Varietal and Commercial Grape Juices

Abstract Quantities were determined of tartaric, malic, citric, lactic, succinic, and shikimic acid present in juices produced by cold and hot pressing from 56 grape cultivars grown in Ontario for the 1988 and 1989 seasons. The individual acids were separated by liquid chromatography (LC) and detected at 210 or 250 nm. Lactic and succinic acids were determined enzymatically. The ranges of acid concentrations found were as follows: tartaric, 4.19-13.51 g/L; malic, 1.68-15.36 g/L; citric, 0.305-1.158 g/L; lactic, 0.015-0.388 g/L; succinic, 0.002-0.075 g/L; and shikimic, 0-0.102 g/L. Tartaric and malic acids were the major acids in every cultivar. The tartaric:malic acid ratio ranged from 0.52 to 4.36, but it was >1.0 in most cases. Genotype had significant effect only on the shikimic acid content. Hot pressing of red cultivars yielded juice with significantly higher pH and tartaric, citric, lactic, and total acid contents than cold pressing. Vintage had no significant effect on acid composition. The total acid content determined by LC was always considerably higher than the titratable acidity, but good correlation existed between the 2 measurements. Most commercial grape juice had similar composition to that of authentic juices. However, tartaric acid content was lower in the majority of commercial juices because of losses during the detartration process. Also, indications of acidulation existed in some of the commercial juices.

Differences in carboxylic acid exudation among p-starved leguminous crops in relation to carboxylic acid contents in plant tissues and phospholipid level in roots

Abstract The amount or composition of carboxylic acids in the root exudates and tissue extracts of leguminous crop plants subjected to P starvation for 3 d in water culture were compared. Also, the changes in the distribution and P content of the P fractions of the roots of the plants subjected to P starvation for 3 d were compared. In the root exudates collected over a 12 h period, malonic, succinic, fumaric, malic, citric, and t-aconitic acids were detected. A large amount of these carboxylic acids, especially citric and malic acids, was exuded from the roots of chickpea as compared with those of soybean, kidney bean, cowpea, and pigeonpea. Groundnut roots exuded an appreciable amount of carboxylic acids, especially fumaric acid. Although the contents of these carboxylic acids in the extracts of leaves and roots of chickpea were the highest as compared with soybean, kidney bean, and cowpea, the differences were much less significant than those in the root exudates. The amount and composition of carboxyl...

Contribution of organic acids to the acidification of the rhizosphere of maize seedlings

The participation of organic acids in the process of soil acidification was related to other H+ pumping processes. The ratio between efflux of organic acids and proton secretion of maize roots was determined with the use of a pH-stat combined with a collecting system for organic acids. Changes in the composition of carboxylic acids influenced by nitrogen supply were monitored by HPLC and via enzymatic conversion. The following substances were found to be secreted by maize roots: glycolate, glyoxylate, fumarate, 2-oxoglutarate and oxalate. Malate, however, could not be detected. There is no organic acid dominantly secreted by the roots, but changes are observed during aging which might result from deficiencies of nutrients e.g. P. Fertilization of N-deficient plants with urea leads to a significant change in the composition of acids secreted. In this case, oxalate was additionally detected with a concomitant increase in glyoxylate, indicating important changes in metabolism. Acidification of the rhizosphere is predominantly maintained by secretion of protons, not by efflux of organic acids, which contributed 0.2 to 0.3% to this process only. The role of organic acids in nutrient uptake is discussed.