Infusion Electrospray Ionization Mass Spectrometry Research Articles

Chemical Diversity of UK-Grown Tea Explored Using Metabolomics and Machine Learning

Background/Objectives: Dartmoor Estate Tea plantation in Devon, UK, is renowned for its unique microclimate and varied soil conditions, which contribute to the distinctive flavours and chemical profiles of tea. The chemical diversity of fresh leaf samples from various garden locations was explored within the plantation. Methods: Fresh leaf, which differed by location, cultivar, time of day, and variety, was analysed using Flow Infusion Electrospray Ionisation Mass Spectrometry (FIE-MS). Results: Random forest classification revealed no significant differences between Georgian N2 cultivar garden locations. However, a significant degree of variability was observed within four tri-clonal variants (Tocklai Variety) with TV9 exhibiting greater similarity to the Georgian N2 cultivar compared to TV8 and TV11, while TV11 was found to be most like TV1. The intraclass variability in leaf composition was similar between the varieties. We explored the metabolic changes over the day in one variant (Camellia assamica Masters), yielding a model with a significant R2 value of 0.617 (p < 0.01, 3000 permutations). Starch and sucrose metabolism was found to be significant where the abundance of these chemical features increased throughout the day and then began to decrease at night. Conclusions: This research highlights the complex interplay of cultivars, geographical location, and temporal factors on the chemical composition of tea. It provides insightful data on the metabolic pathways influencing tea cultivation and production and underscores the importance of these variables in determining the final chemical profile and organoleptic characteristics of tea products.

An electrospray-active N-heterocyclic carbene ligand for real-time analysis of organometallic reactions.

A charge-tagged N-heterocyclic carbene (NHC) has been synthesized and its utility in allowing the dynamic behaviour of metal complexes to be monitored in real time using electrospray ionization mass spectrometry demonstrated. This compound was used to prepare different metal-NHC complexes, and the kinetic behaviour of complex formation and ligand exchange was monitored in real time through the use of pressurized sample infusion electrospray mass spectrometry (PSI-ESI-MS).

Chemical profile of compounds in irrigated arabica coffee by ESI-MS

The use of irrigation in coffee aims productivity increase and better quality of the final product. The impacts of irrigation in productivity and quality are impressive. In this study, ten different varieties of Coffea arabica L., were cultivated with irrigation and no irrigation regimes and these samples were analyzed by direct infusion electrospray ionization mass spectrometry (ESI-MS), in positive mode. The constituents identified were choline; trigonelline; sucrose; βN-arachinoyl-5-hidroxytryptamide; βN-behenoyl-5-hidroxytryptamide; palmitoyl-linoleoyl (PL); dilinoleoyl (LL); dipalmitoyl-linoleoyl (PPL); palmitoyl-dilinoleoyl (PLL) and three new compounds reported in coffee – triacylglycerol (TG 54:6), phosphoethanolamine (PE 40:7) and 1-hexadecyl-2-dodecanoyl-glycero-3-phosphate It was possible to efficiently sort the groups of irrigated and non-irrigated using PLS-DA to obtain all the minimum requirements for evaluation of efficiency of the rating model. Sucrose and the ion m/z 431 (not identified) suffered a negative influence of irrigation. The trigonelline, and the ion m/z 723 (not identified) were influenced positively by irrigation. The cup test showed that the coffees cultivated in not-irrigated regime had slightly larger cupping notes that the ones cultivated under irrigation, probably because they presented higher sucrose content.

Enhancing mass spectrometry interpretability by ComDim-ICA multi-block analysis: Geographical and varietal traceability of Brazilian Coffea canephora

Mass spectrometry can gain analytical interpretability by studying complementarity and synergy between the data obtained by the same technique. To explore its potential in an untargeted metabolomic application, the objective of this work was to obtain organic and aqueous coffee extracts of three coffee Canephora groups produced in Brazil with distinctive aspects: geographical origin and botanical variety. Aqueous and organic extracts of roasted coffee beans were analyzed by direct infusion electrospray ionization mass spectrometry. Due to the large number of samples, the injector of the liquid chromatography system was used to automate the analysis. The column was removed, and a peak tube was added to connect the system directly to the mass spectrometer to inject both polar and nonpolar fractions of the coffee extracts individually. The technique provided characteristic fingerprinting mass spectra that not only allowed for differentiation of geographical origins but also between robusta and conilon botanical varieties. The mass spectra of the organic and water extracts represented two separate data blocks to be analyzed by the ComDim-ICA multi-block data analysis method. While the classical ComDim is based on applying PCA to the iteratively reweighted concatenated matrices, in the ComDim-ICA, the factorization is done using independent components analysis, which promotes specific improvements since it is based on extracting components that are statistically independent of one another. The results highlighted by ComDim-ICA show that both water and organic extracts contributed with important ions to the characterization of the coffee composition. However, the results revealed a high variability of metabolomic composition within each botanical variety (Robusta Amazônico and Conilon Capixaba) and geographical provenance (Rondônia indigenous-1, Rondônia non-indigenous-2 and Espírito Santo-3). Even so, water mass spectra differentiated the botanical variety Conilon from Robusta based on significant ions related to trigonelline, caffeic acid, caffeoylquinic acid, and methylpyridinium; both water and organic mass spectra differentiated Rondônia indigenous from Rondônia non-indigenous and Espírito Santo Conilon based on significant ions related to benzoic acid, pentose, coumaric acid, caffeine in the organic extract and malonic acid, pentose, caffeoylquinic acid, methyl pyridinium, caffeine, and sucrose present in the water extract. With the proposed approach acquiring ion fingerprints of different coffee extracts and their subsequent analysis by ComDim-ICA, new complementary chemical aspects of Brazilian Coffea canephora were put in evidence.

Lipid Marker ESI-MS Method for Quantification of Adulteration in Almond-Based Vegetable Beverage

ABSTRACT Almond-based beverages are valued for their functionalities. However, cases of adulteration are found in the literature aiming to reduce costs. In this study, almond (LA) and peanut (LP)-based beverages were used as investigational controls in commercial products analyzed by gas chromatography and direct infusion electrospray ionization mass spectrometry (ESI-MS) combined with principal component analysis (PCA). Thus, characteristic fatty acids were identified in plant-based beverages. The ESI-MS method combined with PCA indicated individualities regarding the disposition of triacylglycerol (TAG) composition, as higher intensities of TAG were found as a lipid marker at m/z 919 [TAG+NH4]+ of ions formed by arachidic (20:0), 8/heptadecenoic (17:1n-9) and oleic (18:1n-9) fatty acids in LP. The technique demonstrated efficiency in the detection of fraud due to its sensitivity, identifying peanut content in three almond-based commercial beverages (4.4–11.58%). This study highlights the importance of robust analytical methods to the authenticity and quality of food products.

Rapid Analysis of Colonic Metabolomics in High-Fat Diet Mice by Extraction Electrospray Ionization Mass Spectrometry (EESI-MS).

Propolis exhibits significant anti-inflammatory, antidiabetic, and antiobesity properties in both mouse models and clinical applications. However, the underlying metabolic mechanisms remain poorly understood. Traditional metabolomic methods that rely on chromatographic separation require complex preprocessing steps and extended detection periods. In this study, we employed extraction electrospray ionization mass spectrometry combined with multivariate analysis to directly profile metabolites in the colon tissue of mice. Our findings demonstrate the efficacy of ethanol extract of propolis (EEP) in mitigating weight gain, reducing inflammatory cytokines, and improving insulin resistance induced by a high-fat diet. Additionally, EEP enhanced glucose tolerance. Through collision-induced dissociation experiments, we identified 26 metabolites, with 4-hydroxyphenylacetic acid, protocatechuic acid, caffeic acid, ferulic acid, hippuric acid, histidine, and tryptophan emerging as potential biomarkers. Notably, tryptophan exhibited the highest content at 8.25 mg/g. Our research facilitates rapid profiling of colon metabolites, underscoring its significant potential for broader applications in animal metabolomic studies.

A Complementary Multitechnique Approach to Assess the Bias in Molecular Weight Determination of Lignin by Derivatization-Free Gel Permeation Chromatography.

The growing interest in lignin valorization in the past decades calls for analytical techniques for lignin characterization, ranging from wet chemistry techniques to highly sophisticated chromatographic and spectroscopic methods. One of the key parameters to consider is the molecular weight profile of lignin, which is routinely determined by size-exclusion chromatography; however, this is by no means straightforward and is prone to being hampered by considerable errors. Our study expands the fundamental understanding of the bias-inducing mechanisms in gel permeation chromatography (GPC), the magnitude of error originating from using polystyrene standards for mass calibration, and an evaluation of the effects of the solvent and type of lignin on the observed bias. The developed partial least-squares (PLS) regression model for lignin-related monomers revealed that lignin is prone to association mainly via hydrogen bonding. This hypothesis was supported by functional group-based analysis of the bias as well as pulse field gradient (pfg) diffusion NMR spectroscopy of model compounds in THF-d8. Furthermore, although the lack of standards hindered drawing conclusions based on functionalities, direct infusion electrospray ionization mass spectrometry indicated that the relative bias decreases considerably for higher molecular weight species. The results from pfg-diffusion NMR spectroscopy on whole lignin samples were comparable when the same solvents were used in both experiments; in addition, the comparison between results obtained by pfg-diffusion NMR in different solvents gives some additional insights into the aggregation.

Animal Species and Blood Identification with Peptide Mass Fingerprinting.

As more families are acquiring pets and the opportunities for wild animals to appear in human neighborhoods are increasing, the number of cases and accidents involving animals is increasing. Hence, the need to identify animal species from blood left over at accident sites is increasing. Human hemoglobin is used as a marker for human blood. Although tandem mass spectrometry is the dominant methodology used in proteomics research, peptide mass fingerprinting, given its instant applicability, may be useful for screening animal species, as the amino acid sequences of hemoglobin from various animals differ. In this study, solutions that were easily purified─using hemoglobin reagents from humans, Japanese macaques, bears, cattle, goats, sheep, sika deer, pigs, wild boars, dogs, cats, and nutrias─were digested by trypsin, and subjected to database searched using Mascot. No candidate proteins were found in the blood of goats, sheep, sika deer, wild boars, pigs, or nutrias. However, bloodstains from all animal species except nutria (which is not registered in the database) yielded candidates, which were identified as the hemoglobin of origin or its relatives. This difference may be attributed to more contaminants being included in blood. Further narrowing was possible using the average mass obtained via infusion electrospray ionization mass spectrometry measurement of the undigested solution in Mascot results. Saliva, urine, semen, and sweat collected from humans were also examined and searched for mascots, but no hits were obtained. In conclusion, this method may be useful for estimating animal species and identifying blood in forensic science.

Study of metalation of thioredoxin by gold(I) therapeutic compounds using combined liquid chromatography/capillary electrophoresis with inductively coupled plasma/electrospray MS/MS detection.

The reactivity of thioredoxin (Trx1) with the Au(I) drug auranofin (AF) and two therapeutic N-heterocyclic carbene (NHC)2-Au(I) complexes (bis [1-methyl-3-acridineimidazolin-2-ylidene]gold(I) tetrafluoroborate (Au3BC) and [1,3-diethyl-4,5-bis(4methoxyphenyl)imidazol-2-ylidene]gold(I) (Au4BC)) was investigated. Direct infusion (DI) electrospray ionization (ESI) mass spectrometry (MS) allowed information on the structure, stoichiometry, and kinetics of formation of Trx-Au adducts. The fragmentation of the formed adducts in the gas phase gave insights into the exact Au binding site within the protein, demonstrating the preference for Trx1 Cys32 or Cys35 of AF or the (NHC)2-Au(I) complex Au3BC, respectively. Reversed-phase HPLC suffered from the difficulty of elution of gold compounds, did not preserve the formed metal-protein adducts, and favored the loss of ligands (phosphine or NHC) from Au(I). These limitations were eliminated by capillary electrophoresis (CE) which enabled the separation of the gold compounds, Trx1, and the formed adducts. The ICP-MS/MS detection allowed the simultaneous quantitative monitoring of the gold and sulfur isotopes and the determination of the metallation extent of the protein. The hyphenation of the mentioned techniques was used for the analysis of Trx1-Au adducts for the first time.

Development of sequential online extraction electrospray ionization mass spectrometry for accurate authentication of highly-similar Atractylodis Macrocephalae

The accurate and rapid authentication techniques and strategies for highly-similar foods are still lacking. Herein, a novel sequential online extraction electrospray ionization mass spectrometry (S-oEESI-MS) was developed to achieve spatio-temporally resolved ionization and comprehensive characterization of complex foods with multi-components (high, medium, and low polarity substances). Meanwhile, a characteristic marker screening method and an integrated research strategy based on MS fingerprinting, characteristic marker and chemometrics modeling were established, which are especially suitable for the accurate and rapid authentication of highly-similar foods that are difficult to be authenticated by traditional techniques (e.g., LC-MS). Thirty-two batches of highly-similar Atractylodis macrocephalae rhizome from four different origins were used as model samples. As a result, S-oEESI-MS enabled a more comprehensive MS characterization of substance profiles in complex plant samples in 1.0 min. Further, 22 characteristic markers of Atractylodis macrocephalae were ingeniously screened out and combined with multivariate statistical analysis model, the accurate authentication of highly-similar Atractylodis macrocephalae was realized. This study presents a comprehensive strategy for accurate authentication and origin analysis of highly-similar foods, which has potentially significant applications for ensuring food quality and safety.

Identification of metabolic biomarkers for diagnosis of epithelial ovarian cancer using internal extraction electrospray ionization mass spectrometry (iEESI-MS).

Epithelial ovarian cancer (EOC) is the leading cause of death from gynecologic malignancies. The poor prognosis of EOC is mainly due to its asymptomatic early stage, lack of effective screening methods, and a late diagnosis in the advanced stages of the disease. This study investigated metabolomic abnormalities in epithelial ovarian cancers. Our study developed a novel strategy to rapidly identify the metabolic biomarkers in the plasma of the EOC patients using Internal Extraction Electrospray Ionization Mass Spectrometry (IEESI-MS) and Liquid Chromatography-mass Spectrometry (HPLC-MS), which could distinguish the differential metabolites in between plasma samples collected from 98 patients with epithelial ovarian cancer, including 78 cases with original (P), and 20 cases with self-configuration (ZP), as well as 60 healthy subjects, including 30 cases in the original sample (H), 30 cases in self-configuration (ZH), and 6 cases in a blind sample (B). Our study detected 880 metabolites based on criteria variable importance in projection (VIP) > 1, among which 26 metabolites were selected for further identification. They are mainly metabolism-related lipids, amino acids, nucleic acids, and others. The metabolic pathways associated with the differential metabolites were explored by the KEGG analysis, a comprehensive database that integrates genome, chemistry, and system function information. The abnormal metabolites of EOC patients identified by IEESI-MS and HPLC-MS included Lysophosphatidylcholine (16:0) [Lyso PC (16:0)], L-Phenylalanine, L-Leucine, Phenylpyruvic acid, L-Tryptophan, and L-Histidine. Identifying the abnormal metabolites of EOC patients through metabolomics analyses could provide a new strategy to identify valuable potential biomarkers for the screening and early diagnosis of EOC.

Mass spectrometry molecular fingerprinting of mineral and synthetic lubricant oils.

The molecular composition of lubricating oils has a strong impact on how automotive engines function, but the techniques used to monitor the quality parameters of these oils only inspect their gross physical-chemical properties such as viscosity, color, and bulk spectroscopy profiles; hence, bad-quality, adulterated, or counterfeit oils are hard to detect. Herein, we investigated the ability of direct infusion electrospray ionization mass spectrometry (ESI-MS) to provide simple, rapid but characteristic fingerprint profiles for such oils of the mineral and synthetic types. After a simple aqueous extraction, ESI-MS analyses, particularly in the positive ion mode, did indeed show characteristic molecular markers with unique profiles, which were confirmed and more clearly visualized by partial least squares-discriminant analysis (PLS-DA). Nuclear magnetic resonance and Fourier transform infrared-attenuated total reflection spectroscopy were also tested for the bulk samples but showed nearly identical spectra, thus failing to reveal their distinct molecular composition and to differentiate the oil samples. To simulate adulteration, mixtures of mineral and synthetic oils were also analyzed by ESI(+)-MS, and additions as low as 1% of mineral oil to synthetic oil could be detected. The technique therefore offers a simple and fast but powerful tool to monitor the molecular composition of lubricant oils, particularly vias their more polar constituents.

Participants in the Trans-Antarctic Winter Traverse Expedition Showed Increased Bacterial Load and Diversity in Saliva but Maintained Individual Differences within Stool Microbiota and Across Metabolite Fingerprints.

Understanding the impact of long-term physiological and environmental stress on the human microbiota and metabolome may be important for the success of space flight. This work is logistically difficult and has a limited number of available participants. Terrestrial analogies present important opportunities to understand changes in the microbiota and metabolome and how this may impact participant health and fitness. Here, we present work from one such analogy: the Transarctic Winter Traverse expedition, which we believe is the first assessment of the microbiota and metabolome from different bodily locations during prolonged environmental and physiological stress. Bacterial load and diversity were significantly higher during the expedition when compared with baseline levels (p < 0.001) in saliva but not stool, and only a single operational taxonomic unit assigned to the Ruminococcaceae family shows significantly altered levels in stool (p < 0.001). Metabolite fingerprints show the maintenance of individual differences across saliva, stool, and plasma samples when analysed using flow infusion electrospray mass spectrometry and Fourier transform infrared spectroscopy. Significant activity-associated changes in terms of both bacterial diversity and load are seen in saliva but not in stool, and participant differences in metabolite fingerprints persist across all three sample types.

Rapid authentication of different herbal medicines by heating online extraction electrospray ionization mass spectrometry

The rapid and accurate authentication of traditional Chinese medicines (TCMs) has always been a key scientific and technical problem in the field of pharmaceutical analysis. Herein, a novel heating online extraction electrospray ionization mass spectrometry (H-oEESI-MS) was developed for the rapid and direct analysis of extremely complex substances without the requirement for any sample pretreatment or pre-separation steps. The overall molecular profile and fragment structure features of various herbal medicines could be completely captured within 10–15 s, with minimal sample (<0.5 mg) and solvent consumption (<20 μL for one sample). Furthermore, a rapid differentiation and authentication strategy for TCMs based on H-oEESI-MS was proposed, including metabolic profile characterization, characteristic marker screening and identification, and multivariate statistical analysis model validation. In an analysis of 52 batches of seven types of Aconitum medicinal materials, 20 and 21 key compounds were screened out as the characteristic markers of raw and processed Aconitum herbal medicines, respectively, and the possible structures of all the characteristic markers were comprehensively identified based on Compound Discoverer databases. Finally, multivariate statistical analysis showed that all the different types of herbal medicines were well differentiated and identified (R2X > 0.87, R2Y > 0.91, and Q2 > 0.72), which further verified the feasibility and reliability of this comprehensive strategy for the rapid authentication of different TCMs based on H-oEESI-MS. In summary, this rapid authentication strategy realized the ultra-high-throughput, low-cost, and standardized detection of various complex TCMs for the first time, thereby demonstrating wide applicability and value for the development of quality standards for TCMs.

Extractive electrospray ionization mass spectrometry for analytical evaluation and synthetic preparation of pharmaceutical chemicals.

Extraction electrospray ionization mass spectrometry (EESI-MS), due to the unique configuration of its ionization module, enables the effective ionization of trace molecules of interest in samples containing complex matrices with high sensitivity, high selectivity and high responding speed without requiring sample pretreatment, and allows high-energy molecular species to undergo specially designed reactions for advanced functionalization. The typical effects of operating conditions on the analytical performance of extraction electrospray ionization mass spectrometry for various pharmaceutical compounds, pharmaceutical preparations and herbal materials were systematically reviewed. The application prospect of extraction electrospray ionization in molecular functionalization for advanced drug discovery is also briefly introduced.

Simplex centroid mixture design, DI-ESI-MS, and chemometric analysis-guided isolation of parinarioidin C from bark of Brosimum parinarioides (Moraceae)

Brosimum parinarioides , a plant species native to the Amazonian region, is used in folk medicine for the treatment of several diseases. However, knowledge regarding its phytochemical content is scarce. In order to investigate the phytochemical composition of B. parinarioides , an integrative approach based on simplex-centroid design, direct infusion electrospray ionization mass spectrometry (DI-ESI-MS), and chemometric analysis was adopted. According to simplex-centroid design, dichloromethane (DCM), ethyl acetate (AcOEt), and ethanol-based (EtOH) extracts were prepared and analyzed using DI-ESI-MS, and their chemical profile was submitted to principal component analysis (PCA) and hierarchical cluster analysis (HCA). The AcOEt extract from the bark was obtained on a large scale and subjected to chromatographic separation. The multivariate analysis indicated the formation of three groups and highlighted isoliquiritigenin ( 1 ), licoagrochalcone A ( 2 ), caffeic acid glucoside ( 3 ), epicatechin-glycoside ( 4) , caffeic acid ( 5 ), and one unknown compound, as being responsible for the segregation of these groups. Thus, the new compound was isolated and characterized using 1D and 2D nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry (HR-MS) as parinarioidin C ( 10 ). In addition, parinarioidin A ( 6 ), parinarioidin B ( 7 ), 3- O -caffeoylquinic acid ( 8 ), and kanzonol C ( 9 ) were tentatively identified based on manual interpretation of MS/MS spectra. Overall, the integrative approach proposed in the study provided a simple and effective model to dereplicate known compounds and guide the isolation of a new compound from a native amazon species, thus improving the knowledge regarding the phytochemical content of B. parinarioides . • One new compound was isolated from Brosimum parinarioides. • Nine phenolic compounds were identified based on the MS/MS data. • This study provided an effective model to guide the isolation of new natural products.

New insights into the Van Krevelen diagram: Automated molecular formula determination from HRMS for a large chemical profiling of lichen extracts.

In recent years, LC-MS has become the golden standard for metabolomic studies. Indeed, LC is relatively easy to couple with the soft electrospray ionization. As a consequence, many tools have been developed for the structural annotation of tandem mass spectra. However, it is sometimes difficult to do data-dependent acquisition (DDA), especially when developing new methods that stray from the classical LC-MS workflow. An old tool from petroleomics that has recently gained popularity in metabolomics, the Van Krevelen diagram, is adapted for an overview of the molecular diversity profile in lichens through high-resolution mass spectrometry (HRMS). A new method is benchmarked against the state-of-the-art classification tool ClassyFire using a database containing most known lichen metabolites (n ≈2,000). Four lichens known for their contrasted chemical composition were selected, and extractions with apolar, aprotic polar, and protic polar solvents were performed to cover a wide range of polarities. Extracts were analyzed with direct infusion electrospray ionization mass spectrometry (DI-ESI-MS) and atmospheric solids analysis probe mass spectrometry (ASAP-MS) techniques to be compared with the chemical composition described in the literature. The most common lichen metabolites were efficiently classified, with more than 90% of the molecules in some classes being matched with ClassyFire. Results from this method are consistent with the various extraction protocols in the present case study. This approach is a rapid and efficient tool to gain structural insight regarding lichen metabolites analyzed by HRMS without relying on DDA by LC-MS/MS analysis. It may notably be of use during the development phase of novel MS-based metabolomic approaches.

Real-time analysis of metabolites in vivo by online extraction electrospray ionization mass spectrometry coupled to microdialysis

In vivo and real-time analysis could reflect a more real biological state, which was of great significance to the study of complex life processes. In this work, we constructed an online extraction electrospray ionization (OE-ESI) ion source as the interface of microdialysis and mass spectrometry, which realized real-time analysis of metabolites in vivo without sample pretreatment process. The ion source was consisted of three coaxial capillaries, and the parameters of the ion source were optimized. The OE-ESI ion source could simultaneously extract, desalt and ionize the analyte, successfully perform MS analysis of analyte in high salt system, and overcome the ion suppression caused by salt ion. Compared with commercial ESI MS, the OE-ESI ion source had excellent salt tolerance and stability. MD-OE-ESI MS realized the real-time MS detection of metabolites in the living body, avoiding the complex desalting process. In the rat liver ischemia-reperfusion model, a total of 24 metabolites, including glucose, glutamate, glutamine, etc., were monitored in real time mode, and their concentrations had varying degrees of change during the experimental process compared with the control group. This platform, we believed, would be helpful for real-time monitoring of biological metabolites in vivo, and had great application prospects to study physiological processes.

Membrane Sampling Separates Naphthenic Acids from Biogenic Dissolved Organic Matter for Direct Analysis by Mass Spectrometry.

Oil sands process waters can release toxic naphthenic acids (NAs) into aquatic environments. Analytical techniques for NAs are challenged by sample complexity and interference from naturally occurring dissolved organic matter (DOM). Herein, we report the use of a poly(dimethylsiloxane) (PDMS) polymer membrane for the on-line separation of NAs from DOM and use direct infusion electrospray ionization mass spectrometry to yield meaningful qualitative and quantitative information with minimal sample cleanup. We compare the composition of membrane-permeable species from natural waters fortified with a commercial NA mixture to those derived from weak anion exchange solid-phase extraction (SPE) using high-resolution mass spectrometry. The results show that SPE retains a wide range of carboxylic acids, including biogenic DOM, while permeation through PDMS was selective for petrogenic classically defined NAs (CnH2n+zO2). A series of model compounds (log Kow ∼1–7) were used to characterize the perm-selectivity and reveal the separation is based on hydrophobicity. This convenient sample cleanup method is selective for the O2 class of NAs and can be used prior to conventional analysis or as an on-line analytical strategy when coupled directly to mass spectrometry.

Rapid authenticity assessment of Brazilian palm kernel oils by mass spectrometry combined with chemometrics

Adulteration became a serious problem to food industries as it steadily spread across the globe in the past decades, affecting several food products, but especially vegetable oils. Palm kernel oil is a highly susceptible target for adulteration due to its exceptional characteristics and several applications. Hence, this study utilized gas chromatography with flame ionization detector, and direct infusion electrospray ionization mass spectrometry combined with chemometrics to assess the authenticity of seven Brazilian brands of palm kernel oil. Results indicated adulteration with at least 30% in all brands evaluated. Furthermore, presence of a different additive was verified for PKO1, PKO5, and PKO7. Thus, the association of direct infusion electrospray ionization mass spectrometry analysis with pattern recognition methods proved to be an attractive candidate for fast routine analyses to identify adulteration in industries.