Precise measurement of Fe isotopes in marine and biological samples by pseudo-high-resolution multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS).

This paper introduces an enhanced technique for analyzing iron isotopes in complex marine and biological samples. A dedicated iron purification method for biological marine matrices, utilizing three ion exchange columns, is validated. The MC-ICPMS in pseudo-high-resolution mode determines precise iron isotopic ratios, with sensitivity improved through the DSN-100 desolvating nebulizer system and Apex-IR. Only 2 µg of iron on DSN versus 1 µg on Apex is needed for six replicates (30-60 times improvement) while 10 to 20 µg is required for a single measurement on a wet system considering the resolution power (Rp) is maintained at 11,000-13,000. The Ni-doping method with a Fe/Ni ratio of 1 yields more accurate isotopic ratios than standard-sample bracketing alone. Measurement reproducibility of triplicate samples from marine biological experiments on MC-ICPMS is ± 0.03‰ (2SD) for δ56Fe and ± 0.07‰ for δ57Fe (2SD). This study introduces a novel iron purification process specifically designed for marine and biological samples, enhancing sensitivity and enabling more reliable measurements with smaller sample sizes and reduced uncertainties. It proposes iron isotopic compositions for biological reference materials, offering a valuable reference dataset in diverse scientific disciplines.

Removal of heavy metals from wastewater by aerogel derived from date palm waste.

Cellulose that has been sourced from date palm leaves as a primary component was utilised. This cellulose served as the foundational material for the development of an aerogel composite. During this process, MXene (Ti3C2Tx) played a pivotal role in enhancing the overall composition of the aerogel. To ensure the stability and durability of the resulting aerogel structure, calcium ions were introduced to the mix. These ions facilitated the cross-linking process of sodium alginate molecules, ultimately leading to the formation of calcium alginate. This cross-linking step is crucial for the enhanced mechanical and chemical stability of the aerogel. Incorporating alginate and Ti3C2Tx into the cellulose aerogel enhanced its structural integrity in aqueous conditions and increased its adsorption capacity. When evaluated with synthetic wastewater, this composite exhibited remarkable adsorption capacities of 72.9, 114.4, 92.9, and 123.9 mg/g for As, Cd, Ni, and Zn ions, respectively. A systematic study was carried out to see the effect of various parameters, including contact time, MXene concentration, pH, and temperature on the adsorption of these elements. Peak adsorption was achieved at 60 min, favoring a pH range between 6 and 8 and exhibited optimal sorption efficiency at lower temperatures. The adsorption kinetics adhered closely to a pseudo-second-order, while the Freundlich model adeptly described the adsorption isotherms. An interesting result of this research was the aerogel's regenerative potential. After undergoing a basic acid treatment, the MXene/cellulose/alginate aerogel composite could be restored and reused for up to three cycles, all while maintaining its core performance capabilities even after the rigorous cross-linking processes. In three consecutive cycles, the removal percentages for As, Cd, Ni, and Zn were 48.15%, 80.38%, 56.51%, and 86.12% in cycle 1; 37.35%, 65.63%, 45.97%, and 78.42% in cycle 2; and 28.60%, 56.22%, 34.70%, and 65.83% in cycle 3, respectively. The composite was tested in conditions resembling seawater salinity. Impressively, the aerogel continued to demonstrate a significant ability to adsorb metals, reinforcing its potential utility in real-world aquatic scenarios. These findings suggest that the composite aerogel, integrating MXene, cellulose, and alginate, is an effective medium for the targeted removal of heavy metals from aquatic environments.

What is in the fish? Collaborative trial in suspect and non-target screening of organic micropollutants using LC- and GC-HRMS.

A collaborative trial involving 16 participants from nine European countries was conducted within the NORMAN network in efforts to harmonise suspect and non-target screening of environmental contaminants in whole fish samples of bream (Abramis brama). Participants were provided with freeze-dried, homogenised fish samples from a contaminated and a reference site, extracts (spiked and non-spiked) and reference sample preparation protocols for liquid chromatography (LC) and gas chromatography (GC) coupled to high resolution mass spectrometry (HRMS). Participants extracted fish samples using their in-house sample preparation method and/or the protocol provided. Participants correctly identified 9-69 % of spiked compounds using LC-HRMS and 20-60 % of spiked compounds using GC-HRMS. From the contaminated site, suspect screening with participants' own suspect lists led to putative identification of on average ∼145 and ∼20 unique features per participant using LC-HRMS and GC-HRMS, respectively, while non-target screening identified on average ∼42 and ∼56 unique features per participant using LC-HRMS and GC-HRMS, respectively. Within the same sub-group of sample preparation method, only a few features were identified by at least two participants in suspect screening (16 features using LC-HRMS, 0 features using GC-HRMS) and non-target screening (0 features using LC-HRMS, 2 features using GC-HRMS). The compounds identified had log octanol/water partition coefficient (KOW) values from -9.9 to 16 and mass-to-charge ratios (m/z) of 68 to 761 (LC-HRMS and GC-HRMS). A significant linear trend was found between log KOW and m/z for the GC-HRMS data. Overall, these findings indicate that differences in screening results are mainly due to the data analysis workflows used by different participants. Further work is needed to harmonise the results obtained when applying suspect and non-target screening approaches to environmental biota samples.

Biodegradation of saturate fraction of crude oil and production of signature carboxylic acids.

Bacteria degrading large portion of saturated hydrocarbons are important for crude oil bioremediation. This study investigates Novosphingobium sp. S1, Gordonia amicalis S2 and Gordonia terrae S5 capability of degrading wide range of saturated hydrocarbons from Congo Bilondo crude oil and discusses the degradation pathway. A parallel analytical approach combining GC-MS and LC-HRMS enabled characterization of saturated hydrocarbons and comprehensive determination of carboxylic acid metabolites produced during biodegradation, respectively. Results showed that the three strains could efficiently degrade the n-alkanes (C10-C28) as well as methyl-substituted alkanes (C11-C26). The series of mono-, hydroxy- and dicarboxylic acids identified in this study confirmed the active biodegradation of the saturate fraction and suggest their degradation was via the bi-terminal oxidation pathway. This is the first study linking these bacterial species to bi-terminal oxidation of the saturated hydrocarbons. The study highlights the potential application of the bacterial strains in the bioremediation of crude oil contaminated sites. Additionally, while carboxylic acids is indicated as a suitable and valuable metabolic biomarker, its application is considered feasible and cost effective for rapid monitoring and evaluation of hydrocarbon biodegradation.

Cracked and shucked: GC-APCI-IMS-HRMS facilitates identification of unknown halogenated organic chemicals in French marine bivalves.

High resolution mass spectrometry (HRMS)-based non-target analysis coupled with ion mobility spectrometry (IMS) is gaining momentum due to its ability to provide complementary information which can be useful in the identification of unknown organic chemicals in support of efforts in unraveling the complexity of the chemical exposome. The chemical exposome in the marine environment, though not as well studied as its freshwater counterparts, is not foreign to chemical diversity specially when it comes to potentially bioaccumulative and bioactive polyhalogenated organic contaminants and natural products. In this work we present in detail how we utilized IMS-HRMS coupled with gas chromatographic separation and atmospheric pressure chemical ionization (APCI) to annotate polyhalogenated organic chemicals in French bivalves collected from 25 sites along the French coasts. We describe how we used open cheminformatic tools to exploit isotopologue patterns, isotope ratios, Kendrick mass defect (Cl scale), and collisional cross section (CCS), in order to annotate 157 halogenated features (level 1: 54, level 2: 47, level 3: 50, and level 4: 6). Grouping the features into 11 compound classes was facilitated by a KMD vs CCS plot which showed co-clustering of potentially structurally-related compounds. The features were semi-quantified to gain insight into the distribution of these halogenated features along the French coast, ultimately allowing us to differentiate between sites that are more anthropologically impacted versus sites that are potentially biodiverse.

Collision Cross Section Prediction with Molecular Fingerprint Using Machine Learning.

High-resolution mass spectrometry is a promising technique in non-target screening (NTS) to monitor contaminants of emerging concern in complex samples. Current chemical identification strategies in NTS experiments typically depend on spectral libraries, chemical databases, and in silico fragmentation tools. However, small molecule identification remains challenging due to the lack of orthogonal sources of information (e.g., unique fragments). Collision cross section (CCS) values measured by ion mobility spectrometry (IMS) offer an additional identification dimension to increase the confidence level. Thanks to the advances in analytical instrumentation, an increasing application of IMS hybrid with high-resolution mass spectrometry (HRMS) in NTS has been reported in the recent decades. Several CCS prediction tools have been developed. However, limited CCS prediction methods were based on a large scale of chemical classes and cross-platform CCS measurements. We successfully developed two prediction models using a random forest machine learning algorithm. One of the approaches was based on chemicals' super classes; the other model was direct CCS prediction using molecular fingerprint. Over 13,324 CCS values from six different laboratories and PubChem using a variety of ion-mobility separation techniques were used for training and testing the models. The test accuracy for all the prediction models was over 0.85, and the median of relative residual was around 2.2%. The models can be applied to different IMS platforms to eliminate false positives in small molecule identification.

Deciphering the Metal Speciation in Low-Molecular-Weight Complexes by IMS-MS: Application to the Detection of Manganese Superoxide Dismutase Mimics in Cell Lysates.

The detection and quantification of exogenous metal complexes are crucial to understanding their activity in intricate biological media. MnII complexes are difficult to detect and quantify because of low association constants, and high lability. The superoxide dismutase (SOD) mimic (or mimetic) labelled Mn1 is based on a 1,2-di-aminoethane functionalized with imidazole and phenolate and has good intrinsic anti-superoxide, antioxidant and anti-inflammatory activities in lipopolysaccharide (LPS)-activated intestinal epithelial HT29-MD2 cells, similar to that of its propylated analogue labelled Mn1P. Ion mobility spectrometry-mass spectrometry (IMS-MS) is a powerful technique for separating low molecular weight (LMW) metal complexes and can even separate complexes with the same ligand but bound to different divalent metal cations with similar ionic radii. We demonstrated the intracellular presence of the Mn1 and Mn1P complexes, at least partly intact, in lysates of cells incubated with the complexes and estimated the intracellular Mn1P concentration using a Co-13 C6 analogue.

Inertness of Superoxide Dismutase Mimics Mn(II) Complexes Based on an Open-Chain Ligand, Bioactivity, and Detection in Intestinal Epithelial Cells.

Oxidative stress is known to play a major role in the pathogenesis of inflammatory bowel diseases (IBDs), and, in particular, superoxide dismutase (SODs) defenses were shown to be weakened in patients suffering from IBDs. SOD mimics, also called SOD mimetics, as low-molecular-weight complexes reproducing the activity of SOD, constitute promising antioxidant catalytic metallodrugs in the context of IBDs. A Mn(II) complex SOD mimic (Mn1) based on an open-chain diaminoethane ligand exerting antioxidant and anti-inflammatory effects on an intestinal epithelial cellular model was shown to experience metal exchanges between the manganese center and metal ions present in the biological environment (such as Zn(II)) to some degrees. As the resulting complexes (mainly Zn(II)) were shown to be inactive, improving the kinetic inertness of Mn(II) complexes based on open-chain ligands is key to improve their bioactivity in a cellular context. We report here the study of three new Mn(II) complexes resulting from Mn1 functionalization with a cyclohexyl and/or a propyl group meant to limit, respectively, (a) metal exchanges and (b) deprotonation of an amine from the 1,2-diaminoethane central scaffold. The new manganese-based SOD mimics display a higher intrinsic SOD activity and also improved kinetic inertness in metal ion exchange processes (with Zn(II), Cu(II), Ni(II), and Co(II)). They were shown to provide anti-inflammatory and antioxidant effects in cells at lower doses than Mn1 (down to 10 µM). This improvement was due to their higher inertness against metal-assisted dissociation and not to different cellular overall accumulations. Based on its higher inertness, the SOD mimic containing both the propyl and the cyclohexyl moieties was suitable for intracellular detection and quantification by mass spectrometry, quantification, that was achieved by using a 13C-labeled Co-based analog of the SOD mimics as an external heavy standard.

A chemical speciation insight into the palladium(ii) uptake and metabolism by Sinapis alba. Exposure to Pd induces the synthesis of a Pd-histidine complex.

Palladium is recognized as a technologically critical element (TCE) because of its massive use in automobile exhaust gas catalytic converters. The release of Pd into the environment in the form of nanoparticles of various size and chemical composition requires an understanding of their metabolism by leaving organisms. We provide here for the first time a chemical speciation insight into the identity of the ligands produced or used by a plant Sinapis alba L. exposed in hydropony to Pd nanoparticles and soluble Pd (nitrate). The analytical method developed was based on the concept of 2D HPLC with parallel inductively coupled plasma mass spectrometry (ICP MS) and electrospray MS detection. Size exclusion chromatography - ICP MS of the plant extracts showed no difference between the speciation of Pd after the exposure to nanoparticles and after that to Pd2+ which indicated the reactivity and dissolution of Pd nanoparticles. A comparative investigation of the Pd speciation in a control plant extract spiked with Pd2+ and of an extract of a plant having metabolized palladium indicated the response of the Sinapis alba by the formation of a Pd-histidine complex. The complex was identified via Orbitrap MS; the HPLC-MS chromatogram produced two peaks at m/z 415.0341 each corresponding to a Pd-His2 complex. An investigation by ion-mobility MS revealed a difference in their collision cross section indicating that the complexes present varied in terms of spatial conformation. A number of other Pd complexes with different ligands (including nicotianamine) circulating in the plant were detected but these ligands were already observed in a control plant and their concentrations were not affected by the exposure to Pd.

Direct screening of food packaging materials for post-polymerization residues, degradation products and additives by liquid extraction surface analysis nanoelectrospray mass spectrometry (LESA-nESI-MS).

Materials in direct contact with food should be monitored for the presence of species able to migrate into food. A direct method based on liquid extraction surface analysis nanoelectrospray mass spectrometry (LESA-nanoESI-MS) was developed for the analysis of the migrating species from a polymer film. Different types of molecules: post-polymerization residues, degradation products (oligomers resulting from polymer recycling, products of polymer oxidative degradation) and anti-oxidant additives (vitamin E) were demonstrated to be detected and identified, and determined quantitatively if relevant calibration standards are available. The method was validated by a comparison a standard method based on with bulk extraction mass spectrometry. It offers considerable advantages over the latter in terms of drastically reduced analysis time and solvent consumption. Also, LESA-nanoESI-MS produced simpler spectra (limited to compounds able to migrate into food) than Direct Analysis in Real Time (DART).

Assessment of background concentrations of organometallic compounds (methylmercury, ethyllead and butyl- and phenyltin) in French aquatic environments.

The aim of this work is to estimate background concentrations of organometallic compounds, such as tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPhT), diphenyltin (DPhT), monophenyltin (MPhT), methylmercury (MeHg), inorganic mercury (iHg) and diethyllead (Et2Pb) in the aquatic environment at the French national scale. Both water and sediment samples were collected all over the country, resulting in 152 water samples and 123 sediment samples collected at 181 sampling points. Three types of surface water bodies were investigated: rivers (140 sites), lakes (19 sites) and coastal water (42 sites), spread along the 11 French river basins. The choice of sites was made on the basis of previous investigation results and the following target criteria: reference, urban sites, agricultural and industrial areas. The analytical method was properly validated for both matrices prior to analysis, resulting in low limits of quantification (LOQ), good precision and linearity in agreement with the Water Framework Directive demands. The results were first evaluated as a function of their river basins, type of surrounding pressure and water bodies. Later, background concentrations at the French national scale were established for both water and sediment matrices, as well as their threshold, i.e., the concentration that distinguishes background from anomalies or contaminations. Background concentrations in water are ranging between <0.04-0.14 ng Hg. L(-1) for MeHg, <0.14-2.10 ng Hg. L(-1) for iHg, <1.0-8.43 ng Pb. L(-1) for Et2Pb and 0.49-151 ng Sn. L(-1), <0.08-3.04 ng Sn. L(-1) and <0.08-0.25 ng Sn. L(-1) for MBT, DBT and TBT, respectively. For sediments, background concentrations were set as <0.09-1.11 ng Hg. g(-1) for MeHg, <0.06-24.3 ng Pb. g(-1) for Et2Pb and <1.4-13.4 ng Sn. g(-1), <0.82-8.54 ng Sn. g(-1), <0.25-1.16 ng Sn. g(-1) and <0.08-0.61 ng Sn. g(-1) for MBT, DBT, TBT and DPhT, respectively. TBT occurs in higher concentrations than the available environmental protection values in 24 and 38 sampling sites for both water and sediment samples, respectively. Other phenyltins (MPhT and TPhT) did not occur above their LOQ and therefore no background was possible to establish. Throughout this work, which is the first assessment of background concentrations for organometallic compounds at the French national level ever being published, it was possible to conclude that over the last 10-20 years organotin concentrations in French river basins have decreased while MeHg concentration remained stable.

Is container type the biggest predictor of trace element and BPA leaching from drinking water bottles?

The knowledge-base of bottled water leachate is highly contradictory due to varying methodologies and limited multi-elemental and/or molecular analyses; understanding the range of contaminants and their pathways is required. This study determined the leaching potential and leaching kinetics of trace elements, using consistent comprehensive quantitative and semi-quantitative (79 elements total) analyses, and BPA, using isotopic dilution and MEPS pre-concentration with UHPLC-ESI-QTOF. Statistical methods were used to determine confounders and predictors of leaching and human health risk throughout 12days of UV exposure and after exposure to elevated temperature. Various types of water were used to assess the impact of water quality. Results suggest Sb leaching is primarily dependent upon water quality, not container type. Bottle type is a predictor of elemental leaching for Pb, Ba, Cr, Cu, Mn and Sr; BPA was detected in samples from polycarbonate containers. Health risks from the consumption of bottled water increase after UV exposure.

Changes of benthic bacteria and meiofauna assemblages during bio-treatments of anthracene-contaminated sediments from Bizerta lagoon (Tunisia).

Sediments from Bizerta lagoon were used in an experimental microcosm setup involving three scenarios for the bioremediation of anthracene-polluted sediments, namely bioaugmentation, biostimulation, and a combination of both bioaugmentation and biostimulation. In order to investigate the effect of the biotreatments on the benthic biosphere, 16S rRNA gene-based T-RFLP bacterial community structure and the abundance and diversity of the meiofauna were determined throughout the experiment period. Addition of fresh anthracene drastically reduced the benthic bacterial and meiofaunal abundances. The treatment combining biostimulation and bioaugmentation was most efficient in eliminating anthracene, resulting in a less toxic sedimentary environment, which restored meiofaunal abundance and diversity. Furthermore, canonical correspondence analysis showed that the biostimulation treatment promoted a bacterial community favorable to the development of nematodes while the treatment combining biostimulation and bioaugmentation resulted in a bacterial community that advantaged the development of the other meiofauna taxa (copepods, oligochaetes, polychaetes, and other) restoring thus the meiofaunal structure. The results highlight the importance to take into account the bacteria/meiofauna interactions during the implementation of bioremediation treatment.

Impacts of bioremediation schemes for the mitigation of a low-dose anthracene contamination on free-living marine benthic nematodes.

A microcosm experiment was used to examine (1) the effects of different bioremediation schemes on degradation of anthracene and the structure of free-living marine nematodes in a lightly contaminated (4.5 µg g(-1)) sediment from Bizerte lagoon and (2) the responses of the nematode community upon an artificial spiking of a low dose anthracene (1 µg g(-1)). For that purpose sediment microcosms were incubated in laboratory for 40 days. Bioremediation techniques decreased the anthracene contamination, and interestingly, biodegradation were more efficient when anthracene was artificial supplied into the sediment suggesting that the addition of bioavailable anthracene stimulated the bacterial community to adjust towards a PAH-degrading community. Spiking with this low dose of anthracene provoked significant changes in the nematode community structure and abundance, with the elimination of specific species such as Mesacanthion diplechma, the decrease of the dominant species Oncholaimus campylocercoides and the increase in abundance of opportunistic species such as Spirinia parasitifera. This would suggest a low tolerance of the nematode community despite the presence of a weak anthracene contamination in the sediment that could have allow dominance of an anthracene tolerant nematode species. Anthracene toxicity was alleviated in biostimulation treatments, leading to a strong increase in nematode abundance, concomitantly with changes in the nematode community structure; Prochromadorella neapolitana became the most abundant species.

Comprehensive speciation of low-molecular weight selenium metabolites in mustard seeds using HPLC-electrospray linear trap/Orbitrap tandem mass spectrometry.

An analytical methodology based on high-resolution high mass accuracy electrospray ionization (ESI) tandem MS assisted by Se-specific detection using inductively coupled plasma mass spectrometry (ICP MS) was developed for speciation of selenium (Se) in seeds of black mustard (Brassica nigra) grown on Se-rich soil. Size-exclusion LC-ICP MS allowed the determination of the Se distribution according to the molecular mass and the control of the species stability during extraction. The optimization of hydrophilic interaction of LC and cation-exchange HPLC resulted in analytical conditions making it possible to detect and characterize over 30 Se species using ESI MS, including a number of minor (<0.5%) metabolites. Selenoglucosinolates were found to be the most important class of species accounting for at least 15% of the total Se present and over 50% of all the metabolites. They were found particularly unstable during aqueous extraction leading to the loss of Se by volatilization as methylselenonitriles and methylselenoisothiocyanates identified using gas chromatography (GC) with the parallel ICP MS and atmospheric pressure chemical ionization (APCI) MS/MS detection. However, selenoglucosinolates could be efficiently recovered by extraction with 70% methanol. Other classes of identified species included selenoamino acids, selenosugars, selenosinapine and selenourea derivatives. The three types of reactions leading to the formation of selenometabolites were: the Se-S substitution in the metabolic pathway, oxidative reactions of -SeH groups with endogenous biomolecules, and chemical reactions, e.g., esterification, of Se-containing molecules and other biomolecules through functional groups not involving Se.

Large-scale identification of selenium metabolites by online size-exclusion-reversed phase liquid chromatography with combined inductively coupled plasma (ICP-MS) and electrospray ionization linear trap-Orbitrap mass spectrometry (ESI-MS(n)).

A method was developed for the comprehensive cartography of the selenium metabolites synthesized in the process of conversion of selenite [Se(iv)] into organic compounds and enrichment of yeast with selenium. The number of compounds detected was considerably increased (49) owing to the optimization of the fractionation procedure and the use of UPLC. The increased purity of the minor selenoorganic amino acids and oligopeptides allowed successful on-line de-novo identification based on the exact mass (<1 ppm) and fragmentation (MS(2)/MS(3)) mass spectra obtained with high resolution and high mass accuracy. The quality of mass spectra allowed the re-interpretation of previously reported structures of some selenium species.

Physiological characterization of cadmium-exposed Chlamydomonas reinhardtii.

Chlamydomonas reinhardtii is a common model organism for investigation of metal stress. This green alga produces phytochelatins in the presence of metal ions. The influence of cadmium is of main interest, because it is a strong activator of phytochelatin synthase. Cell wall bound and intracellular cadmium content was determined after exposition to 70 µm CdCl(2), showing the main portion of the metal outside the cell. Nevertheless, imported cadmium was sufficient to cause significant changes in thiolpeptide metabolism and its transcriptional regulation. Modern analytical approaches enable new insights into phytochelatin (PC) distribution. A new rapid and precise UPLC-MS method allowed high-throughput PC quantification in algal samples after 1, 4, 24 and 48 h cadmium stress. Initially, canonic PCs were synthesized in C. reinhardtii during cadmium exposition, but afterwards CysPCs became the major thiolpeptides. Thus, after 48 h the concentration of the PC-isoforms CysPC(2-3) and CysGSH attained between 105 and 199 nmol g(-1) fresh weight (FW), whereas the PC(2-3) concentrations were only 15 nmol g(-1) FW. The relative quantification of γ-glutamyl transpeptidase (γ-GT) mRNA suggests the generation of CysPCs by glutamate cleavage from canonic PCs by γ-GT. Furthermore, a homology model of C. reinhardtii phytochelatin synthase was constructed to verify the use of crystal structures from Anabaena sp. phytochelatin synthase (PCS) for docking studies with canonical PCs and CysPCs. From the difference in energy scores, we hypothesize that CysPC may prevent the synthesis of canonical PCs by blocking the binding pocket. Finally, possible physiological reasons for the high abundance of CysPC compared with their canonic precursors are discussed.

Rapid and simple UPLC-MS/MS method for precise phytochelatin quantification in alga extracts.

Quantitative phytochelatin (PC) analysis is, due to oxidation sensitivity of the PCs, matrix effects, and time consuming sample preparation, still a challenging analytical task. In this study, a rapid, simple, and sensitive method for precise determination of native PCs in crude extracts of the green alga Chlamydomonas reinhardtii was developed. Algae were exposed 48 h to 70 µM Cd. Coupling of ultra performance liquid chromatography and electrospray ionization tandem mass spectrometry with multi-reaction mode transitions for detection permitted the required short-time, high-resolution separation and detection specificity. Thus, under optimized chromatographic conditions, 10 thiol peptides were baseline-separated within 7 min. Relative detection limits in the nanomolar range in microliter sample volumes were achieved (corresponding to absolute detection limits at femtomole level). Next to glutathione (GSH), the most abundant cadmium-induced PCs in C. reinhardtii, namely CysGSH, PC(2), PC(3), CysPC(2), and CysPC(3), were quantified with high reproducibility at concentrations between 15 and 198 nmol g(-1) fresh weight. The biological variation of PC synthesis of nine independently grown alga cultures was determined to be on average 13.7%.

Detection and identification of hydrophilic selenium compounds in selenium-rich yeast by size exclusion-microbore normal-phase HPLC with the on-line ICP-MS and electrospray Q-TOF-MS detection.

Normal-phase HPLC and hydrophilic interaction HPLC (HILIC) were investigated for the separation of selenometabolites in a water extract of Se-rich yeast prior to their detection by ICP-MS and identification by electrospray MS/MS. The targeted fraction was a low-abundant fraction co-eluting with salt and sulfur analogues in size-exclusion chromatography which has so far been inaccessible to Se speciation studies. The optimization of the separation conditions resulted in the highest separation efficiency when HILIC was used and elution was carried out isocratically with a low concentration ammonium acetate buffer (1 mM ammonium acetate/10 mM acetic acid) in 80% acetonitrile. Out of 15 peaks observed with the Se-specific ICP-MS detection 12 was identified by electrospray Q-TOF MS/MS (2,3-dihydroxypropionyl (DHP)-Se-methylselenocysteine [M+H]+: 272, Se-methyl-gamma-glutamyl-selenocysteinylglycine dioxide [M+H]+: 402, gamma-glutamyl-Se-methylselenocysteine [M+H]+: 313; isomers of gamma-glutamylselenocystathionine [M+H]+: 400; Se-methyl-selenoglutathione [M+H]+: 370, isomers of N-acetylselenocystathionine [M+H]+: 313, 2,3-DHP-selenohomolanthionine [M+H]+: 373, isomers of 2,3-DHP-selenocystathionine [M+H]+: 359, 2,3-DHP-selenolanthionine [M+H]+: 345 and selenohomolanthionine [M+H]+: 285).

Standardless identification of selenocystathionine and its gamma-glutamyl derivatives in monkeypot nuts by 3D liquid chromatography with ICP-MS detection followed by nanoHPLC-Q-TOF-MS/MS.

A three-step chromatographic procedure using orthogonal separation mechanisms (size-exclusion, cation-exchange and ion-pairing reversed phase) was developed to purify three low molecular weight selenospecies, including the major compound, from the aqueous extract of monkeypot (Lecythis minor) nuts. The following reversed-phase nanoHPLC-electrospray Q-TOF-MS/MS allowed the formal standardless identification of selenocystathionine and two isoforms of gamma-glutamyl-selenocystathionine. This is the first MS and MS/MS-based formal evidence of the presence of these compounds in a biological sample.