Search

This manuscript describes a new multiresidue method utilising ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) via multiple reaction monitoring (MRM), for the identification and quantification of 58 antibiotics and their 26 metabolites, in various solid and liquid environmental matrices. The method was designed with a ‘one health’ approach in mind requiring multidisciplinary and multisectoral collaborative efforts. It enables comprehensive evaluation of antibiotic usage in surveyed communities via wastewater-based epidemiology, as well as allowing for the assessment of potential environmental impacts. The instrumental performance was very good, demonstrating linearity up to 3000 μg L−1, and high accuracy and precision. The method accuracy in several compounds was significantly improved by dividing calibration curves into separate ranges. This was accompanied by applying a weighting factor (1/x). Microwave-assisted and/or solid-phase extraction of analytes from liquid and solid matrices provided good recoveries for most compounds, with only a few analytes underperforming. Method quantification limits were determined as low as 0.017 ng L−1 in river water, 0.044 ng L−1 in wastewater, 0.008 ng g−1 in river sediment, and 0.009 ng g−1 in suspended solids. Overall, the method was successfully validated for the quantification of 64 analytes extracted from aqueous samples, and 45 from solids. The analytes that underperformed are considered on a semi-quantitative basis, including aminoglycosides and carbapenems. The method was applied to both solid and liquid environmental matrices, whereby several antibiotics and their metabolites were quantified. The most notable antibiotic-metabolite pairs are three sulfonamides and their N-acetyl metabolites; four macrolides/lincomycins and their N-desmethyl metabolites; and five quinolone metabolites. Graphical abstract

Graphical abstract The goal of the research was the synthesis and application of an oligonucleotide immobilized stationary phase for the analysis of unmodified and antisense oligonucleotides. The method for attaching these molecules to aminopropyl silica modified with pentanedioic acid was developed. Each step of the synthesis was carefully controlled with the application of spectroscopic, elemental, and chromatographic analyses. The oligonucleotide-based stationary phase was applied for the retention studies. Unmodified oligonucleotides of different complementarity to the molecule attached as a stationary phase, as well as antisense oligonucleotides, were tested. The comparative study upon complex optimization of oligonucleotide analysis in different liquid chromatography modes was performed. Results have shown that this stationary phase may be applied for oligonucleotide analysis in hydrophilic interaction liquid chromatography and ion exchange chromatography, but no unique sequence-based selectivity was obtained. Contrary results were observed for affinity chromatography, which allowed for specific separation of the complementary strands based on hydrogen bonding and stacking interactions, where the temperature was the main factor influencing the selectivity of the separation. Furthermore, the oligonucleotide-based stationary phase may be applied for comparative antisense oligonucleotide hybridization studies to a specific RNA sequence. All of the results have shown that affinity chromatography with oligonucleotide-based stationary phases is a powerful technique for the specific base recognition of polynucleotides. Supplementary Information The online version contains supplementary material available at 10.1007/s00216-021-03473-7.

Recycling will be of increasing importance in the future, especially for plastic packaging waste mainly consisting of polyolefins. One major problem of recyclates comprises impurities which can have a significant negative impact on future product properties. Polyamide 6 can be found widely as contaminant in recycled polyolefins, leading to a need of quantification methods thereof. In this paper, a method development for the quantitative analysis of polyamide 6 is presented based on analysing ε-caprolactam and related cyclic oligomers as marker compounds in model recyclates of high- and low-density polyethylene and polypropylene compounded with low amounts of polyamide 6. For the method development and tentative identification of the different cyclic compounds, a HPLC-QTOF-MS was used and it was possible to detect six different compounds, ε-caprolactam and the corresponding cyclic di- to hexamer. The quantification was performed with a HPLC-QQQ-MS, equipped with a HILIC column, after sample preparation via microwave-assisted extraction. It could be shown that a good linearity from 0.2 up to 5 wt% polyamide 6 in the different polyolefins can be achieved. The cyclic trimer and tetramer show a low limit of quantification and are therefore well-suited for the quantification, whereas the other cyclic compounds can be then used as qualifiers to avoid false positives. To guarantee the applicability of the method, six real recyclate materials were analysed, whereby in three of them low amounts of polyamide 6 could be detected. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s00216-020-03071-z.

Olive quick decline syndrome (OQDS) is a disorder associated with bacterial infections caused by Xylella fastidiosa subsp. pauca ST53 in olive trees. Metabolic profile changes occurring in infected olive trees are still poorly investigated, but have the potential to unravel reliable biomarkers to be exploited for early diagnosis of infections. In this study, an untargeted metabolomic method using high-performance liquid chromatography coupled to quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-ESI-Q-TOF-MS) was used to detect differences in samples (leaves) from healthy (Ctrl) and infected (Xf) olive trees. Both unsupervised and supervised data analysis clearly differentiated the groups. Different metabolites have been identified as potential specific biomarkers, and their characterization strongly suggests that metabolism of flavonoids and long-chain fatty acids is perturbed in Xf samples. In particular, a decrease in the defence capabilities of the host after Xf infection is proposed because of a significant dysregulation of some metabolites belonging to flavonoid family. Moreover, oleic acid is confirmed as a putative diffusible signal factor (DSF). This study provides new insights into the host-pathogen interactions and confirms LC-HRMS-based metabolomics as a powerful approach for disease-associated biomarkers discovery in plants. Graphical abstract

Positional isomers of bisphenol F diglycidyl ether (BFDGE) have been analyzed by high-pressure liquid chromatography-mass spectrometry and by gas chromatography-mass spectrometry (HPLC-MS, GC-MS). Positional isomers of BFDGE derivatives (BFDGEx2H2O, BFDGExH2OxHCl) have been analyzed by HPLC-MS. On the basis of the obtained fragmentation patterns, the elution order of the isomers has been unequivocally determined, in standard solutions and in the sample of liquid obtained after rinsing an empty mackerel fish can with acetonitrile. Under HPLC condition, para,para isomers are eluted first, then ortho,para isomers’ elution follows, and ortho,ortho isomers are eluted last. Under GC condition, the reverse elution order has been obtained. For the first time, two ortho,para isomers of BFDGExH2OxHCl have been detected and their elution order has been determined. The obtained results are of key importance for determination of the isomer distribution of BFDGE and its derivatives in food samples.

Annotation and interpretation of full scan electrospray mass spectra of metabolites is complicated by the presence of a wide variety of ions. Not only protonated, deprotonated, and neutral loss ions but also sodium, potassium, and ammonium adducts as well as oligomers are frequently observed. This diversity challenges automatic annotation and is often poorly addressed by current annotation tools. In many cases, annotation is integrated in metabolomics workflows and is based on specific chromatographic peak-picking tools. We introduce mzAdan, a nonchromatography-based multipurpose standalone application that was developed for the annotation and exploration of convolved high-resolution ESI-MS spectra. The tool annotates single or multiple accurate mass spectra using a customizable adduct annotation list and outputs a list of [M+H]+ candidates. MzAdan was first tested with a collection of 408 analytes acquired with flow injection analysis. This resulted in 402 correct [M+H]+ identifications and, with combinations of sodium, ammonium, and potassium adducts and water and ammonia losses within a tolerance of 10 mmu, explained close to 50% of the total ion current. False positives were monitored with mass accuracy and bias as well as chromatographic behavior which led to the identification of adducts with calcium instead of the expected potassium. MzAdan was then integrated in a workflow with XCMS for the untargeted LC-MS data analysis of a 52 metabolite standard mix and a human urine sample. The results were benchmarked against three other annotation tools, CAMERA, findMAIN, and CliqueMS: findMAIN and mzAdan consistently produced higher numbers of [M+H]+ candidates compared with CliqueMS and CAMERA, especially with co-eluting metabolites. Detection of low-intensity ions and correct grouping were found to be essential for annotation performance. Graphical abstract Electronic supplementary material The online version contains supplementary material available at 10.1007/s00216-020-03019-3.

On-line hyphenation of extraction with chromatography has been explored in several different types of combinations. However, monitoring the complete process of a dynamic, continuous-flow extraction is not possible with any hyphenated system reported so far. The current work demonstrates that this challenging task can be effectively fulfilled by using a parallel sampling interface, which mimics the concept of comprehensive two-dimensional chromatography. In this study, pressurised hot water extraction was coupled on-line with ultra-high-performance liquid chromatography. The set-up was utilised in a kinetic study of dynamic pressurised hot water extraction of curcuminoids from turmeric powder. Compound-specific extraction curves were obtained, which clearly indicated the rate-limiting factors of the extraction processes under different conditions. Additionally, thermal degradation of curcumin during the extraction could also be demonstrated in some of the extractions. Electronic supplementary material The online version of this article (10.1007/s00216-019-01849-4) contains supplementary material, which is available to authorized users.

Sphingosine 1-phosphate (S1P) is a signalling sphingolipid affecting multiple cellular functions of vascular and immune systems. It circulates at submicromolar levels bound to HDL-associated apolipoprotein M (apoM) or to albumin. S1P in blood is mainly produced by platelets and erythrocytes, making blood sampling for S1P quantification delicate. Standardisation of sampling is thereby of great importance to obtain robust data. By optimising and characterising the extraction procedure and the LC-MS/MS analysis, we have developed and validated a highly specific and sensitive method for S1P quantification. Blood was collected from healthy individuals (n = 15) to evaluate the effects of differential blood sampling on S1P levels. To evaluate correlation between S1P and apoM in different types of plasma and serum, apoM was measured by ELISA. The method showed good accuracy and precision in the range of 0.011 to 0.9 μM with less than 0.07 % carryover. We found that the methanol precipitation used to extract S1P co-extracted apoM and several other HDL-proteins from plasma. The platelet-associated S1P was released during coagulation, thus increasing the S1P concentration to double in serum as compared to that in plasma. Gel filtration chromatography revealed that the platelet-released S1P was mainly bound to albumin. This explains why the strong correlation between S1P and apoM levels in plasma is lost upon the clotting process and hence not observed in serum. We have developed, characterised and validated an efficient, highly sensitive and specific method for the quantification of S1P in biological material. Electronic supplementary material The online version of this article (doi:10.1007/s00216-015-9008-4) contains supplementary material, which is available to authorized users.

An analytical workflow was developed for the absolute quantification of uridine diphosphate (UDP)-sugars in plant material in order to compare their metabolism both in wild-type Arabidopsis thaliana and mutated plants (ugd2,3) possessing genetic alterations within the UDP-glucose dehydrogenase genes involved in UDP-sugar metabolism. UDP-sugars were extracted from fresh plant material by chloroform-methanol-water extraction and further purified by solid-phase extraction with a porous graphitic carbon adsorbent with extraction efficiencies between 80 ± 5 % and 90 ± 5 %. Quantitative determination of the UDP-sugars was accomplished through HPLC separation with a porous graphitic carbon column (HypercarbTM) which was interfaced to electrospray ionization Orbitrap mass spectrometry. The problem of instable retention times due to redox processes on the stationary phase were circumvented by grounding of the column effluent and incorporation of a column regeneration procedure using acetonitrile-water containing 0.10 % trifluoroacetic acid. The method was calibrated using external calibration and UDP as internal standard. Calibration functions were approximated by first- or second-order regression analysis for concentrations spanning three orders of magnitude. Upon injecting sample volumes of 2.65 μL, the limits of detection for the UDP-sugars were in the 70 nmol L−1 range. Six different UDP-sugars, including UDP-glucose, UDP-galactose, UDP-arabinose, UDP-xylose, UDP-glucuronic acid, and UDP-galacturonic acid were found in concentrations of 0.4 to 38 μg/g plant material. Data evaluation by analysis of variance (ANOVA) revealed statistically significant differences in UDP-sugar concentrations between wild-type and mutant plants, which were found to conclusively mirror the impaired metabolic pathways in the mutant plants. Figure ᅟ Electronic supplementary material The online version of this article (doi:10.1007/s00216-014-7746-3) contains supplementary material, which is available to authorized users.