Reusable Cavitand‐Based Electrospun Membranes for the Removal of Polycyclic Aromatic Hydrocarbons from Water

The removal of toxic and carcinogenic polycyclic aromatic hydrocarbons (PAHs) from water is one of the most intractable environmental problems nowadays, because of their resistance to remediation. This work introduces a highly efficient, regenerable membrane for the removal of PAHs from water, featuring excellent filter performance and pH-driven release, thanks to the integration of a cavitand receptor in electrospun polyacrylonitrile (PAN) fibers. The role of the cavitand receptor is to act as molecular gripper for the uptake/ release of PAHs. To this purpose, the deep cavity cavitand BenzoQxCav is designed and synthetized and its molecular structure is elucidated via X-Ray diffraction. The removal efficiency of the new adsorbent material toward the 16 priority PAHs is demonstrated via GC-MS analyses at ng L−1 concentration. A removal efficiency in the 32%, to 99% range is obtained. The regeneration of the membrane is performed by exploiting the pH-driven conformational switching of the cavitand between the vase form, where the PAHs uptake takes place, to the kite one, where the PAHs release occurs. The absorbance and regeneration capability of the membrane are successfully tested in four uptake/release cycles and the morphological stability

Novel sample-substrates for the determination of new psychoactive substances in oral fluid by desorption electrospray ionization-high resolution mass spectrometry

A reliable screening and non invasive method based on the use of microextraction by packed sorbent coupled with desorption electrospray ionization-high resolution mass spectrometry was developed and validated for the detection of new psychoactive substances in oral fluid. The role of different sample substrates in enhancing signal intensity and stability was evaluated by testing the performances of two polylactide-based materials, i.e. non-functionalized and functionalized with carbon nanoparticles, and a silica-based material compared to commercially available polytetrafluorethylene supports. The best results were achieved by using the nonfunctionalized polylactide substrates to efficiently ionize compounds in positive ionization mode, whereas the silica coating proved to be the best choice for operating in negative ionization mode. LLOQs in the low μg/L, a good precision with CV% always lower than 16% and RR% in the 83(±4)-120(±2)% range, proved the suitability of the developed method for the determination of the analytes in oral fluid. Finally, the method was applied for screening oral fluid samples for the presence of psychoactive substances during private parties, revealing mephedrone in only one sample out of 40 submitted to analysis

Chemometric-assisted cocrystallization: Supervised pattern recognition for predicting the formation of new functional cocrystals

Owing to the antimicrobial and insecticide properties, the use of natural compounds like essential oils and their active components has proven to be an effective alternative to synthetic chemicals in different fields ranging from drug delivery to agriculture and from nutrition to food preservation. Their limited application due to the high volatility and scarce water solubility can be expanded by using crystal engineering approaches to tune some properties of the active molecule by combining it with a suitable partner molecule (coformer). However, the selection of coformers and the experimental effort required for discovering cocrystals are the bottleneck of cocrystal engineering. This study explores the use of chemometrics to aid the discovery of cocrystals of active ingredients suitable for various applications. Partial Least Squares–Discriminant Analysis is used to discern cocrystals from binary mixtures based on the molecular features of the coformers. For the first time, by including failed cocrystallization data and considering a variety of chemically diverse compounds, the proposed method resulted in a successful prediction rate of 85% for the test set in the model validation phase and of 74% for the external test set

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

New Materials and Improved Ambient Techniques in Mass Spectrometry

Mass spectrometry (MS) is used in several fields, e.g. biology, environmental monitoring, medicine and forensics due to excellent qualitative and quantitative capabilities. The development of new instrumental setups and ionization sources is crucial to analyze a variety of compounds at trace levels. The synergy between material science and analytical chemistry allowed the development of new materials characterized by specific features of polarity, porosity and functionalization, able to interact with targeted analytes in complex matrices, resulting in high extraction efficiency even in presence of overwhelming amounts of interfering compounds. New methods based on the use of new materials and MS techniques for analytes extraction and detection have been proposed, providing fast analysis times, enhanced selectivity and increased sensitivity. In this thesis, the development of new materials and setups for mass spectrometric applications is discussed. In Paper I-III the design, synthesis, characterization and evaluation of the analytical performances of four new supramolecular receptors for targeted extraction of benzene, toluene, ethylbenzene and xylenes (BTEX) are reported. The synthesized materials were used as solid-phase microextraction coatings (SPME) for the GC-MS determination of BTEX at trace levels in urban air. In addition, a portable device for in-situ and real-time monitoring of BTEX using these receptors in the preconcentration unit is presented. In Paper IV the development of coated ion sources able to improve the performances of an interface coupling liquid chromatography (LC) and electron ionization (EI), called Direct-EI LC-MS, is discussed. The coatings, obtained by sol-gel technique, were deposited onto commercial stainless steel EI sources to increase the inertness of its vaporization surface. In Paper V, a rapid screening method for the detection of new psychoactive substances (NPS) in oral fluids is presented. New slides based on polylactide (PLLA), carbon particles and silica were tested as probe materials to promote the ionization of the analytes in desorption electrospray ionization – high resolution mass spectrometry (DESI-HRMS). Microextraction by packed sorbent (MEPS) of the analytes from the saliva samples was required due to the high signal suppression. The developed MEPS-DESI-HRMS method was validated and applied for the determination of NPS in road-collected samples. In Paper VI the development of a new setup called solvent assisted paper spray ionization (SAPSI) is reported. This integrated solution allowed the increased data acquisition time and a close control over the ionization conditions. It was applied for the analysis of biomolecules, namely proteins, lipids, glycans, and amyloid peptides/aggregates, in aqueous solution as well as in human serum and cerebrospinal fluid. Different oligomeric species of amyloid aggregates were detected and it was possible to perform real-time monitoring of disaggregation processes. Modified protein species of physiological relevance such as oxidation, cysteinylation, glycosylation and glycation, and adduct formation were identified. In conclusion, the new materials and setups discussed in this thesis allowed the development of selective and sensitive MS methods for the determination of different target compounds in complex matrices at trace levels with reduced sample pretreatment.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript. Paper 6: Manuscript.</p

Nuovi materiali per spettrometria di massa, trattamento del campione ed applicazioni cliniche

Lo sviluppo e l’utilizzo di nuovi materiali per scopi analitici è un campo di grande interesse per la ricerca scientifica. I progressi ottenuti nell’ambito della chimica dei materiali hanno permesso lo sviluppo di nuovi metodi analitici e tecniche di estrazione caratterizzati da alte performance in termini di selettività e sensibilità. In particolare sono stati incrementati nuovi dispositivi in grado di operare in-situ e in tempo reale tramite controllo remoto, interfacciandosi con smartphones, sistemi clouds e reti aziendali. Il presente lavoro di tesi di dottorato si è focalizzato sullo sviluppo di nuovi materiali per applicazioni in spettrometria di massa, trattamento del campione e per scopi clinici. Il monitoraggio ambientale è un campo di ricerca molto attivo negli ultimi anni: l’incremento della industrializzazione e delle attività antropogeniche hanno portato ad un innalzamento generale dei livelli di inquinamento, richiedendo lo sviluppo di nuovi metodi e dispositivi in grado di rivelare la presenza in tracce di inquinanti in aria, acqua e suolo. La preconcentrazione è l’approccio più comunemente impiegato per aumentare le performance dei metodi analitici: il design e la sintesi di materiali innovativi caratterizzati sia da alta selettività rispetto specifiche classi di inquinanti, che da alti fattori di arricchimento, ha permesso lo sviluppo di nuovi metodi analitici e dispositivi per l’analisi in tempo reale e in-situ di composti pericolosi a livelli di µg/m3. Nel caso in cui sia richiesta un’analisi non mirata ma globale (untargeted) degli inquinanti, si è reso necessario lo sviluppo di nuovi materiali in grado di adsorbire il più ampio possibile range di composti. Nella presente tesi di dottorato, i capitoli 1 e 2 sono volti alla ricerca di nuovi materiali per il monitoraggio ambientale, in particolare nel comparto aria. Più in dettaglio, nel capitolo 1, è descritto lo sviluppo di nuovi recettori supramolecolari per la rivelazione di benzene, toluene, etilbenzene e xileni (BTEX): il design, la sintesi, la caratterizzazione e l’utilizzo come coating per microestrazione in fase solida (SPME) sono stati approfonditamente descritti. Particolare attenzione è stata rivolta alla complessazione del benzene, analita riconosciuto a livello mondiale come cancerogeno. Le fibre SPME ottenute sono state caratterizzate in termini di spessore del film, morfologia del materiale e stabilità termica, e hanno mostrato capacità di estrazione dei BTEX superiore a quella dei materiali oggi disponibili in commercio. I metodi sviluppati sono stati validati secondo le linee guida Eurachem e testati per l’analisi di campioni reali. Infine è stato descritto lo sviluppo di un dispositivo stand-alone miniaturizzato che utilizza come materiale adsorbente i recettori studiati. Nel capitolo 2 sono state testate le capacità di un nuovo materiale adsorbente, basato sull’utilizzo di carbone non granulare, per l’analisi untargeted di composti semi-volatili (SVOCs) mediante desorbimento termico e spettrometria di massa (TD-GC-MS). Poiché gli SVOCs sono caratterizzati da proprietà molto diverse, in termini di peso molecolare e polarità, la loro rivelazione risulta molto complessa. Oggi viene effettuata tramite l’utilizzo di tubi a più componenti (mutli-sorbent) ma presenta un notevole limite: l’umidità dell’aria causa una notevole diminuzione delle capacità di estrazione del materiale. Al contrario, il materiale proposto nella presente tesi di dottorato non è influenzato dall’ umidità, permettendo lo sviluppo di un metodo GC-MS per la rivelazione di clorobenzeni e idrocarburi policiclici aromatici in aria, non riportando alcun problema di intasamento del tubo dovuto a condensa. L’analisi biologica è un altro importante campo di ricerca: nuovi materiali e metodi analitici per la rivelazione di biomolecole, insieme all’utilizzo di metodi statistici, hanno permesso di identificare biomarker di malattie. Il pretrattamento del campione è un aspetto chiave nella bioanalisi: sono infatti state sviluppate nuove tecniche di estrazione in grado di rimuovere possibili interferenti, presenti in matrici complesse come i fluidi biologici, e di preconcentrare gli analiti anche a partire da bassi volumi di campione (decine di microlitri). Nel capitolo 3, le performance della microestrazione in fase solida (MEPS) sono state testate per sviluppare un metodo MEPS-LC-MS per la determinazione di desametasone e desametasone sodio fosfato, nell’umor acqueo di pazienti affetti da uveite. Il disegno sperimentale e l’utilizzo delle funzioni di desiderabilità sono stati impiegati per ottimizzare le condizioni di estrazione. Infine il metodo è stato validato seguendo le linee guida per i metodi bioanalitici. Un altro campo di ricerca studiato nel presente lavoro di tesi è legato allo sviluppo di nuovi materiali per applicazioni in spettrometria di massa, sia in campo ambientale che in campo bioanalitico. Nel capitolo 4 sono stati riportati progressi nello sviluppo di una interfaccia in grado di accoppiare la cromatografia liquida con la sorgente a ionizzazione elettronica. In particolare si è discusso il miglioramento di un prototipo Direct EI LC-MS mediante l’utilizzo di coating inorganici ottenuti mediante tecnica sol-gel. La superficie di vaporizzazione della sorgente elettronica è un parametro chiave per la rivelazione e la caratterizzazione dei vari analiti: in particolare composti caratterizzati da alti pesi molecolari e polarità richiedono alte temperature della sorgente EI per essere rivelati, mostrando comunque enormi limiti in termini di ripetibilità e qualità del picco. Tre coatings inorganici basati su silice, titania e zirconia, sintetizzati tramite tecnica sol-gel, sono stati depositati mediante spray sulla superfice di acciaio di sorgenti commerciali per aumentarne l’inerzia. I materiali sono stati quindi caratterizzati in termini di spessore, morfologia e stabilità termica. Infine, le sorgenti sviluppate sono state testate per l’analisi di inquinanti ambientali, in particolare di idrocarburi policiclici aromatici e ormoni: i risultati hanno evidenziato come il coating a base di silice sia quello caratterizzato dalle migliori prestazioni. La spettrometria di massa, in particolar modo nuove tecniche spettroscopiche come la Desorption Electrospray Ionization High Resolution Mass Spectrometry (DESI-HRMS), è cruciale per lo sviluppo di metodi caratterizzati da elevata rapidità, selettività e sensibilità, da utilizzarsi quando è richiesta l’analisi di un alto numero di campioni. Nel capitolo 5 è riportato lo sviluppo di materiali per l’analisi DESI-HRMS di nuove sostanze psicoattive (NPS). Come NPS sono classificate diverse droghe che non sono ancora soggette a controlli internazionali, la cui struttura e attività è assimilabile a droghe illegali. Sono quindi considerate come una potenziale minaccia alla salute pubblica. Nel capitolo 5 è stato proposto un metodo di screening basato sulla tecnica MEPS-DESI-HRMS per l’analisi di NPS in saliva. Tale metodo è stato sviluppato per combattere il fenomeno della guida sotto l’effetto di sostanze stupefacenti. Films di polilattato, tal quale e funzionalizzato, sono stati testati come materiali di supporto per analisi DESI e le loro capacità sono state confrontate con lastrine commerciali in PTFE. Infatti, sia l’idrofilia che la morfologia della superficie sono in grado di influenzare l’efficienza di ionizzazione dei composti studiati. Il metodo sviluppato è stato validato seguendo le linee guida per i metodi bioanalitici, ottenendo LOD e LOQ a livello di µg/l. I progressi nel campo della chimica dei materiali hanno inoltre permesso lo sviluppo di nuovi farmaci caratterizzati da dimensioni in scala nanometrica, elevata attività farmacologica e minori effetti collaterali. Nel capitolo 6 è stato trattato lo sviluppo di un nuovo sistema ibrido caratterizzato da un core superparamagnetico in ossido di ferro, funzionalizzato con odorant binding proteins (OBPs). Queste proteine, essendo in grado di complessare sia gli induttori che i metaboliti prodotti da diversi batteri antibiotico-resistenti, sono state proposte come quorum quenching agents. Le nanoparticelle sono state rivestite con un acido fosfonico a lunga catena, coniugato con le OBPs. Sono state quindi ottenute le dimensioni, la composizione e la magnetizzazione delle nanoparticelle sviluppate. La quantità di proteina caricata è stata ottenuta mediante l’utilizzo del BCA protein assay kit. Il vantaggio più importante del nuovo farmaco è la possibilità di guidare mediante un campo magnetico esterno le nanoparticelle in una specifica area infetta dei polmoni, aumentandone la concentrazione locale e diminuendo gli effetti collaterali.The development and application of new materials for analytical purposes is a very promising and attractive research area. In analytical chemistry the progresses achieved in this field allowed to develop both new detection and extraction techniques characterized by enhanced performances in terms of selectivity and sensitivity. In this context, great attention is focused also on the development of new devices able to perform in-situ and real-time analyses through remote control (smartphone interfaces, clouds systems, LAN networks...). This PhD thesis has the aim of developing new materials for MS-based methods, sample pretreatment and clinical applications. Two main different analytical fields are involved: environmental monitoring and bioanalysis. Environmental monitoring is a very active field of research: industrialization and anthropogenic activities led to a dramatic increase in pollution, thus requiring the development of new methods and devices able to detect pollutants in air, water and solid at trace levels. Pre-concentration is a common approach used to increase the performances of the analytical methods in terms of sensitivity and selectivity. The design and synthesis of novel materials characterized by both enhanced selectivity toward specific classes of pollutants and high enrichment factors, paved the way to develop new methods and devices able to perform real-time and in-situ analyses of hazardous compounds at sub-µg/m3 levels. In addition, when untargeted analyses have to be performed, materials characterized by high absorption capabilities toward the widest possible range of pollutants are required. In the present thesis, Chapter 1 and 2 are devoted to the development of new sorbent materials for environmental analysis with particular attention to air monitoring. More precisely, in Chapter 1, a comprehensive study including the design, synthesis and characterization of new supramolecular receptors to be used as coatings for solid-phase microextraction (SPME) for the selective monitoring of airborne pollutants, namely benzene, toluene, ethylbenzene and xylenes (BTEX) is reported. The receptors were designed in order to be selective toward BTEX and characterized by enhanced extraction capabilities toward benzene, a well-recognized carcinogenic compound. The SPME fibers were characterized in terms of film thickness, morphology and thermal stability showing extraction capabilities higher than those achieved by using commercially available materials. All the developed methods were fully validated and used for real sample analyses. Finally, the development of a simple, stand-alone, and unsupervised sensing device using the synthetized receptors as preconcentrating unit is reported. In Chapter 2, the capabilities of new multipurpose absorbent tubes, using non granular active carbon were tested for the untargeted analysis of semi-volatile pollutants. Since these compounds are characterized by different properties in terms of molecular weight and polarity, their detection is very challenging. Nowadays, the use of multi-sorbent tubes is affected by a major drawback: environmental humidity causes a dramatic decrease in the extraction capabilities of the adsorptive materials. By contrast, the material proposed in this study was not influenced by the presence of moisture, thus allowing to develop and validate a thermal desorption GC-MS method for the determination of chlorobenzenes and polycyclic aromatic hydrocarbons in air. No clogging of the adsorbent material was observed even when analyses were performed under high relative humidity conditions. Bioanalysis is another important field of research: new materials and methods devoted to the analysis of biomolecules coupled with the use of statistical tools in order to identify disease biomarkers have been successfully developed. Sample pretreatment is a key parameter also in bioanalysis: the development of new extraction techniques allows both to remove possible interfering compounds from complex matrices like body fluids (urine, blood and saliva) and to perform clean-up and preconcentration of the analytes even when low sample volumes (tens of microliters) are available. In Chapter 3, the performances of microextraction by packed sorbent (MEPS) technique were tested in order to develop a MEPS-LC-MS method for the determination of dexamethasone and dexamethasone disodium phosphate in human aqueous humor. Experimental design and the multicriteria method of the desirability functions were applied to optimized the extraction conditions. Finally the method was validated following the guidelines for bioanalytical methods. Another part of the research activity was devoted to the development of novel materials for MS-based methods with applications in the both environmental and bioanalytical field. Advances in interfacing liquid chromatography and electron ionization (EI) mass spectrometry were are presented in Chapter 4. The improvement of a new prototype for Direct-EI LC-MS analyses based on the development of new ion source coatings is discussed. In fact, the vaporization surface of the ion source is a key issue for the detection and characterization of targeted and untargeted compounds, especially for analytes characterized by high-molecular weight which require high-source temperatures to be detected properly. Three inorganic coatings, based on silica, titania and zirconia synthesized by sol-gel technology were developed in order to increase the chemical inertness of the commercial stainless steel ion sources. The materials were characterized in terms of film thickness, morphology and thermal stability. Finally, they were tested for the Direct-EI LC-MS determination of environmental pollutants, i.e. polycyclic aromatic hydrocarbons and hormones: the results achieved proved that silica coating allowed to obtain better performances compared to the uncoated ion sources. Mass spectrometry and in particular novel analytical techniques like Desorption Electrospray Ionization High Resolution Mass Spectrometry (DESI-HRMS) are crucial when fast, selective and sensitive methods for high throughput analyses are required. In Chapter 5, new materials for the DESI-HRMS analysis of new psychoactive (NPS) substances are presented. NPS are a very large group of drugs of abuse not controlled by international conventions, thus being considered as a major threat to public health. In order to take preventive actions so as to be able to reduce driving under the influence of drugs of abuse, a MEPS-DESI-HRMS screening method for the detection of NPS at low concentration in oral fluids was developed. Unmodified and functionalized polylactide films were used as DESI supporting materials and their performances were compared with those of commercially available polytetrafluoroethylene slides. Both surface hydrophobicity and morphology proved to be able to affect the ionization efficiency of the investigated analytes. Finally, the MEPS-DESI-HRMS method was optimized and validated following the guideline for bioanalytical methods, thus obtaining detection and quantitation limits at µg/l level. The progresses in material chemistry made also possible to develop new drugs characterized by nm-size, high pharmaceutical activity and low side effects. In Chapter 6, a new hybrid system characterized by a superparamagnetic iron oxide core and functionalized by odorant binding proteins (OBPs) acting as quorum quenching agents, was developed in order to bind different inducers and metabolites (like pyocyanin) produced by antibiotic resistant bacteria. The iron oxide nanoparticle cores were functionalized by a long-chain phosphonic acid and then conjugated with the OBPs. Nanoparticles were characterized in terms of magnetization, composition and dimensions. Finally, the amount of conjugated protein was assessed by using the BCA protein assay kit. The major advantage of the proposed approach relies on the possibility of using an external magnetic field to drive the nanodrugs to a specific inflamed area of the lungs, thus both increasing the local concentration of the active principle and reducing the side-effects

Supramolecular Materials as Solid-Phase Microextraction Coatings in Environmental Analysis

Solid-phase microextraction (SPME) has been widely proposed for the extraction, clean-up, and preconcentration of analytes of environmental concern. Enrichment capabilities, preconcentration efficiency, sample throughput, and selectivity in extracting target compounds greatly depend on the materials used as SPME coatings. Supramolecular materials have emerged as promising porous coatings to be used for the extraction of target compounds due to their unique selectivity, three-dimensional framework, flexible design, and possibility to promote the interaction between the analytes and the coating by means of multiple oriented functional groups. The present review will cover the state of the art of the last 5 years related to SPME coatings based on metal organic frameworks (MOFs), covalent organic frameworks (COFs), and supramolecular macrocycles used for environmental applications

Sol-gel coated ion sources for liquid chromatography-direct electron ionization mass spectrometry

Advances in interfacing liquid chromatography and electron ionization mass spectrometry are presented. New ion source coatings synthesized by sol-gel technology were developed and tested as vaporization surfaces in terms of peak intensity, peak width and peak delay for the liquid chromatography-direct electron ionization mass spectrometry (Direct-EI) determination of environmental pollutants like polycyclic aromatic hydrocarbons and steroids. Silica-, titania-, and zirconia-based coatings were sprayed inside the stainless steel ion source and characterized in terms of thermal stability, film thickness and morphology. Negligible weight losses until 350-400 °C were observed for all the materials, with coating thicknesses in the 6 (±1)-11 (±2) μm range for optimal ionization process. The best performances in terms of both peak intensity and peak width were obtained by using the silica-based coating: the detection of the investigated compounds was feasible at low ng μl(-1) levels with a good precision (RSD < 9% for polycyclic aromatic hydrocarbons and <11% for hormones)

Reversed-phase and weak anion-exchange mixed-mode stationary phase for fast separation of medium-, long- and very long chain free fatty acids by ultra-high- performance liquid chromatography-high resolution mass spectrometry

Two commercial stationary phases allowing both reversed phase mechanism and anion-exchange with different selectivity, i.e. CSH C18 and Atlantis PREMIER BEH C18 AX, were tested for the separation of a complex mixture of 21 fatty acids (FAs) encompassing saturated medium-, long- and very long chain FAs, unsaturated long and very long chain FAs, cis/trans isomers, and isomers of odd- and branched-chain FAs. For this purpose, the role of surface area of stationary phase and the effect of pH of the mobile phase on the retention of the analytes were investigated. Separation was performed by ultra-high-performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS). BEH C18 AX was shown to be more versatile and to offer superior retention of these analytes to CSH C18 owing to a higher surface area and anion-exchange capacity up to pH 8.5. The UHPLC system allows shortening analysis time, the chromatographic analysis being accomplished in about 5 min, affording a high throughput of samples without the need for derivatization or ion-pairing reagents compared to techniques based upon gas chromatography approaches or LC. Finally, the application of the BEH C18 AX column using UHPLC-HRMS was demonstrated for the separation and unambiguous identification of FAs of nutritional interest in a dietary supplement sample

A rapid microextraction by packed sorbent - liquid chromatography tandem mass spectrometry method for the determination of dexamethasone disodium phosphate and dexamethasone in aqueous humor of patients with uveitis

A new method based on microextraction by packed sorbent(MEPS) coupled with liquid chromatographytandem mass spectrometry (LC–MS/MS) was developed and validated for the determination of dexamethasone and dexamethasone disodium phosphate in human aqueous humor. A central composite design was applied to investigate the effects of both loading and eluting cycles in the MEPS procedure; subsequently the multicriteria method of the desirability functions allowed to find the best conditions for the simultaneous extraction of both the analytes. Detection was performed on a LTQ XL linear ion trap mass spectrometer operating in the positive electrospray ionization mode applying multiple reaction monitoring mode. The assay was validated in accordance with the guidelines bioanalytical method validation obtaining quantitation limits in the low g/L range, a precision characterized by RSD ≤ 16% and recovery rates in the 91–119% rang