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As many as 40% of all plant protection products currently used contain chiral active ingredients. Enantiomers of the same pesticide have identical physicochemical properties in an isotropic medium, but they may display different activity and toxicity because of their interaction with enzymes or other naturally occurring asymmetric molecules. This difference may also lead to variations in biotic degradation rates, making one enantiomer more persistent than the other in natural and agricultural environments. In terms of methodological aspects, this critical review describes the most used chiral stationary phases for HPLC enantioseparations of chiral pesticides, pinpointing their strengths and weaknesses. As far as their applicability is concerned, most research has been carried out by means of columns based on derivatized amylose/cellulose due to their rather universal analyte coverage. The chromatographic compatibility with sensitive detection techniques, such as mass spectrometry, has allowed the trace analysis of stereoisomers, revealing ubiquitous occurrence of some chiral pesticides in surface waters, sediments, plants, agricultural soils, roots, fruit and vegetables. The study of their distribution and degradation in various environmental compartments and agricultural soil-plant systems has highlighted the enrichment with one enantiomer over the other in certain matrices following the enantioselective dissipation catalysed by microorganisms or plant enzymes as well as the phenomenon of chiral inversion in some cases. Irrespective of the reliability of a chiral method, such investigations are often hindered by the lack of pure standards of single enantiomers, which makes it difficult to identify their stereochemical configuration and requires precise strategies of quantification. Surely, the research in this field has been grown over the last few years due to the necessity of assessing and limiting risks related to exposure to chiral pesticides, which can be considered emerging contaminants in all aspects., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: member of the Editorial Advisory Board of JCA, A.G. member of the Editorial Advisory Board of JCA, B.C. Editor of JCA, S.F., (Copyright © 2022 Elsevier B.V. All rights reserved.)

In this paper enantiomers of selected chiral agrochemicals representing various structural classes were separated by using nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) employing a capillary column packed with silica particles containing immobilized amylose tris(3‑chloro-5-methylphenylcarbamate) (i-ADMPC) as a chiral selector (CS). Special attention was paid to peak dispersion in nano-LC and CEC instruments used in order to make comparison between these two techniques more reliable. Enantioseparations were studied utilizing methanol (MeOH) or acetonitrile-water (ACNH 2 O), both containing 5 mM of ammonium acetate as the mobile phases (MPs). The tested chiral stationary phase (CSP), containing 20% (w/w) of the neutral CS onto native silica, allowed the generation of sufficiently strong electroosmotic flow (EOF) to observe separation of enantiomers of studied agrochemicals in a reasonable time also in CEC mode. Modestly higher efficiencies and enantioresolutions were obtained in CEC than in nano-LC. Just a moderate preference of CEC over nano-LC in this particular study can be explained with a significant mass transfer resistance through the CSP that is caused due to high content of the CS in CSP., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Capillary electromigration (CE) and liquid chromatographic techniques (CLC/nano-LC) are miniaturized techniques offering distinct advantages over conventional ones in the field of separation science. Among these, high efficiency, high chromatographic resolution, and use of minute volumes of both mobile phase and sample volumes are the most important. CE and CLC/nano-LC have been applied to the analysis of many compounds including peptides, proteins, drugs, enantiomers, ions, etc. Over the years, the methods described here have also been used for the analysis of compounds of clinical, forensic, and toxicological interest. In this review article, the main features of the mentioned techniques are summarized. Their potentiality for the analysis of drugs of abuse are discussed. Some selected applications in this field in the period of 2015-present are also reported., (© 2021 Wiley-VCH GmbH.)

In the present work, dispersive liquid-liquid microextraction (DLLME) was used to extract six synthetic cannabinoids (JWH-018, JWH-019, JWH-073, JWH-200, or WIN 55,225, JWH-250, and AM-694) from oral fluids. A rapid baseline separation of the analytes was achieved on a bidentate octadecyl silica hydride phase (Cogent Bidentate C 18 ; 4.6 mm × 250 mm, 4 μm) maintained at 37 °C, by eluting in isocratic conditions (water:acetonitrile (25:75, V/V )). Detection was performed using positive electrospray ionization-tandem mass spectrometry. The parameters affecting DLLME (pH and ionic strength of the aqueous phase, type and volume of the extractant and dispersive solvent, vortex and centrifugation time) were optimized for maximizing yields. In particular, using 0.5 mL of oral fluid, acetonitrile (1 mL), was identified as the best option, both as a solvent to precipitate proteins and as a dispersing solvent in the DLLME procedure. To select an extraction solvent, a low transition temperature mixture (LTTM; composed of sesamol and chlorine chloride with a molar ratio of 1:3) and dichloromethane were compared; the latter (100 μL) was proved to be a better extractant, with recoveries ranging from 73% to 101 % by vortexing for 2 min. The method was validated according to the guidelines of Food and Drug Administration bioanalytical methods: intra-day and inter-day precisions ranged between 4 % and 18 % depending on the spike level and analyte; limits of detection spanned from 2 to 18 ng/mL; matrix-matched calibration curves were characterized by determination coefficients greater than 0.9914. Finally, the extraction procedure was compared with previous methods and with innovative techniques, presenting superior reliability, rapidity, simplicity, inexpensiveness, and efficiency., Competing Interests: The authors declare that there are no conflicts of interest., (© 2020 Xi'an Jiaotong University. Production and hosting by Elsevier B.V.)

Capillary electrochromatography (CEC) represents a technique with less than 30 years of intense development and in this period this technique has seen huge promise, fast development, stagnation, and significant decline of innovative activity. The major goal of the present overview is not to present an extensive review of the literature on chiral CEC but to analyze the reasons for this dramatic development and attempting to answer questions such as: 1) Was the potential of CEC reasonably evaluated in 1990s before starting the explosive development in this field? 2) Did the development of this technique take the right track? 3) What other developments and competitive trends led to stagnation in the advancement of CEC? 4) Why is the activity in this field currently decreasing? 5) What are the current challenges and promises and what is the future of chiral CEC?, Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)

The implant primary stability is a fundamental condition for avoiding implant micro-motions that might result in fibrous encapsulation; its achievement is facilitated by macro- and micro-geometry of the implant, and by the bone density and architecture at the intended implant site. The aim was to evaluate an osteocondensing drilling protocol for dental implant positioning compared to standard protocol on polyurethane block. A total of 40 implants, 20 for each osteocondensing group (Test) and 20 for standard drilling group (Control), were positioned. Insertion torque (IT), removal torque (RT), and Periotest were measured. A IT, RT, and Periotest significant difference was present in favor of the implant osteocondensing protocol. The results suggested that osteocondensing protocol represents a useful technique for implant placement in poor density bone.

In the present study separation of enantiomers of some chiral neutral, basic and weakly acidic analytes was investigated on the chiral stationary phase (CSP) made by covalent immobilization of amylose tris(3-chloro-5-methylphenylcarbamate) onto aminopropylsilanized (APS) silica in nano-liquid chromatography (nano-LC) in aqueous methanol or acetonitrile mixtures. It has been shown that similar to high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) this chiral selector is useful for separation of enantiomers of neutral, basic and acidic analytes also in nano-LC. In comparison to our previous research, in which the chiral selector (CS) was bonded on native silica, in this study, the CS was immobilized on APS silica in order to improve chromatographic performance towards basic analytes. In fact, some improvement was observed and surprisingly not only for basic but also for neutral and acidic analytes. Again, quite unexpectedly almost no electroosmotic flow (EOF) was observed in capillaries packed with ca. 20% (w/w) amylose tris(3-chloro-5-methylphenylcarbamate) immobilized onto APS silica although the same APS silica before attachment of chiral selector exhibited significant EOF. In order to generate EOF in the capillaries with the CSP and enable capillary electrochromatographic (CEC) experiment on it, the short segment of the capillary column was packed with APS silica without chiral selector. The EOF in such capillary enabled CEC experiment and some preliminary results are reported here., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

This paper describes a procedure for the isolation of 20 organic micro-pollutants among pesticides, drugs, recreational drugs, flame retardants from river sediments. After a solid-liquid extraction with a methanol:water (50:50, v/v) solution, the supernatant was diluted with water and cleaned up by stir-disc solid-phase extraction (SPE). The disc was made of buckypaper, a self-supporting entangled assembly of carbon nanotubes, which was used as a highly porous, two-sided, sorbent membrane. In the preliminary activation step, the membrane was oxidised for 2-hours with nitric acid to extend its extraction capability also to more polar compounds. All extracts were analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. A comparative investigation with commercial Strata-X Polymeric Reversed Phase SPE cartridges proved the effectiveness of the lab-made device. On the average, the analytes were recovered with yields around 69% (low spike level) and 80% (medium and high spike level), while only a couple of analytes exhibited values less than 50%. The relative standard deviation was always less than 20%. Limits of detections were in the range 0.02-9.9 ng g -1 . The validated method was then applied for the analysis of sediment samples from different sites of the River Turia basin in the area of Valencia (Spain), finding tris(2-chloroisopropyl)-phosphate in all sediments at a level ranging from 6.9 to 387.9 ng g -1 . Other compounds, such as pesticides and pharmaceuticals were more sporadically in these samples., Competing Interests: Declaration of Competing Interest Regarding the manuscript entitled “Multi-residue determination of organic micro-pollutants in river sediment by stir-disc solid phase extraction based on oxidized buckypaper” by P. Tomai, A. Gentili, S. Fanali, Yolanda Picó, the authors certify that there is no conflict of interest including any financial, personal or other relationships with other people or organizations regarding the material discussed., (Copyright © 2020. Published by Elsevier B.V.)

A novel chiral stationary phase (CSP), based on a monolithic organic polymer chemically modified with teicoplanin, was fabricated within a 100 μm I.D. fused silica capillary. The teicoplanin was firstly derivatized with 2-isocyanatoethyl methacrylate (ICNEML) and then thermally co-polymerized with the crosslinker ethylene dimethacrylate (EDMA) in presence of porogens (methanol and dimethylsulfoxide). The optimal experimental conditions (e.g., concentration and ratio of the reagents), considering enantioresolution and permeability, were systematically investigated. The prepared monolith was evaluated using scanning electron microscopy, and the column exhibited quite good morphology. In order to further evaluate the enantioresolving power of the poly(ICNEML-teicoplanin-co-EDMA) monolith, a series of basic and acidic chiral compounds were analyzed using an isocratic mode of polar organic solvents (methanol and acetonitrile) or the same solvents in combination with water (reversed-phase) by nano-liquid chromatography. Five mandelic acids and six derivatized amino acids were enantioresolved under reversed-phase mode (R s  = 1.22-3.47 and α = 1.43-6.33). This monolithic teicoplanin-CSP was also effective in the enantioseparations of 17 amino alcohol drugs employing polar-organic phase mode (MeOH/ACN/TEA/HOAc (80/20/0.03/0.055, v/v/v/v)). Ten of them were baseline enantioresolved (alprenolol, betaxolol, clenbuterol, isoproterenol, metoprolol, pindolol, propranolol, salbutamol, sotalol, tertatolol) (R s  = 1.55-2.48 and α = 1.21-1.55), while the others were partially enantioseparated (R s  = 1.14-1.48)., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In the present study separation of enantiomers of some chiral neutral and weakly acidic analytes was investigated on the chiral stationary phase (CSP) made by covalent immobilization of amylose tris(3-chloro-5-methylphenylcarbamate) onto silica in nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) in acetonitrile and aqueous acetonitrile. Few comparisons were made also between the enantioseparations in nano-LC and high-performance liquid chromatography (HPLC) with the chiral column of 4.6 × 250 mm dimension. Slightly better separation of enantiomers was observed in HPLC mode compared to nano-LC mode. It was shown that in the capillary columns packed with the CSP containing about 20% (w/w) of a covalently immobilized neutral chiral selector, amylose tris(3-chloro-5-methylphenylcarbamate), sufficient electroosmotic flow has been generated and enantioseparations with reasonable analysis time were performed also in CEC mode. It was shown once again that CEC offers a clear advantage over nano-LC from the viewpoint of plate numbers and peak resolution., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The chiral separation of baclofen (Bac) was obtained by nano-liquid chromatography tandem mass spectrometry (nano-LC-MS/MS) using a 100 μm I.D. fused silica capillary column packed with silica particles chemically modified with vancomycin. Various experimental parameters, such as composition (buffer concentration, water content, organic modifier) and pH of the mobile phase and sample solvent were investigated for method optimization. In order to increase the sensitivity an on-column focusing procedure was applied. Acceptable separation of Bac enantiomers was obtained in less than 11 min eluting in isocratic mode, with 90:10 MeOH/water (v/v) containing 10 mM ammonium acetate at pH 4.5. These optimized experimental conditions were applied to the analysis of human plasma samples spiked with racemic mixture of Bac. The use of a Buckypaper disc as sorbent membrane allows one to recover both enantiomers with yields ≥ 65%. The method was fully validated, following the identification criteria of the European Commission Decision 2002/657/EC., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this overview the goal of the authors was to analyze from the historical perspective the reasons of success and failure of chiral capillary electrophoresis. In addition, the current trends are analyzed, unique advantages of capillary electrophoresis are highlighted and some future directions are discussed., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This work deals with the potentiality of nano liquid chromatography (Nano-LC) for the chiral separation of racemic mixture of tryptophan and some selected derivatives by using 100 µm i.d. fused silica capillary packed with teicoplanin bonded to 5 µm diol silica stationary phase. The experiments were carried out by using a cheap and laboratory-assembled nano-LC-UV system. Elution was done in an isocratic mode using a polar organic mobile phase. In order to find the optimum chiral separation of the studied enantiomers, some chromatographic experimental parameters were systematically studied and optimized. Among them, mobile phase composition, namely organic modifier type and concentration, buffer type and pH and aqueous content and sample solvent dilution on retention time, retention factor and enantioresolution factor were studied. Baseline enantioresolution and good peak shape was achieved utilizing the mobile phase containing 40 mM ammonium formate at pH pH 2.5 in ACN/water/acetone (60:30:10, v/v/v) at 520 nL/min in less than 8 min analysis time., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The separation of enantiomers has been started in the past and continues to be a topic of great interest in various fields of research, mainly because these compounds could be involved in biological processes such as, for example, those related to human health. Great attention has been devoted to studies for the analysis of enantiomers present in food products in order to assess authenticity and safety. The separation of these compounds can be carried out utilizing analytical techniques such as gas chromatography, high-performance liquid chromatography, supercritical fluid chromatography, and other methods. The separation is performed mainly employing chromatographic columns containing particles modified with chiral selectors (CS). Among the CS used, modified polysaccharides, glycopeptide antibiotics, and cyclodextrins are currently applied.

This paper describes the development of an original micro-solid phase extraction device and its evaluation for the isolation of F2-isoprostanes (F2-IsoPs) from cord and maternal plasma samples. The unit is very simple and consists in a rotating disc (1.8 cm diameter) of oxidized buckypaper (BP), enwrapped in a polypropylene mesh pouch. Even if the selected F2-IsoPs have logP and pKa values that make them suitable candidates for their sorption on BP, several parameters were optimized to maximize recoveries: time of adsorption and desorption; stirring speed; volume, pH and ionic strength of the sample; type, volume, and fractions of the elution solvent; oxidation grade of BP. Among all, the last one was crucial in affecting extraction yields because of the analyte interactions with polar functionalities, introduced by a preliminary oxidative acid treatment. The investigation established the optimal oxidation time and highlighted the pros and cons of the acid activation step. All extracts were analyzed by means of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Validation was performed according to the main FDA guidelines for bioanalytical methods. Depending on the spike level and analyte, recoveries ranged between 30 and 120% with precision and accuracy values lower than 20%. Quantitative analysis was accomplished by matrix-matched calibration curves whose determination coefficients were higher than 0.95. Lower limit of quantitation (LLOQ) spanned the range 2.45-6.77 μg L -1 . The validated method was applied to the analysis of eight pairs of mother/child plasma samples, revealing the presence of 8-iso-15-keto-PGF 2α and 8-iso-PGE 2 at a concentration of about 10 μg L -1 in most cord plasma samples of preterm newborns., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Analysis of carotenoids is very complex and demanding in terms of both separation and detection. In this article, an analytical strategy relying on high-performance liquid chromatography-photodiode array detection-tandem mass spectrometry (HPLC-PAD-MS/MS) is presented for the large-scale screening of these phytochemicals. Separation was realized by means of Non-Aqueous Reversed Phase (NARP) chromatography on a triacontyl stationary phase kept at subambient temperature, using a mobile phase compatible with atmospheric pressure chemical ionization (APCI). The standards of 14 analytes were used to optimize the method and to predict the chromatographic behaviour of untargeted carotenoids. MS and MS/MS data, obtained during Information Dependent Acquisition (IDA) experiments, were utilized to set up a sensitive HPLC- selected reaction monitoring (SRM) method. Relative abundance between SRM ion currents (ion ratio) allowed the MS distinction of structural isomers (for example, bicyclic, monocyclic and acyclic isomers), while the identification of geometrical isomers was based on Q ratio and fine structure, as calculated from UV-vis spectra. The comparison of LC-PAD- SRM chromatograms, acquired after applying two different extraction procedures (matrix solid-phase dispersion and overnight cold saponification), allowed verifying that sweet peppers are a good source of xanthophylls, prevalently occurring as esterified forms. The overall strategy could identify more than 40 carotenoids in some sweet pepper varieties (Jolly, horn and sweet chili pepper) available on the Italian and European food market., (Copyright © 2018 Elsevier B.V. All rights reserved.)

1.8 μm Silica hydride particles have been derivatized with vancomycin and applied to the enantioseparation of some racemic herbicides and nonsteroidal anti-inflammatory drugs (NSAIDs) by nano-liquid chromatography. The chiral stationary phase (CSP) was packed for only 11 cm and the enantiomers were separated utilizing a laboratory-assembled instrumentation. The new CSP was very effective for the separation of the above mentioned acidic compounds, while poor resolutions were obtained for basic compounds. Mixtures of acetate buffer with methanol or acetonitrile allowed the chiral resolution of all compounds. Fast chiral separation of a NSAIDs-related compound can be achieved in less than 60 s.

A facile single-step preparation strategy for fabricating vancomycin functionalized organic polymer-based monolith within 100μm fused-silica capillary was developed. The synthetic chiral functional monomer, i.e 2-isocyanatoethyl methacrylate (ICNEML) derivative of vancomycin, was co-polymerized with the cross-linker ethylene dimethacrylate (EDMA) in the presence of methanol and dimethyl sulfoxide as the selected porogens. The co-polymerization conditions were systematically optimized in order to obtain satisfactory column performance. Adequate permeability, stability and column morphology were observed for the optimized poly(ICNEML-vancomycin-co-EDMA) monolith. A series of chiral drugs were evaluated on the monolith in either polar organic-phase or reversed-phase modes. After the optimization of separation conditions, baseline or partial enantioseparation were obtained for series of drugs including thalidomide, colchicine, carteolol, salbutamol, clenbuterol and several other β-blockers. The proposed single-step approach not only resulted in a vancomycin functionalized organic polymer-based monolith with acceptable performance, but also significantly simplified the preparation procedure by reducing time and labor., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This paper describes, for the first time, the use of oxidized buckypaper (BP) as a sorbent membrane of a stir-disc solid phase extraction module. The original device, consisting of a BP disc ( d = 34 mm) enveloped in a polypropylene mesh pouch, was designed to extract organic micropollutants (OMPs) from environmental water samples in dynamic mode. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to analyze the extracts. Several classes of pesticides and pharmaceuticals were chosen as model compounds to evaluate key parameters affecting the recovery rates. To this end, the effects of adsorption time, desorption time, stirring speed, type and volume of solvent, and sample volume were thoroughly examined. After optimization, a novel and in-depth study was conducted to find a correlation between physicochemical properties of the analytes and extraction yields. Recoveries were mainly governed by a combination of log P and p K a values. As indicated, hydrophilic compounds with log P < 1 showed poor affinity for the oxidized BP, compounds having log P > 1 exhibited recoveries ranging between 50% and 100% depending on their p K a , while compounds with p K a between 6 and 7.5 gave low yields irrespective of their log P. The analytical method was also validated and tested as large scale screening method of OMPs in surface waters. The analysis of real samples revealed the presence of some nonsteroidal anti-inflammatory drugs, sulfonamides, and pesticides at low ng L -1 concentration levels with relative standard deviations lower than 8%.

A new experimental chiral stationary phase containing amylose 3,5-dimethylphenylcarbamate immobilized onto silica gel (i-ADMPC) was packed in 100μm I.D. fused silica capillary and used for the chiral separation of eight selected flavanone derivatives in polar organic mobile phase by using different miniaturized techniques, such as nano-liquid chromatography (nano-LC), capillary electrochromatography (CEC) and pressure-assisted CEC (pCEC). A comparative study of different elution modes in terms of chromatographic efficiency, analysis time and enantiomeric resolution was carried out. In pCEC mode, the highest chromatography performance was obtained applying +2.5kV voltage and inlet pressure 10bar. Under these conditions, the analysis times were shorter than 20min, and chromatographic efficiencies were in the range 33,000-49,000 plates/m (first eluted peak). The solvent versatility of packed i- ADMPC capillary column was also investigated. In nano-LC, the CSP was stressed under the use of strong organic solvents such as ethyl acetate, acetone and methyl t-butyl ether (MTBE). After at least 40 working hours and over 50 sample injections, the CSP resulted to be very stable allowing to achieve good repeatability employing again the mobile phase containing polar organic solvent. Enantioresolutions and chromatographic efficiencies decreased by 1.60 and 10%, respectively as the result of using above mentioned strong solvents., (Copyright © 2017 Elsevier B.V. All rights reserved.)

When splinting multiple implants passive fit of the framework should be achieved to avoid excessive force distribution on the implants. Recently, a protocol was suggested for immediate loading of multiple implants by welding a titanium bar to implant abutments directly in the oral cavity so as to create a customized, precise and passive metal-reinforced provisional restoration. The intraoral welding technique subsequently proves to be a successful option in the full-arch immediate restorations of the mandible and maxilla. The aim of this article is to present a case report in which a new prosthetic approach, using trans-mucosal implants, is described. Dental implants are instantly loaded with a provisional prosthesis supported by an intraoral welded titanium framework to obtain a precise passive fit of the immediate loaded prosthesis.

Among the thousands of chemicals having potential to enter the environment, the NORMAN network has identified at least 700 substances categorized into 20 classes in the European surface waters. Pesticides, pharmaceuticals, disinfection by-products, wood preservation and industrial chemicals are the prominent classes. Since the impact of these substances on aquatic life and human health might be dramatic, action is urgently required at multiple levels; one of them is just related to the development of more and more sensible and selective analytical methods. This review highlights the latest advancements and trends in liquid chromatography-mass spectrometry based environmental analysis. Specific sections are dedicated to novelties in sample preparation, chromatographic separation and mass spectrometry detection of emerging pollutants. The review also offers insights on last generation chromatographic and extraction materials, technological progresses and innovative methodological approaches for target and non-target analysis. As numerous papers have been published in this field, this overview covers the most representative and original works published in the 2011-2016 period., (Copyright © 2017 Elsevier B.V. All rights reserved.)

In the present study, an attempt was made to achieve separation of enantiomers within a minute in nano-LC and CEC. In order to achieve this goal several parameters were optimized from the viewpoint of the property of chiral analytes, concentration of the chiral selector in the packing material, capillary dimensions, and separation mode. The enantiomers of several of the applied chiral sulfoxides could be resolved with the analysis time <1 min. Some instrumental obstacles hindering further reduction of analysis time are also highlighted., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nano-liquid chromatography (nano-LC) and CEC are microfluidic techniques mainly used for analytical purposes. They have been applied to the separation and analysis of a large number of compounds, e.g., peptides, proteins, drugs, enantiomers, antibiotics, pesticides, nutraceutical, etc. Analytes separation is carried out into capillaries containing selected stationary phase. The mobile phase is moved either by a pump (nano-LC) or by an EOF, respectively. The two tools can offer some advantages over conventional techniques, e.g., high selectivity, separation efficiency, resolution, short analysis time and consumption of low volumes of mobile phase. Flow rates in the range 50-800 nL/min are usually applied. The low flow rate reduces the chromatographic dilution increasing the mass sensitivity. Special attention must be paid in avoiding peak dispersion selecting the appropriate detector, injector and tube connection. Finally due to the low flow rate these microfluidic techniques can be easily coupled with mass spectrometry., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The aim of the present study is to define the optimal thread form and why the macroscopic shape of the dental intra-osseous implant interacts with the biological environment thus conditioning its lifespan and long-term success.

The aim of this study is to determine in an experimental way through mechanical tests the static, fatigue and torque resistance of two types of implant/abutment connectors with diameters of 3.4–5.2 mm.

In this paper a chiral stationary phase (CSP) was prepared by the immobilization of a β-CD derivative (3,5-dimethylphenylcarbamoylated β-CD) onto the surface of amino-functionalized spherical ordered mesoporous silica (denoted as SM) via a urea linkage using the Staudinger reaction. The CSP was packed into fused silica capillaries 100μm I.D. and evaluated by means of nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) using model compounds for the enantio- and the diastereomeric separation. The compounds flavanone, 2'-hydroxyflavanone, 4'-hydroxyflavanone, 6-hydroxyflavanone, 4'-methoxyflavanone, 7-methoxyflavanone, hesperetin, hesperidin, naringenin, and naringin were studied using reversed and polar organic elution modes. Baseline stereoisomer resolution and good results in terms of peak efficiency and short analysis time of all studied flavonoids and flavanones glycosides were achieved in reversed phase mode, using as mobile phase a mixture of MeOH/H 2 O, 10mM ammonium acetate pH 4.5 at different ratios. For the polar organic mode using 100% of MeOH as mobile phase, the CSP showed better performances and the baseline chiral separation of several studied compounds occurred in an analysis time of less than 10min. Good results were also achieved by CEC employing two different mobile phases. The use of MeOH/H 2 O, 5mM ammonium acetate buffer pH 6.0 (90/10, v/v) was very effective for the chiral resolution of flavanone and its methoxy and hydroxy derivatives., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This paper presents the state of the art concerning the separation of chiral compounds by means of nano-liquid chromatography (nano-LC). The enantiomers' separation and determination are a subject of fundamental importance in various application fields such as pharmaceutical industry, biomedicine, food, agrochemical etc. Nano-LC is a miniaturized chromatographic technique offering some advantages over conventional ones such as low consumption of mobile phase, sample volume and amount of chiral stationary phase, reduced costs etc. This is reported in the first part of the paper illustrating the features of the nano-LC. In addition, chiral resolution methods are briefly illustrated. Some chiral selectors, used in high-performance liquid chromatography have also been applied in nano-LC including cyclodextrins, glycopeptide antibiotics, modified polysaccharides etc. This is discussed in the second part of the review. Finally some examples of the applications available in literature are reported., (Copyright © 2016 Elsevier B.V. All rights reserved.)

An environmentally friendly method based on hollow-fibre liquid-phase microextraction (HF-LPME) was developed for the extraction of selected estrogenic compounds (i.e. four natural sexual hormones: estrone, 17β-estradiol, 17α-estradiol and estriol; two exoestrogens: 17α-ethynylestradiol and 2-methoxyestradiol; two synthetic stilbenes: dienestrol and hexestrol; and five resorcylic acid lactones: zearalenone, α-zearalanol, β-zearalanol, α-zearalenol and β-zearalenol), from whole cow and semi-skimmed goat milk and whole natural yogurt. After the optimization of the sample preparation procedure, spiked extracts were derivatized to their trimethylsilyl products using N,O-bis(trimethylsilyl)trifluoroacetamide reagent and then analyzed by gas chromatography-tandem mass spectrometry (GC-MS/MS). Once optimum extraction conditions were established (protein precipitation with acetonitrile, extraction and the back-extraction in acetonitrile following the HF-LPME procedure), the method was validated and the calibration range, precision and accuracy were studied. The RSD values for the intra- and inter-day precision of the peak areas were in the range 0.65-9.69 and 1.00-11.47 %, respectively. The determination coefficients were higher than 0.991 for method calibration curves while LOD and LOQ values were between 0.06-2.55 and 0.16-6.11 μg/L for whole cow milk, 0.04-1.70 and 0.11-4.86 μg/L for semi-skimmed goat milk and 0.07-3.73 and 0.23-9.81 μg/L for natural yogurt, respectively. Finally, the accuracy and precision of the method were evaluated, obtaining a value in the range 84 81-119 % and RSD values lower than 20 % in all cases.

A sensitive and rapid CZE-UV method was developed to determine drugs and their metabolites' presence in human urine. Ten drugs of abuse were analyzed including four amphetamines, cocaine, cocaethylene, heroin, morphine, 6-monoacetylmorphine, and 4-methylmethcathinone. An MSS (micelle to solvent stacking) approach was evaluated to enhance method sensitivity. This method considers composition of the micellar sample solution matrix and the injection time. Several analytical conditions influencing the resolution of the drugs mixture as pH and buffer concentration, organic solvent content, were also investigated. The base-line separation of all studied analytes in the same run was achieved within 18 min in an uncoated fused silica capillary (50 μm id × 60 cm) using a background solution containing 50 mM phosphate buffer pH 2.5 and 30% ACN v/v. Other experimental parameters such as applied voltage and capillary temperature were set up at 20 kV and 20°C, respectively. LOD values ranging between 15 and 75 ng/mL for all studied compounds were obtained. From a comparison with conventional CZE, the proposed method provides an increase of sensitivity (39- to 55-fold enhancement factor). Under optimal MSS-CZE conditions, good linearity was achieved (R 2 ≤ 0.9998). The method was finally applied to the analysis of urine samples spiked with a standard mixture after a sample pretreatment, reaching satisfactory recovery values., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A rapid method for the quantification of five ribonucleotides 5'- monophophates (adenosine, cytidine, guanosine, inosine, uridine, 5'-monophosphate), in infant formula, has been proposed using nano-LC. To separate the studied compounds, capillary columns packed with different C18-based stationary phases were investigated. All the columns tested were laboratory prepared. The experiments were performed in ion-pairing RP chromatographic mode using tetrabutylammonium hydroxide as ion-pairing reagent. The method was developed using a core-shell XB-C18 capillary column with a mobile phase consisting of 5% v/v methanol and 95% v/v 100 mM ammonium formate, pH 8, containing 20 mM tetrabutylammonium hydroxide. All compounds were baseline resolved in less than 5 min with a flow rate of 500 nL/min in isocratic elution mode. Nucleotides were detected at 260 nm. Analytical validation parameters were evaluated. The RSD values for intraday and interday repeatability for retention time and peak area were <2.4 and 4.2%, respectively. The method linearity was good (R(2) < 0.9995) for the studied compounds. LOD and limit of quantitation were 0.25 and 0.50 μg/mL, respectively. The method was applied to the determination of nucleotides in infant formula, subjected to a centrifugal ultrafiltration process, prior their analysis. The amounts found were in agreement to the labeled contents., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Nano-liquid chromatography and conventional HPLC were used for the separation of diastereomers of (+)-catechin-ethyl-malvidin-3-glucoside. Those bridged anthocyanin dyes were obtained by reaction of (+)-catechin with malvidin-3-glucoside in the presence of acetaldehyde. Both diastereomers were isolated with semipreparative chromatography and their structures were confirmed by nuclear magnetic resonance and mass spectrometry. In-laboratory prepared capillary columns packed with fully porous particles Chromosphere C18, dp=3μm, core-shell particles Kinetex C18, dp=2.6μm (100μm i.d.) and monolithic column Chromolith CapRod (100μm i.d.) were used for the separation of (+)-catechin, malvidin-3-glucoside and both diastereomers. Chromosphere C18 stationary phase provided the best chromatographic performance. Mobile phase containing water:acetonitrile (80:20) acidified with trifluoroacetic acid (0.1%, v/v/v) was used in an isocratic elution mode with a flow rate of 360nLmin(-1). Separation of studied compounds was achieved in less than 7min under optimized conditions. The nano-liquid chromatographic method and a conventional HPLC one using the same fully porous particles (Chromosphere C18, 3μm, 100mm×4.6mm) were compared providing higher separation efficiency with the first analytical method and similar selectivity. A better peak symmetry and higher resolution of the studied diastereomers was achieved by conventional chromatography. Nevertheless, nano-liquid chromatography appeared to be useful for the separation of complex anthocyanin dyes and can be utilized for their analysis in plant and food micro-samples. The developed method was used for analysis of red wine grape pomace., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Nano-LC and CEC were coupled to MS through a nanospray or a pressurized liquid-junction interface for the simultaneous separation and determination of 11 estrogenic compounds. Different stationary phases, that is, phenyl, C18, and C18 bidentate silica hydrate, were studied. For both techniques, the phenyl stationary phase was the best option, considering separation efficiency, selectivity, and resolution. Under the optimized conditions, the baseline separation of the target compounds (including estradiol and zearalanol epimers) was achieved in less than 20 min in nano-LC-MS and less than 13 min in CEC-MS. Molecular imprinted polymer SPE was used for extracting the target compounds from mineral water samples with the analysis of nano-LC-MS. The whole molecular imprinted polymer SPE nano-LC-MS method was validated through a recovery study at two levels of concentration. Sensitivity was improved by on-column focusing technique obtaining LODs in the range 1.4-55.4 ng/L., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Recently, screening of bioactive compounds by on-line ultra-high performance liquid chromatography (UHPLC) draws increasing attentions for the advantages of rapidity and intuition. Nevertheless, most on-line methods were limited to the shortcoming like low resolution and peak capacity, which could interfere the active ingredient identification. Comprehensive two-dimensional UHPLC (LC×LC) has revealed to be a powerful tool to separate complex mixtures. Herein, a strategy based on LC×LC analysis coupled with pre-column 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was proposed to screen the antioxidants from the extract of Ginkgo biloba (EGB). A total of 61 compounds were identified in EGB, and 25 of them showed appreciable radical scavenging capacity. This work may offer pharmacodynamics base for further research about EGB, also the strategy is likelihood to be applied in screening antioxidant in other herbal medicine., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A novel vancomycin silica hydride stationary phase was synthesized and the particles of 1.8 µm were packed into fused silica capillaries of 75 µm internal diameter (I.D.). The chiral stationary phase (CSP) was tested for the separation of some derivatized amino acid enantiomers by using nano-liquid chromatography (nano-LC). Some experimental parameters such as the type and the content of organic modifier, the pH, and the concentration of the buffer added to the mobile phase were modified and the effect on enantioselectivity, retention time, and enantioresolution factor was studied. The separation of selected dansyl amino acids (Dns-AAs), e.g., Asp, Glu, Leu, and Phe in their enantiomers was initially achieved utilizing a mobile phase containing 85% (v/v) methanol (MeOH) and formate buffer measuring the enantioresolution factor and enantioselectivity in the range 1.74-4.17 and 1.39-1.59, respectively. Better results were obtained employing a more polar organic solvent as acetonitrile (ACN) in the mobile phase. Optimum results (Rs 1.41-6.09 and α 1.28-2.36) were obtained using a mobile phase containing formate buffer pH 2.5/water/MeOH/ACN 6:19:12.5:62.5 (v/v/v/v) in isocratic elution mode at flow rate of 130 nL/min., (© 2015 Wiley Periodicals, Inc.)

The separation of eight antibiotics belonging to 5-nitroimidazole family was carried out by means of CEC coupled with MS. Preliminary experiments were carried out with ultraviolet detection in order to select the proper stationary and mobile phase. Among the different stationary phases studied (namely Lichrospher C18, 5 μm particle size; Cogent(TM) Bidentate C18, 4.2 μm; Pinnacle II™ Phenyl, 3 μm; Pinnacle II™ Cyano, 3 μm), Cogent™ Bidentate C18 (4.2 μm) gave the best performance. For CEC-MS coupling, a laboratory assembled liquid-junction-nano-spray interface was used. In order to achieve a good sensitivity, special attention was paid to both optimization of the sheath liquid composition as well as selection of the injection mode. Under optimized CEC-ESI-MS conditions, the separation was accomplished within 22 min by using a column packed with a mixture of Bidentate C18:Lichrospher Silica-60 (5 μm) 3:1 w/w, an inlet pressure of 11 bar, a voltage of 15 kV, and a mobile phase composed by 45:10:45 v/v/v ACN/MeOH/water containing ammonium acetate (5 mM pH 5). A combined hydrodynamic and electrokinetic injection of 8 bar, 15 kV, and 96 s was adopted. The method was validated in terms of repeatability and intermediate precision of retention times and peak areas, linearity, and LODs and LOQs. RSDs values were <2.9% for retention times and <16.1% for peak areas in both intraday and interday experiments. LOQ values were between 0.09 and 0.42 μg/mL for all compounds. Finally, the method was applied to the determination of three most employed 5-nitroimidazole antibiotics (metronidazole, secnidazole, and ternidazole) in spiked urine samples, subjected to a SPE procedure. Recovery values in the 67-103% range were obtained. Furthermore, for the selected antibiotics, CEC-MS(2) spectra were obtained providing the unambiguous confirmation of these drugs in urine samples., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hydrolysis plays an important role in the metabolic transformations of lactones. Analysis of lactones and their hydrolyzed metabolites in biological samples is challenging, because unexpected hydrolysis or reversed dehydration may occur depending on the test environments. In this work, a supercritical fluid chromatography hybrid triple-quadrupole mass spectrometry (SFC-QQQ MS) method has been proposed for simultaneous analysis of ginkgolides and hydrolyzed metabolites. The SFC utilizes carbon dioxide as the mobile phase, avoiding hydrolysis of ginkgolides that always happens during reversed phase liquid chromatographic detection. Compared with normal phase liquid chromatography, the SFC provides good resolutions especially for ginkgolide with similar structures. This SFC-QQQ MS method was validated in linearity, precision, accuracy, and stability for ginkgolides and metabolites. Then this method was successfully applied to pharmacokinetic study of 3 ginkgolides and their 6 hydrolyzed metabolites after intravenous administration of total ginkgolide extract. Ginkgolides and metabolites showed different clear rates and excluded in 2-4h. The developed SFC-QQQ MS method allows accurate determination of ginkgolides and metabolites with high resolutions, and can be extended to analysis of other water-unstable compounds., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A novel sub-2 μm chiral stationary phase (CSP) was prepared immobilizing vancomycin onto 1.8 μm diol hydride-based silica particles. The CSP was packed into fused silica capillaries of 75 μm i.d. with a length of 11 cm and evaluated by means of nano-liquid chromatography (nano-LC) using model compounds of both pharmaceutical and environmental interest (some non-steroidal anti-inflammatory drugs, β-blockers and herbicides). The study of the effect of the linear velocity of the mobile phase on chromatographic efficiency showed good enantioresolutions up to a value of 5.11 at the optimal linear velocity with efficiencies in terms of number of plates per meter in the range 51,650-68,330. The results were compared with the ones obtained employing 5 μm vancomycin modified diol-silica particles packed in capillaries of the same i.d. For the acidic analytes the sub-2 μm CSP showed better performances, the baseline chiral separation of several studied compounds occurred in an analysis time of less than 3 min. Column-to-column packing reproducibility (n=3) expressed as relative standard deviation was in the range 2.2-5.8% and 0.5-7.7% for retention times and peak areas, respectively., (Copyright © 2015. Published by Elsevier B.V.)

In this work, the suitability of a methodology based on dispersive liquid-liquid microextraction (DLLME) has been evaluated for the extraction of four endoestrogens (estriol, 17α-estradiol, 17β-estradiol, and estrone), an exoestrogen (17α-etynylestradiol), and a mycotoxin (zearalenone), together with some of their major metabolites (2-methoxyestradiol, α-zearalanol, β-zearalanol, α-zearalenol, and β-zearalenol) from different types of milk (whole and skimmed cow milk and semiskimmed goat milk) and whole natural yogurt. The methodology includes a previous protein precipitation with acidified ACN and a defatting step with n-hexane. Separation of the analytes, determination, and quantification were developed by MEKC coupled to ESI-MS using a BGE containing an aqueous solution of ammonium perfluorooctanoate as MS friendly surfactant. Calibration, precision, and accuracy studies of the described DLLME-MEKC-MS/MS method were evaluated obtaining a good linearity and LODs in the low micrograms per liter range., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)