Reaction In Presence Research Articles

Rhodium-Catalyzed Functionalization and Annulation of N-Aryl Phthalazinediones with Allyl Alcohols.

A direct ortho-Csp2-H acylalkylation of 2-aryl-2,3-dihydrophthalazine-1,4-diones with unsubstituted and substituted allyl alcohols is achieved in high yields through Rh(III)-catalyzed C-H bond activation process. The additional employment of Cu(OAc)2⋅2H2O as an oxidant detour the reaction towards [4+1] annulation, producing 13-(2-oxopropyl)-13H-indazolo[1,2-b]phthalazine-6,11-diones in moderate yields. Interestingly, Lawesson's reagent-mediated conditions accomplished intramolecular cyclization in ortho-(formylalkylated)-2,3-dihydrophthalazine-1,4-diones to produce diazepino[1,2-b]phthalazine-diones in moderate yields. Furthermore, allyl alcohol showcased distinct reactivity in presence of different additives to produce ortho-allylated, oxidative and non-oxidative [4+2] annulated products.

Sequential Hydroperoxylation and Amberlyst‐15 Catalyzed Hock‐type Rearrangement of Spiroepoxy/Spiroaziridine Oxindoles for the Synthesis of 2‐Hydroxybenzo[b][1,4]oxazin‐3(4H)‐ones

AbstractA sequential one‐pot direct strategy for the synthesis of 2‐hydroxy‐2‐substituted‐2H‐benzo[b][1,4]oxazin‐3(4H)‐ones is developed under ambient conditions with moderate to good yields (up to 75 %) by regioselective ring‐opening of spiro‐epoxy/aziridine oxindoles with 50 % aq. H2O2 followed by rearrangement reaction in presence of amberlyst‐15 catalyst. Further, sequential reaction with aldehydes/ketones and carbonyldiimidazole (CDI) gave spiro[benzo[b][1,4]oxazine‐2,4′‐[1,3]dioxolan]‐3(4H)‐ones and spiro[benzo[b][1,4]oxazine‐2,4′‐[1,3]dioxolane]‐2′,3(4H)‐diones, respectively.

Thermo-catalytic decomposition of walnut shells waste over cobalt doped cerium oxide: Impact of catalyst on kinetic parameters and composition of bio-oil

This research work is aimed at investigating the pyrolysis of walnut shells mixed with cobalt doped cerium oxide and non-catalytic pyrolysis of walnut shells. The pyrolysis experiments were performed in a locally designed pyrolysis chamber. The oils from catalytic and non-catalytic pyrolysis were characterized with GC–MS. It was found that in case of catalytic pyrolysis, the bio-oil obtained has several short-chain compounds as compared to bio-oil obtained through non-catalytic pyrolysis. Thermogravimetric analysis was conducted to assess the kinetics of pyrolysis of biomass both with and without catalyst. The kinetic parameters were determined using Kissinger equation. The activation energy (Ea) values for the decomposition of hemicelluloses, cellulose, and lignin were found as 167.72, 181.35, and 191.22 kJ mol−1 for non-catalytic pyrolysis and 107.48, 121.79, and 137.57 kJ mol−1 for catalytic pyrolysis. Moreover, the optimumtemperature of pyrolysis was effectively reduced to 410 °C employing a catalyst, as opposed to the maximum temperature of 430 °C in the case of non-catalytic pyrolysis. Keeping in view the reduction in activation energy and improvement in quality of oil from catalyzed reaction in presence of cobalt doped cerium oxide, it can be concluded that the findings of this study can contribute to the development of a process for sustainable utilization of walnut shells as energy source.

Hydroaminoalkyl Functionalization of Pyrimidin‐2(1H)‐ones by Visible Light Organophotocatalysis: A Radical Approach to Biginelli‐Type Dihydropyrimidines

AbstractHerein, we report a visible‐light‐mediated hydroaminoalkylation of pyrimidin‐2(1H)‐ones via the aza‐Giese‐type reaction in presence of acridinium dye as photocatalyst under mild aerobic conditions. Using N‐Boc protected aminoalkyl trifluoroborates as radical precursors and various pyrimidine‐2(1H)‐one substrates, a diverse set of Biginelli‐type 3,4‐dihydropyrimidin‐2(1H)‐ones was prepared in 31–73% yields. Further transformation of the products obtained enabled the synthesis of 3,6,7,7a‐tetrahydro‐1H‐pyrrolo[3,4‐d]pyrimidine‐2,5‐dione derivatives which showed promise as inhibitors of poly (ADP‐ribose) polymerase (PARP) enzymes (IC50 0.46–1.12 μM for PARP‐2 in a fluorometric assay).

Prospects of sustainable geotechnical applications of manufactured sand slurry as controlled low strength material

Rapid changes in the construction industry for infrastructure development require extensive use of building materials from a variety of sources. As natural resources deplete at a faster rate in recent years, new materials are being explored, and recycled materials are being discovered for various applications. The slurry obtained during the washing of mined quarry sand (also called as M Sand Slurry or MSS) is found to be disposed as mining waste causing environmental pollution. In the present study, we propose an innovative methodology to recycle the MSS as a suitable replacement of fine aggregate by imparting sufficient strength and workability to produce a composite, commonly called as controlled low strength material (CLSM). We have optimized the mix proportioning of MSS by adding fly ash (up to 15%) and Portland cement (up to 10%). Various tests on the plastic properties (flowability, bleeding, hardening time) and hardened properties (ultimate compressive strength or UCS) were performed on the selected mixtures. The optimum mixture of CLSM with MSS provided excellent flowability (at 200 mm), bleeding rate (3–5%) and UCS up to 1.12 MPa. The improved binding effect on the poor-graded MSS has been attributed to the pozzolanic reaction in presence of fly ash and cement, as evident from the microstructural analysis. Based on the excavation criteria (ACI 229R), the selected mixtures have high removability modulus (1.2–2.5) except for two proportions (with only MSS, and with very low fly ash) while all combinations have sufficient strength (UCS < 2.1 MPa), making them suitable for various geotechnical applications. Further, to address the sustainability aspects of MSS-based CLSM utilization, a strategic framework is proposed based on the Life Cycle Assessment (LCA) approach for the mining industries. It is observed that MSS-based CLSM can reduce the cost of earthworks approximately by 62% (compared to the river sand) and 32% (compared to the available alternate sand). Hence, based on the environmental, economic and mechanistic aspects, we demonstrate that MSS-based CLSM can be effectively adopted for sustainable geotechnical applications.

Four-Membered Bimetallic Carbon Complex [(MCp*)2(μ-NPh)(μ-C)] (M = Fe, Ru, Os) - An Ambiphilic Carbene with Lone Pair and σ-Hole Reactivity.

Singlet carbenes are extensively studied compounds capable of electrophilic, nucleophilic or ambiphillic behaviour. The ambiphilic reactivity of singlet carbenes have been conventionally observed in orthogonal planes. Here, we report a detailed bonding and reactivity study of a homobimetallic carbon complex [(MCp*)2(μ-NPh)(μ-C)] (1M, M = Fe, Ru, Os) that shows ambiphilicity in the same direction. The structure of this complex can be considered as two fused three-membered M-C-M and M-N-M rings. The bonding analysis suggests that these 17VE homobimetallic complexes have one formal M-M bond with a bridging carbene centre featuring a high lying spn-hybridised lone pair. Accordingly, the carbene centre shows high proton affinity and act as a good 2e- donor to Lewis acids and transition metal fragment. Apart from the transition metal non-bonding electrons, the π-framework of M-C-M and M-N-M arms can be best described as 3c-2e- bonds. The two transition metals in the four-membered skeleton generate many low-lying, virtual orbitals. These low-lying virtual orbitals induces electron excitation from the spn-hybrid orbital in presence of H- and other 2e- donor ligands such as PMe3, NHC and CO. Hence, the spn-hybrid lone pair orbital shows σ-hole reactivity in presence of Lewis bases.

Solvation Environments in Porous Ionic Liquids Determine Selectivity in CO2 Conversion to Cyclic Carbonates.

Porous ionic liquids, which are suspensions of nanoporous particles in ionic liquids that maintain permanent porosity, are effective and selective media for the conversion of styrene oxide into styrene carbonate, absorbing CO2 [Zhou et al. Chem. Commun. 2021, 57, 7922-7925]. Here we elucidate the mechanism of selectivity using polarizable molecular dynamics simulations, which provide a detailed view on the structure of the porous ionic liquid and on the local solvation environments of the reacting species. The porous ionic liquids studied are composed of tetradecyltrihexylphosphonium chloride, or [P66614]Cl, and the ZIF-8 zinc-methylimidazolate metal-organic framework (MOF). The CL&Pol polarizable force field was extended to represent epoxide and cyclic carbonate functional groups, allowing the ionic liquid, the reactants, and the MOF to be all represented by fully flexible, polarizable force fields, providing a detailed description of interactions. The presence of reactant and product molecules leads to changes in the structure of the ionic liquid, revealed by domain analysis. The structure of local solvation environments, namely, the arrangement of charged moieties and CO2 around the epoxide ring of the reactant molecules, clearly indicate ring-opening the reaction mechanism. The MOF acts as a reservoir of CO2 through its free volume. The solute molecules are found in the accessible outer cavities of the MOF, which promotes reaction of the epoxide with CO2 excluding other epoxide molecules, thereby preventing the formation of oligomers, which explains the selectivity toward conversion to cyclic carbonates.

Solute dispersion phenomena in a free and forced convective flow with boundary reactions

The applications of solute dispersion in a free and forced convective flow are highly important in the diversified fields of chemical industries, nuclear power plants, etc. In the present work, the dispersion of tracers between two parallel plates in a combined free and force convective flow under the effect of wall absorption and bulk chemical reaction is explored using Mei’s multi-scale homogenization method. A uniform temperature variation is considered along both the plates. The main focus of this study is to investigate the effect of the Grashof number not only on Taylor diffusivity but also on the longitudinal and transverse concentration distribution. The effects of the boundary absorption and bulk chemical reaction in presence of the Grashof number are analyzed. The most interesting fact of this study is that the Taylor dispersivity is equal for both the positive and negative Grashof number i.e. for heating and cooling respectively. Also, the longitudinal concentration of solute reduces when both the process of cooling and heating increases. But the opposite scenario arises in the case of transverse concentration distribution. The results of the present study may be applied to waste management systems in chemical industries.

Sulfur Polymer as Emerging Advanced Materials: Synthesis and Applications

AbstractAbundant availability of inexpensive sulfur coupled with its reactivity triggered the interest of scientific community to explore the unique chemistry of sulfur for developing advanced materials. The reactivity of sulfur diradicals is used for making copolymers with cross‐linker monomer dienes through inverse vulcanization principle which is later upgraded by conducting reactions in presence of catalysts so as to achieve functionalized sulfur copolymers at lower reaction temperatures and lower time. Multi‐component reactions provide an opportunity for the direct utilization of sulfur at mild conditions. The diverse processing methodologies have further expanded the applicability of sulfur polymeric materials. The dynamicity of the S−S bonds has potential to create avenue for making self‐healing materials and usher the generation of more functionalized segmented block co‐polymers with superior properties. Interfacial condensation polymerization has successfully been implemented for the generation of sulfur nanoparticles in aqueous medium. The recent emergence of sulfur quantum dots through various approaches generated more advanced sulfur based materials in terms of expanding sulfur applications. This review provides an account on advanced materials synthesized using sulfur as raw material and their respective applications.

The preparation of 3.0F-Co3O4 catalyst with “Yardang Landform” structure and its performance for catalyzing N2O decomposition

In this work, the 3.0F-Co3O4 catalyst was synthesized by sol-gel method with the assistance of F127 and used for eliminating the N2O pollution from nitric acid plants. Research indicated that the presence of F127 in the preparation process endowed the 3.0F-Co3O4 catalyst with unique “Yardang Landform” microstructure, which possessed a rich number of “edges and corners”. The unique microstructure enables the 3.0F-Co3O4 catalyst to mainly expose highly active (400) and (511) crystal planes. Based on this unique microstructure, the surface active site density for 3.0F-Co3O4 catalyst was 7.62 µmol g−1 m2, which was about 9 times that of Co3O4(CP) catalyst prepared by traditional co-precipitation method. In addition, the 3.0F-Co3O4 catalyst demonstrated high catalytic activity and stability for the reaction in presence of impurity gases. For example, the catalyst can maintain a conversion of more than 60% for N2O at least 10 h in the feed stream of 2000 ppmv N2O/Ar with 5 vol% O2, 100 ppmv NO and 2 vol% H2O at 400 °C and GHSV = 20,000 h−1.

Synthesis, characterization, DFT and biological study of new methylene thio-linked coumarin derivatives

A series of new methylene thio-linked coumarin derivatives 3(a-j) were synthesized by the reaction substituted 4-(bromomethyl)-2H-chromen-2-one with different heterocyclic mercapto compounds via SN2 reaction in presence of K2CO3 as a catalyst. The structural conformation of synthesized compounds was performed using different spectroscopic techniques like FT-IR,1H NMR, 13C NMR, and LC-MS. DFT studies were performed to determine the electronic properties and vibrational frequencies for all the synthesized compounds. The synthesized compounds were evaluated for in vitro anti-cancer and anti-tuberculosis activityin vitro anticancer activity revealed that 3g molecule with methoxy substituted benzimidazole ring showed an IC50 value of 0.18 µM which is a more effective compound against MCF-7 cell line. Tuberculosis activity against, the H37Rv strain showed the moderate result. The molecular docking studies revealed that 3h molecule containing benzoxazole ring showed the highest binding affinity -9.4 kcal/mol and other molecules showed promising results compared to standard isoniazid. Molecular docking was performed with protein to study the binding mode of designed compounds.

Ratiometric sensing of α-glucosidase and its inhibitor based on MnO2 nanosheets promoted in-situ fluorescent reactions

Determination of α-glucosidase (α-Glu) activity and screening its inhibitors have great significance in disease diagnosis and biomedical research. In contrast to the flourishing development in fluorescent α-Glu assays, very few fluorescent ratiometric methods have been designed, especially the simplified one with two in-situ formed fluorescent signals derived from the same precursor. In this work, we have demonstrated that bovine serum albumin (BSA) templated MnO2 nanosheets (NSs) are robust oxidase mimics and oxidants that can switch o-phenylenediamine (OPD)-based fluorescent reactions in presence of ascorbic acid (AA). MnO2 NSs exert oxidase-like effects to simulate the oxidation of non-fluorescent OPD to orange fluorescent 2,3-diaminophenol (DAP) with fluorescence emission at 565 nm. In the presence of AA, MnO2 NSs as oxidants can effectively promote the dehydrogenation of AA and thus facilitate the fluorescent reaction between AA and OPD to generates fluorescent probe with emission at 425 nm. At the same time, generation of DAP is hindered due to OPD consuming and MnO2 NSs decomposition. AA-induced reversed fluorescence response at 425 and 565 nm lays the foundation for fluorescent ratiometric detection of α-Glu by using 2-O-α-d-glucopyranose-l-ascorbic acid (AAG) as substrate. This α-Glu assay features with the merits of strong anti-interference ability, easy operation and time-saving, and can be further used for inhibitor screening and inhibition efficiency evaluation.

Porous Crosslinked Zwitterionic Microparticles Based on Glycidyl Methacrylate and N-Vinylimidazole as Possible Drug Delivery Systems

Crosslinked porous microparticles have received great attention as drug delivery systems lately due to their unique set of properties: the capability to form various polymer-drug combinations, low immunogenicity, patient compliance and ability to release drugs in a delayed or controlled manner. Moreover, polymers with betaine groups have shown some unique features such as antifouling, antimicrobial activity, biocompatibility and strong hydration properties. Herein, novel porous zwitterionic microparticles were prepared in two stages. The first step involves the synthesis of porous microparticles based on glycidyl methacrylate, N-vinylimidazole and triethyleneglycol dimethacrylate using the suspension polymerization technique, the second step being the synthesis of zwitterionic porous microparticles by polymer-analogous reaction in presence of sodium monochloroacetate as betainization agent. Both types of microparticles were characterized structurally and morphologically by FT-IR spectroscopy, energy dispersive X-ray analysis, scanning electron microscopy, dynamic vapors sorption and mercury porosimetry. The tetracycline loading into crosslinked and zwitterionic microparticles was also performed, the maximum tetracycline loading capacities being 87 mg/g and 135 mg/g, respectively. The drug release mechanism, elucidated by various mathematical models, is controlled by both diffusion and swelling processes as a function of the zwitterionic and/or porous microparticle structure. Both types of microparticles presented antibacterial activity against the two reference strains used in this study: Escherichia coli and Staphylococcus aureus.

Controlling C-steel dissolution in 1 M HCl solution using newly synthesized ρ-substituted imine derivatives: Theoretical (DFT and MCs) and experimental investigations

• ρ- substituted imines as C-steel corrosion inhibitor. • Δ N of SB-OCH 3 is higher than SB-CH 3 . • SB-OCH 3 enhances the R ct of C-steel to 374.9 Ω.cm 2 . • Adsorption type of tested imine compounds was physicosorption. • SB-OCH 3 resisted C-steel corrosion under severe conditions. Corrosion is an inevitable process, but its control is the goal of the researchers using organic inhibitors. So, newly successfully prepared ρ-substituted imine compounds namely;( E )- N,N -dimethyl1-4-((tolylimino)methyl)aniline (SB-CH 3 ) and ( E )-4 (((4methoxyphenyl)imino)methyl)- N,N -dimethylaniline (SB-OCH 3 ) have been fabricated to control the C-steel dissolution in 1M HCl. Hammett concept and theoretical calculated parameters were applied to predict the adsorption affinity of the prepared imine derivatives and the laboratory gravimetric and electrochemical tests accompanied with surface analysis tools were conducted to confirm these predictions. The fabricated imine compounds suppressed the C-steel reaction with efficacy of more than 90 %. The SB-OCH 3 exhibited higher adsorption affinity than SB-CH 3 and they acted as hydride C-steel corrosion inhibitors and followed Langmuir isotherm. The Δ G a d s * values of C-steel reactions in presence of these compounds were around -37 kJmol −1 . The inhibition performance of SB-CH 3 and SB-OCH 3 was function in their concentrations, molecular weight, and solution temperature. SB-CH 3 and SB-OCH 3 suppressed C-steel reaction at high temperature and the SB-OCH 3 showed highest efficiency (76.8%) at 60 °C. The activated thermodynamic parameters of C-steel reaction in existence and nonexistence of 1 × 10 −3 M imine compounds were calculated and discussed. The comparison findings with the previously published compounds confirmed the superiority of the understudied imine derivatives.

Studies of ninhydrin and phenylalanine in cationic dimeric gemini micellar system: Spectrophotometric and conductometric measurements

Present work deals with studies of ninhydrin (N) and phenylalanine (Phe) in cationic gemini micellar system by spectrophotometer under diverge kinetic environments. The results of the current study follow fractional-order in N and first-order in Phe. The study is intensely catalyzed by gemini surfactant (GS) system and rate constants (kψ) are enriched even though at [GS] lower than critical micelle concentration (cmc). The noticed enhancement in rates between reactant molecules and gemini is attributed to hydrophobic and electrostatic interactions. To interpret the influence of various [GS], ranging from (1–3000) x 10−5 mol dm−3, on kψ, a model so-called pseudo-phase originally proposed by Berezin et al. and improved by Bunton was applied. Various parameters and constants (like binding constants, thermodynamic parameters and micellar rate constants) have been evaluated. Under the present kinetic condition, a probable reaction mechanism between N and Phe is recommended. The conductivities of pure gemini and the presence of reactants at two temperatures, i.e., at 303 K and 343 K were measured using a conductivity instrument. The cmc of pure geminis in the current case determined at 303 K is consistent with those data reported, earlier.

Effect of hydroxyl (·OH) radicals on the progression of NaBH4 hydrolysis reaction on fcc-Co surfaces: A DFT study

The effect of ·OH radical in the medium for the sodium borohydride (NaBH4) hydrolysis reaction in presence of face-centered cubic (fcc) Cobalt (Co) catalyst was investigated based on density functional theory (DFT). The main purpose is to determine the effective cobalt surface for the disassociation of hydrogen from NaBH4, and the catalyst performance for the intermediate steps formed by the decomposition of water on the cobalt surface. Low index fcc-Co catalyst surfaces were used for the catalyzed NaBH4 hydrolysis reaction. As a result of the calculations, Co(111) is the most effective surface among the low index fcc-Co surfaces for the hydrolysis reaction. Therefore, the possible steps of the NaBH4 hydrolysis reaction are modeled on the Co(111) surface for ambient conditions containing different concentrations of H* atoms, ·OH* radicals, and H2O* molecules. According to our results, the concentration of ·OH* radicals adsorbed on the surface is directly proportional to the change in activation energy. In addition, calculations for the possible second and third steps of the hydrolysis reaction showed that the steps involving NaBH3OH and NaBH3O base molecular structures, respectively, are more feasible than others. This will be a guide for experimental studies in terms of time and cost.

Syntheses, X-ray structure and biological studies of binuclear µ-oxo diiron complexes with s-triazine pincer ligand

The new binuclear µ-oxo diiron complexes, [Fe2(PMT)2(H2O)4O]X2 (X = NO3¯; 1 or Br¯; 2), were synthesized. The bis-pyrazol-methoxy-s-triazine (MBPT) ligand underwent O-demethylation in presence of Fe(NO3)3 affording 4,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,3,5-triazin-2(1H)-one (HPMT) followed by in situ complexation to give 1 in a good yield. Repeating the reaction in presence of KBr, complex 2 was obtained. The Fe(III) is hexa-coordinated in both complexes with 1 PMT¯ as an anionic tridentate N-chelator, two water molecules in addition to the oxo-bridge. Both complexes have promisinig anticancer activity against lung carcinoma with IC50 of 15.27 ± 0.75 and 46.14 ± 2.07 µg/mL for complex 1 and 2, respectively compare to cis-platin (IC50 = 7.53 ± 0.69 µg/mL) as control. Hence, complex 1 outer performed complex 2 by three times. The antioxidant activity of complex 2 (IC50 = 50.36 ± 2.96 µg/mL) is better than 1 (IC50 = 349.92 ± 17.48 µg/mL). Also, the studied Fe(III) complexes have weak to moderate activities compared to Ketoconazole and Gentamycin as antibacterial and antifungal controls.

Oxygen vacancy rich α-MnO2 @B/O-g-C3N4 photocatalyst: A thriving 1D-2D surface interaction effective towards photocatalytic O2 and H2 evolution through Z-scheme charge dynamics

Herein, we have prepared a 1D-2D junction based Oxygen Vacancy rich α-MnO2@B/O-g-C3N4 photocatalyst by using 1D α-MnO2 nanorods over 2D nanosheets of boron, oxygen co-doped exfoliated graphitic carbon nitride (BOCN). The important feature of the above composite material is the availability of oxygen vacancy as well as the presence of dual oxidation state of Mn (Mn4+, Mn3+) which enhances surface activity as well as chemical reaction output of the material. Among the synthesized materials α-MnO2@B/O-g-C3N4 (MBOCN-20) shows best photocatalytic activity by following Z-Scheme charge dynamics towards water oxidation (295.1 μmol h−1) and reduction (560.1 μmol h−1) reactions in presence of methanol (hole scavenger) and AgNO3 (electron scavenger) as sacrificial agent. However, 44.2 and 86.5 μmol h−1 of O2 and H2 evolution was observed in absence of any sacrificial agent. This analysis will confer a valuable blue-print to construct stimulating photocatalysts to achieve the paramount performance towards photocatalytic water redox reaction.

A novel 2‐D accordion like Al‐BPED MOF as reusable and selective catalyst for N‐alkylation of amines with dialkylcarbonates

A novel 2‐D flakes like Al‐BPED ((N1,N2‐bis [pyridine‐2‐yl]methyl)ethane‐1,2‐diamine) metal–organic framework (MOF) have been explored for its catalytic potential in the N‐alkylation of amines with dialkyl carbonates. The Al‐BPED MOF catalyst has been synthesized by hydrothermal route. The X‐ray diffraction, Fourier Transform Infrared Spectroscope (FTIR), and High Resolution Transmission Electron Microscopy (HRTEM) images were used to analyze the morphology of the synthesized Al‐BPED MOF samples. With the use of Al‐BPED MOF, the primary and secondary aromatic amines were selectively and efficiently methylated with dimethyl carbonate. The effect of process conditions has been investigated toward N‐methylation, N‐ethylation, and N‐benzylation of aromatic amines. Under the optimal conditions with 10 mol% of the MOF catalyst, a maximum aniline conversion of 88% and a selectivity &gt;90% toward N‐alkylation was achieved. The kinetic studies revealed the N‐alkylation reaction in presence of Al‐BPED MOF followed pseudo‐first order rate kinetics.

Quantification of phosphatidylethanol combining dried blood spots sampling with Orbitrap-based LC-HRMS platform: Method validation and proficiency testing

Phosphatidylethanols (PEth) are phospholipids specifically synthetised by an enzymatic reaction in presence of ethanol. PEth is a mid-term direct biomarker for alcohol consumption or abstinence, leading to a growing interest for forensic toxicology purposes. Blood deposition onto a filter paper card as dried blood spots (DBS) allows PEth stabilisation which is otherwise easily degraded at room temperature. The goal of this study was to develop and validate a procedure for the quantification of PEth 16:0/18:1, the most abundant analogue, in DBS samples benefiting from the selectivity brought by Orbitrap-based high-resolution mass spectrometry (HRMS). Calibration samples and quality controls (QCs) are volumetrically spotted (10 μL) onto filter paper card (Whatman 903 protein saver) either using HemaXis DB10™ device, or using laboratory micropipette. The whole DBS is manually punched out and the PEth is then directly extracted using an in vial approach with 100 μL of PEth 16:0/18:1-D5 in methanol. Analyses are then performed by LC-HRMS in PRM mode using a QExactive Orbitrap platform. Validation was carried out on with respect to the Food and Drug Administration (FDA) criteria, using three different QC concentrations (39, 87 and 350 ng/mL) over three non-consecutive days. To assess the robustness of our method, an interlaboratory proficiency testing was carried out using 3 different commercial standards at 4 levels (50, 100, 200, and 300 ng/mL) of quality controls (QCs) provided by ACQ Science (Germany). The method was fully validated according to guidelines set forth by the FDA. Calibration curve was built using a weighting factor of 1/x. Trueness was measured between 100.1 and 103.6% for the tested concentrations. Repeatability and intermediate precision were found to be lower than 5%. Linearity was evaluated between the lower limit of quantification of 20 ng/mL and the upper limit of quantification of 2000 ng/mL with an R2 greater than 0.998. Recovery (RE) and matrix effect (ME) evaluated at 2 concentrations ranged from 76 to 99% and 8 to 10%, respectively. During the proficiency test, precision was evaluated below 8.0%, while the accuracy ranged from 93.8% to 105.9% and from 101 to 104.5% when compared with the expected concentration and the mean measured value of all the labs participating respectively. The validation results demonstrate that the use of Orbitrap-based PRM quantification present an interesting alternative over triple quadrupole platforms considered as the gold standard for LC-MS/MS quantitative approaches. Indeed, multiple reaction monitoring (MRM) and PRM provide comparable performance in terms of sensitivity, linearity, dynamic range, precision and repeatability. Moreover, the use of PRM provides access to the full fragmentation spectra without any preanalytical considerations. The proficiency testing results confirm the suitability of PRM mode showing great quantification performances. In addition, those results and especially the repeatability exhibit the precision of the volume control provided by the use of HemaXis™ device. This tool enables the standardisation of the DBS collection at the fingertip in a non-hospital environment either by minimally-trained medical staff or by the patient himself. A rapid, sensitive, and robust method was developed and fully validated for the detection and quantification of PEth 16:0/18:1 in DBS samples. The results of the validation process and the proficiency testing confirm that the use of DBS associated with HRMS PRM-based analyses does not hinder the analytical performances, while providing full information over the MS-MS spectra. The development of analytical tools enabling the use of DBS microsampling that can be performed in almost every environment opens new opportunities toward clinical and forensic toxicological applications.