Electrospray Ionization Technique Research Articles

Development and Validation of UPLC-ESI-MS/MS Technique for the Determination of 2-Isopropyl-4-(chloromethyl)thiazole in Ritonavir

The objective of this work was to develop and validate a rapid, highly sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS) method for the quantification of 2-isopropyl-4-(chloromethyl)thiazole in ritonavir. Chromatographic conditions of this impurity were achieved on an AQUITY UPLC column HSS (high strength silica) T3 column (100 mm long, 2.1 mm internal diameter, 1.8 μm diameter) using a gradient elution with 0.1% formic acid in water and methanol at a flow rate of 0.3 mL/min. LCMS/MS was operated under the multiple reaction mode (MRM) using electrospray ionization technique in positive ion mode and the transitions of m/z 176.1[M+H]+→140.1 for quantifier, 176.1[M+H]+→71.0 for qualifier were used to measure the impurity, respectively. The total chromatographic run time was 10 min. Full validation of the analytical method was carried out, including its system precision, selectivity, linearity, accuracy, recovery, ruggedness, stability and robustness. A linear response function was achieved in the concentration range of 0.12-1.86 μg/g with r > 0.99. The detection limit and quantitation limit of this impurity were 0.06 and 0.12 μg/g, respectively. Consistent recoveries were obtained during intra- and inter-day precision experiments in validation ranged from 80-120%. The developed method could be helpful not only for quality control and also for risk management of potential genotoxicity of this impurity in ritonavir drug substance.

Rapid and Sensitive Bioanalytical Method Development and Validation for Quantification of Metoprolol Using LC-MS/MS in Human Plasma

A novel, accurate, simple and selective LC-MS/MS method was developed and validated for the determination of metoprolol in human plasma. Due to structural resemblance Propranolol was selected as internal standard. Anti coagulant used was K2 EDTA. Metoprolol, used in the therapy and management of hypertension, myocardial infraction and other cardio vascular diseases. Liquid – liquid extraction technique with tert-butyl methyl ether was applied for the extraction of analyte from human plasma. Kromasil C18 column (5and#181;, 100 and#215; 4.6 mm) with an isocratic mobile phase of 5mM Ammonium Formate pH 3.5 and Acetonitrile (15:85 % V/V) was used for the resolution. Sample ionization was done with Electrospray ionization technique in positive ion mode. Selectivity was enhanced by tandem mass spectrometric analysis via two multiple reaction monitoring (MRM) transitions, m/z 268.15→115.90 for metoprolol and 260.17→115.90 for Propranolol respectively. The linearity of the method was established over a concentration range of 1.505 – 538.254 ng/mL, in human plasma, with the precision and accuracy ranging from 4.67 to 7.41% and 90.66 to 98.15% respectively. The stability of the analyte was evaluated in plasma under different storage conditions.

Nanostructured Ni-Cu Electrocatalysts for the Oxygen Evolution Reaction.

Ni-based materials are promising electrocatalysts for the oxygen evolution reaction (OER) for water splitting in alkaline media. We report the synthesis and OER electrocatalysis of both Ni-Cu nanoparticles (20-50 nm in diameter) and Ni-Cu nanoclusters (<20 metal atoms). Analysis of mass spectral data from matrix-assisted laser desorption/ionization and electrospray ionization techniques demonstrates that discrete heterobimetallic Ni-Cu nanoclusters capped with glutathione ligands were successfully synthesized. Ni-Cu nanoclusters with a 52:48 mol % Ni:Cu metal composition display an OER onset overpotential of 50 mV and an overpotential of 150 mV at 10 mA cm-2, which makes this catalyst one of the most efficient nonprecious metal OER catalysts. The durability of the nanocluster catalysts on carbon electrodes can be extended by appending them to electrodes modified with TiO2 nanoparticles. Infrared spectroscopy results indicate that the aggregation dynamics of the glutathione ligands change during catalysis. Taken together, these results help explain the reactivity of a novel class of nanostructured Ni-Cu OER catalysts, which are underexplored alternatives to more commonly studied Ni-Fe, Ni-Co, and Ni-Mn materials.

A critical analysis of electrospray techniques for the determination of accelerated rates and mechanisms of chemical reactions in droplets.

Electrospray and Electrosonic Spray Ionization Mass Spectrometry (ESI-MS and ESSI-MS) have been widely used to report evidence that many chemical reactions in micro- and nano-droplets are dramatically accelerated by factors of ∼102 to 106 relative to macroscale bulk solutions. Despite electrospray's relative simplicity to both generate and detect reaction products in charged droplets using mass spectrometry, substantial complexity exists in how the electrospray process itself impacts the interpretation of the mechanism of these observed accelerated rates. ESI and ESSI are both coupled multi-phase processes, in which analytes in small charged droplets are transferred and detected as gas-phase ions with a mass spectrometer. As such, quantitative examination is needed to evaluate the impact of multiple experimental factors on the magnitude and mechanisms of reaction acceleration. These include: (1) evaporative concentration of reactants as a function of droplet size and initial concentration, (2) competition from gas-phase chemistry and reactions on experimental surfaces, (3) differences in ionization efficiency and ion transmission and (4) droplet charge. We examine (1–4) using numerical models, new ESI/ESSI-MS experimental data, and prior literature to assess the limitations of these approaches and the experimental best practices required to robustly interpret acceleration factors in micro- and nano-droplets produced by ESI and ESSI.

Self-decoupled tetrapodal perylene molecules for luminescence studies of isolated emitters on Au(111)

Self-decoupled tetrapodal perylene molecules were designed, synthesized, and deposited on the Au(111) surface through the electrospray ionization technique. Photoluminescence and lifetime measurements show that the chromophore groups of the designed molecules are well decoupled from the gold substrate. Preliminary scanning tunneling microscopy induced luminescence measurements indicate the observation of molecule-specific emissions from isolated single tetrapodal perylene molecules adsorbed directly on Au(111). The emergence of significant emission when the tip is positioned at the molecular center suggests that there is a considerable vertical component of the transition dipole of the designed molecule along the tip axial direction. Our results may open up a route for the realization of nanolight sources and plasmonic devices based on organic molecules.

Determination of pioglitazone, its metabolite and alogliptin in human plasma by a novel LC-MS/MS method; application to a pharmacokinetic study

A novel, high throughput and sensitive LC-MS/MS assay method was developed and fully validated for quantitative determination of pioglitazone, its hydroxyl metabolite and alogliptin in human plasma. A simple and rapid sample preparation procedure based on protein precipitation technique with acetonitrile was utilized. Chromatographic separation was achieved on C8 (50 × 4.6 mm, 5 μm) Kinetex® analytical column using methanol and 0.1% formic acid in a gradient elution mode at a flow rate of 0.7 mL/min with injection volume of 8 μL. Detection was performed on a triple quadrupole mass spectrometer accompanied with electrospray ionization (ESI) technique in positive mode, operating in multiple reaction monitoring, with the transitions of 357.2 → 119.1, 373.1 → 150.1, 340.3 → 116.1, 361.1 → 138.1 and 343.2 → 116.1 m/z for pioglitazone, its hydroxyl metabolite, alogliptin, pioglitazone-d4 (IS-1) and alogliptin-d3 (IS-2), in order. Analysis was achieved within 4 min over a linear concentration range of 10–3000 ng/mL, 5–2000 ng/mL and 3–300 ng/mL, for pioglitazone, hydroxyl pioglitazone and alogliptin, in order. The method was fully validated according to FDA guidelines. The developed method was used for estimation of the three studied analytes in human plasma and pharmacokinetic parameters were demonstrated after oral dose administration of Oseni® tablets to Egyptian healthy volunteers.

Validated LC-ESI-MS/MS method for the determination of tunicamycin in rat plasma: Application to a pharmacokinetic study.

A liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantification of tunicamycin in rat plasma as per regulatory guideline. Chromatography of tunicamycin and the IS in the processed plasma samples was achieved on an X-Terra phenyl column using a binary gradient (mobile phase A, acetonitrile and mobile phase B, 5 mm ammonium formate) elution at a flow rate of 0.6 ml/min. LC-MS/MS was operated under the multiple reaction monitoring mode using the electrospray ionization technique in positive ion mode and the transitions of m/z 817.18 → 596.10, 831.43 → 610.10, 845.29 → 624.10, 859.23 → 638.10 and 309.24 → 163.20 were used to quantitate homologs A-D and the IS, respectively. The total chromatographic run time was 4.5 min. The correlation coefficient (r2 ) was >0.99 for all homologs with accuracy 90.7-107.4% and precision 0.74-15.1%. The recovery of homologs was 78.6-90.2%. No carryover was observed and the matrix effect was minimal. Tunicamycin four homologs were found to be stable on the bench-top for 6 h, for up to three freeze-thaw cycles, in the injector for 24 h and for 1 month at -80°C. The applicability of the validated method has been demonstrated in a rat pharmacokinetic study.

Simultaneous determination of levocetirizine dihydrochloride and montelukast sodium in human plasma by LC–MS/MS: development, validation, and application to a human pharmacokinetic study

Objectives A simple, rapid, selective, and sensitive high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed for the simultaneous determination of levocetirizine dihydrochloride and montelukast sodium in human plasma using fexofenadine hydrochloride as an internal standard. Method Liquid–liquid extraction of both drugs and internal standard from plasma into ethyl acetate was used for sample preparation and analysis. Separation of both drugs and internal standard was achieved on an Inertsil ODS-3 (4.6 mm × 50 cm, dp 5 μm, particle size) column using an isocratic mobile phase of acetonitrile and 10 mM ammonium formate adjusted to pH 8 with 50 μL ammonium hydroxide in composition of 73:27 (v/v) at a flow rate of 0.7 mL/min. The LC–MS/MS was operated under the multiple reaction monitoring mode (MRM) using an electrospray ionization technique. Mass parameters were optimized to monitor transitions at m/z [M + H]+ 389.0 → 200.8 for levocetirizine dihydrochloride, m/z [M + H]+ 586.2 → 422.2 for montelukast sodium, and m/z [M + H]+ 502.2 → 466.0 for fexofenadine hydrochloride. Results The method was found to be linear in the range of 1–500 ng/mL for both drugs. The intra-day and inter-day precision were in the range of 0.96–1.92% and 1.03–1.55%, respectively. Matrix effect was acceptable with %RSD &lt; 15. Conclusion The proposed method was validated and successfully applied for a pharmacokinetic study of both drugs in human plasma after oral administration of their pharmaceutical preparation.

Simultaneous Quantification and Pharmacokinetic Study of Nine Bioactive Components of Orthosiphon stamineus Benth. Extract in Rat Plasma by UHPLC-MS/MS.

Orthosiphon stamineus Benth. (OS) is a traditional folk medicine for the treatment of kidney stones and other urinary tract diseases. In this study, a rapid and sensitive Ultra high-performance liquid chromatography (UHPLC)-MS/MS approach was established and validated for the simultaneous quantification of nine bioactive components in rat plasma. The nine components from OS extract detected in rat plasma were danshensu, protocatechuic acid, caffeic acid, rosmarinic acid, salvianolic acid A, salvianolic acid B, cichoric acid, sinensetin and eupatorin. After liquid-liquid extraction with ethyl acetate, the plasma samples were subjected to a triple quadrupole mass spectrometer employing electrospray ionization (ESI) technique and operating in multiple reaction monitoring (MRM) with both positive and negative ion modes. The standard curves showed good linear regression (r > 0.9915) over the concentration range for the nine analytes. The inter-day and intra-day precision and accuracy were found to be within 15% of the nominal concentration. The recovery and stability of nine compounds were all demonstrated to be within acceptable limits. The approach was successfully applied to investigate the pharmacokinetic analysis of the nine bioactive components after oral administration of OS extract in rats.

Combination of Low-Temperature Electrosurgical Unit and Extractive Electrospray Ionization Mass Spectrometry for Molecular Profiling and Classification of Tissues.

Real-time molecular navigation of tissue surgeries is an important goal at present. Combination of electrosurgical units and mass spectrometry (MS) to perform accurate molecular visualization of biological tissues has been pursued by many research groups. Determination of molecular tissue composition at a particular location by surgical smoke analysis is now of increasing interest for clinical use. However, molecular analysis of surgical smoke is commonly lacking molecular specificity and is associated with significant carbonization and chemical contamination, which are mainly related to the high temperature of smoke at which many molecules become unstable. Unlike traditional electrosurgical tools, low-temperature electrosurgical units allow tissue dissection without substantial heating. Here, we show that low-temperature electrosurgical units can be used for desorption of molecules from biological tissues without thermal degradation. The use of extractive electrospray ionization technique for the ionization of desorbed molecules allowed us to obtain mass spectra of healthy and pathological tissues with high degree of differentiation. Overall, the data indicate that the described approach has potential for intraoperative use.

Lipid Coverage in Nanospray Desorption Electrospray Ionization Mass Spectrometry Imaging of Mouse Lung Tissues

Lipids are a naturally occurring group of molecules that not only contribute to the structural integrity of the lung preventing alveolar collapse but also play important roles in the anti-inflammatory responses and antiviral protection. Alteration in the type and spatial localization of lipids in the lung plays a crucial role in various diseases, such as respiratory distress syndrome (RDS) in preterm infants and oxidative stress-influenced diseases, such as pneumonia, emphysema, and lung cancer following exposure to environmental stressors. The ability to accurately measure spatial distributions of lipids and metabolites in lung tissues provides important molecular insights related to lung function, development, and disease states. Nanospray desorption electrospray ionization (nano-DESI) and other ambient ionization mass spectrometry techniques enable label-free imaging of complex samples in their native state with minimal to absolutely no sample preparation. However, lipid coverage obtained in nano-DESI mass spectrometry imaging (MSI) experiments has not been previously characterized. In this work, the depth of lipid coverage in nano-DESI MSI of mouse lung tissues was compared to liquid chromatography tandem mass spectrometry (LC-MS/MS) lipidomics analysis of tissue extracts prepared using two different procedures: standard Folch extraction method of the whole lung samples and extraction into a 90% methanol/10% water mixture used in nano-DESI MSI experiments. A combination of positive and negative ionization mode nano-DESI MSI identified 265 unique lipids across 20 lipids subclasses and 19 metabolites (284 in total) in mouse lung tissues. Except for triacylglycerols (TG) species, nano-DESI MSI provided comparable coverage to LC-MS/MS experiments performed using methanol/water tissue extracts and up to 50% coverage in comparison with the Folch extraction-based whole lung lipidomics analysis. These results demonstrate the utility of nano-DESI MSI for comprehensive spatially resolved analysis of lipids in tissue sections. A combination of nano-DESI MSI and LC-MS/MS lipidomics is particularly useful for exploring changes in lipid distributions during lung development, as well as resulting from disease or exposure to environmental toxicants.

Simultaneous determination of fourteen main active components in Gumiganghwal-tang tablet by using a newly developed UPLC-ESI-MS/MS method

The purpose of this study was to develop a method for simultaneous analysis of fourteen major active components in Gumiganghwal-tang tablet widely prescribed for cold related diseases using UPLC-ESI-MS/MS. Twelve of these 14 components were separated using 0.1% formic acid and acetonitrile as a mobile phase by gradient elution at a flow rate of 0.3 mL/min equipped with a KINETEX C18 column (2.1 × 50 mm, 1.7 μm). The remaining two components were separated using 10 mM aqueous ammonium formate containing 0.01% formic acid and acetonitrile as a mobile phase by gradient elution at a flow rate of 0.2 mL/min equipped with an Inertsil C8–3 column (2.1 × 100 mm, 2.0 μm). Quantitation of this analysis was performed on a triple quadrupole mass spectrometer using electrospray ionization technique operating in multiple reaction monitoring mode. Full validation of the analysis method was carried out, including its linearity, selectivity, sensitivity, precision, accuracy, recovery, and stability. Chromatograms showed high resolution, sensitivity, and selectivity without interference by impurities. Calibration curves of all 14 components ranged from 0.5 to 1000 ng/mL, displaying excellent linearity (correlation coefficients >0.99). The relative standard deviations (RSD) of intra- and inter-day were <11.75%. Recoveries were within the range 95.41–103.24% (RSD value of 1.62–9.09%). These results demonstrate that the developed method is simple, rapid, reliable, specific, accurate, and sensitive for the quantification of bioactive components of Gumiganghwal-tang. The developed method was successfully applied to the analysis of Gumiganghwal-tang tablet. The developed UPLC-ESI-MS/MS method could be useful not only for quality control, but also for effectiveness and safety evaluation of Gumiganghwal-tang tablet.

Oxidation-Sensitive Dextran-Based Polymer with Improved Processability through Stable Boronic Ester Groups.

Particulate immunotherapy holds promise to vaccinate or treat a broad array of illnesses, including cancer, infectious diseases, and autoimmune disorders. The rate of antigen release from nano/microparticles (MPs) can impact both the type and quality of the immune response they elicit. The lysosomes of antigen-presenting cells are highly oxidizing. Thus, an oxidation-sensitive vehicle could enable a significant advancement in effective MP immunotherapy. One promising class of materials being developed toward this end is aryl-boronate-modified dextran polymers. The boronic esters used for oxidation-sensitive materials and sensors are typically made using pinacol (Pin) as a diol. However, Pin-based aryl-boronate-modified polymers are capable of transesterifying with biogenic diols, which can lead to undesirable interactions and poor material properties. To solve this, pinanediol (PD) was used in place of Pin in the synthesis of an aryl-boronate-modified dextran polymer (PDB-Dex), yielding a highly stable boronic ester. This modified dextran reverses its water solubility as desired, and improves on Pin-based materials by maintaining its solubility in organic solvents. MPs could be prepared by emulsion, nanoprecipitation, and electrospray techniques. The hydrogen peroxide-triggered degradation of microparticles was quantified colorimetrically, and the mechanism was probed using 1H NMR. Preliminary in vitro studies show low cytotoxicity and the ability to deliver an immunostimulatory agent.

A novel and sensitive UPLC-MS/MS method to determine mequitazine in rat plasma and urine: Validation and its application to pharmacokinetic studies.

The aim of this study was to develop an analytical method to determine mequitazine in rat plasma and urine. Mequitazine was separated by UPLC-MS/MS equipped with a Kinetex core-shell C18 column (50 × 2.1 mm, 1.7 μm) using 0.1% (v/v) aqueous formic acid and acetonitrile containing 0.1% (v/v) formic acid as a mobile phase by gradient elution at a flow rate of 0.3 mL/min. Quantitation of this analysis was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique operating in multiple reaction monitoring positive ion mode. Mass transitions were m/z 323.3 → 83.1 for mequitazine and 281.3 → 86.3 for imipramine as internal standard. Liquid-liquid extraction with ethyl acetate and protein precipitation with methanol were used for sample extraction. Chromatograms showed that the method had high resolution, sensitivity and selectivity without interference from plasma constituents. Calibration curves for mequitazine in rat plasma and urine were 0.02-200 ng/mL, showing excellent linearity with correlation coefficients (r2 ) >0.99. Both intra- and inter-day precisions (CV%) were within 4.08% for rat plasma and urine. The accuracies were 99.58-102.03%. The developed analytical method satisfied the criteria of international guidance. It could be successfully applied to pharmacokinetic studies of mequitazine after oral and intravenous administration to rats.

A fast paraquat quantitation method in human serum using probe electrospray ionization–tandem mass spectrometry for emergency settings

IntroductionParaquat (PQ) is one of the most toxic herbicides to humans. However, it is still in use in many countries, including Japan, and many incidents, such as homicides, intentional ingestions, and occupational accidents, have been reported thus far. In PQ poisoning cases, it is possible to predict severity and prognosis using nomograms. Therefore, if the serum PQ level is determined immediately, a treatment plan can be rapidly established. However, most known analytical methods are time-consuming and therefore hardly ever contribute to patient treatment. MethodsWe developed a new method for PQ quantitation in serum by combining a probe electrospray ionization technique with mass spectrometry. This method requires virtually no serum pretreatment and can yield quantitation values in 18 s. ResultsWe applied the proposed method to samples from real poisoning cases and compared the results with those obtained via liquid-chromatography–tandem mass spectrometry, revealing the absence of any significant differences at the 5% significance level (t(8) = 1.000, p > .05). The limits of detection and quantitation were 0.004 and 0.015 μg/L, respectively, and the calibration curve exhibited good linearity over the concentration range of 0.015–4.0 μg/mL (r2 = 0.998). DiscussionAs the proposed method is fast and easy to perform, it should be useful in emergency medical settings.

A quarter century of wine pigment discovery.

The red grape berry pigments, anthocyanins, were characterized in the early 20th century, but investigations of wine pigments were stymied during that era. The question of their identity was a major challenge for wine chemists. A number of techniques showed that the pigments were polymeric in nature. Some structures were postulated by mid-century based on reactions between anthocyanins and condensed tannin, and later postulated wine pigments were observed in model reactions. Some related compounds were then observed in wine. By the end of the 20th century, the ionization of non-volatiles for mass spectrometry opened the door to these compounds. In addition, a new class of compounds was observed, the pyranoanthocyanins, a product of fermentation and aging metabolites with anthocyanins. These compounds possess the pigment stability to SO2 and pH change that is characteristic of aged red wine. Aging experiments show a dynamic situation with shifts in the population of pigment classes over time. The very large number of diverse pigments explains why it has been so difficult to answer the century-old question of the structure of wine pigments. Our current understanding is founded on the use of mass spectral analysis using electrospray and related ionization techniques over the last 25 years. Future progress will rely on more sophisticated analysis of this very complex mixture of substances. © 2019 Society of Chemical Industry.

Novel LC\u2013MS/MS method for analysis of metformin and canagliflozin in human plasma: application to a pharmacokinetic study

Highly sensitive and selective liquid chromatography/tandem mass spectrometry (LC–MS/MS) method was developed and validated for the simultaneous estimation of the recently approved oral hypoglycemic mixture; metformin (MET) and canagliflozin (CFZ) in human plasma using propranolol HCl (PPL) and tadalafil (TDF) as internal standards (IS), respectively. Analytes were extracted using protein precipitation induced by acetonitrile then liquid–liquid extraction was performed using ethyl acetate. Reversed phase HPLC was carried out using C18 analytical column (50 mm × 4.6 mm i.d., 5 µm) with a simple isocratic mobile phase composed of 0.1% formic acid and acetonitrile (60:40, v/v). Detection was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring (MRM), with the transitions of m/z 130.2 → 60.1, m/z 462.3 → 191.0, m/z 260.2 → 183.0 and m/z 390.2 → 268.2 for MET, CFZ, PPL and TDF, respectively, in the positive ion mode. The analysis was carried out within 5 min over a linear concentration range of 50–5000 ng/mL for MET and 10–1000 ng/mL for CFZ. The method was validated in accordance with the FDA guidelines for bioanalytical method. All obtained recoveries were higher than 90.0% while the accuracy was in the range of 88.14–113.05% and the relative standard deviation was below 10.0% for all investigated drugs by the proposed method. The achieved promising results has allowed for the successful application of the developed LC–MS/MS method to a pharmacokinetic study of the target drugs after their oral administration to Egyptian healthy volunteers. The pharmacokinetic study was accomplished after the agreement of the ethics committee.

Novel piperaziniumpolyoxometalate-based acidic ionic liquids as highly efficient catalysts for the selective oxidation of alcohols

Two novel heteropolyanion-based Brønsted Acidic Ionic Liquids (BAILs), butane mono and bis sulfoacid-functionalized 1,4-dimethylpiperazinium salts of phosphotungstate catalyst ([PipBs1]3-PW and [PipBs2]3-(PW)2) were synthesized and well characterized with FTIR, 1H and 13C NMR, Electro-Spray Ionization Mass Spectrometry (ESI-MS), Elemental Analysis, EDX, BET and TGA techniques. Selective oxidation of benzyl alcohol with 35% aqueous hydrogen peroxide under solvent-free conditions was carried out using these catalysts without adding any phase transfer catalyst. The introduced catalysts presented a self-separation performance after reaction, which can be easily recovered and quite steadily reused as confirmed by six-run recycling tests. Moreover, bis sulfoacid-functionalized 1,4-dimethylpiperazinium salt of phosphortungstate showed the best catalytic performance among the prepared catalysts for the oxidation reaction.

Novel SO3H-functionalized phenanthrolinum-phosphotungstate ionic liquid for highly promoted three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones

A novel heteropolyanion-based Bronsted acidic ionic liquid material [PhBS]3PW12O40, butane mono-sulfoacid-functionalized phenanthrolinum salt of phosphortungstate catalyst (PhBS-PW), was synthesized and well characterized with FTIR, 1H and 13C NMR, electro-spray ionization mass spectrometry (ESI-MS), EDX and TG analysis techniques. The new prepared catalyst was used for the efficient one-pot synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives from a three-component condensation reaction between aromatic aldehydes, dimedone, and phthalhydrazide in H2O under thermal conditions. This green approach has several advantages such as short reaction times, clean reaction profiles, and simple experimental and workup procedures. Moreover, the catalyst can be easily recovered and reused at least nine times with only slight reduction in its catalytic activity with no leaching amount of catalyst into the reaction mixture. These economical factors (time, cost, waste, etc.) for this three-component reaction hold promise for the future of organic synthesis. In this work we introduced a new efficient Bronsted acidic ionic liquid (BAIL) and then its catalytic activities have been considered in the three-component synthesis of 2H-indazolo[2,1-b]phthalazine-triones via the domino Knoevenagel condensation/Michael addition/intramolecular cyclodehydration sequence in water under reflux condition.

A sensitive UPLC–ESI–MS/MS method for the quantification of cinnamic acid in vivo and in vitro: application to pharmacokinetic and protein binding study in human plasma

The purpose of this study was to develop a sensitive method for quantifying cinnamic acid in human plasma using UPLC–ESI–MS/MS. Cinnamic acid was separated using water containing 0.005% (v/v) formic acid and acetonitrile as a mobile phase by gradient elution at a flow rate 0.2 mL/min, equipped with a HALO-C18 column (2.1 × 100 mm, 2.7 μm). Quantitation of this analysis was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring negative ion mode. The mass transitions were m/z 146.8 → 103.0 for cinnamic acid, and 432.9 → 225.0 for geniposide as internal standard. Liquid–liquid extraction and protein precipitation with ethyl acetate–methanol-1.2% acetic acid (4/16/1, v/v/v) were used in the sample extraction. The chromatograms showed high resolution, sensitivity, and selectivity with no interference with plasma constituents. The calibration curves for cinnamic acid in human plasma were 0.1–500 ng/mL and displayed excellent linearity with correlation coefficients (r) greater than 0.99. Both the intra- and inter-day precisions (CV%) were within 3.88% for human plasma. The accuracy was 99.34–106.69% for human plasma. In vitro plasma protein binding of cinnamic acid was 64.26 ± 1.89 and 65.50 ± 1.78% for the spiked human plasma concentrations of 100 and 1000 ng/mL, respectively. The developed analytical method satisfied the criteria of international guidance and could be successfully applied to the pharmacokinetic study of cinnamic acid after oral administration of Socheongryong-tang tablets to humans.