Ammonia Buffer Research Articles

Separation of polyphenols by HILIC methods with diode array detection, charged aerosol detection and mass spectrometry: Application to grapevine extracts rich in stilbenoids

The characterization of plant extracts is usually accomplished by reverse-phase liquid chromatography, but the development of new complementary approaches, such as HILIC, offers an orthogonal method. In this study, five HILIC stationary phases were evaluated to assess their ability to retain polyphenols. They were selected to cover the main different HILIC mechanisms: bare silica; silica with ethylene bridge; neutral amide; amino; zwitterionic. A total of 31 polyphenol standards were used for the screening, including 9 stilbenes, 8 flavonoids, 6 anthocyanins, and 8 phenolic acids. Three different detections were tested: diode array detector, charged aerosol detector and mass spectrometry.Results indicated that silica supports were not suitable for retaining polyphenols, with no or low retention observed except for anthocyanins. The effectiveness of stationary phases in retention of phenolics following the order related to increased retention: zwitterionic, amide, and amino.The choice of mobile phase also influenced retention. Mobile phases containing TFA as pH modifier limited retention, while formic acid was found to be more effective for polyphenol retention. Ammonium buffers also improved retention but often compromised peak shape. pH changes mainly impacted ionizable compounds, such as phenolic acids, by increasing their retention when they were ionized.DAD was wellsuited for detecting polyphenols that possess aromatic rings, though peak wavelengths depend on the structures of the polyphenols. CAD, while less sensitive than DAD and MS, provided an almost similar response for structurally related compounds, even with gradient elution. MS was the preferred detector for quantification when resolution between compounds was challenging, as it is often the case with natural extracts.The study successfully demonstrated that best HILIC conditions were obtained using an amino stationary phase composed of a polyethylenimine and formic acid-based mobile phase. These conditions were successfully applied to the analysis of stilbenoid-rich extracts from different parts of the vine. The elution order of stilbenoids followed the degree of polymerization. With CAD, the chromatographic profile was more representative of sample composition. It was demonstrated for the first time the interest of a combination of HILIC and CAD for analyzing stilbenes, offering a complementary approach to the classic RP analysis.

PREPARATION OF DEEP EUTECTIC SOLVENTS FOR MAKING AN OIL-DISPLACING COMPOSITION BASED ON TETRAHYDROXY ALCOHOL, CARBAMIDE, QUATERNARY AMMONIUM SALT, AND A SURFACTANTS

The binary systems of deep eutectic solvents (DESs) have been synthesised and investigated: tetraxydroxy alcohol - a salt of a quaternary ammonium base (DES1), tetrahydroxy alcohol - carbamide (DES2), a salt of a quaternary ammonium base - carbamide (DES3), and the ternary system tetrahydroxy alcohol - a salt of a quaternary ammonium base - carbamide (DES4). Eutectic compositions of binary systems DES1, DES2 and DES3 are characterised by significantly lower pour/melting points than those of the initial components. The lowest pour point among the binary mixtures is that of eutectic composition DES3. The ternary system is characterised by an even lower melting point (-14 °C), which is associated with the formation of intermolecular donor-acceptor hydrogen bonds within the system. An aqueous solution of DES4 with the concentration of 26 wt% was prepared, and its pH value was determined depending on temperature during preparation. At room temperature, pH of three-component DES is 6.6-7.1, but after thermostating for 6 h at 150 °C pH increases to 9.2 due to carbamide hydrolysis. It is assumed that further on, using DES4 as the basis for an alkaline oil-displacing composition directly in the reservoir, under the influence of the temperature of injected heat carrier, CO2 is formed, along with the ammonia buffer system with the maximal buffer capacity within the pH range 9-10. Resulting carbon dioxide, dissolving predominantly in oil, will cause a decrease in its viscosity, on the one hand, while the formed alkaline medium, being most favourable for surfactant performance due to a decrease in interfacial tension, liquefaction of high-viscosity layers or films at the oil-water-rock boundaries, on the other hand, will ensure efficient use of this system for oil displacement. In addition, the oil-displacing composition based on DES4 will be low-solidifying, which opens the possibility of its transportation and use in the northern regions and the Arctic zone.

Physico-chemical characteristics of Ca/P ratio on the composition and structure of oxygenated apatite

Phosphocalcic apatites have osteoconductive and bioactive properties that make them suitable for bone reconstruction. But, they are inactive against pathogenic microorganisms that can infect bone tissue. To overcome this limitation, we synthesized oxygen-doped phosphocalcic apatites that can release molecular oxygen as a bioactive molecule. We investigated how the calcium-to-phosphorus ratio (Ca/P) gave impacts on the chemical and structural composition of the oxygen-doped phosphocalcic apatites. We here used the double decomposition method, which involved mixing calcium nitrate and diammonium phosphate solutions in an ammonia buffer. We then characterized the products using several analysis, including infrared absorption spectroscopy, X-ray diffraction, thermal analysis, nitrogen adsorption-desorption, and elemental chemical analysis. It was found that the oxygen-doped phosphocalcic apatites were calcium-deficient and had a well-defined crystallinity at room temperature. After calcination at 900°C, the crystallinity improved further. The thermal analysis showed two mass losses: one at 50°C due to water adsorption and another at 450°C due to CO2 release. The specific surface area was about 100 ± 2 m2/g without any change with the Ca/P ratio. The quantity of molecular oxygen increased with the Ca/P ratio and reached an optimal value of the order of 3.6 ×10-4 mol for Ca/P=1/65 with the chemical formula of Ca9.9(PO4)6(OH)1.25(O2)0.74(CO3)0.01. It is important to make further analysis to know more about the properties of oxygenated apatite, and to combine this apatite with polymers purposely to have biomedical composites. It then can be concluded that the oxygen-doped phosphocalcic apatites could be a promising biomaterial for bone infection prevention and treatment. This research highlights an oxygenation treatment of phosphocalcic apatite and brings new ideas and possibilities for future research and development to get better understanding of the behavior of these biomaterials to be more effective, especially in the biological field. As a perspective, improving the biological properties in these biomaterials needs to be further explored, including experimental parameters for the obtainment of more conclusive results.

Multi-criteria-based decision-making assessment for anaerobic digestion of ammonia-rich distillery wastewater: Effect of pyrochar and temperature

Energy-efficient wastewater treatment units are imperative to achieve carbon neutrality and a circular economy at the industrial scale. In the present study, pyrochar loading and digestion temperature were tested to assess their impact on the performance of an anaerobic digester running on distillery wastewater. The digestion temperature (37 °C and 55 °C) and pyrochar loading (7.5 – 30 g/L.feed) were selected as two primary design factors. Experiments were designed using Taguchi’s design of experiments and specific methane yield, total ammonia nitrogen, pH and buffering capacity were selected as experimental outputs for multi-criteria assessment. The results from the confirmation test indicated that the addition of pyrochar (7.5 g/Lfeed) improved the methane yield (276 ± 15 L/kg VS) significantly compared to the control (167 ± 15 L/kg VS) at 37 °C. The detailed post-digestion analysis showed that the adsorption of ammonia on pyrochar may be the primary reason for enhanced digester performance.

Smart colorimetric sensing films based on carboxymethyl cellulose incorporated with a natural pH indicator

This study aimed to combine various natural pH indicators of anthocyanin from Karanda (CA) with anthocyanin from butterfly pea flower (BA) or curcumin (CC) to improve the sensitivity of CA. CA75/BA25 and CA25/CC75 enhanced the sensitivity of the endpoint colour change of CA. A smart colorimetric sensing film was also developed and characterised by loading different natural pH indicators on carboxymethyl cellulose (CMC) films. The addition of different natural pH indicators increased the thickness, elongation, colour (a* and b* values), and contact angle of CMC films (p < 0.05). However, the tensile strength, water vapour permeability, film solubility, light transmission, and L* value decreased when different natural pH indicators were added (p < 0.05). The indicator films demonstrated enhanced antioxidant capacity and thermal stability. The FTIR spectra showed that natural pH indicators were successfully immobilised into the CMC films. Notably, the CMC/CA75/BA25 film was the most sensitive film to changes in volatile ammonia and different pH buffer solutions. The CMC/CA75/BA25 film changed from purple to green with exposure to ammonia solution and from pink to purple to blue to green with increasing pH. Therefore, the CMC/CA75/BA25 film has potential as a colorimetric sensing film, providing a more accurate assessment result.

Identifying routes for transferring spin polarization from parahydrogen to protic solvents.

Repeatable hyperpolarization of high concentrations of mobile protons (>6 M) using parahydrogen in protic methanol/water mixtures is reported here. Different ammonium buffers with increasing mobile proton concentrations were added to an IrCl(COD)(IMes) catalyst in the presence of pyridine. We reach a maximum molar polarization of 1.79 mM at 6 mT. Field-cycling experiments in an 18.8 T detection field distinguished two solvent polarization transfer pathways: chemical exchange with labile protons from ammonia and cross-relaxation with pyridine aromatic protons.

Carbon Paste Electrodes Surface-Modified with Surfactants: Principles of Surface Interactions at the Interface between Two Immiscible Liquid Phases.

Carbon paste electrodes ex-situ modified with different surfactants were studied using cyclic voltammetry with two model redox couples, namely hexaammineruthenium (II)/(III) and hexacyanoferrate (II)/(III), in 0.1 mol L-1 acetate buffer (pH 4), 0.1 mol L-1 phosphate buffer (pH 7), and 0.1 mol L-1 ammonia buffer (pH 9) at a scan rate ranging from 50 to 500 mV s-1. Distinct effects of pH, ionic strength, and the composition of supporting media, as well as of the amount of surfactant and its accumulation at the electrode surface, could be observed and found reflected in changes of double-layer capacitance and electrode kinetics. It has been proved that, at the two-phase interface, the presence of surfactants results in elctrostatic interactions that dominate in the transfer of model substances, possibly accompanied also by the effect of erosion at the carbon paste surface. The individual findings depend on the configurations investigated, which are also illustrated on numerous schemes of the actual microstructure at the respective electrode surface. Finally, principal observations and results are highlighted and discussed with respect to the future development and possible applications of sensors based on surfactant-modified composited electrodes.

Multi-Timescale Trading Strategy for Renewable Power to Ammonia Virtual Power Plant in the Electricity, Hydrogen, and Ammonia Markets

Renewable power to ammonia (RePtA) is a prominent zero-carbon pathway for decarbonization. Due to the imbalance between renewables and production energy demand, the RePtA system relies on electricity exchange with the power grid. Participating in the electricity market as a virtual power plant (VPP) may help to reduce energy costs. However, the power profile of local photovoltaics and wind turbines is similar to those in the market, resulting in rising energy costs under the conventional strategy. Hence, we develop a multi-timescale trading strategy for the RePtA VPP in the electricity, hydrogen, and ammonia markets. By utilizing the hydrogen and ammonia buffer systems, the RePtA VPP can optimally coordinate production planning. Moreover, we find it possible to describe the trading of electricity, ammonia, and hydrogen in a unified timeframe. The two-stage robust optimization model of the electricity market is extended to multiple markets and solved by the column and constraint generation (CC&G) algorithm. The case is derived from an actual project in the Inner Mongolia Autonomous Region. Sensitivity analysis demonstrates the economic advantages of the RePtA VPP joining multiple markets over the conventional strategy and reveals the necessity of the hydrogen and ammonia buffer and reactor flexibility.

Techno-economic optimization of renewable urea production for sustainable agriculture and CO2 utilization

Urea is the most used nitrogen fertilizer due to its ease of storage, transportation, and application. It is made by combining ammonia and carbon dioxide (CO2), both of which are produced predominantly from fossil fuels at present. The recent momentum behind ammonia production using renewable-powered electrolysis offers an opportunity to both make urea in a more sustainable way and utilize CO2 from external sources. In this work, we present a techno-economic optimization model to minimize the cost of making urea in this way. The model allows for time-varying chemical production in response to renewable variability by simultaneously optimizing production facility design and hourly operation. We performed a case study for Minnesota considering the use of byproduct CO2 from bioethanol production. We found that the present-day levelized cost of renewable urea is between $268 mt−1 and $413 mt−1 at likely implementable production scales up to 250 000 mt yr−1. This is within the range of historical conventional urea prices while offering at least 78% carbon intensity reduction. Projecting to 2030, there is a clear economic case for renewable urea production with levelized cost as low as $135 mt−1 due to technology improvement and electrolysis manufacturing expansion, facilitating a urea production scale increase to 525 000 mt yr−1. Optimal facilities use wind energy, with hydrogen and ammonia production operating in a flexible, time-varying way to minimize battery and hydrogen storage capacities. Urea production operates near steady state due to the relatively low cost of intermediate ammonia buffer storage. A mix of imported methane and locally produced hydrogen are used to provide heat for steam consumed in the urea synthesis.

Modeling and simulation of dynamic characteristics of a green ammonia synthesis system

Green ammonia production system driven by renewable electricity will be under frequent dynamic operation due to the fluctuation of renewable energy. The nonlinear dynamic model of a green ammonia synthesis system is developed and the dynamic responses of PEM (proton exchange membrane) electrolysis subsystem, PSA (Pressure swing adsorption) subsystem and ammonia synthesis subsystem during the start-up process and under the fluctuation of renewable electrical current are analyzed. The start-up dynamic results show that the hydrogen production rate of PEM electrolysis system is positively correlated to the current. The nitrogen output of PSA system is affected by the adsorption time, adsorption pressure, bed length, and air velocity. A start-up period of 300 min from the warmed-up state to the design state can maintain the temperature rise rate of the ammonia synthesis reactor at approximately 40 K/h. The dynamic results under step fluctuations of electrical current show that the PEM electrolysis subsystem and the PSA subsystem response fast compared to the ammonia synthesis reactor and buffer tanks. Using large buffer tanks to smooth the fluctuation allows the system to slide with the variation of renewable current to some extent, resulting in a higher outlet ammonia fraction when the current increases. Different volume ratios of the hydrogen tank to the nitrogen tank volume can lead to different variations of the hydrogen/nitrogen ratio. PID controllers can effectively maintain the bed temperatures, hydrogen/nitrogen ratio, and pressure of the ammonia synthesis reactor at their set points despite fluctuations in renewable electrical current. Buffer tanks are necessary to compensate for the imbalance between the flow rate fluctuation caused by current change and the flow rate regulation caused by PID controllers.

Optimization of chromatographic buffer conditions for the simultaneous analysis of phosphatidylinositol and phosphatidylinositol phosphate species in canola.

The phosphatidylinositols and phosphatidylinositol phosphates are a set of closely related lipids known to influence various cellular functions. Irregular distributions of these molecules have been correlated with the development and progression of multiple diseases, including Alzheimer's, bipolar disorder, and various cancers. As a result, there is continued interest regarding the speciation of these compounds, with specific consideration on how their distribution may differ between healthy and diseased tissue. The comprehensive analysis of these compounds is challenging due to their varied and unique chemical characteristics, and current generalized lipidomics methods have proven unsuitable for phosphatidylinositol analysis and remain incapable of phosphatidylinositol phosphate analysis. Here we improved upon current methods by enabling the sensitive and simultaneous analysis of phosphatidylinositol and phosphatidylinositol phosphate species, whilst enhancing their characterization through chromatographic resolution between isomeric species. A 1mM ammonium bicarbonate and ammonia buffer was determined optimal for this goal, enabling the identification of 148 phosphatidylinositide species, including 23 lyso-phosphatidylinositols, 51 phosphatidylinositols, 59 oxidized-phosphatidylinositols, and 15 phosphatidylinositol phosphates. As a result of this analysis, four distinct canola cultivars were differentiated based exclusively on their unique phosphatidylinositide-lipidome, indicating analyses of this type may be of use when considering the development and progression of the disease through lipidomic profiles.

Long-term performance on volatile fatty acids production improved in a kitchen wastewater fermenter by co-fermentation of sludge and membrane separation

Kitchen wastewater can be transformed into a valuable resource through anaerobic fermentation. However, the efficiency of this process is hindered by various factors including salt inhibition and nutrient imbalance. In this study, we examined the effects of co-fermentation with sludge and membrane filtration on the anaerobic fermentation of kitchen wastewater. Our findings indicate that co-fermentation with sludge resulted in a 4-fold increase in fermentation rate and a 2-fold increase in short-chain fatty acids (SCFAs) production. This suggests that the addition of sludge helped to alleviate salt and acid inhibition through ammonia buffering and elemental balancing. The membrane filtration retained 60% of soluble carbohydrates and 15% of proteins in the reactor for further fermentation and recovered nearly 100% of NH4+ and SCFAs in the filtrate, which helped to alleviate acid and ammonia inhibition. The combined fermentation system significantly increased the richness and diversity of microorganisms, particularly caproiciproducens and Clostridium_sensu_stricto_12. The membrane flux remained stable and at a relatively high level, indicating that the combined process may be economically feasible. However, scaling up the co-anaerobic fermentation of kitchen wastewater and sludge in a membrane reactor is necessary for further economic evaluation in the future.

Effects of citrulline on endurance performance in young healthy adults: a systematic review and meta-analysis.

Citrulline is a popular dietary supplement, primarily thought to exert ergogenic effects on exercise performance through the enhancement of nitric oxide (NO) synthesis and ammonia buffering. However, recent findings surrounding citrulline's effect on endurance performance have been inconsistent. A systematic review and meta-analysis of the relevant literature have yet to be undertaken. To determine if acute ingestion of citrulline has an ergogenic effect on endurance performance in young healthy adults. A systematic search of three databases was undertaken to find peer-reviewed randomized controlled trials (RCTs) published in English investigating the effects of citrulline supplementation on endurance performance in young healthy adults. Two independent investigators completed a three-phased screening procedure against pre-determined eligibility criteria. Included studies evaluated loading or bolus dosage regimes of citrulline in participants aged 18 or over that were at least recreationally active. Outcome measures focused on time-to-completion (TTC) or time-to-exhaustion (TTE) in continuous submaximal intensity exercise. Cochrane's Risk of Bias 2 (RoB 2) tool was used to assess the risk of bias in individual studies. Meta-analysis was conducted using a fixed-effects model to pool the weighted estimate of standardized mean differences (SMD) across studies. A chi-squared test assessed heterogeneity between studies. This review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Nine studies (n = 158 participants) met the eligibility criteria; five reported TTE outcomes (I2 = 0%, χ2 = 0.37, df = 4, P = 0.99) and four reported TTC outcomes (I2 = 0%, χ2 = 0.46, df = 3, P = 0.93), both with a low between-study heterogeneity. The results of the meta-analyses showed no significant difference in the endurance performance measures, TTE (pooled SMD = 0.03 [-0.27, 0.33]) and TTC (pooled SMD = -0.07 [-0.50, 0.15]), after acute ingestion of citrulline supplementation or a control in young healthy adults. The current evidence suggests no significant benefit of citrulline supplementation for endurance performance. However, the small evidence base requires further research to fully evaluate this topic. Recommendations include a focus on female populations; higher continuous doses of citrulline over seven days; and TTC outcome measures over longer distances to simulate competition.

Bimetallic BaTiO3 and Cu nanoparticle synthesis via pulsed laser ablation in liquid of powder targets

Laser processing has become a viable method of synthesising bimetallic and biomolecule-free nanoparticles. Laser processing enable for different materials to be processed via the same laser system with ease, unlike chemical and biological methods that require special equipment/organisms for each material. The objective of this paper is to study the laser processing of powders for the fabrication of nanoparticles of various types, shapes, sizes and concentration. A Nd:YAG 1064 nm laser system was used to perform ablation processes of Cu and BaTiO3 powders under isopropyl alcohol, hydrochloric acid and ammonium buffer solution. This produced nanoparticles of various shapes including rods, spheres and pyramids and various sizes (14–280 nm). The effect of the laser processing parameters such as hatch spacing (10 or 30 μm) and scan speed (2 or 3 m/s) were examined. These processing parameters are seldom studied in the literature. Furthermore, this paper describes a way to produce nanoparticles from powder targets instead of the conventional rod, plate or thin film targets that are difficult to reuse. However, powders are compatible with a limited number of liquids than rods, plates and thin films and this issue is addressed herein.

Electrochemical sensing platform based on Zeolite/Graphite/Dimethylglyoxime nanocomposite for highly selective and ultrasensitive determination of nickel

In this work, the fabrication and analytical application of a novel, unique, mercury-free, and user-friendly voltammetric sensor of Ni(II) based on glassy carbon electrode (GCE) modified with zeolite(MOR)/graphite(G)/dimethylglyoxime(DMG) composite (MOR/G/DMG-GCE) and the voltammetric procedure for highly selective, ultra-trace determination of nickel ions were reported for the first time. Deposition of a thin layer of the chemically active MOR/G/DMG nanocomposite enables the selective and effective accumulation of Ni(II) ions in the form of the DMG-Ni(II) complex. In 0.1 mol L−1 ammonia buffer (pH 9.0), the MOR/G/DMG-GCE exhibited linear response in the Ni(II) ions concentration range of 0.86 − 19.61 µg L−1 and 0.57 − 15.75 µg L−1, for the accumulation time of 30 s and 60 s, respectively. For 60 s of accumulation time, the limit of detection (S/N = 3) was 0.18 µg L−1 (3.04 nM), and sensitivity of 0.202 µA L µg−1 was achieved. The developed protocol was validated by the analysis of wastewater certified reference materials. Its practical usefulness was confirmed by the determination of nickel released from metallic jewelry submerged in artificial sweat and stainless steel pot during water boiling. The obtained results were verified by electrothermal atomic absorption spectroscopy as a reference method.

A novel integrated circular economy approach in green synthesis of copper oxide nanoparticles from waste printed circuit boards and utilization of its residue for preparation of carbon engulfed nano polymer membrane

Electronic waste is a major threat to our environment. Handling and recycling of electronic waste towards the circular economy is a tedious process. Researchers are trying to enhance the existing recycling techniques to improvise the process for better efficiency and also to result in lower by-products. Pre-treatment of Waste Printed Circuit Board (WPCB) using sodium hydroxide solution as solvent under autoclaving conditions results in 100% of epoxy removal efficiency. Further, the selective leaching process of WPCB utilizing ammonium chloride solution and ammonia buffer solution, reduced with the help of Cathantharaus roseus plant leaf extract, clears the way for the generation of copper oxide nanoparticles. Synthesized nanoparticles are separated by repeated centrifugation at 10000 rpm for 30 min using sterile distilled water, then drying it in a hot air oven for 2 h. Samples are characterized using HRTEM and FESEM-EDX. The residual thermoset of WPCB is muffle treated at 550 °C for 3 h to get desired carbon forms and is characterized using Raman spectroscopy, FESEM-EDX. Grounded carbon forms are utilized for synthesizing carbon-engulfed polyvinyl alcohol (PVA) membrane using electro-spinning, which finds its application in dye removal. Synthesized nano-sized polymer membrane is characterized using TGA, FESEM-EDX, FTIR and tensile strength through Universal Testing Machine.

Validated LC-MS method for the estimation of genotoxic nitroso amines impurities in empagliflozin

Background: Nitrosamine impurities are known to be mutagenic and carcinogenic, and even minor exposure to these impurities can result in genotoxicity. Objective: The objective of this study was to develop and validate simple, robust and accurate Liquid Chromatography coupled with Mass spectroscopy (LC-MS) method for estimation of nitroso amine impurities [N-nitroso dimethyl amine (NDMA), N-nitroso diethylamine (NDEA), N-nitroso ethyl isopropylamine (NEIA), N- Nitroso diisopropylamine (NDIPA)] in empagliflozin. Method &amp; Results: Aqueous ammonia buffer (0.10%) in a mixture of methanol (5:95 v/v), flow rate, and injection volume were 0.4mL/min, 20µL, respectively. Linearity was observed in the concentration range of 0.05-0.5 ppm (r2 =1). The retention time of NDMA, NDEA, NEIA and NDIPA were 6.412, 7.172, 7.486 and 7.719, respectively. The method was validated according to ICH guidelines with good reproducibility, and the limits of detection were 0.03 ppm for NDMA, NEIA and NDIPA and 0.02 ppm for NDEA, respectively. The limit of quantitation for NDMA, NEIA and NDIPA was 0.09 ppm and 0.06 ppm for NDEA, respectively. Conclusion: The proposed method is helpful for the best analysis of nitrosamine impurities in dosage forms of empagliflozin within a shorter duration of time.

Sensitive liquid chromatography/tandem mass spectrometry method for the simultaneous determination of seventeen beta blockers

In recent years, examples of drugs responsible for acute drug intoxication in elderly people include benzodiazepines, phenobarbital, digitalis preparations, phenytoin, beta blockers or calcium antagonists, and antidepressants in Japan. Due to the diversity of underlying diseases, the reasons for this include increasing number of prescription medicines due to regular oral medicines themselves interacting, and age-related changes in drug metabolism. Beta blockers for clinical use are employed in the management of a range of disorders, including hypertension, heart failure, arrhythmias, migraine headache and tremor. Beta blockers are prescribed widely and also have a high frequency of accidental ingestion by the elderly people. Cardiovascular drugs (beta blockers) present more serious symptoms of intoxication than the underlying diseases themselves. The aim of this study is to develop and validate a sensitive liquid chromatography–tandem mass spectrometry (LC-MS/MS) with ESI method for the simultaneous determination of seventeen beta blockers (atenolol, carteolol, nadolol, pindolol, timolol, acebutolol, arotinolol, metoprolol, esmolol, celiprolol, labetalol, bisoprolol, propranolol, alprenolol, betaxolol, bevantolol and carvedilol). The extractions of beta blockers in human serum were performed by solid-phase extraction method using Oasis® PRiME HLB column (Waters). LC-MS/MS experiments were performed with a HPLC system, which consisted of Shimadzu LC-20AD pumps, a SIL-20AC autosampler and the 4000 QTRAP mass spectrometer (AB SCIEX). The chromatographic separation was performed on a Mightysil-RP-18 MS column (150 × 2.0-mm i.d., 5 μm). For the gradient elution, two solvents were used: (A) 10 mM acetic ammonium buffer and (B) acetonitrile. The flow rate was 0.20 mL/min and the column and autosampler were maintained at 37 and 4˚C, respectively. The settings of the turbo ion-spray were as follows; curtain gas, N2:40 psi, collision gas, N2:4 psi, collision energy: 27∼41 V, ion-spray voltage: 5500 V, ionization mode: ESI positive, source temperature: 600˚C. Separation and sensitivity for the detection of seventeen beta blockers by LC-MS/MS were sufficient and the precursor [M + H]+ ion was detected in the mass spectrum for each drug. This method had a chromatographic total run time of 15 min. The calibration curves were linear over the concentration range of 20–400 ng/mL for seventeen beta blockers (r = 0.9686∼0.9997). The extraction yields of human serum sample with Oasis® PRiME HLB column were ranged from 66.1 to 93.5%, the precision within 0.07 CV values were acceptable of this method. But the extraction yields of bevantlol (37.5%) and carvedilol (26.2%) were low. Currently, we are experimenting to improve the extraction yields of bevantolol and carvedilol. Phyo Lwin EM, et al (2017, Bioanalysis.) developed a method for the determination of atenolol in human plasma and milk sample by LC-MS/MS. The limits of detection (LOD) and quantification (LOQ) were in the range 1.0 ng/mL and 5.0 ng/mL for atenolol. Our LC-MS/MS with ESI method was able to measure compounds at approximately the same concentrations as the analytical methods of Phyo Lwin EM, et al. In our experiments, LOD and LOQ in the range 0.0034–1.6 ng/mL and were 20 ng/mL for seventeen beta blockers. The presently established method is very useful for simultaneous measurements of beta blockers in human serum by LC-MS/MS in clinical and forensic investigations.

Effects of homofermentative lactic acid bacteria and powdered molasses on fermentative losses, chemical composition and aerobic stability in whole-plant soybean silage

ABSTRACT This study evaluated the effects of homolactic bacteria and molasses (MOL) in whole-plant soybean silage on dry matter (DM) losses, content of organic acids, bromatological composition, in situ degradation of DM and aerobic stability. Mini-silos (n = 200) were blocked (n = 5) by phenological stage and assigned into a 2×2 factorial treatment arrangement with 2 levels of microbial inoculation (INO, 0 or 105 colony forming units of Lactobacillus plantarum and Pediococcus pentosaceus per kg of fresh forage) and 2 levels of powdered MOL (0 and 40 g/kg fresh forage). Mini-silos were opened after 90 days of fermentation. Total losses were lower in silos with MOL. Whole-plant soybean ensiled with the combination of INO and MOL had the highest DM recovery. Adding MOL increased lactic acid content and decreased ammonia nitrogen content (marker of proteolysis), pH and buffering capacity. MOL reduced the contents of NDF. Silage with both INO and MOL had the highest DM content. MOL increased DM degradation. No effects were detected on aerobic stability. INO does not show positive effects on soybean silage nutritive quality when not associated with MOL. Molasses has a positive impact on whole-plant soybean silage by decreasing fermentation losses and pH, while increasing silage nutritive value.

Recovery of copper from printed circuit board (PCB) acidic etching wastewater: Ammonia regulates the crystallization of high valued copper salt

In electronic and electrical industries, a huge amount of acidic cupric etching wastewater was produced during the manufacture of printed circuit board (PCB). Reclamation of copper is necessary for resource recovery and environmental protection. Herein, ammonia (NH3·H2O) and sodium hydroxide (NaOH) were investigated and compared as neutralizers to regulate the sequential crystallization of basic copper chloride (Cu2(OH)3Cl), copper hydroxide (Cu(OH)2), and copper sulfate (CuSO4·5H2O). Crystal phase and micro-morphology were analyzed by X-ray diffraction and scanning electron microscope; product quality was evaluated by laser particle size analyzer, thermogravimetry, and inductively coupled plasma. The results showed that ammonia as the neutralizer can regulate the formation of spherical Cu2Cl(OH)3 particles with compact surface, good fluidity, and low moisture-absorption-ability, which can be used as a precursor to producing Cu(OH)2 and CuSO4·5H2O with higher purity. Mechanism analysis revealed that ammonia acts as “a storage of OH− and Cu2+” in the aqueous phase due to its weak alkalinity and the ability to complex with Cu2+ to form stable Cu(NH3)n2+. As a result, OH− and Cu2+ were slowly released to the solution and slowed down the crystallization kinetics of copper-containing precipitates. This work proposed a promising and harmless resource recycling method, and also inspired the understanding and utilization of metal crystallization law in the ammonia buffer system.