Bicarbonate-buffered Solution Research Articles

Rapid Mass Spectrometry-Based Multiattribute Method for Glycation Analysis with Integrated Afucosylation Detection Capability.

The multiattribute method (MAM) has emerged as a powerful tool for simultaneously screening multiple product quality attributes of therapeutic antibodies. One such potential critical quality attribute (CQA) is glycation, a common modification that can impact the heterogeneity, functional activity, and immunogenicity of therapeutic antibodies. However, current methods for monitoring glycation levels in MAM are rare and not sufficiently rapid and accurate. In this study, an improved mass spectrometry (MS)-based MAM was developed to simultaneously monitor glycation and other quality attributes including afucosylation. The method was evaluated using two therapeutic antibodies with different glycosylation site numbers. Treatment with IdeS, Endo F2, and dithiothreitol generated three distinct subunits, and the glycation results obtained were similar to those treated with PNGase F, which is routinely used to release glycans; the sample processing time was greatly reduced while providing additional quality attribute information. The MS-based MAM was also employed to assess the glycation progression following forced glycation in various buffer solutions. A significant increase in oxidation was observed when forced glycation was conducted in an ammonium bicarbonate buffer solution, and a total of 23 potential glycation sites and 4 significantly oxidized sites were identified. Notably, we found that ammonium bicarbonate was found to specifically stimulate oxidation, while glycation had a synergistic effect on oxidation. These findings establish this study as a novel methodology for achieving a technologically advanced platform and concept that enhances the efficacy of product development and quality control, characterized by its broad-spectrum, rapid, and accurate nature.

Enhancing energy efficiency and H2 production in lab-scale dual chamber microbial electrolysis cells: A focus on catholyte composition and voltage losses

Microbial electrolysis cells (MECs) have emerged as a promising technology for sustainable hydrogen production from wastewater treatment. An MEC consists of a microbial anode and a hydrogen evolution cathode, where microorganisms in the anode oxidize organic compounds, allowing the cathodic hydrogen production at lower potentials compared to abiotic electrolysis. The present study focuses on optimizing the catholyte composition and configuration in a MEC reactor to maximize hydrogen production rates while minimizing energy consumption. Indeed, buffer solutions of HCO3-, HPO42-, and H2PO4- at different concentrations and operation mode were tested as catholytes analysing hydrogen production rates and energy consumptions of the process. The results demonstrate the stability of the anodic electroactive biofilm over a 220-day period, achieving consistent COD removal and hydrogen production. The findings reveal that the catholyte composition and operating mode significantly affect the cathodic performances of the MEC. Indeed, catholytes with higher buffer concentrations allow for a limited catholyte alkalinisation improving hydrogen production rates while a low buffer solution promotes an increase in process energy consumption. Bicarbonate buffer solution utilized under batch operation mode showed the better performances for hydrogen production at the cathodic side of MECs showing a higher cathodic coulombic efficiency coupled with stable pH levels and cathodic potentials. Overall, this research demonstrates the potential of MECs for sustainable hydrogen production and highlights the importance of optimizing catholyte composition and operating mode to increase energy efficiency of process.

Bicarbonate buffer dissolution test with gentle mechanistic stress for bioequivalence prediction of enteric-coated pellet formulations

This study aimed to develop a dissolution test that can predict the bioequivalence (BE) of enteric-coated pellet formulations. The original duloxetine hydrochloride capsule (reference formulation (RF); Cymbalta® 30 mg capsule) and four generic test formulations (two capsules (CP) and two orally disintegrating tablets (OD)) were used as model formulations. Clinical BE studies were conducted on 24–47 healthy male subjects under fasting conditions. Dissolution tests were performed using a compendial paddle method (PD) (paddle speed: 50 rpm) and a flow-through cell method (FTC) (flow rate: 4 mL/min). For a further test, cotton balls were added to the vessel to apply gentle mechanistic stress to the formulations, and paddle speed was reduced to 10 rpm (paddle with cotton ball method (PDCB)).All the dissolution tests were conducted with 0.01 M HCl (pH 2.0) for 0.5 h followed by 10 mM bicarbonate buffer solutions (pH 6.5) for 4 h. One each of the two CP and two OD showed BE with RF. PDCB was able to discriminate between BE and non-BE formulations, while this was not possible with PD and FTC. In PDCB, the cotton balls intermittently moved the pellets near the vessel bottom. PDCB is useful for predicting BE during formulation development.

Performance of the Dual-Chamber Fungal Fuel Cell in Treating Tannery Wastewater

Fungi are typically expressed as excellent microorganisms that produce extracellular enzymes used in the bioaccumulation phenomenon. In this study, laboratory-scale dual-chamber fungal fuel cells (FFCs) were applied as an alternate approach for the available degradation of complex organic pollutants represented in chemical oxygen demand (COD) and total nitrogen (TN), as well as inorganic pollutants represented as total chromium (Cr), and the generation of bioenergy represented in output voltages (V), power density (PD) and current density (CD), as applied to tannery effluent. Aspergillus niger strain, (A. niger), which makes up 40% of the fungal population in tannery effluent was examined in a training study for efficient hexavalent chromium bioaccumulation, especially in high concentrations. The trained A. niger showed a faster growth rate than the untrained one in broth media containing different loaded chromium concentrations. For an external resistance of 1000 Ω, two FFCs were utilized, one with electrolytic matrices including phosphate buffer solution (PBS) and bicarbonate buffer solution (BBS), and the other without electrolytic matrices, where the energy generation and treatment efficacy of the two dual-chamber FFCs were evaluated for a period of 165 h. At 15 h, the electrolytic FFCs showed a high voltage output of 0.814 V, a power density of 0.097 mW·m−2, and a current density of 0.119 mAm−2 compared to the non-electrolytic FFC. At 165 h, the electrolytic FFCs showed high removal efficiency percentages for COD, TN, and total Cr of up to 77.9%, 94.2%, and 73%, respectively, compared to the non-electrolytic FFC.

Accelerating clinical development of a live attenuated vaccine against Salmonella Paratyphi A (VASP): study protocol for an observer-participant-blind randomised control trial of a novel oral vaccine using a human challenge model of Salmonella Paratyphi A infection in healthy adult volunteers

IntroductionThis is the first efficacy study of an oral live attenuated vaccine against Salmonella Paratyphi A using a human challenge model of paratyphoid infection. S. Paratyphi A is responsible for...

Selection and Evaluation of Model Pollutants for Performance Assessment of Advanced Treatment of Industrial Park Wastewater by Ozonation

Ozonation has gradually become a routine process for advanced wastewater treatment. During the technology innovation on the advanced treatment of wastewater by ozonation, researchers have to assess the performance of abundant new technologies, new reactors, and new materials. However, they are usually puzzled by the rational selection of model pollutants to assess the capability of such new technologies to eliminate the chemical oxygen demand (COD) and total organic carbon (TOC) of practical wastewater. It is unclear how well the various model pollutants reported in the literature could represent the COD/TOC removal of actual wastewater. The rational selection and evaluation of model pollutants for advanced treatment of industrial wastewater is of great significance in establishing the technological standard system for advanced treatment of wastewater via ozonation. Herein, the aqueous solutions (including unbuffered solutions and bicarbonate-buffered solutions) of 19 model pollutants and four practical secondary effluents from industrial parks were investigated through ozonation under identical conditions. The similarity in COD/TOC removal of the above wastewater/solutions were evaluated using mainly clustering analysis. The results showed that the dissimilarity among the model pollutants was greater than that among the actual wastewaters, thus enabling the rational selection of several model pollutants to assess the performance of advanced treatment of wastewater using ozonation by different technologies. The errors of predicting the COD removal of secondary sedimentation tank effluent by ozonation in 60 min using the unbuffered aqueous solutions of ketoprofen (KTP), dichlorophenoxyacetic acid (2,4-D), and sulfamethazine (SMT) were less than 9%, and those using the bicarbonate-buffered solutions of phenacetin (PNT), SMT, and sucralose were less than 5%. The evolution of pH by using the bicarbonate-buffered solutions was more similar to that in practical wastewater than by using unbuffered aqueous solutions. In the similarity evaluation of COD/TOC removal between the bicarbonate-buffered solutions and the practical wastewaters, the results were almost the same whether considering different input ozone concentration conditions. Therefore, the protocol proposed in this study based on similarity evaluation to assess the performance treating actual wastewater could be extended to different ozone concentration conditions with certain universality.

Biogas utilization without desulfurization pretreatment in a bioelectrochemical system

Utilizing biogas as a fuel for heating and power generation usually requires desulfurization pretreatment. In this study, the biogas utilization without desulfurization pretreatment in a bioelectrochemical system (BES) was explored. The results showed that the biogas-fueled BES was successfully started up within 36 d and the presence of hydrogen sulfide promoted both methane consumption and electricity generation. The optimal performance (i.e., a methane consumption of 0.523 ± 0.004 mmol/d, a peak voltage of 577 ± 1 mV, a coulomb production of 37.86 ± 0.43C/d, a coulombic efficiency of 9.37 ± 0.06 % and the maximum power density of 2.070 W/m3) was obtained under bicarbonate buffer solution and 40 °C conditions. The addition of 1 mg/L sulfide and 5 mg/L L-cysteine facilitated methane consumption and electricity generation. In the anode biofilm, the dominant bacteria were Sulfurivermis, unclassified_o__Ignavibacteriales and Lentimicrobium, while Methanobacterium, Methanosarcina and Methanothrix were the predominant archaea. Besides, the metagenomics profiles reveal that anaerobic methane oxidation and electricity generation were closely related to sulfur metabolism. These findings provide a novel approach for utilizing biogas without desulfurization pretreatment.

Evaluation of electroactive denitrifiers at different potentials, temperatures and buffers based on microcalorimetry

Electroactive denitrifiers contribute to the nitrate removal in a bioelectrochemical system, but their metabolism and growth parameters remain vague. In this study, microcalorimetry as a suitable method was used to evaluate the metabolism and growth parameters of electroactive denitrifiers at different cathode potentials, temperatures and buffer solutions. The suitable cathode potential and temperature for electroactive denitrifiers were deemed as −100 mV and 30 °C, respectively. The suitable buffer was found to be phosphate buffer solution but can be replaced by bicarbonate buffer solution. When cultivated with bicarbonate buffer solution at −100 mV and 30 °C, electroactive denitrifiers achieved a specific nitrate removal rate of 2.20 ± 0.08 × 10−10 mg NO3−-N·(min·cell)−1 and two growth rate constants (k1 = 0.0051 ± 0.0004 min−1, k2 = 0.0030 ± 0.0004 min−1), with gaseous nitrogen as the end product. The bioelectrochemical denitrification behaved as a two-step process, in which the nitrite reduction to gaseous nitrogen was the rate-limiting step.

Development of bicarbonate buffer flow-through cell dissolution test and its application in prediction of in vivo performance of colon targeting tablets

The purpose of this study was to develop a bicarbonate buffer flow-through cell (FTC) dissolution test. Mesalazine colon targeting tablets of a generic development product (test formulation, TF; Mesalazine 400 mg tablet) and the original product (reference formulation, RF; Asacol® 400 mg tablet) were used as model formulations. A clinical bioequivalence (BE) study was conducted on 48 healthy male subjects under fasting conditions. The oral absorption time profiles were calculated by point-area deconvolution. The compendial paddle and FTC apparatus were used for dissolution tests. Bicarbonate or phosphate-citrate buffer solutions (McIlvaine buffer) were used as the dissolution media. A floating lid was used to maintain the pH value of the bicarbonate buffer solution in the vessel (paddle) or the reservoir (FTC). In the development of bicarbonate FTC method, the pH changes of bicarbonate buffer solution (pH 5.5–7.5; 5–50 mM bicarbonate) were evaluated. For the evaluation of colon targeting tablets, the dissolution profiles of TF and RF were measured at a pH of 7.5. The TF and RF formulations were exposed to 0.01 HCl (pH 2.0) for 2 h before pH 7.5. In the clinical BE study, drug dissolution started 4–8 h after oral administration and continued slowly more than 10 h. Both the area under the curve (AUC) and maximum plasma concentration (Cmax) of TF were approximately twice as high as those of RF. In the development of the bicarbonate FTC method, the pH change of the bicarbonate buffer solution was suppressed by the floating lid within ∆pH < 0.1 over 10 h. In the dissolution test of McIlvaine buffer solutions, TF and RF showed faster disintegration and higher dissolution than those observed in the clinical BE study. When using the paddle apparatus the dissolution profiles of TF and RF in both buffer solutions were not consistent with those of the clinical result. In bicarbonate FTC, the disintegration time, dissolution rate, and dissolution inequivalence between TF and RF were consistent with the results of the clinical BE study. In conclusion, the bicarbonate FTC method was constructed for the first time in this study. This method is simple and practically useful for predicting in vivo performance of colon targeting tablets during drug development.

Comparison of Performance of Conventional Ozonation and Heterogeneous Catalytic Ozonation Processes in Phosphate- and Bicarbonate-Buffered Solutions

Comparison of Performance of Conventional Ozonation and Heterogeneous Catalytic Ozonation Processes in Phosphate- and Bicarbonate-Buffered Solutions

A comparative study on the energy generation through wastewater purification in microbial fuel cell

Rapid depletion of fossil fuel resources because of increase in energy demands and increasing of climate change phenomena due to global warming by green-house gases have raised demand for cleaner energy. Therefore, probing a simple and cost-effective electrochemical energy conversion and treatment technology is a promising as well as an alternative to produce power through the treatment of wastewater. The Microbial Fuel Cell (MFC) is thus an emerging technology device to treat wastewater and simultaneously producing green energy and reducing the energy crisis and global warming. This novel technology is cost effective as well as proves itself as an alternative energy source for off-grid power solutions.One of the major drawbacks for producing electricity from wastewater is that it’s low buffering capacity. A buffer is added to maintain pH, thus decreasing the voltage efficiency in microbial systems. In this study, the performance of the Single Chamber MFC is reported for the sodium bicarbonate buffer solution for the treatment of wastewater. Moreover, the results were compared with the various buffer solution as reported elsewhere. The different types of buffer solutions were compared like Phosphate Buffer Solution (PBS), Borax Buffer Solution, and Bicarbonate Buffer Solution to improve production of electrical energy. This communication tries to highlight the comparison of quantity, effectiveness, removal of Chemical Oxygen Demand (COD) and analysis of free proton transfer rates, rate of diffusion and the electricity generated by different buffer solution. The optimum power density was found to be 50.25 mW/cm2 for the sodium bicarbonate buffer solution. A comparison among three types of Proton Exchange Membrane also make us aware of the power outputs in microbial fuel cells.

Dissolution Kinetics of Nifedipine-Ionizable Polymer Amorphous Solid Dispersion: Comparison Between Bicarbonate and Phosphate Buffers.

The intestinal fluid pH is maintained by the bicarbonate buffer system that shows unique properties regarding drug dissolution. Nevertheless, current compendial dissolution tests use phosphate buffers. The purpose of the present study was to investigate the effect of bicarbonate and phosphate buffers on the dissolution profiles of amorphous solid dispersions (ASD) composed of ionizable polymers. Hydroxypropylmethylcellulose acetate succinate (HPMCAS), amino methacrylate copolymer (AMC), and hydroxypropylmethylcellulose (HPMC) were employed as acidic, basic, and neutral polymers, respectively. Nifedipine (NIF) was used as a model drug. Dissolution profiles were measured in pH 6.5 bicarbonate and phosphate buffers by a mini-scale paddle dissolution test. The pH of bicarbonate buffers was maintained by the floating lid method. The pH change of the bicarbonate buffer was suppressed to less than + 0.25 pH for 3h by the floating lid method. In all cases, the NIF concentration was supersaturated against the solubility of crystalline NIF. The dissolution rates of HPMCAS and AMC ASDs were 1.5 to 2.0-fold slower in the bicarbonate buffer than in the phosphate buffer when compared at the same buffer capacity. The dissolution profile of HPMC ASD was not affected by the buffer species. The higher the buffer capacity and ionic strength, the faster the dissolution rate of HPMCAS ASD. The dissolution rate of ASDs with ionizable polymers would be overestimated by using unphysiological phosphate buffer solutions. It is important to use a biorelevant bicarbonate buffer solution for dissolution testing.

Short communication: Saliva and salivary components affect goat rumen fermentation in short-term batch incubations

The research about the role of saliva in ruminants has been mainly focused on its buffering capacity together with facilitation of the rumination process. However, the role of salivary bioactive components on modulating the activity of the rumen microbiota has been neglected until recently. This study developed an in vitro approach to assess the impact of different components in saliva on rumen microbial fermentation. Four different salivary fractions were prepared from four goats: (i) non-filtrated saliva (NFS), (ii) filtrated through 0.25 µm to remove microorganisms and large particles (FS1), (iii) centrifuged through a 30 kDa filter to remove large proteins, (FS2), and (iv) autoclaved saliva (AS) to keep only the minerals. Two experiments were conducted in 24 h batch culture incubations with 6 ml of total volume consisting of 2 ml of rumen fluid and 4 ml of saliva/buffer mix. In Experiment 1, the effect of increasing the proportion of saliva (either NFS or FS1) in the solution (0%, 16%, 33% and 50% of the total volume) was evaluated. Treatment FS1 promoted greater total volatile fatty acids (VFA) (+8.4%) and butyrate molar proportion (+2.8%) but lower NH3-N concentrations than NFS fraction. Replacing the bicarbonate buffer solution by increasing proportions of saliva resulted in higher NH3-N, total VFA (+8.0%) and propionate molar proportion (+11%). Experiment 2 addressed the effect of the different fractions of saliva (NFS, FS1, FS2 and AS). Saliva fractions led to higher total VFA and NH3-N concentrations than non-saliva incubations, which suggests that the presence of some salivary elements enhanced rumen microbial activity. Fraction FS1 promoted a higher concentration of total VFA (+7.8%) than the other three fractions, and higher propionate (+26%) than NFS and AS. This agrees with findings from Experiment 1 and supports that ‘microbe-free saliva’, in which large salivary proteins are maintained, boosts rumen fermentation. Our results show the usefulness of this in vitro approach and suggest that different salivary components can modulate rumen microbial fermentation, although the specific metabolites and effects they cause need further research.

A234 EVALUATING THE EFFECT OF STOOL SUPERNATANTS FROM IBS PATIENTS AND HEALTHY CONTROLS ON THE EXCITABILITY OF DRG NEURONS

Abstract Background Abdominal pain is commonly described in chronic disorders such as irritable bowel syndrome (IBS), but the underlying mechanisms are currently unclear. The stool metabolomic and microbiota profiles of IBS and healthy patients have shown distinct differences. Additionally, IBS stool supernatants have previously been demonstrated to induce hypersensitivity of nociceptive nerves in the ex vivo mouse colon, suggesting that mediators in the stool can sensitize nociceptors. However, the effects of healthy control (HC) or IBS patient stool supernatants on the excitability of DRG neurons have not been clarified. Aims To evaluate the effect of HC and IBS supernatant on DRG neurons. Methods HC (n=8 patients) or IBS (n=10 patients) stool was collected, dissolved and homogenized with bicarbonate-buffered Krebs solution at 37°C in a 1/10 dilution. DRG neurons from C57BL/6 mice were dissociated and incubated overnight with HC or IBS supernatant in a Krebs dissolution. Changes in DRG neuronal excitability were recorded using perforated patch-clamp techniques to measure the rheobase (amount of current needed to elicit an action potential). The effect of the IBS and HC stool supernatants on the resting membrane potential (RMP) was also recorded. Results Overnight incubations with supernatant of HC stool diluted in Krebs solution (n=28 neurons) did not significantly decrease the rheobase compared to control neurons (n=22) (62.7 ± 3.9 pA vs 64.2 ± 2.7 pA). In a parallel experiment, we evaluated the effect of IBS stool supernatants diluted in Krebs (n=52 neurons) and found that they significantly decreased the rheobase compared to the supernatant of HC diluted in Krebs and control neurons (52.3 ± 2.3; p&amp;lt;0.05). The data were analyzed with a one-way ANOVA and Tukey’s test. Incubations with IBS supernatant decreased the RMP compared to HC supernatant (-42.6 ± 0.6 mV vs. -46.0 ± 0.9 mV; p&amp;lt;0.01), which was calculated with an unpaired t-test. Conclusions These findings suggest that mediators in IBS stool increase the excitability of DRG neurons compared to HC stool supernatant, and thus may contribute to pain signaling in IBS patients. Funding Agencies CIHR

Intraoperative Cell Saving: Is the Solution the Actual Problem?

Allogenic blood is a scarce, precious, and expensive resource that is not always available on demand. After termination of cardiopulmonary bypass, a large amount of residual pump blood remains in the extracorporeal circuit. The cell saver washes and concentrates this blood with .9% normal saline (NS), making autologous blood available and reducing the demand for allogenic blood. To quantify the quality of residual pump blood it was washed with either NS or a bicarbonate-buffered solution (Balsol). A qualitative in vitro analysis was conducted. Residual cardiopulmonary bypass blood from forty bypass circuits was processed with a cell saver device, using NS or Balsol solution. Measurements made compared the pH, electrolytes, metabolites, hematocrit, hemoglobin, osmolality, albumin, total protein, and strong ion difference. There were significant differences between the NS and Balsol groups. In the Balsol group, osmolality, electrolytes, and strong ion difference were similar to the constitution of Balsol solution after washing, but not with the normal saline group. Washing residual cardiopulmonary bypass pump blood with Balsol solution results in a resuspended red cell concentrate with a superior electrolyte profile and a strong ion difference similar to that of residual pump blood.

Simple bicarbonate buffer system for dissolution testing: Floating lid method and its application to colonic drug delivery system

In this study, we developed a simple and easy method to use bicarbonate buffer solutions for dissolution tests. A floating lid was newly introduced to prevent the evaporation of CO2 from bicarbonate buffer solutions (the floating lid method). This method was used to evaluate the dissolution profiles of 5-aminosalicylic acid (5-ASA) colonic delivery tablets with a pH-sensitive film coating (5-ASA CDT) (Asacol® 400 mg tablet and the generic products A and B). A sodium bicarbonate solution was added to the dissolution test vessel, covered with the floating lid made of foamed styrol, and adjusted to each pH with an HCl solution (total 500 mL, 2–50 mM, pH 6.0 to 7.5). Without the floating lid, the pH value increased by more than one pH unit within 3.5 h. The floating lid suppressed the increase in pH to less than 0.1 pH unit at 3.5 h and 0.7 pH unit at 22 h. According to the drug product information, all 5-ASA CDTs show similar disintegration times (approximately 0.5 h) and release profiles in the diluted McIlvaine buffer (pH 7.5, 50 mM phosphate, 25 mM citrate). However, in the bicarbonate buffer (pH 7.5, 10 mM), the disintegration time was prolonged to 4.3 h for Asacol®, 8.0 h for generic A, and 7.6 h for generic B. The floating lid method would be useful for formulation development.

Growth performance of heat stressed rabbits fed diets supplemented with synthetic and organic antioxidants

The aimof the studywas to evaluate the growth performance of heat stressed rabbits fed diets supplemented with synthetic and organic antioxidants. The antioxidants used were bicarbonate buffers, vitamin C and baobab fruit pulp meal (BFPM). A total of thirty (30) growing rabbits were used. The rabbits were allotted into the treatment groups with six (6) rabbits per treatment in a completely randomized design. Rabbits in the first group (T ) were the control, animals in treatment 2 and treatment 3 (T ) and (T ) were fed similar diets as in the control but with potassium bicarbonate (KHCO ) and sodium bicarbonate (NaHCO ) buffer solutions, respectively. Rabbits in treatment four (T ) were fed diet containing synthetic vitamin C and the fifth group (T ) were fed diet containing Baobab Fruit PulpMeal (BFPM). Rabbits were given access to feed and water ad libitum. All recommended managerial practices were duly observed.Microclimate parameters of ambient temperature (AT) and relative humidity (RH) of the rabbitry were taken daily from February through June. The values were used to calculate temperature-humidity index (THI). It was found that vitamin C and BFPM significantly (P&lt;0.05) enhanced feed intake compared to the treatments with buffers. It was concluded that BFPM is more effective in ameliorating heat stress in rabbit production and can be used up to 5.5% inclusion level.

High-throughput method based on a novel thin-film microextraction coating for determining macrolides and lincosamides in honey

A high-throughput method using a new ZIF-8@GO thin-film microextraction coating was established for determining macrolides and lincosamides in honey. The coating preparation parameters (ZIF-8@GO synthesis conditions, coating material proportions, dipping time) and analysis parameters (sample diluent solvent, adsorption and desorption conditions using the ZIF-8@GO coating) were optimized. The optimized parameters were: diluent solvent sodium carbonate/sodium bicarbonate buffer solution (pH 9), adsorption time 45 min, desorption time 5 min, desorption solvent 45:40:15 v/v/v methanol/acetonitrile/water. The extracted targets were determined by ultra-high performance liquid chromatography tandem mass spectrometry. The recoveries of 10 analytes were 67.5–107.2% and the detection and quantification limits were 0.1–0.4 and 0.4–1.4 μg/kg, respectively. The method could analyze 96 samples per run. The minimal manual time and effort is required since the bulk of the sample processing is fully automated. It was a useful and efficient method for monitoring drug residues and was successfully used to analyze real samples.

Effect of pH on bacterial distributions within cathodic biofilm of the microbial fuel cell with maltodextrin as the substrate

The aim of this study was to investigate pH effect on stratification of bacterial community in cathodic biofilm of the microbial fuel cell (MFC) under alkaline conditions. A single-chamber MFC with air-cathode was operated with 0.8 g/L maltodextrin and bicarbonate buffer solutions under pH values of 8.5, 9.5, and 10.5, respectively. The cathodic biofilms were characterized by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), confocal laser scanning microscopy (CLSM), freezing microtome and high-throughput sequencing analysis on bacterial communities, respectively. Results showed that the maximum power densities in the MFC increased with the pH values and reached 1221 ± 96 mW/m2 at pH = 10.5 during ∼30 d of operation. With different pH values, the composition and relative abundance of bacterial community significantly changed in the bottom (0–50 μm), middle (50–100 μm), and top (100–150 μm) layers of the cathodic biofilm. With pH = 10.5, aerobic bacteria accounted for 12%, 13%, and 34% of the bacterial community in the top, middle, and bottom layers, respectively. The amount of anaerobic bacteria in the top and middle layers (i.e., 52%, and 50% of the bacterial community, respectively) was higher than that in the bottom layer (22%). The distribution of aerobic and anaerobic bacteria showed a “valley-peak” structure within the layers. The high CO32− concentration facilitates the hydroxyl transfer and the neutralization in the anode of the MFC under high alkali conditions. The results from this study should be useful to develop new catalyst and cathode in the MFC.

Enhanced Hemocompatibility and In Vivo Analytical Accuracy of Intravascular Potentiometric Carbon Dioxide Sensors via Nitric Oxide Release.

In this letter, the innate ability of nitric oxide (NO) to inhibit platelet activation/adhesion/thrombus formation is employed to improve the hemocompatibility and in vivo accuracy of an intravascular (IV) potentiometric PCO2 (partial pressure of carbon dioxide) sensor. The catheter-type sensor is fabricated by impregnating a segment of dual lumen silicone tubing with a proton ionophore, plasticizer, and lipophilic cation-exchanger. Subsequent filling of bicarbonate and strong buffer solutions and placement of Ag/AgCl reference electrode wires within each lumen, respectively, enables measurement of the membrane potential difference across the inner wall of the tube, with this potential changing as a function of the logarithm of sample PCO2. The dual lumen device is further encapsulated within a S-nitroso-N-acetyl-DL-penicillamine (SNAP)-doped silicone tube that releases physiological levels of NO. The NO releasing sensor exhibits near-Nernstian sensitivity toward PCO2 (slope = 59.31 ± 0.78 mV/decade) and low drift rates (<2 mV/24 h after initial equilibration). In vivo evaluation of the NO releasing sensors, performed in the arteries and veins of anesthetized pigs for 20 h, shows enhanced accuracy (vs non-NO releasing sensors) when benchmarked to measurements of discrete blood samples made with a commercial blood gas analyzer. The accurate, continuous monitoring of blood PCO2 levels achieved with this new IV NO releasing PCO2 sensor configuration could help better manage hospitalized patients in critical care units.