Sodium Acetate Medium Research Articles

Adding glucose delays the conversion of ethanol and acetic acid to caproic acid in Lacrimispora celerecrescens JSJ-1.

Caproic acid is an important fatty acid with diverse applications. In this study, the biomass growth and metabolites of Lacrimispora celerecrescens JSJ-1 were investigated under different carbon sources (ethanol, starch, sucrose, and glucose), with a focus on the effect of the coexistence of glucose and ethanol on the synthesis of caproic acid. The results showed that starch, glucose, and sucrose all contributed to the biomass of L. celerecrescens JSJ-1. Under the three carbon sources, L. celerecrescens JSJ-1 produced acetic acid, butyric acid, lactic acid, ethanol, and butanol, but caproic acid was not produced. Ethanol was the optimal substrate for the production of caproic acid. When glucose and ethanol coexisted, the generation time of caproic acid was delayed compared with that in ethanol sodiumacetate medium (ES medium). This was because glucose was preferentially consumed over ethanol. Lactic acid was generated as a result of glucose consumption, which led to a significant decrease in pH from 6.45 to 4.68. The low pH (< 5) inhibited the synthesis of caproic acid. Then, the strain's usage of lactic acid and the reaction between CaCO3 and lactic acid caused the pH to increase. L. celerecrescens JSJ-1 did not start producing caproic acid using ethanol and acetic acid until the pH increased to 5.8. This research enriches the knowledge regarding the metabolism of L. celerecrescens JSJ-1 and provides guidelines for the industrial production of caproic acid by using L. celerecrescences JSJ-1. KEY POINTS: • Ethanol is the optimal substrate for the synthesis of caproic acid by Lacrimispora celerecrescens JSJ-1. • Lacrimispora celerecrescens JSJ-1 produced lactic acid rapidly when it used glucose, causing a sharp drop in pH. • pH is a crucial factor affecting the synthesis of caproic acid from ethanol by Lacrimispora celerecrescens JSJ-1.

Liquid–liquid extraction of uranium(VI) from weak sodium acetate medium using 2-octylaminopyridine: real sample analysis

Liquid–liquid extraction of uranium(VI) from weak sodium acetate medium using 2-octylaminopyridine: real sample analysis

A metal-catex composite electrode for determination of paraquat in various samples by Ad-differential pulse cathodic stripping voltammetry

In this work, a novel kind of metal-catex composite electrode for determination of paraquat (PQ) by adsorptive differential pulse voltammetry is introduced. The metal-catex composite electrode was fabricated by cathodic electropolymerization of p-nitrophenol and p-nitrobenzoic acid in the presence of tin (II) chloride as a scaffold for composite structure on prepared glassy carbon electrode. Electropolymerization was carried out in sodium acetate medium. The surface of the fabricated electrode was characterized with field emission scanning electron microscope and energy-dispersive X-ray spectrometry. The obtained results show that there are Sn nanoparticles in the structure of the catex-composite. Chemical structure of metal-catex composite electrode was investigated using FTIR (ATR), 13C NMR, H NMR and a suitable mechanism for electropolymerization has been proposed. This metal-catex composite electrode was applied for determinations of PQ using sodium acetate buffer solutions at pH = 6.5 as an electrolyte solution. All parameters influencing the performance of the fabricated electrode were studied and optimized. The proposed electrode exhibits good linearity versus PQ concentration in the range of 3.8 × 10−8 to 7.7 × 10−7 mol L−1 and shows a manifold increase in sensitivity (more than 30 times) as compared to the glassy carbon electrode. The LOQ of this electrode was 7.78 × 10−9 mol L−1, which is comparable with that of other electrochemical methods. The mean, standard deviation and relative standard deviation for seven repetitive determinations of paraquat (7.78 × 10−8 mol L−1) were measured to be 7.75 × 10−8 mol L−1, ±0.29 × 10−8 mol L−1, and 3.75% respectively. This electrode was applied for the determination of paraquat in natural water, natural juice, potatoes and onions. The introduced electrode shows good stability with repeated use and over long periods (about 20 days). There is a good agreement between the results for water analysis by this method and the standard method.

Preliminary Study on Caproic Acid Production by Compound Bacterial Agent of Luzhou-Flavor Liquor Pit Mud

Pit mud plays an important role in the fermentation of Luzhou-flavor liquor, It is a common problem for Luzhou-flavor liquors when the mud is aging and the fragrance is not prominent.Choose high quality mud, Inoculating the mash extract as a mixed bacterial solution in sodium acetate medium, Anaerobic culture method to increase the activity of anaerobic microorganisms, Increase hexanoic acid production; Characterization of hexanoic acid by color reaction of copper sulfate diethyl ether, Determination of hexanoic acid by gas chromatography, Its output is in the range of 1.5g/Lto 3.6 g/L, This is the production of mud maintenance liquid, Technical support is provided to prevent aging of the mud and improve the fragrance of the main body.

Sequential Isomerization of a Macrocyclic Polyoxometalate Archetype.

Controlled isomerization of individual {α-P2W12O48} polyoxotungstate building blocks under the constricted conditions of the macrocyclic [P8W48O184]40- archetype ({P8W48}) is linked to site-specific CuII coordination. The derivatives [αγαγ-P8W48O184{Cu(H2O)}2]36- (1), [γγγγ-P8W48O184{Cu(H2O)0.5}4]32- (2), and [αγγγ-P8W48O184{Cu(H2O)}3]34- (3) feature the {αγαγ-P8W48} and the hitherto unknown {γγγγ-P8W48} and {αγγγ-P8W48} isomers based on {α-P2W12} and/or CuII-stabilized {γ-P2W12} units and form from the reactions of the classical {P8W48} (={αααα-P8W48}) and CuCl2 in sodium acetate medium (pH 5.2). All products were thoroughly characterized in both the solid state and aqueous solutions, including electrocatalysis assessments.

Isolation, Purification, and Identification of a Novel HX-Producing Strain and Optimization of Its Fermentation Medium

Hexanoic acid (HX) is a crucial flavor compound and precursor of ethyl caproate (EA), which determines the quality of Chinese Luzhou-flavor liquor (CLFL). The isolation, purification, identification, and optimization of fermentation conditions of HX-producing bacteria are essential for industrial CLFL production. In this study, one strain of HX-producing bacterium was isolated from six candidate bacterial strains and identified as Clostridium sartagoneforme. Then, the growth characteristics and HX production of C. sartagoneforme were investigated. Sodium acetate medium was identified as the optimal fermentation medium from four candidate media. C. sartagoneforme yielded 800.85 ± 12.87 mg/100mL HX in sodium acetate medium. Then, to further optimize the formula of the fermentation medium, the carbon and nitrogen sources and inorganic salt component of the fermentation medium were investigated using HX yields as an optimization index. Optimization was performed with a single-factor experiment and the Taguchi design method. The single-factor experiment showed that the highest HX outputs were obtained when the sodium acetate medium contained 2.5 g/L yeast extract, 1.8 g/L KCl, 20 g/L sodium acetate, 15 mL/L ethanol, and 1.5 g/L glucose. In the orthogonal experiment designed using the Taguchi design method, HX yields reached 2018.29 ± 46.37 mg/100mL in sodium acetate medium that contained 3.5 g/L yeast extract, 1.8 g/L KCl, 25 g/L sodium acetate, and 15 mL/L ethanol.

Development of a New Methodology for Indirect Determination of Nitrite, Nitrate, and Total Nitrite in the Selected Two Groups of Foods by Spectrophotometry

A new indirect preconcentration procedure was developed for micellar sensitive detection of trace nitrite as analyte by spectrophotometry. The method is based on ion association of triiodide ion, I3− or I2, produced by the reaction of nitrite at low concentrations with excess iodide in presence of ion-pairing agent, Coomassie brilliant blue R 250 (CBB), and electrophilic attack of nitrosyl cation produced by disproportionation of nitrite depending on concentration to ion-pairing agent at higher concentrations than 5 μg L−1 in acidic medium, and then extraction of the ion-pairing complex formed from aqueous solution into the micelles of Triton X-114 at sodium acetate medium. The calibration graphs were rectilinear in the range of 0.5–5 and 5–200 μg L−1 with increasing and decreasing slopes in micellar phase, respectively. The detection and quantification limits of the method were 0.15 and 0.50 μg L−1, and the precision (as RSD) for five replicate measurements of different concentrations of nitrite was in the range of 2.3–4.8%. The average recoveries of spiked nitrite residues ranged from 97 to 104%. The method is free of matrix interferences and successfully applied to the indirect determination of nitrite, nitrate, and total nitrite in selected two groups of foods. Also, the accuracy was validated by analysis of a certified reference material as well as recoveries of spiked samples. The objective of the study is to provide an alternate economical method to determine the contents of nitrite, nitrate, and total nitrite after homogenization, extraction, reduction, and preconcentration from sample matrix.

A novel Pb-poly aminophenol glassy carbon electrode for determination of tetracycline by adsorptive differential pulse cathodic stripping voltammetry

A novel type of Pb-polyaminophenol filmed glassy carbon electrode for adsorptive cathodic stripping analysis of trace amounts of tetracycline was developed. The Pb-polymer electrode was fabricated in situ by simultaneous electrodeposition of Pb and cathodic electropolymerization of 4-nitrophenol in a sodium acetate medium at −1.5volt. The prepared Pb-polymeric film was characterized by CV, FT-IR (ATR), H-NMR, SEM, EDS and a suitable mechanism for the electrode-reaction was proposed. The outputs of some experiments showed that tetracycline can be adsorbed on the surface of this Pb-polymer filmed electrode in an open circuit condition. Therefore it was used in adsorptive cathodic stripping analysis of tetracycline. The response of the electrode was enhanced in the presence of cetyltrimethylammonium bromide. Some parameters affecting the performance of the electrode were studied and optimized. The response of the electrode was linear in the range of 5×10−8−1×10−5molL−1 of tetracycline with a correlation coefficient of 0.9981. The relative standard deviation for 5×10−7molL−1 of tetracycline was 1.8% (n=5). The L.O.D and L.O.Q were 4×10−9 and 1.3×10−8molL−1 of tetracycline, respectively. The introduced electrode was used for determination of tetracycline residues in some samples and the obtained results were in good agreement with the results of HPLC.

Electricity and H2 generation from hemicellulose by sequential fermentation and microbial fuel/electrolysis cell

Electricity and hydrogen generation by bacteria Geobacter sulfurreducens in a dual-chamber microbial fuel/electrolysis cell following the fermentation of hemicellulose by bacteria Moorella thermoacetica was investigated. Experimental results showed that 10 g l−1 xylose under 60 °C was appropriate for the fermentation of xylose by M. thermoacetica, yielding 0.87 g-acetic acid per gram of xylose consumed. Corncob hydrolysate could also be fermented to produce acetic acid, but with lower yield (0.74 g-acid per g-xylose). The broths of xylose and corncob hydrolysate fermented by M. thermoacetica containing acetic acid were fed to G. sulfurreducens in a dual-chamber microbial fuel/electrolysis cell for electricity and hydrogen generation. The highest open-circuit cell voltages generated were 802 and 745 mV, and hydrogen yields were 41.7 and 23.3 mmol per mol-acetate, in xylose and corncob hydrolysate fermentation broth media, respectively. The internal resistance of the microbial fuel/electrolysis cell fed with corncob hydrolysate fermentation broth (3472 Ω) was much higher than that with xylose fermentation broth (1993 Ω) or sodium acetate medium (467 Ω), which was believed to be the main cause of the variation in hydrogen yield of the three feeding media.

Determination of the Purity of Cucurbit[n]uril (n = 7, 8) Host Samples

The formation of highly stable inclusion complexes in aqueous solution between the organometallic cobaltocenium cation (Cob(+)) and the hosts cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) was used to develop a simple method, based on UV-vis titrations, to assay the purity of samples of these two hosts. The equilibrium association constant (K) of the Cob(+)@CB7 complex had been previously reported by our group as 5.7 × 10(9) M(-1) at 25 °C in 50 mM sodium acetate medium. In this work, we determine a K value of 1.9 × 10(8) M(-1) at 25 °C in the same medium for the Cob(+)@CB8 complex. The high stability of these complexes and their decreased molar absorptivity coefficients (at 261 nm), compared to that for free Cob(+), lead to straightforward titration plots when graphing absorbance versus concentration of added CB7 (or CB8) host, at constant Cob(+) concentration.

Electrocatalytic reduction of diethyl oximinomalonate at a Ti/nanoporous TiO 2 electrode

A “green” method for production of diethyl aminomalonate was presented by electrocatalytic reduction of diethyl oximinomalonate (DEOM) to diethyl aminomalonate in the acetic acid and sodium acetate medium at the surface of Ti/nanoporous TiO 2 electrode. The heterogeneous catalytic redox behaviour of a nanoporous TiO 2 film electrode surface was investigated by cyclic voltammetry (CV). A comparison of the CV recorded in the absence and in the presence of DEOM confirmed the catalytic reduction of DEOM by Ti(IV)/Ti(III) redox system on the nanoporous TiO 2 film surface.

Adsorptive stripping voltammetric determination of the antidepressant drug sulpiride

The electrochemical behaviour of the antidepressant drug sulpiride (SP) at a hanging mercury drop electrode (HMDE) is investigated. Linear sweep cathodic stripping voltammetry (LSCSV) was used to determine sulpiride in the presence of 0.01 M sodium acetate medium pH 10.5 and 25±1°C. Different parameters such as, supporting electrolyte, pH, accumulation potential, scan rate, accumulation time and ionic strength, were tested to optimize the conditions for the determination of SP. The adsorbed form is reduced irreversibly. The linear concentration range is from 2×10 −9 to 5×10 −8 M SP. Experimentally, 2×10 −9 M (0.68 ppb) with accumulation time 60 s can be determined successfully. Furthermore, a theoretical detection limit of 2×10 −10 M (0.068 ppb) Sp was calculated. The interferences of some metal ions, ascorbic acid and some amino acids were studied. The method was applied to the analysis of tablets and spiked urine, with recoveries of 104±3 and 101±3, and the relative standard deviation of 3.3 and 3.4%, respectively.

Changes in fatty acids of Pseudomonas nautica, a marine denitrifying bacterium, in response to n-eicosane as carbon source and various culture conditions

This study determined the effects of shifts in environmental conditions on the fatty acid composition of a sedimentary facultative anaerobic denitrifying marine bacteria (Pseudomonas nautica strain IP 617). The effects of carbon source (n-eicosane, sodium acetate and rich medium), temperature (13, 20 and 30°C), presence or lack of oxygen and growth phase (stationary and exponential) were investigated. As demonstrated by correspondence analysis, the effect of the various conditions tested, in descending order of importance, were carbon source>temperature>growth phase≥oxygen. Among the different growth substrates, n-eicosane (nC20) led to the most distinct FA profiles, characterised by high amounts of saturated and branched FA, the appearance of 20-carbon acids (20:1ω9 and 20:0) and a Δ10 methyl branched series with mainly the 10Me16:0. With regard to temperature effects, P. nautica showed a mean acyl chain length thermoregulation process for the major monounsaturated fatty acids which led to increased values of the ratio ΣC18:1/ΣC16:1 with increasing temperatures. The effect of growth phase and anaerobiosis were less marked. The analysis of bacterial fatty acids could enable the detection of hydrocarbonoclastic bacterial communities in marine sediments contaminated by hydrocarbons.

Changes in fatty acids of Pseudomonas nautica, a marine denitrifying bacterium, in response to n-eicosane as carbon source and various culture conditions

This study determined the effects of shifts in environmental conditions on the fatty acid composition of a sedimentary facultative anaerobic denitrifying marine bacteria ( Pseudomonas nautica strain IP 617). The effects of carbon source ( n-eicosane, sodium acetate and rich medium), temperature (13, 20 and 30°C), presence or lack of oxygen and growth phase (stationary and exponential) were investigated. As demonstrated by correspondence analysis, the effect of the various conditions tested, in descending order of importance, were carbon source>temperature>growth phase≥oxygen. Among the different growth substrates, n-eicosane ( nC 20) led to the most distinct FA profiles, characterised by high amounts of saturated and branched FA, the appearance of 20-carbon acids (20:1ω9 and 20:0) and a Δ 10 methyl branched series with mainly the 10Me16:0. With regard to temperature effects, P. nautica showed a mean acyl chain length thermoregulation process for the major monounsaturated fatty acids which led to increased values of the ratio ΣC 18:1/ΣC 16:1 with increasing temperatures. The effect of growth phase and anaerobiosis were less marked. The analysis of bacterial fatty acids could enable the detection of hydrocarbonoclastic bacterial communities in marine sediments contaminated by hydrocarbons.

Electrocatalytic effects of deoxyribonucleic acids, adenine and guanine on the reduction of Ni(II) at a mercury electrode

Adenine, guanine, and native and denatured DNA lower the overpotential for the reduction of Ni(II) at a mercury electrode in a sodium acetate medium. A mechanism for the electrode reaction underlying the electrocatalytic effects observed is proposed. The similarity of the electrocatalytic effects of native and thermally denatured DNA adsorbed on the electrode at full coverage reveals that Ni(II) species interact with basic residues within the double-helical structure, thus reflecting the high diffusivity of these species throughout the native DNA molecule. A simple differential pulse voltammetric method for the simultaneous determination of adenine and guanine in mixtures based on the peak for the reduction of protonated adenine and the single prepeak produced by the reduction of Ni(II) catalysed by unprotonated adenine and guanine was developed. Finally, a sensitive adsorptive stripping differential pulse voltammetric method for the determination of native and denatured DNA is proposed.

Electroreduction of the fungicides Folpet, Captan and Captafol on mercury electrodes

Abstract An electrochemical study based on direct current (dc) and differential pulse (dp) polarography and coulometry for Folpet, Captan, Captafol and their hydrolyses products was carried out. It was conducted in 10% (v/v) dimethylformamide–water, 0.20 M acetic acid–sodium acetate medium, pH 2.6. The electrochemical behaviour of the fungicides assayed was interpreted according to the polarographic and coulometric data and with the aid of other techniques such as Fourier transform-infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS), that were used to identify the products obtained in the coulometry assays. The possible reduction mechanisms of the electrochemical processes shown by the three fungicides are discussed. Also, different polarographic procedures are proposed for the determination of the fungicides, reporting that it is not possible to perform simultaneous polarographic quantification of the three compounds.

Determination of casein by square‐wave voltammetry using electrocatalytic reduction of nickel(II)

AbstractThe catalytic peak produced at −0.80 V (vs Ag/AgCl) by the presence of casein in the reduction of NIII on a dropping mercury electrode in sodium acetate medium was explored using square‐wave voltammetry (SWV). The effects of the electrochemical variables on SW voltammograms were studied and optimum operating conditions were established (10−2 M NiII, 1 M sodium acetate, pH 7.0 and temperature of 23° C). Good linearity between the SW voltammetric peak current and casein concentrations in the 0–128 mg L−1 range was obtained. An electrocatalytic method is proposed for the determination of casein with rapid and precise results (relative standard deviation of 5.2 %).

Study of the catalytic polarographic reduction of Ni(II) in the presence of albumin, immunoglobulins and serum proteins Determination of total proteins in serum

A study on the catalytic reduction of nickel(II) ion in the presence of albumin, immunoglobulins and serum proteins in sodium acetate medium has been carried out using differential-pulse polarography. The catalytic reduction of nickel ion gives two peaks at −0.60 V and −0.78 V versus a saturated calomel reference electrode. The adsorption of proteins on the electrode surface and the formation of Ni(II)-protein complexes, which greatly reduces the high overvoltage for the polarographic reduction of nickel(II), is shown. The peak obtained at −0.60 V is sufficiently well-defined and can be exploited for analytical purposes. The electrochemical variables affecting the polarographic behavior of nickel(II) in the presence of proteins were investigated; the prepeak obtained at −0.60 V using 10 −2 M Ni(II) in 1 M sodium acetate, at pH 8.3, permits the quantitative determination of proteins in the following ranges: 3–75 μg/ml of albumin, 6–175 μg/ml of immunoglobulins and 2–5 μg/ml total serum proteins. Application of the proposed method for rapid and direct determination of total proteins in human serum samples is demonstrated; the results agree with those obtained with the established biuret automated method.

Study of the electrocatalytic effect of casein on the polarographic reduction of nickel(II). Determination of total proteins in milk by polarographic chronoamperometry

Casein greatly reduces the overvoltage for the polarographic reduction of NiII in sodium acetate medium. Using polarographic chronoamperometry, current–time curves were obtained from which the electrocatalytic effect of casein could be evaluated. The variables affecting the electrochemical response were investigated and under selected experimental conditions [1 × 10–2 mol l–1 NiII, 1 mol l–1 sodium acetate, pH = 7.0, T= 20 °C and E=–0.750 V (versus SCE)] casein was determined in the range 27–191 µg ml–1. Application of the proposed method to the direct determination of total proteins in milk is demonstrated. The results obtained are consistent with those obtained with the established Kjeldahl method.

Analytical properties of the amidoxime group: spectrophotometric and thermometric behaviour of ethanediamidoxime and its Cu(II) and U(VI) complexes

The spectrophotometric behaviour of ethanediamidoxime (EDA) and its Cu(II) and U(VI) complexes has been studied. EDA p K values were first calculated and then refined using the MINISPEF (p K 1 = 2.84 and p K 2 =11.23) and SQUAD programs (p K 1 = 2.84 and p K 2 =11.25). The optimum formation conditions for the EDA complexes with Cu(II) and U(VI) have been established, as well as the precision for the spectrophotometric determination of these elements. Stoichiometries for the EDA-Cu(II) complexes are found to be 1:1 and 1:2. The behaviour of the Cu(II)-EDA complexes has also been studied thermometrically. A green 1:2 complex is formed in an acetic acid medium (Δ H= −35.6 kJ mol −1) and a brown precipitate in a sodium acetate medium with 1:1 stoichiometry (Δ H= −23.01 kJ mol −1).