Concentration Of H2PO4 Research Articles

Probing Chemical Equilibrium in Frozen Sodium Phosphate Buffer Solution by 31P Solid-State NMR.

Phosphate buffers are crucial for cryopreservative stability in pharmaceuticals, food processing, biomedical sciences, and biology. However, their freeze concentrates lack quantitative characterization, especially regarding the physicochemical properties of phosphate salt species in equilibrium at subzero temperatures. This study employs 31P solid-state NMR (ssNMR) to analyze frozen sodium phosphate (NaP) solutions, providing insights into phase composition, ionic strength, and pH. For the first time, we have directly quantified phosphate species in frozen NaP buffer, including crystallized disodium phosphate dodecahydrate (Na2HPO4·12H2O) content and the concentrations of H2PO4- and HPO42- in the freeze concentrate. This enabled the calculation of the pH as well as the ionic strength in the freeze concentrate. Trehalose effectively mitigated pH shifts in buffer solutions by preventing the selective crystallization of salt, a spectroscopic phenomenon not previously observed experimentally.

Fluorescence detection for H2PO4 - based on carbon dots/Fe3+ composite

A novel fluorescent probe for H2PO4- was designed and fabricated based on the carbon dots/Fe3+ composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe3+ composite was obtained by aqueous mixing of carbon dots and FeCl3, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe3+ cations, resulting in the low fluorescence intensity of the carbon dots/Fe3+ composite. On the other hand, H2PO4- reduced the concentration of Fe3+ by chemical reaction and enhanced the fluorescence of the carbon dots/Fe3+ composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe3+ composite and the concentration of H2PO4-, and a fine linearity (R2=0.997) was found in the range of H2PO4- concentration of 0.4-12 mM.

A novel approach to synthesize hollow α-Fe2O3 spheres via hydrothermal treatment

Novel α-Fe2O3 hollow crystal spheres were formed on a large scale by a facile and efficient hydrothermal process. In this paper, the inorganic anions are important in the formation of α-Fe2O3. And the concentration of H2PO4− is important for forming hollow spheres. The coordination effect of phosphate ions with Fe3+ ions is another important aspect in the formation of hollow spheres. H2PO4− is important for forming hollow structures. The samples were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction.

EFFECT OF MODIFIED STEINER NUTRIENT SOLUTION ON MACRONUTRIENT IN ASIATIC HYBRID LILIUM 'BRUNEL'

In order to determine the effect of different concentrations of the universal Steiner nutrient solution on the Asiatic hybrid Lilium 'Brunel' grown in hydroponics under greenhouse a 3×3×3 factorial experiment was carried out. The studied factors were 1) (-30, -50, -70 kPa); 2) N-NH4+ relationship (0, 12.5 and 25% of the total of cation concentration), and 3) H2PO4- anions (80, 120 and 160% with respect to the concentration of this ion in the Steiner solution. The solution was provided daily with a pH ranging between 5.0-5.5. The culture substrate was a local volcanic tuff known as tezontle, whose particle diameter ranged from 1 to 7 mm. Micronutrient analyses to determine Mn, B, Zn, Cu, and Fe were carried out in stem, leaf, and flower. Analyses of variance and mean comparisons (Scheffe) were performed (P≤0.05). It was observed that the selection of levels was appropriate, since the mean level of each factor produced the largest values of B in leaf and Fe in leaf. In addition, with the level combination -70 kPa, 120% H2PO4-, and 0% N-NH4+ the largest concentrations of Mn, Fe, and B in flower, leaf or stem were found. It was also found that the concentration of H2PO4- was negatively related with the concentration of Mn in flower, and/or Fe in stem. Finally, the nutrient solution with the mean level of the three studied factors produced the largest concentration of Mn in the flower of Asiatic hybrid Lilium ‘Brunel’.

Mineral composition of frozen taro for determination of geographic origin

The mineral composition of frozen food of taro [Colocasia esculenta (L.) Schott] was analyzed to categorize the geographical production place of taro. The concentrations of Co and H2PO4− were found to be useful to separate the producing place between Japan and China. The analysis was performed by instrumental neutron activation analysis (INAA) and ion chromatography (IC). In the case of INAA, the samples were dried and sealed in a vinyl bag and irradiated with thermal neutrons from JRR3M, installed at Japan Atomic Energy Agency (JAEA). The activated samples were cooled down for a few weeks and the elements (Co, Cr, Fe, Rb, Zn) were determined. Cobalt concentration of frozen taro from China was higher than that from Japan. The tendency was the same in the fresh sample of taro. When concentration of H2PO4− of frozen sample was measured, taro from Japanese product was higher than that of Chinese one, contrary to fresh sample. This result might be caused by the leakage of H2PO4− during freezing process, indicating that we should be careful to apply the discrimination indicators. In addition to Co, there was a significant difference of Rb and Fe concentrations between frozen taro from Japan and China.

A novel colorimetric sensor of dihydrogen-phosphate based on metal complex between 8-hydroxy quinoline-5-azo-4′-nitrobenzene and cobalt

A novel colorimetric sensor based on 8-hydroxy quinoline-5-azo-4′-nitrobenzene (1) was prepared and used for recognizing anions. 1 and its metal complex (1·Co) were found to show response to anions such as CH3CO2−, H2PO4−, HSO4−, F− and dramatic color changes were observed. The selectivity and sensitivity of 1 and 1·Co for sensing anions were different, which was in the order of CH3CO2−>F−>H2PO4−≫HSO4− for 1 and H2PO4−>HSO4−>CH3CO2−∼F− for 1·Co, respectively. In CH3CN, sensor 1·Co exhibited excellent specificity toward H2PO4−, and the color variety was dependent on the concentration of H2PO4− which was attributed to anion structure and stability of anionic complex (1-anion), metal complex (1-Co) and inorganic complex (Co-anion).

Anion recognition and electrochemical characteristics of the self-assembled monolayer of nickel(II) azamacrocyclic complex

Anionic recognition of the self-assembled monolayer of dinickel(II) (2,2-bis(1,3,5,8,12-pentaazacyclotetradec-3-yl)-diethyl disulfide) perchlorate (1) was studied electrochemically. The dinickel(II) complex 1 adsorbs on gold electrodes from methanol solutions and yields stable, self-assembled electroactive monolayers (SEMs); the SEM of 1 shows a reversible redox wave at 0.82 V in aqueous 0.1 M NaNO3 corresponding to the Ni3+/2+ redox reaction. The surface coverage, Γ, of the self-assembly of 1 determined by cyclic voltammetry is constant (Γ=(1.4±0.08)×10−10 mol cm−2) with change in the deposition time (2–36 h) and the concentration of 1 in methanol solution (0.2–5 mM) and is equivalent to a monolayer coverage of the nickel macrocyclic complex. The capacitance of the monolayer of 1 was determined from the double-layer capacitance measurements by chronoamperometry; the monolayer of 1 is assigned to be well-solvated by observing that the dielectric constant of the self-assembly domain (ϵfilm=74) is nearly equal to that of water (ϵwater=78). Electrochemical investigations reveal that the monolayer of 1 can sense electrochemically various non-electroactive anions, NO3−, CF3COO−, SO42−, H2PO4−, HPO42−, ClO4−, PF6− and SCN−, from the variation of the formal potential, E°′, in aqueous solutions of different anions. The E°′ of the monolayer of 1 is 0.82 V in aqueous 0.1 M NaNO3 and shifts to a less positive potential, 0.55 V, in aqueous 0.1 M Na2SO4; the shift in the E°′ was reversible on exchanging the monolayer of 1 between 0.1 M NaNO3 and 0.1 M Na2SO4. The shift in the E°′ of the monolayer has been explained by an axial coordination of electrolyte anions with the trivalent nickel ion. The redox reaction of the SEM of 1 is not observed in aqueous solutions of 0.1 M NaClO4 and 0.1 M NaSCN; but the redox activity was retained on changing the monolayer electrode to an aqueous solution of 0.1 M Na2SO4 or 0.1 M NaNO3. The monolayer of 1 could detect electrochemically the biologically important phosphate anion, adenosine triphosphate (ATP), at submillimolar concentrations; on addition of 1 mM ATP, the formal potential of the monolayer shifts towards the less positive potential region by about 250 mV. The CVs of the SEM of 1 were recorded in aqueous solutions containing different concentrations of NaH2PO4 or Na2SO4, keeping the ionic strength of the electrolyte solution constant with added NaNO3. The E°′ of the monolayer shifts to the less positive potential region with an increase in the concentration of H2PO4− or SO42− anion in solution phase, and the analysis of cyclic voltammetric results reveals that the nickel(III) complex forms a 1:1 complex with SO42− anion but a 1:2 complex with H2PO4− anion.

PH Influenced by the elemental composition of nutrient solutions

Nutrient solutions can be considered as aqueous solutions of inorganic ions. The pH of a nutrient solution is a property that is inherent to its composition. If another pH is aimed at, this can only be reached by changing the elemental composition. The pH of an aqueous solution is determined by the initial concentration of acids and bases. In the case of nutrient solutions, this is dihydrogen phosphate (H2PO4 ‐), bicarbonate (HCO3 ‐) and/or ammonium (NH4 +). In this study, formulas are derived to calculate the pH of a nutrient solution as a function of the concentration of H2PO4 ‐, NH4 +, and/or HCO3 ‐. The pH of a nutrient solution affects the dissociation, complexation, and precipitation reactions occurring in nutrient solutions. These chemical reactions significantly impact elemental speciation and bioavailability, and therefore, have to be taken into account in hydroponic plant nutritional research. The term “speciation”; indicates the distribution of elements among their various chemical and physical forms like: free ions, soluble complexes, chelates, ion pairs, solid and gaseous phases, and different oxidation states, all of which influences their reactivity, mobility and bioavailability. A good knowledge of the chemical reactions occurring in nutrient solutions is the first prerequisite in hydroponic plant nutritional research. The pH of a nutrient solution is determined by its initial concentration of H2PO4 ‐, NH4 +, and HCO3 ‐.

Electrocatalytic Oxidation of Chlorpromazine in Phosphate Solution

Abstract The kinetics of electrocatalytic oxidation process of chlorpromazine (CPZ) at a pyrolytic graphite electrode in a phosphate solution was investigated by rotating disk voltammetry. The reactions involving regeneration process of CPZ through the disproportionation of reaction intermediates are proposed and the rate constants of the chemical reaction (kobsd), following the electrochemical oxidation of CPZ to the CPZ cation radical, were evaluated from the electrode rotation-rate dependence of the limiting currents obtained in the CPZ solution with and without phosphate. The proportional relations between the logarithm of kobsd and pH, and between kobsd and the concentration of H2PO4− were obtained.

THE EFFECT OF pH ON THE UPTAKE AND ACCUMULATION OF PHOSPHATE AND SULFATE IONS BY BEAN PLANTS

Phosphate uptake above pH 6.0 followed the concentration of H2PO4. Sulfate studies were used to aid evaluation of phosphate data. Phosphate absorption was nearly linearly proportional to transpiration at pH 4.0; at pH 8.7, phosphate absorption occurred only early in the experiments. It was inferred that phosphate entered as H2PO4; that which entered at pH 8.7 did so as the result of a depressed pH at the absorption sites.