Alkaline Sodium Phosphate Research Articles

Simultaneous analysis of filgrastim and pegfilgrastim aggregates by size-exclusion chromatography

A new size-exclusion high-performance liquid chromatographic (SE-HPLC) method for the simultaneous analysis of filgrastim and pegfilgrastim aggregates was developed and validated. A cross-linked agarose and dextran column was used at ambient temperature and an alkaline sodium phosphate buffer as mobile phase eliminated non-ideal interactions with the stationary phase. The robustness of the method was assessed by varying injection volumes, flow rates and sample vehicles. Other reliability assessments include calibration curve, intra and inter-day precision and accuracy, repeatability of retention times, application to real in-process production samples and column lifetime. The method exhibited linearity over the concentration of 0.02–4 mg/ml range for filgrastim and pegfilgrastim monomer with a correlation coefficient of greater than 0.999. The lower limit of quantification was 0.02 mg/ml and the limit of detection was 0.005 mg/ml. This SE-HPLC technique has been successfully used for several years and more than 10,000 samples.

A procedure for separate recovery of extra- and intracellular DNA from a single marine sediment sample

Extracellular DNA (eDNA) is a ubiquitous biological compound in aquatic sediment and soil. Previous studies suggested that eDNA plays an important role in biogeochemical element cycling, horizontal gene transfer and stabilization of biofilm structures. Previous methods for eDNA extraction were either not suitable for oligotrophic sediments or only allowed quantification but no genetic analyses. Our procedure is based on cell detachment and eDNA liberation from sediment particles by sequential washing with an alkaline sodium phosphate buffer followed by a separation of cells and eDNA. The separated eDNA is then bound onto silica particles and purified, whereas the intracellular DNA from the separated cells is extracted using a commercial kit. The method provides extra- and intracellular DNA of high purity that is suitable for downstream applications like PCR. Extracellular DNA was extracted from organic-rich shallow sediment of the Baltic Sea, glacially influenced sediment of the Barents Sea and from the oligotrophic South Pacific Gyre. The eDNA concentration in these samples varied from 23 to 626ngg−1 wet weight sediment. A number of experiments were performed to verify each processing step. Although extraction efficiency is higher than other published methods, it is not fully quantitative.

A Novel Process to Produce Nano Porous Aluminum Oxide Using Alkaline Sodium Phosphate Electrolyte

A Novel Process to Produce Nano Porous Aluminum Oxide Using Alkaline Sodium Phosphate Electrolyte

Structure–property relations and cytotoxicity of isosorbide‐based biodegradable polyurethane scaffolds for tissue repair and regeneration

Microporous scaffolds with potential applications for tissue engineering were produced from the biodegradable aliphatic isosorbide-based polyurethane using a combined salt leaching-solvent evaporation-coagulation process. Alkaline sodium phosphate heptahydrate crystals were used as a solid porogene, and acetone-water mixture was used as a nonsolvent-coagulant. The scaffolds used in this study had interconnected pores with sizes in the range of 70-120 microm and a pore-to-volume ratio of 87%. The XPS measurements showed that the residence of the scaffold in an aqueous solution of the alkaline porogene changed its surface atomic composition, that is increased the surface concentration of oxygen and nitrogen and reduced the surface concentration of hydrocarbons relative to the control material. This also enhanced the hydrophilicity of the scaffold's surfaces as assessed from contact angle measurements. The alkaline porogene did not affect the polymer's molecular weight. The MTT cytotoxicity assay showed that the isosorbide-based polyurethane scaffold is noncytotoxic. The amounts of interleukin-6 and interleukin-8 proinflammatory cytokines released from human blood leukocytes exposed to the polyurethane scaffolds in vitro were comparable and/or lower than the amount of the cytokines released by leukocytes exposed to the culture-grade polystyrene control.

Stability of tea theaflavins and catechins

Green tea catechins (GTC) and theaflavins (TF) possess a variety of biological activities. The present study focused on stability of GTC and TF in various solutions and drinks. It was observed that both GTC and TF were vulnerable to degradation caused by elevation of temperature and pH of incubation media. In general, GTC was more stable than TF. When boiled in water, four GTCs showed similar rates of degradation, but in sodium phosphate buffer (pH7.4) at room temperature, four GTCs demonstrated varying stability, with epigallocatechin gallate (EGCG) and epigallocatechin (EGC) being completely degraded in 6 h of incubation, while epicatechin (EC) and epicatechin gallate (ECG) were only degraded by less than 35%. Four TFs also demonstrated varying stability, with theaflavin-3,3′-digallate (TF3) and theaflavin-3′-gallate- B (TF2B) in general being more stable than theaflavin-1 (TF1) and theaflavin-3-gallate-A (TF2A) in either boiling water or alkaline sodium phosphate buffer. When incubated in various solutions and soft drinks, both GTC and TF had poor long-term stability and decayed by at least 50% during the first month of storage at room temperature.

Solubility and phase behavior of Cr(III) oxides in alkaline media at elevated temperatures

A platinum-lined, flowing autoclave facility is used to investigate the solubility behavior of Cr2O3 and FeCr2O4 in alkaline sodium phosphate, sodium hydroxide, and ammonium hydroxide solutions between 21 and 288°C. Baseline Cr(III) ion solubilities were found to be on the order of 0.1 nmolal, which were enhanced by the formation of anionic hydroxo and phosphato complexes. At temperatures below 51°C, the activity of Cr(III) ions in aqueous solution is controlled by a Cr(OH)3·3H2O solid phase rather than Cr2O3; above 51°C the saturating solid phase is γ-CrOOH. Measured chromium solubilities were interpreted via a Cr(III) ion hydrolysis/complexing model and thermodynamic functions for the hydrolysis/complexing reaction equilibria were obtained from least-squares analyses of the data. The existence of four new Cr(III) ion complexes is reported: Cr(OH)3(H2PO4)−, Cr(OH)3(HPO4)2−, Cr(OH)3(PO4)3−, and Cr(OH)4(HPO4)-(H2PO4)4−. The last species is the dominant Cr(III) ion complex in concentrated, alkaline phosphate solutions at elevated temperatures.

Magnetite solubility and phase stability in alkaline media at elevated temperatures

A platinum-lined flowing autocláve facility was used to investigate the solubility behavior of magnetite (Fe3O4) in alkaline sodium phosphate and ammonium hydroxide solutions between 21 and 288°C. Measured iron solubilities were interpreted via a Fe(II)/Fe(III) ion hydroxo-, phosphato-, and ammino-complexing model and thermodynamic functions for these equilibria were obtained from a least-squares analysis of the data. A total of 14 iron ion species were fitted. Complexing equilibria are reported for 8 new species: Fe(OH)(HPO4)−, Fe(OH)2(HPO4)2−, Fe(OH)3(HPO4)2−, Fe(OH)(NH3)+, Fe(OH)2(PO4)3−, Fe(OH)4(HPO4)3−, Fe(OH)2(H2PO4)−, and Fe(OH)3(H2PO4)3−. At elevated temperatures, hydrolysis and phosphato complexing tended to stabilize Fe(III) relative to Fe(II), as evidenced by free energy changes fitted to the oxidation reactions. $$\begin{gathered} Fe(OH)_3^ - + H_2 O_ \leftarrow ^ \to Fe(OH)_4^ - + (1/2)H_2 (g) \hfill \\ Fe(OH)_2^{} (HPO_4 )^{2 - } + H_2 O_ \leftarrow ^ \to Fe(OH)_3 (HPO_4 )^{2 - } + (1/2)H_2 (g) \hfill \\ \end{gathered}$$ For temperatures below 83°C and for a dissolved hydrogen concentration of 234 μmol-kg−1, the activity of ferrous iron in aqueous solution is controlled by a hydrous Fe(II) oxide solid phase rather than magnetite.

Zinc(II) Oxide Stability in Alkaline Sodium Phosphate Solutions at Elevated Temperatures

Zinc oxide (ZnO) is shown to transform into either of two phosphate-containing compounds in relatively dilute alkaline sodium phosphate solutions at elevated temperatures via ZnO(s) + Na[sup +] + H[sub 2]PO[sub 4]- [l reversible] NaZnPO[sub 4](s) + H[sub 2]O or 2ZnO(s) + H[sub 3]PO[sub 4](aq) [l reversible] Zn[sub 2](OH)PO[sub 4](s) + H[sub 2]O. X-ray diffraction analyses indicate that NaZnPO[sub 4] possesses an orthorhombic unit cell having lattice parameters a = 8.710 [+-] 0.013, b = 15.175 [+-] 0.010, c = 8.027 [+-] 0.004 [angstrom]. The thermodynamic equilibria for these reactions were defined in the system ZnO-Na[sub 2]O-P[sub 2]O[sub 5]-H[sub 2]O for Na/P molar ratios between 2.1 and 3. On the basis of observed reaction threshold values for sodium phosphate concentration and temperature, the standard entropy (S[degrees]) and free energy of formation ([delta]G[sub f][degrees]) for NaZnPO[sub 4] were calculated to be 169.0 J/(mol K) and -1510.6 kJ/mol, respectively; similar values for Zn[sub 2](OH)PO[sub 4] (tarbuttite) were 235.9 J/(mol K) and -1604.6 kJ/mol. Additions of sodium sulfite and sulfate did not alter the above reactions. 26 refs., 5 figs., 7 tabs.

Titanium(IV) oxide phase stability in alkaline sodium phosphate solutions at elevated temperatures

Titanium(IV) oxide is shown to transform to a sodium titanium hydroxphosphate compound in concentrated sodium phosphate solutions at elevated temperatures via TiO[sub 2](s) + 4Na[sup +] + 2HPO[sub 4][sup =] [r reversible] Na[sub 4]T(OH)[sub 2](PO[sub 4])[sub 2](S). The thermodynamic equilibrium for this reaction was investigated in the system TiO[sub 2]Na[sub 2]O-P[sub 2]O[sub 5]-H[sub 2]O for Na/P atom ratios between 2 and 3. Based on observed reaction threshold values for sodium phosphate concentration and temperature, the respective standard entropy and free energy of formation for Na[sub 4]Ti(OH)[sub 2](PO[sub 4])[sub 2] were calculated to be 823. 1 J/mol-K and -4025.1 kJ/mol at 298 K.

The effects of cholesterol depletion on the sodium pump in human red cells

Sodium pump function has been studied in human erythrocytes depleted of membrane cholesterol by incubation with phosphatidylcholine liposomes. The cells were sodium loaded by incubation in alkaline sodium phosphate and sodium pump activity was assessed by measurements of ouabain-sensitive 86Rb uptake at 37 degrees C. Cholesterol depletion had a biphasic effect; depletion by 5-25% increased sodium pump activity by a mean of 16.1% (S.D. 3.2%), whereas depletion by 35-50% decreased sodium pump activity by a mean of 14.8% (S.D. 3.8%). Cholesterol depletion had no reproducible effect on the ouabain-insensitive uptake of Rb. These results support the hypothesis that there may be an optimum membrane cholesterol content for sodium pump function.

A Microbiological Method of Standardizing Liver Extracts

The insect Cicadella viridis has two symbiotic bacteria, one producing a green pigment, the other B. carotene. The red bacterium is a diagenete1, or dysgonic commensal, of the other partner. However, a pure culture has been grown on media with liver extracts. It thus appeared that if the organism is dependent upon a metabolite present in liver extracts, its quantity present in the latter can be judged by the growth of this organism. For this purpose a basal medium was prepared with the following composition: glucose 2 per cent; peptone 1 per cent; citric acid 0.2 per cent; alkaline sodium phosphate 0.4 per cent; sodium chloride 0.2 per cent; magnesium sulphate 0.1 per cent. Only upon the addition of liver extracts would the bacterium grow. Growth was apparent after 72 hours and was suitable for comparison after seven days.

Phosphate and Kidney Weight

The addition of a certain amount of sodium phosphate to the food of young albino rats is followed by a remarkable increase in the weight of the kidneys, an increase which considerably exceeds that which is found after the ingestion of excessive amounts of other minerals or of protein. Female rats, 30 days of age at the beginning of the experiment, were given a casein-starch-lard diet in which adequate concentrations of cod liver oil, yeast, wheat germ and salt mixture were incorporated. To other groups of animals the same diet was given, except that part of the corn starch was replaced by acid or alkaline sodium phosphate. The total phosphate (PO4 concentration in the control diet was 0.68 per cent, in the acid phosphate diet 5.03 per cent, and in the alkaline phosphate diet 5.02 per cent. Measurements of food consumption showed that nearly equal amounts of food were taken by each group. After 44 days the rats were killed. The kidney weights are given in Table 1. No such pronounced increases in kidney weight were seen in similar experiments in which as much or more sodium than was taken in the above experiments was given in the form of sodium chloride or sodium bicarbonate. Parallel experiments showed that neither acid nor alkaline phosphate had any effect on the degree of compensatory hypertrophy of the kidney after unilateral nephrectomy.