Alkaline Reagents Research Articles

Effects of Acid and Alkaline Reagents on the Color and Gel-forming Ability of Milkfish Kamaboko

Effects of Acid and Alkaline Reagents on the Color and Gel-forming Ability of Milkfish Kamaboko

Measurement of different types of endotoxin in murine plasma by pretreatment with alkaline reagent and kinetic chromogenic Limulus test

Using a combined pretreatment methodology employing an alkaline reagent and a kinetic chromogenic Limulus test using Endospecy®, different types of endotoxins in murine plasma were able to be measured quantitatively. The detection of smooth (S)-form Salmonella abortus equi LPS (S-LPS) was approximately twice as sensitive as Helicobacter pylori LPS in aqueous solution. S-LPS added to whole mouse blood was recovered quantitatively from plasma, but the rough (R)-form S. minnesota LPS was not. The rates of clearance of S-LPS from the circulation following intravenous injection were shown to be different among BALB/c, C3H/HeN and B10Sn mice. Infection of mice with Salmonella typhimurium 3 days earlier resulted in accelerated clearance of subsequently injected LPS from the circulation. Significantly higher amounts of free non-microbe-associated LPS were detected in the blood of mice 1 h after infection with Escherichia coli O111:B4 followed by immediate treatment with ceftazidime, in comparison with non-antibiotic-treated but infected mice.

97/01896 A comparison between alkaline and de-complexing reagents to extract humic acids from low rank coals

97/01896 A comparison between alkaline and de-complexing reagents to extract humic acids from low rank coals

On crystallization and phase separation phenomena in PEN/PHBA copolyesters

Abstract Two different etching techniques that reveal the semicrystalline morphology of polyesters have been developed and applied to an analysis of the phase structure of copolyesters made by reacting poly(hydroxybenzoic acid) (PHBA), and poly(ethylene naphtha-lene-dicarboxylate) (PEN). One technique is based on oxidation with acidic permanganate solutions and is used to study the macroscopic distribution of different phases. The other is based on sa-ponification with alkaline reagents and reveals more detailed structure within the various phases. Etching and electron microscopic examinations have been carried out for three different PEN-co-PHBA compositions. Three different types of solid phase are revealed: (1) a phase rich in PEN; (2) a phase containing roughly equal proportions of the two components, liquid crystalline at high temperatures; (3) a solid phase of crystalline HBA-rich molecules, which segregate into laminar regions. These observations are consistent with the previously published thermal, x-ray, and dynamic mechanical analyses of these materials.

A comparison between alkaline and decomplexing reagents to extract humic acids from low rank coals

Humic acids (HAs) were obtained from two low rank coals (lignite and leonardite) by using either alkali extractants (0.1 M NaOH, 0.1 M KOH or 0.25 M KOH) or solutions containing Na 4P 2O 7 (0.1 M Na 4P 2O 7 or 0.1 M NaOH Na 4P 2O 7 ). In both coals, the greatest yields were obtained with 0.25 M KOH and the lowest with the 0.1 M alkalis, whereas the extractants based on Na 4P 2O 7 yielded intermediate values and were more effective on the lignite. Chemical analysis showed that the leonardite HAs consisted of molecules that were less oxidized and had fewer functional groups than the HAs released from the lignite. Moreover, the HAs extracted by reagents containing Na 4P 2O 7 exhibited more functional groups than those extracted with alkali, this effect being more apparent in lignite because of its greater cation exchange capacity. Gel permeation chromatography indicated that the leonardite HAs contained a greater proportion of higher molecular size compounds than the lignite HAs, and that both solutions containing Na 4P 2O 7 released HAs with a greater proportion of smaller molecular compounds from the lignite than did the alkali extractants.

Molecular Characterization of Alkalilignin-1M30C: a Valid Alternative Preparation to the Björkman Lignin in the Analytical Study of Wheat Straw Lignin

Bjorkman lignin, obtained by extensive grinding and dioxane extraction, is considered one of the most suitable standard preparations close to the native lignin from lignocellulosic materials. In this study, alkalilignin extracted with 1 M NaOH at 30 °C (AL-1M30C), and the Bjorkman lignin from wheat straw (Triticum aestivum) were compared using spectroscopic and degradative techniques. The very small chemical differences between the two preparations are mainly that the Bjorkman method yields a lignin with slightly higher proportion of p-hydroxyphenyl units, and some co-extracted aliphatic fractions. The AL-1M30C preparation, on the other hand, showed a somewhat higher proportion of syringyl units, as well as the probable effects of the selective removal of structures associated with ester carbonyl groups. The evident similarity between both lignin samples suggests that AL-1M30C produced from wheat straw may represent a convenient alternative to Bjorkman lignin preparation for analytical purposes. These results also point towards the possibility of producing suitable lignin preparations from other Gramineae plants showing high solubility in alkaline reagents.

Growth, preparation and surface modification of microcrystalline diamond powder for the synthesis of diamond ceramics

Chemically modified microcrystalline diamond surfaces have been prepared and investigated on the basis of thermodesorption measurements, X-ray diffraction and X-ray photoemission spectroscopy. X-ray investigations and SEM-images show that the synthesized diamond powder consists of pure carbon crystals of cubic modification with unbroken facets. Investigation of acidic functional groups, having different oxygen content and bound on the diamond surface by an oxidizing process, was carried out by the method of neutralization with different alkaline reagents. It has been shown that the concentration of the groups neutralized by each reagent decreases as the temperature of the heat treatment during preparation is raised. Under thermal treatment, the oxy- functional groups decompose at T > 600 ° C, leaving a hydrogen terminated diamond surface. Hydrogen desorbs at T > 1000 ° C, thus generating an atomically clean surface, such as is required for direct bonding of the nano- and microcrystals during sintering.

Use of acidobasic indicators to detect interfacial reactivity during alkaline flooding

A novel technique has been developed to detect the depletion of the alkaline reagent that occurs during the displacement of an acidified oil by an aqueous alkaline solution in a consolidated model porous medium. An acidobasic indicator (thymolphthalein) was added to the displacing aqueous solution in order to monitor the progress of the chemical reaction. The initially blue alkaline solution turned colorless after prolonged contact with the acidified oil, indicating that the alkali in the vicinity of the interface became depleted as a direct result of interfacial chemical reaction. Under such conditions, the displacement front changes to a nonreactive one, very similar to a pure water displacement. The disappearance of color was particularly pronounced at low alkali concentrations and low flowrates.

Procedure for refolding and purification of recombinant proteins from Escherichia coli inclusion bodies using a strong anion exchanger.

Using Escherichia coli system expressing papilloma virus HPV16 E7MS2 fusion protein as a model system, a novel procedure was applied to solubilize, purify and refold recombinant proteins from E. coli inclusion bodies. The necessity to reactivate proteins at low protein concentrations (owing to their tendency to aggregate at high concentrations) was overcome by solubilization of inclusion bodies in alkaline solution and immobilization of proteins on a strong and resistant anion exchanger. This procedure has an inherent advantage of combining refolding and purification procedures in one step. The solubilization of the fusion protein in an alkaline reagent with the use of an anion exchanger resulted in considerable purification of the recombinant protein at a fairly high concentration. The protein was soluble under mild conditions and reacted with antibodies against the "native" papilloma virus.

Recovery of a Saskatchewan Heavy Oil Using Alkaline Solutions

Abstract The feasibility of employing various alkaline agents (sodium hydroxide, sodium metasilicate and sodium orthosilicate) to enhance the recovery of a specific Saskatchewan heavy oil from the Kindersley region has been investigated. The dynamic interfacial tension behaviors of solutions of these alkalis in contact with the crude oil were measured for a range of concentrations and temperatures, and the most interfacially active formulations were then tested for their oil recovery efficacies by conducting oil displacement experiments in unconsolidated linear sand packs at 25 °C and 65 °C. The most promising of the three alkalis tested was found to be sodium hydroxide, which was capable of producing very significant enhancements in oil recovery relative to that obtained with pure waterflooding. Introduction The so-called heavy oil belt of Saskatchewan covers a wide area that stretches from Lloydminster in the north to Kindersley in the south. The estimated ultimate oil in place amounts to some 4 × 109 m3. In a recent appraisal of this huge reserve, Reid(1) suggested that 20% of the oil in place could be recovered by using enhanced oil recovery techniques. To date, only thermal processes such as in-situ combustion and steamflooding/stimulation are being applied to these reservoirs. However, since the density of the crude ranges from 11 to 20 °API and since the average temperature of these reservoirs is about 20 °C, the viscosity of the crude at reservoir conditions will be of the order of 1000 mPa.s or higher. Another significant characteristic of these deposits is the occurrence of the oil in relatively thin zones. According to Selby et al.(2), the thinness of the formations coupled with the large depths and low permeabilities makes thermal processes unsuitable for about 50% of the heavy oil deposits of Canada, the U.S. and Venezuela. Amongst the various non-thermal processes, alkaline flooding appears to be the most attractive. Alkaline reagents are abundant and quite cheap compared with conventional surfactants. Their effectiveness for the recovery of acidic crudes has been known since 1927 by virtue of the work of Nutting(3) and Atkinson(4). It is now generally accepted(5–8) that alkaline reagents react with surface active materials present in the crude resulting in the in-situ formation of surfactant soap species. The adsorption of these generated surfactants at the oil/water/sand interfaces often results in a drastic reduction of the interfacial tension and/or in a change in matrix wettability. The end result is the mobilization of residual oil trapped in the fine pores of the reservoir sand. Selby et al.(2) listed 15 recent field alkaline flood tests in Canada and the U.S. However, only one of those tests was considered successful, while the majority were abandoned. One reason for this dismal performance is the inadequate understanding of the complex interactions that occur between alkaline reagents, crude oil, formation water and matrix minerals. Even basic oil-water interfacial tension (IFT) behavior becomes very complex when dealing with crude oil/caustic systems. Several researchers(9,10) have reported variations in IFT of one or more orders of magnitude when crude oil was contacted with caustic solutions for contact times ranging between 10 and 60 minutes.

Calcium determination in serum with stable alkaline Arsenazo III and triglyceride clearing

We describe an analytical procedure for determining serum calcium, using the ligand Arsenazo III in an aqueous alkaline medium. The choice of pH for the proposed technique differs from current procedures, which are for the most part carried out in a slightly acidic medium. An acidic medium avoids interference from magnesium, but is spectrophotometrically suboptimal for this pH-dependent reaction: the molar absorptivity of the Arsenazo III complex with calcium at acid pH is 13,787 L mol-1 cm-1, about one-half of that at a more optimal alkaline pH (26,574 L mol-1 cm-1). We have included a clearing technique in the reagent to avoid spectral aberrations from hypertriglyceridemic samples. alpha-Cyclodextrin absorbs the nonesterified fatty acids liberated from triglycerides by a microbial lipase. This modification may also be helpful for binding nonesterified fatty acids, which are known to interfere with calcium procedures by forming calcium soaps and thus preventing the reaction with intended ligands. The use of 8-hydroxyquinoline sulfonate as the magnesium-masking agent facilitates the use of alkaline pH. The less-water-soluble alternative, 8-hydroxyquinoline, commonly used as a precipitating agent for several methods, is difficult to solubilize in the alkaline reagent and tends to precipitate when complexed to magnesium. Finally, the use of alkaline pH results in a prolonged (> or = 6 weeks) shelf life for the reagent.

Continuous-flow determination of low concentrations of urea in natural waters using an immobilized urease enzyme reactor and an ammonia gas-sensing membrane electrode detector system

The continuous-flow determination of low concentrations of urea in river and lake water is described. Coexisting ammonium ions up to a concentration of 2 × 10–4 mol dm–3 were effectively removed by passing through a gas-permeable poly(tetrafluoroethylene)(PTFE) tube after the addition of an alkaline reagent solution. The solution was then brought back to neutral pH by passing through another gas-permeable PTFE tube immersed in hydrochloric acid, to ensure the optimum pH for the urease enzyme. Urea in the sample solution was enzymically decomposed into ammonium ions and then detected by an ammonia gas-sensing membrane electrode, as ammonia, after the addition of sodium hydroxide solution. The detection limit of urea was about 1 × 10–7 mol dm–3. This system was applied to the analysis of natural waters containing (0.2–4)× 10–6 mol dm–3 urea and the results were compared with those obtained by spectrophotometry using the reagent diacetylmonoxime.

Enzymic flow injection determination of lactose in milk with on-line dialysis

Milk samples were analysed to determine their lactose content by using flow injection (FI) and incorporating immobilized β-galactosidase and glucose oxidase—mutarotase bioreactors. A dialysis unit was placed after the injection valve to avoid the need for sample pre-treatment. The methodology was based on the chemiluminescence determination of hydrogen peroxide produced by the enzymic reactions, with use of an alkaline reagent containing luminol and hexacyanoferrate(III). Linearity was observed over the concentration range 20–200 mmol l–1 with lactose as standard (r= 0.9995), and 20 milk samples h–1 could be analysed. Comparisons were made with high-performance liquid chromatography and chloramine-T methods. The enzymic FI method afforded a low relative standard deviation (0.49%) and was free from interference. Additionally, the proposed method was simple and did not require precipitation of proteins, or filtration or centrifugation. The enzymic reactors were stable for 6 months when used daily at optimum pH.

Changes in the Surface Characteristics of Artificially Aged Mastic Varnishes after Cleaning Using Alkaline Reagents

Changes in the Surface Characteristics of Artificially Aged Mastic Varnishes after Cleaning Using Alkaline Reagents

Treatment with different chemicals and their effects on the digestibility of maize stalks. 1. In vitro studies

Ground maize stalks (60% moisture) were treated with different chemical reagents to study their effects on in vitro organic matter disappearance (IVOMD). Urea (6.6%), urea (6.6%) + Ca(OH) 2 (5.0%), Ca(OH) 2 (5.0%), NaOH (1%) + Ca(OH) 2 (5.0%), SO 2 (5.0%) and urea (6.6%) followed by SO 2 (5.0%) were the chemicals used. The treated maize stalks were incubated at 45 °C for 0, 1, 2, 3, 6, 8, 10 and 14 days. In addition to these, hydrogen peroxide (H 2O 2) was used in different H 2O 2: substrate ratios (0:1, 1:20, 1:15, 1:10, 1:8, 1:6, 1:5 and 1:4) to react with alkaline maize stalks. Ca(OH) 2 was used as an alkaline reagent. The IVOMD of treated maize stalks was improved by 21.97%, 19.21% and 46.81% when treated with urea, SO 2 and urea + SO 2 respectively. Using H 2O 2 to react with alkaline maize stalks in a ratio of 1:5 (H 2O 2: substrate) improved the IVOMD by 29.01%.

Changes in the surface characteristics of artificially aged mastic varnishes after cleaning using alkaline reagents

AbstractThis study investigates the effects of a selection of alkaline reagents, including solutions, pastes and soap gels, used to remove an artificially aged mastic film applied over a primed canvas. Surface changes were examined using visible light and scanning electron microscopy (SEM). Ammonia, whether in solution or gelled with hydroxypropylmethylcellulose (HPMC), required a pH of 10 or higher to remove varnish at an appreciable rate, whereas ammonia in wax paste worked at pH 9. Soap gels based on deoxycholic acid (DCA) were effective at pH 9·5. The rate of removal increases significantly with the addition of benzyl alcohol, while anthracene-9-carboxylic acid (A9C) and 9-fluorenone-4-carboxylic acid (9FOC) soap gels of pH 7·9 worked quickly without the addition of alcohol. Where reagents with a pH of more than 9 were used, some erosion of the priming was observed under SEM. Examination of the topography of residual varnish after treatment and Fourier transform infrared spectroscopy (FTIR) measuremen...

Chemiluminescent Assay for Glycerol in Wine Using Flow‐Injection

ABSTRACTA flow‐injection method was developed for the enzymatic determination of glycerol in wines using a reactor containing immobilized glycerokinase and glycerol‐3′‐phosphate oxidase. Hydrogen peroxide from the reaction was monitored by chemiluminescence after reaction with an alkaline reagent containing luminol and hexacyanoferrate (III). Calibration curves were linear between 25 mg/L and 250 mg/L of glycerol for injected volume 29 μL. The method gave satisfactory results compared with a gas‐chromatographic method. No sample pre‐treatment was necessary and a sampling frequency of 30/hr could be achieved.

Determination of urea in serum by using naturally immobilized urease in a flow injection conductimetric system

A flow injection method was developed, aimed at the determination of urea in human serum. The system makes use of the naturally immobilized urease present in Canavalia ensiformis DC (jack bean). A column is filled with small pieces of this bean, and the sample (50 microliters) containing urea passes through it carried by a 1% NaCl solution. On leaving the column the stream is merged with an alkaline reagent (0.5 mol dm-3 NaOH; 0.5% disodium dihydrogen ethylenediaminetetraacetate). The ammonium ions, arising from the enzymatic reaction that occurs inside the column, are changed into the molecular form, which permeates a polytetrafluoroethylene membrane and is received in a de-ionized water acceptor stream. The ammonia ionizes causing an increase in the conductance, which is proportional to the urea content of the sample. About 40 samples can be processed in 1 h with negligible carry-over and with a relative standard deviation of 1% or less. The results are in agreement with those obtained by a standard spectrophotometric method.

Automated system for the determination of total silica in geothermal water by flow injection/spectrophotometric method.

A new FIA system was developed for the continuous determination of total silica in natural water. The system includes the conversion of polymerized silica into its monomer. A sample (20μI) sandwiched between two 100 μl layers of alkaline reagent is introduced into a stream of distilled water at a flow rate of 1.3 ml/min. The polymerized silica in the sample is decomposed to monomer in 10 m Teflon tubing heated in an air bath at 145°C. The sample is merged with a stream of acidic molybdate reagent at a flow rate of 0.6 ml/min, and then is heated at 90°C to produce yellow molybdosilicate. The absorbance of the yellow complex is measured at 400 nm. The silica, ranging from 0.5 to 100 mgSi/l, could be determined at a sampling rate of 30 samples/h. The precision of the method is 1.5% (RSD) for 50 mgSi/l. The flow injection method proposed here was applied to the quantitative analyses of total silica in several geothermal water and colloidal silica samples. The results obtained by the proposed FIA were in good agreement with those obtained by the conventional method (PS K 0101).

Determination of Free Amino Acids in Cheese by Flow Injection Analysis with an Enzymic Reactor and Chemiluminescence Detector

ABSTRACTThe substrate is degraded enzymatically by L‐amino acid oxidase immobilized on controlled porosity glass. The hydrogen peroxide generated by the reaction is determined by chemiluminescence with an alkaline reagent containing luminol and hexacyanoferrate (III). The log‐log calibration graphs for L‐leucine were rectilinear from 0.025 mM to 1.0 mM (R = 0.9998). The coefficients of variation (rds) for n = 10 were 1.4% and 0.3% for 0.1 mM and 0.8 mM of L‐leucine, respectively. The sample throughout was 40 h‐1. The concentration of free amino acids in cheese samples was 14 to 50 mg L‐leu/g product. The enzyme reactor showed good stability over 4‐months.