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Showing papers on "Oxalic acid published in 1985"


Journal ArticleDOI
TL;DR: In this article, the authors investigated the performance of both partial and total oxidization of Ag(111) single crystal surface at pressures of up to 50 Torr, and showed that H-transfer rather than C-C cleavage is rate-determining in the combustion of both ethylene and ethylene oxide.

289 citations


Journal ArticleDOI
TL;DR: The layer was evaluated by scanning electron microscopy and by measurement of hydraulic conductance before and after 2-min topical treatment with potassium chloride, neutral potassium oxalate, half-neutralized oxalic acid or both neutral and acidic oxalates to determine whether the layer was acid-resistant or susceptible to acid etching.

165 citations


Journal ArticleDOI
01 Mar 1985-Langmuir
TL;DR: Etudes de l'adsorption des ions oxalate et citrate sur des particules spheriques colloidales d'hematite and leur influence sur l'elimination du fer a partir de celles-ci, en fonction de la concentration du solute, du pH and de la temperature.
Abstract: Etudes de l'adsorption des ions oxalate et citrate sur des particules spheriques colloidales d'hematite et de leur influence sur l'elimination du fer a partir de celles-ci, en fonction de la concentration du solute, du pH et de la temperature

141 citations


Journal ArticleDOI
TL;DR: Carothers et al. as discussed by the authors showed that carboxylic and phenolic acids also have the ability to dissolve carbonate grains and cements, which is a natural consequence of the interaction of organic and inorganic reactions during progressive diagenesis.
Abstract: The development of porosity and permeability enhancement and preservation or both in many sandstones is a function of aluminosilicate or carbonate mineral stability. The dissolution of aluminosilicate minerals and subsequent porosity and permeability enhancement is a problem of aluminium mobility. Our experimental data demonstrate that it is possible to increase the mobility of aluminium significantly and to transport it as an organic complex in organic acid solutions. These organic acids, primarily carboxylic and phenolic acids, also have the ability to dissolve carbonate grains and cements. W. W. Carothers & Y. K. Kharaka (Geochim. cosmochim. Acta 44, 323-332 (1980)) have shown that concentrations of carboxylic acid anions range up to 5000/10$^{6}$ (by mass) over a temperature range of 80-100 degrees C in some oil-field formation waters. Our experiments show that acetic acid solutions at the same concentration and over the same temperature range can increase the solubility of aluminium by one order of magnitude, whereas oxalic acid solutions increase the solubility by three orders of magnitude. Phenols such as hydroquinone and catechol are almost as effective as oxalate. The textural relations observed in the experiments are identical to those in sandstones containing porosity enhancement as a result of aluminosilicate dissolution. A natural consequence of the burial of sedimentary prisms is the maturation of organic material. Nuclear magnetic resonance (n.m.r.) studies have shown that carbonyl and phenol groups are removed from the kerogen molecule before the generation of hydrocarbons. Thermal degradation or the action of mineral oxidants, or both (the reduction of Fe$^{3+}$ released from clay diagenesis and the reduction of polysulphides are two examples) may be the mechanisms by which the peripheral groups containing the phenols and carboxylic acids are released from the kerogen molecule. The experiments suggest that the enhancement of porosity in a sandstone as the result of aluminosilicate or carbonate dissolution is the natural consequence of the interaction of organic and inorganic reactions during progressive diagenesis. Because of the time and temperature dependence of these reactions, the actual reaction sequences will be sensitive to the thermal and stratigraphic history of the source reservoir sediments.

100 citations


Journal ArticleDOI
TL;DR: Barium titanyl oxalate was prepared by addition of ethanol solution in oxalic acid to barium-titanium mixed aqueous solution at room temperature.

72 citations


Journal ArticleDOI
TL;DR: A continuous-flow assay for measuring oxalate in urine is described and correlates well with another established enzymatic method (using oxalates decar­ boxylase), which is accurate, sensitive, reproducible and relatively rapid.
Abstract: SUMMARY. A continuous-flow assay for measuring oxalate in urine is described. Covalently attached oxalate oxidase (EC 1.2.3.4) is used to oxidise the oxalate anion to carbon dioxide and hydrogen peroxide. The formed hydrogen peroxide is measured colorimetrically (A,RlJ) with an established reaction using horseradish peroxidase (EC 1.11.17), 3-methyl-2-benzothiazolinone hydrazone (MBTH) and 3-dimethylaminobenzoic acid (DMAB). Ascorbate interference is eliminated by treating the urine sample with sodium nitrite prior to assaying. The assay is accurate (mean recovery of added oxalate in spiked urine sample is 93±1l%), sensitive (detection limit 1·0 ILmoUL), reproducible (within-batch CV 3·5%; between-batch CV 5%) and relatively rapid (15 samples/h). This assay correlates well (R=0'99) with another established enzymatic method (using oxalate decar­ boxylase). A number of analytical procedures for the estimation of urinary oxalate have been de­ veloped and several reviews on these methods have been published. 1-3 Most of these methods are prone to error (see below), time consuming and require tedious sample pretreatment. The need for a simple and accurate assay capable of handling a large number of samples still remains.

69 citations


Journal ArticleDOI
TL;DR: Disodium EDTA, 10 mmol/L final concentration, stabilizes ascorbate in urine and inhibits its conversion to oxalate at pH values of 4.4 to 7.0 during a 24-h period, and it is proposed that urine specimens for asCorbate and oxalates analyses be collected with disodium EDta present such as to give about this final concentration.
Abstract: Ascorbate is unstable in urine at room temperature at pH values ranging from 1 to 12. At pH 7 and above, oxalate is generated in amounts directly proportional to the ascorbate concentration. In 12 different urines, adjusted to pH 12 and incubated for 20 h at room temperature, there was a significant correlation between the amount of oxalate formed and the initial ascorbate concentration (r = 0.97, p less than 0.01). The mean (+/- SD) concentration of oxalate (1.32 +/- 0.70 mmol/L) formed during this period approximated the initial ascorbate concentration (1.57 +/- 1.09 mmol/L). Disodium EDTA, 10 mmol/L final concentration, stabilizes ascorbate in urine and inhibits its conversion to oxalate at pH values of 4.4 to 7.0 during a 24-h period. We therefore propose that urine specimens for ascorbate and oxalate analyses be collected with disodium EDTA present such as to give about this final concentration.

67 citations


Journal ArticleDOI
TL;DR: In this paper, the main products are oxalic acid at Pb electrode and carbon monoxide at Sn and In electrodes, and substantial amounts of oxal acid, glyoxylic acid and carbon dioxide have been produced.
Abstract: Regarding the electrochemical reduction of carbon dioxide in nonaqueous electrolytes, it has been clarified that the main products are oxalic acid at a Pb electrode and carbon monoxide at Sn and In electrodes. In the case of a Zn electrode, substantial amounts of oxalic acid, glyoxylic acid and carbon monoxide have been produced.

67 citations



Journal ArticleDOI
TL;DR: In this article, equilibria between Al3+, oxalic acid (H2L), and OH were studied in 0.6 mol dm-3 NaCl medium at 25 °C.
Abstract: Equilibria between Al3+, oxalic acid (H2L), and OH– were studied in 0.6 mol dm–3 NaCl medium at 25 °C. Potentiometric titrations (glass electrode) and 27Al n.m.r. measurements were performed to study speciation and equilibria within the concentration ranges 0.2 ⩽–log [H+]⩽ 7.2, 0.0005 ⩽b⩽ 0.02 mol dm–3, 0.0005 ⩽c⩽ 0.025 mol dm–3, and 0.5 ⩽c/b⩽ 16 [b and c are the total concentrations of aluminium(III) and oxalic acid respectively]. Besides a series of [AILn]3 – 2n complexes with n= 1,2, and 3, the formation of the polynuclear mixed hydroxo-complexes Al3(OH)3L3 and [Al2(OH)2L4]4 – were established. N.m.r. data also indicated the formation of an [AlHL]2+ complex in strongly acidic solutions: pKa([AlHL]2+)≈ 0.0. The significance of the different Al complexes to conditions prevailing in natural waters is discussed, including a model calculation of the solubility of a clay mineral (kaolinite) in the presence of oxalate. Data were analysed using the least-squares computer program LETAGROPVRID.

55 citations


Journal ArticleDOI
TL;DR: New homegenous catalysts, AgII and PdII metalloporphyrins, were found for the electrochemical reduction of CO2 in CH2Cl2; oxalic acid and H2 were detected as products.
Abstract: New homegenous catalysts, AgII and PdII metalloporphyrins, were found for the electrochemical reduction of CO2 in CH2Cl2; oxalic acid and H2 were detected as products.

Journal ArticleDOI
TL;DR: In this article, a capillary GC and GC-MS method employing dibutyl esters was described for determining short-chain dicarboxylic acids in rain, fog and mist samples collected in the Los Angeles area.
Abstract: A capillary GC and GC-MS method, employing dibutyl esters is described for determining short-chain dicarboxylic acids in rain, fog and mist samples collected in the Los Angeles area. Approximately twenty dicarboxylic acids (C2-C10) were identified in the water samples, including cis (maleic) and trans (fumaric) unsaturated, saturated, normal, branched and aromatic. Oxalic acid is the dominant acid, followed by succinic and malonic acids. The total concentrations measured are 2.9–51μM, 64–66 μM and 12 μM for rain, fog and mist samples, respectively. These diacids are probably produced by photooxidation of anthropogenic and possibly biogenic organic compounds in the atmosphere.

Journal Article
TL;DR: The identity of calcium oxalate can be confirmed by its insolubility in 2M acetic acid, since both calcium carbonate and calcium phosphate are soluble.
Abstract: Calcium oxalate crystals stain with alizarin red S at a pH of 7.0 but not at a pH of 4.2. In contrast, calcium phosphate and calcium carbonate stain at a pH of both 7.0 and 4.2. This difference allows presumptive identification of calcium oxalate deposits. The identity of calcium oxalate can then be confirmed by its insolubility in 2M acetic acid, since both calcium carbonate and calcium phosphate are soluble. We have applied this procedure for several years and have found it to be a rapid, reliable, and technically simple procedure for distinguishing calcium oxalate from other calcium deposits.

Patent
16 Dec 1985
TL;DR: In this paper, a method for producing a stable preparation containing nicorandil, a saturated higher aliphatic acid or saturated higher alcohol which is solid at ordinary temperatures, and optionally, an organic acid such as fumaric acid, oxalic acid or glutaric acid is disclosed.
Abstract: A method for producing a stable preparation containing nicorandil, a saturated higher aliphatic acid or a saturated higher alcohol which is solid at ordinary temperatures, and optionally, an organic acid such as fumaric acid, oxalic acid, salicylic acid, tartaric acid or glutaric acid is disclosed. Nicorandil is useful as a curative for various types of angina pectoris. However, it is unstable in humid conditions and under the compressive pressure exerted by punching operations in tablets making and, therefore, the development of a stable nicorandil preparation has been desired.

Journal ArticleDOI
TL;DR: In this paper, the authors describe a decomposition of CO 2, CO, H 2 O and HCOOH in 257-313 nm correspondant to the singingulet A(A u,π * ←n + ).
Abstract: Etude realisee dans le domaine 257-313 nm correspondant a l'excitation de l'etat singulet A(A u ,π * ←n + ). Obtention de CO 2 , CO, H 2 O et HCOOH. Processus conduisant a CO 2 +HCOOH et CO 2 +CO+H 2 O. Rendements. Decomposition photosensibilisee par Hg( 3 P 1 ). Decomposition IR multiphotonique. Mecanismes des divers systemes de decomposition

Journal ArticleDOI
TL;DR: It was concluded that the enzymic method was useful for the assay of urinary oxalate and in detecting elevated levels of plasma oxalATE such as those in hemodialysis patients but was not sensitive enough to determine accurately the normal or decreased level of oxalates in plasma.
Abstract: In order to establish a standard procedure for the spectrophotometric determination of urinary and plasma oxalate with oxalate oxidase (Laker, M.F., et al. (1980) Clin. Chem. 26, 827-830; Sugiura, M., et al. (1980) Clin. Chim. Acta 105, 393-399) and to define the limitations of the method, the procedures and reactions involved in the assay have been examined. Among the chromogenic hydrogen donors for peroxidase tested, a combination of 3-methyl-2-benzothiazolinone hydrazone (MBTH) and sodium N-sulfopropylaniline (HALPS) was found to be best for the oxalate determination under the conditions used. Urine contained substance(s) which were inhibitory to the measurement of hydrogen peroxide by the peroxidase-catalyzed oxidative condensation of MBTH and HALPS, but they were largely removed by charcoal treatment at pH 5.6 without significant loss of oxalate. Deproteinization of plasma was carried out by ultrafiltration through a membrane cone (Centriflo CF-25) at neutral pH. The plasma oxalate ultrafiltrability under the conditions employed was calculated to be approximately 95%. A standard assay system for oxalate in these urine and plasma samples was then set up based on a series of studies on the reactions involved in the assay. In the case of normal plasma, however, the absorbance change was very small due to the low concentration of oxalate, and in addition, pretreatment of plasma with excess oxalate decarboxylase followed by the ultrafiltration and oxalate determination did not abolish completely the oxalate oxidase-dependent absorbance increase. It was concluded that the enzymic method was useful for the assay of urinary oxalate and in detecting elevated levels of plasma oxalate such as those in hemodialysis patients but was not sensitive enough to determine accurately the normal or decreased level of oxalate in plasma. The apparent concentration of oxalate in normal human plasma was measured in this work as 3.5 +/- 0.8 microM (mean +/- S.D., n = 8), and this result was interpreted to mean that the concentration of plasma oxalate was less than approximately 3.5 microM, as estimated by the present method.

Journal ArticleDOI
Hironori Ohkawa1
TL;DR: A new quantitative gas chromatographic (GC) method has been developed for the determination of oxalic acid in foods and it is shown that the technique is simple, rapid, and accurate, and small samples may be used.
Abstract: A new quantitative gas chromatographic (GC) method has been developed for the determination of oxalic acid in foods. Solid sample is extracted with water (soluble oxalic acid) or 2N hydrochloric acid (total oxalic acid) at room temperature. An aliquot of sample extract is evaporated to dryness, and the oxalic acid in the residue is methylated with 7% hydrochloric acid-methanol. The reaction mixture is extracted with chloroform, and dimethyl oxalate is quantitated by GC. Recovery of oxalic acid added to liquid samples averaged 100.6%; recoveries from extracts of solid samples were 96.2-99.5 and 97.2-100.1% for water and hydrochloric acid extractions, respectively. Results are shown for determination of oxalic acid in spinach and beverages. The technique is simple, rapid, and accurate, and small samples may be used. The limit of determination is 20 micrograms.


Journal ArticleDOI
TL;DR: In this article, a simple single-step procedure for the determination of α-ketoacids and oxalic acid in rain, fog and mist is reported, based upon the reversed phase liquid chromatography of the quinoxilinol derivative of the α-ketoacids.
Abstract: A simple single-step procedure for the determination of α-ketoacids and oxalic acid in rain, fog and mist is reported. The method is based upon the reversed-phase liquid chromatography of the quinoxilinol derivative of the α-ketoacids and the hydroxy-quinoxilinol of oxalic acid. This procedure is sensitive at the submicromolar level and measurements are reproducible to better than ± 10%. Oxalic acid, glyoxylic acid and pyruvic acid concentrations in fog, mist, and rain samples, collected in the Los Angeles area have been determined by the methods described in this study.

Patent
23 Aug 1985
TL;DR: In this article, a cellulose ether and a solid acid are combined to form a thickening agent suitable for thickening carpet backing formulations, paints and drilling muds, which can be used in a variety of applications.
Abstract: A thickening agent suitable for thickening carpet backing formulations, paints and drilling muds is provided. The thickening agent comprises (1) a cellulose ether and (2) a solid acid for example citric acid, tartaric acid, oxalic acid, malonic acid, succinic acid and polyacrylic acid.

Journal ArticleDOI
Fredrik Winquist1, Bengt Danielsson1, J-Y. Malpote1, L. Persson1, M-B. Larsson1 
TL;DR: A rapid enzymic procedure, based on calorimetry, for specific determination of oxalic acid, using the enzyme thermistor for purification and immobilization of the enzyme, as well as the effect of some of its inhibitors.
Abstract: This paper describes a rapid enzymic procedure, based on calorimetry, for specific determination of oxalic acid. Oxalate is oxidized by immobilized oxalate oxidase to hydrogen peroxide and carbon dioxide. The heat generated by this reaction is measured in a calorimetric device, the enzyme thermistor. Oxalate concentrations as low as 0.02 mM can be determined. Also described is purification and immobilization of the enzyme, as well as the effect of some of its inhibitors. The urinary oxalate content of 16 persons was determined using the enzyme thermistor. For samples containing a very low concentration of oxalate (less than 0.2 mM) an extraction step with tributylphosphate can be introduced to purify and concentrate the oxalate. The oxalate content in different kinds of food was also determined.

Journal ArticleDOI
TL;DR: In this paper, an ethanol solution of oxalic acid was added to an aqueous solution with Pb, La, Zr, and Ti at 30°C.

Patent
02 Apr 1985
TL;DR: In this article, a method for recovering a denitrating catalyst which is characterized by washing, with an aqueous oxalic acid solution, the used tungsten-titania or the Tungsten titania-vanadium denitrated catalyst which dust components have adhered to or have accumulated on and in which an SO 2 -oxidizing power has thus risen.
Abstract: A method for recovering a denitrating catalyst which is characterized by washing, with an aqueous oxalic acid solution, the used tungsten-titania or the tungsten-titania-vanadium denitrating catalyst which dust components have adhered to or have accumulated on and in which an SO 2 -oxidizing power has thus risen; impregnating the catalyst with a tungsten compound; and drying and calcining the thus treated catalyst.


Journal ArticleDOI
TL;DR: In this paper, a method for the determination of ascorbic acid in vegetables and fruits using differential pulse polarography was developed, and the precision of the procedure was found to be 1.4% at the 1 mg litre−1 level.
Abstract: A method for the determination of ascorbic acid in vegetables and fruits using differential pulse polarography has been developed. The extraction medium recommended is a mixture of oxalic acid (1%), trichloroacetic acid (2%) and sodium sulphate (1%), and simple filtration is used to remove the residue. An acetate buffer (2M) is recommended to keep the pH at 4.5. The polarograms were recorded using a modulation amplitude of 50mV, a scan rate of 2mVs−1, and a drop time of 1 s. The precision of the procedure was found to be 1.4% at the 1 mg litre−1 level of ascorbic acid. The calibration graph was linear in the range of 0–20 mg litre −1 of ascorbic acid with a slope of 0.48μA mg litre−1. Most common anions and cations did not interfere, however, Fe3+ and EDTA interfered, and Br− and I− seriously interfered with the determination. The method was applied to determine the ascorbic acid content of a number of vegetables and fruits using the standard-addition calibration.

Patent
05 Mar 1985
TL;DR: In this paper, the acid addition salt of a compound of formula I (R 1 is lower alkyl or lower alkoxy; R 2 is H or lower alkanoyl; R 3 and R 4 are lower alkane; R 5 and R 6 are lower alkane; and R 8 is lower ammonium; n is 2 or 3) can be synthesized by condensing the novel substance of formula II or its salt with the compounds of formula III (X is halogen).
Abstract: NEW MATERIAL:The compound of formula I (R 1 is lower alkyl or lower alkoxy; R 2 is H or lower alkanoyl; R 3 and R 4 are lower alkyl; R 5 is lower alkyl, lower alkoxy, NH 2 , lower alkylthio, OH, benzyloxy or CF 3 ; n is 2 or 3) and its acid addition salt. EXAMPLE: (±)-cis-2-( 4-methylphenyl )-3-acetoxy-5-[2-( dimethylamino )ethyl]-8-methoxy-2,3-dihydro-1,5-benzothiazepin-4(5H)-one oxalic acid salt. USE: Hypotensor, cerebral and coronary vasodilator, and thrombocyte coagulation suppressing agent. PREPARATION: The compound of formula I can be prepared by condensing the novel substance of formula II or its salt with the compound of formula III (X is halogen). The novel substance of formula II can be synthesized e.g. from the compound of formula IV and the compound of formula V (R 8 is lower alkyl). COPYRIGHT: (C)1985,JPO&Japio

Journal ArticleDOI
TL;DR: This work has adapted and verified a capillary gas chromatographic method for measuring urinary and plasma oxalic acid and applied the method to normal adults and patients with primary hyperoxaluria, finding a normal range closer to that obtained by in vivo isotopic dilution.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the anodization voltage-time curves of tantalum in terms of an avalanche model originally proposed by Ikonopisov (2), and showed that the decrease of the slope of these curves during the anodic process at constant current (and hence at constant field) is brought about by the avalanche current originated in the electrolyte species incorporated into the oxide.
Abstract: In a recent paper we have analyzed the anodization voltage-time curves of tantalum in terms of an avalanche model originally proposed by Ikonopisov (2). According to this analysis, the decrease of the slope of these curves during the anodization process at constant current (and hence at constant field) is brought about by the avalanche current originated in the electrolyte species incorporated into the oxide. Thus, incorporated impurities seem to play an important role in the control not only of the anodization rate but also of the avalanche electron current. This electron current turns out to be the direct cause of electrical breakdown during anodization. Following our studies on the influence of the incorporated anions on the anodization and breakdown characteristics, new results are now presented here, concerning the anodization in oxalic acid at different current densities. They are also compared with our previous results in phosphoric acid. The oxalic acid is known to have low anion incorporation into the anodic Ta/sub 2/O/sub 5/ films since such cannot be detected by surface techniques such as Auger and ESCA spectroscopies. On the contrary, the incorporation of phosphate anions may amount up to 3% in anodization experiments in very diluted electrolytes (10/sup -3/M).more » In addition, the oxalic acid along with other organic acids such as citric is widely used in the technology of tantalym thin film circuits.« less

Journal ArticleDOI
TL;DR: In this article, a batch of studies were carried out to investigate the removal of organic acids by adsorption on fly ash impregnated with hydroxides of Al, Cd, Cu, Fe and Ni.

Journal ArticleDOI
TL;DR: In this paper, the fraction of Fe in maize tissues (Zea mays L. cv. Tipakhia) was identified as an indicator of Fe supply in the rooting medium to distinguish plants which are deficient in Fe from those containing a sufficient amount of Fe.
Abstract: An investigation was carried out to identify the fraction of Fe in maize tissues (Zea mays L. cv. Tipakhia) as an indicator of Fe supply in the rooting medium to distinguish plants which are deficient in Fe from those containing a sufficient amount of Fe. In plants grown at graded levels of Fe supply ranging from acute deficiency to excess, the content of Fe in fresh leaf tissues, extracted in 14 different extractants was estimated. The concentration of Fe in 5 of the extracts-using 1 N HCl, l N oxalic acid, 1 N citric acid, 0.1 N EDTA, and 0.1 N DTPA, was found to be positively correlated with the Fe supply in the medium. Critical Fe concentrations in plant tissues were determined using 1 N oxalic acid and 1 N HCl-extractable Fe fractions.