Studies on the Ion-Exchange Chromatographic Separation of L-Ascorbic Acid and Oxalic Acid

L-Ascorbic acid and oxalic acid could be successfully separated with a column of 8% cross-linked sulfonated polystyrene cation-exchange resin in hydrogen form, and eluted with 0.01% aqueous solution of nitric acid, sulfuric acid, or phosphoric acid. Among the mineral acids used, nitric acid showed the best separatory effect. The minimum detectable quantities of the acids were 0.05 μg and 0.5 μg per 0.5 ml sample solution for L-ascorbic acid and oxalic acid, respectively. Under this condition, the acids could be detected by using automatic UV-monitor apparatus.     

Recherches sur la formation et la transformation des esters LXXVI [1] Sur la réaction de l'isocyanate d'o-méthoxycarbonyl-phényle avec quelques acides amino (ou hydrazino) alcoyl-orthophosphoriques et -sulfuriques

o-Methoxycarbonyl-phenyl isocyanate reacts with mono-aminoalkyl orthophosphoric and sulfuric acids to yield the corresponding 1,2,3,4-tetrahydroquinazoline-2,4-dione-3-ethyl phosphoric (or sulfuric) monoesters which are isolated as sodium salts. 1,2,3,4-Tetrahydroquinazoline-2,4-dione-3-ethyl phosphoric acid has been isolated by adding hydrochloric acid to an aquous solution of its sodium salt.     

Some studies on the extraction of plutonium from phosphate containing nitric acid solutions using DBDECMP as extractant

Extraction studies have been carried out to explore the feasibility of separation of Pu(IV) from phosphate containing analytical wastes generated in the laboratory. Distribution data on the extraction of Pu(IV) from DBDECMP (di-butyl, N,N-diethylcarbamoyl methyl phosphonate) in xylene from an aqueous nitric acid and its mixture with sulfuric as well as with sulfuric and phosphoric acids were obtained. Based on the data obtained, the conditions for the recovery of plutonium from such waste solutions are suggested.     

Extraction of Am(III) from different acid media by di-2-ethyl hexyl phosphoric acid containing phosphorous pentoxide

The extraction of Am(III) from nitric, hydrochloric, oxalic, phosphoric and hydrofluoric acids was studied using 0.4F di-2-ethyl hexyl phosphoric acid (HDEHP) containing 0.1M phosphorous pentoxide (P₂O₅) in dodecane/xylene. The extraction with pure 0.4F HDEHP was found to be negligible from all the media studied. However, the presence of a small amount of P₂O₅ in it increased the extraction substantially. The distribution ratios of Am(III) obtained for HDEHP - P₂O₅ mixture 3M nitric acid containing different concentrations of oxalic acid/phosphoric acid/hydrofluoric acid are in the order of 200-250. The same for 3M hydrochloric acid is very high (800). These distribution ratios are sufficiently high for the quantitative extraction of Am(III) from all the acid media studied. Different reagents such as ammonium oxalate, sodium oxalate, oxalic acid, hydrofluoric acid, sodium carbonate and potassium sulphate were explored for the back extraction of Am(III) from 0.4F HDEHP + 0.1M P₂O₅ in dodecane/xylene. Of these, 0.35M ammonium oxalate and 1M sodium carbonate were found to be most suitable. The back extraction of Am(III) was also attempted with water and 1M H₂SO₄, HNO₃, HClO₄ and HCl solutions after allowing the extracted organics to degrade on its own. It was found that more than 90% of Am could be back extracted with these acids. Using this method more than 90% of Am(III) was recovered from nitric acid solutions containing calcium and fluoride ions.     

Induction of an Oxalate decarboxylase in the Filamentous Fungus Trametes versicolor by Addition of Inorganic Acids

In order to improve yields and to reduce the cost of oxalate decarboxylase (OxDC, EC 4.1.1.2), the induction of OxDC in the white-rot fungus Trametes versicolor was studied in this work. OxDC was induced by addition of inorganic acids including hydrochloric acid, sulfuric acid, and phosphoric acid to culture media. The results showed that all the acids could enhance OxDC expression. The activity of the acid-induced OxDC rose continuously. All of the OxDC volumetric activities induced by the inorganic acids were higher than 20.0 U/L and were two times higher than that obtained with oxalic acid. OxDC productivity was around 4.0 U•L⁻¹•day⁻¹. The highest specific activity against total protein was 3.2 U/mg protein at day 8 after induction of sulfuric acid, and the specific activity against mycelial dry weight was 10.6 U/g at day 9 after induction of hydrochloric acid. The growth of mycelia was inhibited slightly when the pH values in culture media was around 2.5–3.0, while the growth was inhibited heavily when the pH was lower than 2.5.     

电位滴定法测定抛光液中的三酸含量

探讨了利用自动电位滴定仪对抛光液中磷酸、硫酸及硝酸的分析方法,以及对溶剂的标定方法。电位滴定法测定三酸,先用硫酸亚铁铵滴定硝酸,再用氢氧化钠滴定磷酸和硫酸,从而计算三酸含量。结果表明,与传统滴定法相比,电位滴定法标定硫酸亚铁铵的相对标准偏差(RSD)从1.1%降至0.13%,标定氢氧化钠的RSD从0.72%降至0.06%。电位滴定法测定自配样品及工厂抛光产品中的硝酸,回收率分别在96%及93%以上。电位滴定法测定自配样品及工厂抛光产品中磷酸和硫酸的回收率偏差在3%以内。手动滴定法测定磷酸和硫酸的回收率偏差在5%~10%,回收效果不如电位滴定法。电位滴定法测定工厂抛光液的三酸加标回收率偏差均小于3%。自动电位滴定法比手工滴定的准确性和精密度明显提高,弥补了手工滴定法只能分析磷酸和硫酸,而无法测定硝酸的缺陷。     

Simple model of surface-induced electrolytic dissociation of weak acids in organic solvents

The electric conductivity of solutions of oxalic and phosphoric acid (up to 0.025 M) in ethanol and methanol has been studied in the presence of TiO₂ (1–10% by mass). TiO₂ enhanced the conductivity of solutions of oxalic and phosphoric acid in the both alcohols. The experimentally observed behavior was successfully modeled using a model with two types of surface sites. Sites of the first type bind the acids in molecular form. Sites of the second type bind the acids in form of hydrogen oxalate and dihydrogen phosphate anions, respectively, and protons are released to the solution, and contribute to enhanced conductivity. The adsorption model properly reflects the electrokinetic potential of titania particles in alcoholic solutions of oxalic and phosphoric acid.     

Treatment of phosphate rocks with hydrochloric acid

Phosphate rocks were leached with hydrochloric acid; and radium was removed by co-precipitation with BaSO₄. Uranium and lanthanides were extracted by di(2-ethyl hexyl) phosphoric acid and tributyl phosphate. Phosphoric acid was then separated from calcium chloride solution and other impurities by extraction using undiluted iso-amyl alcohol. Gypsum was precipitated by sulfuric acid to regenerate hydrochloric acid for recycling. Fluorine was precipitated from the initial leach solution as Na₂SiF₆.     

Measurement of inorganic acids with rotating ball inlet mass spectrometry

Using a new acid resistant inlet we have evaluated the use of rotating ball inlet mass spectrometry (ROBIN-MS) as a tool for the measurement of inorganic acids in aqueous solution. EI-spectra of sulfuric, sulfurous, nitric, perchloric, bromic, iodic and boric acids were recorded and interpreted with respect to preionization decomposition and electron impact fragmentation. With the exception of sulfuric acid the detection limits for these acids were in the order of 1 mM and the response times are in the order of 1 s. Sulfuric acid had a significantly higher detection limit and response time than the other acids. No mass spectrum of phosphoric acid could be detected. High concentrations of phosphoric acid reduced the signals of other acids. HCl formed by decomposition of perchloric acid caused a strong and slowly recovering decrease of the sensitivity of the mass spectrometer. Sodium sulfate or sodium nitrate in neutral solution did not yield any mass spectrum. The intensity of the sulfuric acid peak of acid solutions of sodium sulfate was measured at different molar ratios of sodium and sulfate. The results indicate that the evaporation of such samples leaves a remnant containing three molecules of sulfuric acid per sodium ion. Similar measurements on acid solutions of sodium nitrate indicate that the remnant contains one molecule of nitric acid per sodium ion.     

A study of various self deposition solutions for 210Po analysis in tap water

The purpose of the present study was to examine the use of various inorganic acids as self deposition solutions and their macroscopic effects on nickel plates which could potentially deteriorate polonium analysis in tap water. 0.5 M, 2 M and 0.1 M hydrochloric acid solutions in addition to 0.1 M and 0.5 M solutions of nitric, hydrofluoric, hydrobromic, hydriodic, sulfuric, phosphoric, sulfamic and perchloric acid were studied and compared. Polonium was plated via self deposition while the chemical recoveries were determined by alpha spectrometry.

     

Determination de l'etain dans les sediments et les boues de stations d'epuration par spectrometrie d'absorption atomique avec generation d'hydruresDetermination of tin in sediments and sewage sludges by atomic absorption spectrometry with hydride generation.

The conditions for the determination of tin in sediments and sewage sludges by atomic absorption spectrometry with hydride generation are evaluated. Hydride generation is achieved in a 0.4 M nitric acid/0.2 tartaric acid solution. The effects of hydrochloric, nitric, sulfuric and hydrofluoric acids are discussed. Matrix effect and interferences from other trace elements are studied. Seven sample decomposition procedures are compared. Refluxing with a (1 + 3) niric acid/hydrochloric acid mixture was the preferred procedure for decomposing such samples.     

Use of iridium plus rhodium as permanent modifier to determine As, Cd and Pb in acids and ethanol by electrothermal atomic absorption spectrometry

The most severe interferences in atomic absorption spectrometry are caused by the presence of anions when they are in different concentrations in the samples and in the calibration solutions. The analyte addition technique or matrix matching calibration can be employed to minimize or compensate the non-spectral interferences, but they are time consuming or difficult to be carried out. The use of chemical modifiers usually allows higher pyrolysis temperatures and consequently the removal of components of the sample matrix, equalizing the analyte signal in the sample and in the calibration solution. In this work, a mixture of Ir and Rh is proposed as permanent modifier to determine As, Cd and Pb in diluted hydrochloric, sulfuric and phosphoric acids and in ethanol and methanol by electrothermal atomic absorption spectrometry (ET AAS) with calibration against 1% v/v nitric acid aqueous solutions. The performance of the proposed permanent modifier was compared to that of Pd plus Mg nitrates in solution. Better recoveries, low background levels and faster analysis were obtained with the permanent modifier. The permanent modifier was also successfully employed for the determination of As, Cd and Pb in different concentrations of sulfuric and hydrochloric acids. For the phosphoric acid, the proposed modifier was only efficient for acid concentrations up to 2% v/v for As and up to 5% v/v for Cd and Pb. The precision, expressed as the relative standard deviation (n=3), was lower than 10%, for all samples, including ethanol and methanol.     

Determination of boron in boron-alloyed steels by inductively coupled plasma atomic emission spectrometry

An inductively coupled plasma atomic emission spectrometry (ICP-AES) procedure has been developed and examined for the determination of boron content (0.01 up to about 2% B) in boron-alloyed steels such as POLDI ATA BOR (65% Fe, 19%Cr, 12% Ni, 1.5% Mn, 1% B), POLDI ATA BOR EXTRA (62% Fe, 18% Cr, 13% Ni, 2.5% Mo, 1.5% Mn, 1% B) and POLDI ATA BOR-R (75% Fe, 18% Cr, 3.5% Ti, 1.8% B). The steel sample is dissolved with a mixture of hydrochloric, nitric, sulfuric and phosphoric acids in a quartz vessel. Borides of alloyed metals, especially of iron and chromium, are quantitatively decomposed. The presence of phosphoric acid in a sample solution reduces the volatility of boric acid with water vapour.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Acid Effects on the Measurement of Mercury by Cold Vapor Atomic Absorption Spectrometry

Abstract

The influence of nitric, hydrochloric and sulfuric acids on the measurement of mercury by cold vapor atomic absorption spectrometry has been investigated. Small pre-reduction peaks associated with the instability of mercury were observed in solutions containing ≤ 12.5, < 2 and ≥ 12.5% v/v of each acid, respectively. Mercury was found to be most stable in ≥, 2% v/v hydrochloric acid and the measured absorbance was not greatly influenced by varying concentration of the acid. The mercury absorbance measurements were more sensitive in solutions containing ≤ 6.3% v/v hydrochloric acid than in similar concentrations of nitric and sulfuric acids. The use of the three acids as a digestion mixture result in serious interference from nitrogen oxides. The interferant was removed by use of expelling agents such as urea and sulfamic acid or overcome by use of excess stannous chloride, prior to the reduction of mercury(II) ions. The determination of mercury in NBS albacore tuna using both of these approaches to overcome the interference problem proved to be successful.     

Extraction of rhenium(VII) and molybdenum(VI) with hexabutyltriamide of phosphoric acid from acid media

Extraction of rhenium(VII) and molybdenum(VI) from sulfuric, hydrochloric, and nitric acid solutions with hexabutyltriamide of phosphoric acid was studied. The influence exerted on the extraction of Re(VII) and Mo(VI) by the nature and concentration of an acid in the aqueous phase, temperature, time of contact between phases, and concentration of the extracting agent in the organic phase was analyzed. Isotherms of extraction of rhenium(VII) and molybdenum(VI) with solutions of hexabutyltriamide phosphoric acid in kerosene were obtained, the composition of the complexes being extracted was determined, the enthalpies and entropies were evaluated, and the concentration constants of extraction of the metals were found.     

Determination of Hydrofluoric Acid in Mixed Acids with an Acid Concentration Meter

Abstract

A commercial acid concentration meter containing an N-type silicon anode and stainless cathode has been used to selectively measure hydrofluoric acid in mixtures containing nitric, phosphoric and sulfuric acids. At very high weight ratios of acid to HF (> 10:1) a suppression in HF response was noted for all acids examined. At lower ratios or higher HF values only nitric acid influences HF response with a sensitizing or catalytic effect not appreciably dependent on HNO, concentration.     

从叔醇制备叔硫醇

实验室中合成叔硫醇缺少简便方法。用叔醇和氢溴酸与硫脲直接反应是目前采用的方法。Lee和Akerstrom曾用此法合成了叔硫醇,但碳原子数没超过七个。Sprague及Kresze分别用干燥氯化氢及盐酸代替氢溴酸也合成了叔硫醇,但产率不高。本文提出了用叔醇、硫酸与硫脲反应来制备叔硫醇的方法,并合成了六个叔硫醇。     

Interference by acids in the determination of molybdenum by atomic absorption spectrometry

The nature of the acid environment in the determination of molybdenum by atomic absorption spectrometry is shown to be of considerable importance. The most favourable conditions are provided by dilute hydrochloric acid and especially nitric acid. Sulphuric and phosphoric acids are not recommended because of their marked but opposite effects. The air-acetylene flame gives more reproducible results than the nitrous oxide-acetylene flame.     

Hierarchically organized silica monoliths: influence of different acids on macro- and mesoporous formation

The influence of different acids, such as hydrochloric acid, sulfuric acid, nitric acid, hydrobromic acid and acetic acid on the polymerization-induced phase separation process in the formation of hierarchically organized silica monoliths was investigated in detail. Special emphasis is given to systems synthesized from tetrakis(2-hydroxyethoxy)silane (EGMS) or tetramethoxysilane (TMOS) as the silica source in the presence of Pluronic^® P123 serving as structure-directing agent. The obtained silica monoliths exhibited a co-continuous and cellular macroporous structure comprising 2D hexagonally arranged mesopores with high specific surface areas ranging from 320–787 m² g^?1 independent of the applied silane precursor and regardless whether hydrochloric acid or sulfuric acid was used. A drastic change in macropore morphology to closed pores or particulate structures was observed for nitric, bromic as well as acetic acid. For sulfuric and nitric acid, the influence on the mesostructure was not as pronounced and 2D hexagonally arranged mesopores were obtained. With bromic and acetic acid a loss in mesopore ordering has been observed. Best developed hierarchically organized networks with respect to a co-continuous, cellular macroporous network, specific surface area and 2D hexagonally arranged mesopores were obtained for EGMS as well as for TMOS with P123 in sulfuric acid.

     

Simultaneous determination of 14 lanthanides and yttrium in rare earth ores by inductively-coupled plasma atomic emission spectrometry

A method is described for simultaneous determination of 14 lanthanides and yttrium in monazites and xenotimes by inductively-coupled plasma atomic emission spectrometry. The ore samples were decomposed by heating with nitric acid/perchloric acid or hydrofluoric/nitric/perchloric acids, or sulfuric acid, or by fusion with sodium carbonate. Among these methods, treatment of the samples with sulfuric acid, by evaporation to dryness followed by dissolution of the residue with hydrochloric acid is recommended; it provided complete decomposition for the five monazites and xenotimes examined. The accuracy and precision of the results were significantly influenced by spectral interferences of the rare earth elements themselves; correction methods and factors are given. The chondrite-normalized rare-earth patterns were examined to characterize the monazite and xenotime samples.