Oxidation of some sugars with copper(III)

The titrimetric determination of glucose, fructose, mannose, galactose, arabinose, xylose and sucrose with potassium ditelluratocuprate(III) is described. On heating, pentoses and hexoses consume 20 and 24 equivalents of copper(III) per mole respectively, and sucrose consumes 48 equivalents.     

Potentiometric Flow-Injection Determination of Sugars Using a Metallic Copper Electrode

Abstract

The determination of reducing sugars is shown to be possible by use of potentiometric detection with a metallic copper indicator electrode by either flow-injection analysis (FIA) or high-performance liquid chromatography. Various sugars including arabinose, maltose, sorbose, glucose, fructose, sucrose, lactose and xylose, give an electrode response when injected into different carrier streams composed of cupric ions in weakly complexing ligand solutions comprised of either ammonia or tartrate. Optimization of response depends on flow-rate, temperature, pH, and concentrations of carrier components. Chromatography using a cation-exchange column and post-column addition of carrier reagents similar to those used for FIA is demonstrated to give detectable separation of four sugar components with umole injection quantities.     

Anionic gemini surfactant viz. sodium salt of bis(1-dodecenylsuccinamic acid); synthesis,surface properties and micellar effect on oxidation of reducing sugars by hexacyanoferrate(III)

An anionic gemini surfactant viz. sodium salt of bis(1-dodecenylsuccinamic acid) has been synthesized. Conductivity and surface tension measurements were performed in order to characterize the synthesized surfactant. The foaming power and contact angle have also been determined. Micellar effect of synthesized gemini surfactant on the rate of oxidation of reducing sugars (viz. glucose, fructose and xylose) by alkaline hexacyanoferrate(III) has been studied in the temperature range (40–60 °C). It has been observed that reducing sugar associates/binds with surfactant micelle to form mixed aggregate which is resistant to react with hexacyanoferrate(III). The binding parameters have also been evaluated using Menger and Portnoy model.     

Chemiluminescent reaction of lucigenin with reducing sugars

The chemiluminescent reaction, in alkaline solution, of lucigenin with the reducing sugars sorbose, fructose, lactose, glucose, xylose, galactose, arabinose and mannose has been studied. There is a linear relationship (correlation coefficient = 0.996) between the emission intensity and the second-order rate constant for the alkaline oxidation of these sugars. The emission intensity is linearly related to the sugar concentration; at high sugar concentrations (5mM) it is independent of the lucigenin concentration, but at low concentrations (<0.05mM) is linearly related to the lucigenin concentration. These facts support the view that the rate-limiting step is the tautomerization of the sugars to the 1,2-enediol form; the enediol then undergoes reaction with lucigenin.     

Kinetics and mechanism of the ruthenium(III) catalysed oxidation of reducing sugars by chloramine-T in alkaline medium

The kinetics of the ruthenium(III) catalysed oxidation of reducing sugars, viz. arabinose, xylose, galactose, glucose, fructose, lactose and maltose by chloramine-T have been studied in alkaline medium. The reactions exhibit a first order rate dependence with respect to: [substrate], [chloramine-T] and [OH⁻]. The rate is proportional to {k ^′ + k ^″[Ru^III]}, where k ^′ and k ^″ are rate constants for uncatalysed and catalysed path respectively. A suitable mechanism, consistent with the kinetic data, is proposed and discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pectin substances ofAmaranthus cruentus

Pectin substances have been isolated from the epigeal pan of love-lies-bleeding,Amaranthus cruentus (A. caudatus), and have been characterized. The presence in them of galacturonic acid, galactose, rhamnose, xylose, arabinose, fructose, and glucose residues has been established. The titrimetric indices of the substances isolated have been determined and they have been studied by IR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 7–9, January–February, 1996. Original article submitted August 14, 1995.     

Analysis of biomass sugars using a novel HPLC method

The precise quantitative analysis of biomass sugars is a very important step in the conversion of biomass feedstocks to fuels and chemicals. However, the most accurate method of biomass sugar analysis is based on the gas chromatography analysis of derivatized sugars either as alditol acetates or trimethylsilanes. The derivatization method is time consuming but the alternative high-performance liquid chromatography (HPLC) method cannot resolve most sugars found in biomass hydrolysates. We have demonstrated for the first time that by careful manipulation of the HPLC mobile phase, biomass monomeric sugars (arabinose, xylose, fructose, glucose, mannose, and galactose) can be analyzed quantitatively and there is excellent baseline resolution of all the sugars. This method was demonstrated for standard sugars, pretreated corn stover liquid and solid fractions. Our method can also be used to analyze dimeric sugars (cellobiose and sucrose).     

Analysis of Reducing Carbohydrates and Fructosyl Saccharides in Maple Syrup and Maple Sugar by CE

Reducing carbohydrates in maple syrup and maple sugar were separated by capillary electrophoresis using derivatization with 1-phenyl-3-methyl-5-pyrazolone (PMP) and the characteristics of these samples were studied. Reducing carbohydrate standards including nine monosaccharides and five disaccharides as PMP derivatives could be easily resolved by using 200 mM borate buffer (pH 10.5) as a background electrolyte. Glucose was the most abundant reducing sugar in both maple samples, and mannose was abundant relative to the other sugars. The other monosaccharides (xylose, arabinose, ribose, galactose and N-acetylglucosamine) were also detected. When maple syrup and maple sugar were treated with invertase, which removed fructose residues from the reducing ends of fructosyl saccharides, melibiose was detected, suggesting that raffinose exists in both samples. The differences of carbohydrate contents between maple syrup and maple sugar were also discussed.

     

The determination of reducing carbohydrates using a cation-exchange column and potentiometric detection with a metallic copper electrode

Summary A metallic copper electrode is employed as a potentiometric detector for reducing carbohydrates after their separation on a cation-exchange column. A post-column reactant solution comprising 1 mM copper (II) and 35 mM ammonia is mixed with the column effluent and the metallic copper electrode provides a steady baseline potential by responding in a Nernstian manner to the level of copper ions present. This in turn is affected by the presence of eluted reducing carbohydrates, leading to an indirect detection method for these species. The method is applied to the detection of maltose, lactose, xylose, glucose, sorbose, fructose and arabinose. The electrode response mechanism is discussed and detection limits in the low nanomole range are reported. The potentiometric detector is shown to be more sensitive than refractive index detection.     

Carbohydrate complex of the fruit of Chaenomeles maulei

The carbohydrate complex of the fruit ofChaenomeles maulei contains more than 70% of water-soluble sugars, including sucrose, arabinose, galactose, fructose, and glucose. The bulk of the carbohydrate is represented by water-soluble pectin, and protopectin, hemicellulose, and cellulose. The monomeric compositions of all the fractions of carbohydrates and the ratio between the reducing and inverted sugars have been studied.M. V. Lomonosov Odessa Technological Institute of the Food Industry. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 460–463, July–August, 1990.     

Cofermentation of glucose,xylose, and arabinose by mixed cultures of two genetically engineeredZymomonas mobilis strains

Cofermentation of xylose and arabinose, in addition to glucose, is critical for complete bioconversion of lignocellulosic biomass, such as agricultural residues and herbaceous energy crops, to ethanol. A factorial design experiment was used to evaluate the cofermentation of glucose, xylose, and arabinose with mixed cultures of two genetically engineeredZymomonas mobilis strains (one ferments xylose and the other arabinose). The pH range studied was 5.0-6.0, and the temperature range was 30-37°C The individual sugar concentrations used were 30 g/L glucose, 30 g/L xylose, and 20 g/L arabinose. The optimal cofermentation conditions obtained by data analysis, using Design Expert software, were pH 5.85 and temperature 31.5°C. The cofermentation process yield at optimal conditions was 72.5% of theoritical maximum. The results showed that neither the arabinose strain nor arabinose affected the performance of the xylose strain; however, both xylose strain and xylose had a significant effect on the performance of the arabinose strain. Although cofermentation of all three sugars is achieved by the mixed cultures, there is a preferential order of sugar utilization. Glucose is used rapidly, then xylose, followed by arabinose.     

超高效液相色谱-串联质谱法测定螺旋藻多糖的单糖组成

建立了同时测定螺旋藻多糖水解产物中鼠李糖、木糖、阿拉伯糖、果糖、甘露糖、葡萄糖、半乳糖、甘露醇、核糖、岩藻糖、葡萄糖醛酸、半乳糖醛酸12种糖类化合物的超高效液相色谱-串联质谱分析方法。螺旋藻样品经超声波辅助提取,用三氟乙酸水解,经Waters Acquity BEH Amide色谱柱(100 mm×2.1 mm,1.7μm)分离,以10mmol/L甲酸铵和10 mmol/L甲酸铵-乙腈为流动相,在电喷雾电离源负离子(ESI-)模式下,用多反应监测(MRM)模式检测。结果表明,12种糖类化合物的定量限为0.005~0.15 mg/kg,线性范围为0.05~5 mg/L。按照样品中每种糖本底含量的50%、100%、150%进行添加,回收率为80.21%~121.6%。应用该方法对螺旋藻样品进行分析,结果发现:大部分样品都能检测到岩藻糖、半乳糖、阿拉伯糖、鼠李糖、葡萄糖、果糖、木糖、核糖,含量在0.3~889.4 mg/g之间。此外,测定的15个样品中岩藻糖、半乳糖、阿拉伯糖、鼠李糖、葡萄糖、果糖、木糖、核糖是共有组分,含量差异较大,但在所有样品中均未检测到甘露醇和甘露糖。该方法的建立可为阐明螺旋藻多糖的结构组成及其活性提供技术支撑及基础数据。     

Optimization of carbohydrate silylation for gas chromatography

We developed and optimized a new carbohydrate mono- and disaccharides silylation reaction, replacing pyridine and requiring lower reaction temperature and less time. Our method consists of three basic steps. The first one is oxime formation, the second one silylate derivative and the last one gas chromatography separation and quantification with an internal standard. We evaluated several solvents, including acetonitrile, hydroxylamine and aniline. We found aniline to be the best reaction media for oxime formation with hydroxylamine hydrochloride. Among silylation agents we found N,O-bis(trimethyl)trifluoroacetamide (BSTFA) was the most efficient. Together these reagents favored both a short analysis time and fewer by-products. We evaluated the method with model solutions containing: arabinose and co-eluting xylose, fructose, glucose, sucrose and salicin (internal standard) and found it suitable for processed food analysis.     

Kinetic Studies on the Product Inhibition of Enzymatic Lignocellulose Hydrolysis

In order to understand the product inhibition of enzymatic lignocellulose hydrolysis, the enzymatic hydrolysis of pretreated rice straw was carried out over an enzyme loading range of 2 to 30 FPU/g substrate, and the inhibition of enzymatic hydrolysis was analyzed kinetically based on the reducing sugars produced. It was shown that glucose, xylose, and arabinose were the main reducing sugar components contained in the hydrolysate. The mass ratio of glucose, xylose, and arabinose to the total reducing sugars was almost constant at 52.0?%, 29.7?% and 18.8?%, respectively, in the enzyme loading range. The reducing sugars exerted competitive inhibitory interferences to the enzymatic hydrolysis. Glucose, xylose, and arabinose had a dissociation constant of 1.24, 0.54 and 0.33?g/l, respectively. The inhibitory interferences by reducing sugars were superimposed on the enzymatic hydrolysis. The enzymatic hydrolysis could be improved by the removal of the produced reducing sugars from hydrolysate.     

Enzymatic hydrolysis of ammonia-treated rice straw

Rice straw pretreated with liquid anhydrous ammonia was hydrolyzed with cellulase, cellobiase, and hemicellulase. Ammonia-processing conditions were 1.5 g of NH₃/g of dry matter, 85°C, and several sample moisture contents. There were four ammonia addition time (min)-processing time (min) combinations. Sugars produced were analyzed as reducing sugars (dinitrosalicylic acid method) and by high-performance liquid chromatography. Monomeric sugars increased from 11% in the nontreated rice straw to 61% of theoretical in treated rice straw (79.2% conversion as reducing sugars). Production of monosaccharides was greater at higher moisture content and was processing time dependent. Glucose was the monosaccharide produced in greater amounts, 56.0%, followed by xylose, arabinose, and fructose, with 35.8, 6.6, and 1.4%, respectively.     

Production of Primary Metabolites by Rhizopus stolonifer,Causal Agent of Almond Hull Rot Disease

Species in the fungal genus Rhizopus are able to convert simple sugars into primary metabolites such as fumaric acid, lactic acid, citric acid, and, to a lesser extent, malic acid in the presence of specific carbon and nitrogen sources. This ability has been linked to plant pathogenicity. Rhizopus stolonifer causes hull rot disease in almonds, symptoms of which have been previously associated with the fungus’s production of fumaric acid. Six isolates of R. stolonifer taken from infected almond hulls were grown in artificial media amended with one of four carbon sources (glucose, fructose, sucrose, and xylose) and two nitrogen sources (asparagine and ammonium sulphate) chosen based on almond hull composition and used in industry. Proton nuclear magnetic resonance (¹H NMR)–based metabolomics identified that R. stolonifer could metabolise glucose, fructose, sucrose, and to a lesser extent xylose, and both nitrogen sources, to produce three metabolites, i.e., fumaric acid, lactic acid, and ethanol, under in vitro conditions. Sugar metabolisation and acid production were significantly influenced by sugar source and isolates, with five isolates depleting glucose most rapidly, followed by fructose, sucrose, and then xylose. The maximum amounts of metabolites were produced when glucose was the carbon source, with fumaric acid produced in higher amounts than lactic acid. Isolate 19A–0069, however, preferred sucrose as the carbon source, and Isolate 19A–0030 produced higher amounts of lactic acid than fumaric acid. This is the first report, to our knowledge, of R. stolonifer producing lactic acid in preference to fumaric acid. Additionally, R. stolonifer isolate 19–0030 was inoculated into Nonpareil almond fruit on trees grown under high– and low–nitrogen and water treatments, and hull compositions of infected and uninfected fruit were analysed using ¹H NMR–based metabolomics. Glucose and asparagine content of uninfected hulls was influenced by the nitrogen and water treatments provided to the trees, being higher in the high–nitrogen and water treatments. In infected hulls, glucose and fructose were significantly reduced but not sucrose or xylose. Large amounts of both fumaric and lactic acid were produced, particularly under high–nitrogen treatments. Moreover, almond shoots placed in dilute solutions of fumaric acid or lactic acid developed leaf symptoms very similar to the ‘strike’ symptoms seen in hull rot disease in the field, suggesting both acids are involved in causing disease.     

Ion Chromatographic Analysis of Monosaccharides and Disaccharides in Raw Sugar

A simple and effective method using ion chromatography was developed for the simultaneous determination of five monosaccharides (arabinose, glucose, fructose, xylose, and ribose) and two disaccharides (sucrose and lactose) in raw sugar samples. The separation was performed on a CarboPac PA 10 column using the gradient elution of sodium hydroxide and water as the mobile phase. Monosaccharides and disaccharides were detected by an integrated pulsed amperometric detection (IPAD) using gold working electrode. Acid hydrolysis was used for sample preparation before the analysis of glucose and fructose. All the studied sugars showed good linear ranges within 0.5–100 µg mL⁻¹ with the correlation coefficients higher than 0.997. The limits of detection were all less than 0.5 µg mL⁻¹. The RSDs of the method were less than 10 %. The recoveries of the sugars that spiked in raw sugar samples ranged from 96.1 to 102.4 %. The method was successfully applied for the analysis of sugars in raw sugar samples. Sucrose is the major constituent found in the samples at 97 %.

     

半叶马尾藻粗糖中单糖的离子色谱法分析

以60～80 ℃的水从半叶马尾藻干粉中提取粗多糖,用Sevage溶剂去蛋白纯化后,将粗多糖用4.0 g/L 的三氟乙酸在 80 ℃下水解,水解液在CarboPacTM PA10离子色谱柱(2 mm i.d.×250 mm)上以14.0 mmol/L NaOH溶液为流动相进行 分离,以电化学检测器检测半叶马尾藻粗糖水解产生的单糖成分及含量。结果表明,半叶马尾藻粗糖中木糖、半乳糖、阿 拉伯糖、葡萄糖、鼠李糖和果糖的含量分别为2200,820,98,4560,358和740 mg/kg,加标回收率范围为86.0%~108.0%,检出限范围为5.6～89.6 μg/kg。该方法具有灵敏度高、精密度好、样品不需 要衍生化处理等优点,适合藻类样品中单糖的分析。     

Enthalpy and entropy interaction parameters of sodium chloride with some monosaccharides in water

Dilution enthalpies of sodium chloride and some monosaccharides (glucose, ga-lactose, xylose, arabinose, and fructose) in water and mixing enthalpies of aqueous sodium chloride and these monosaccharide solutions were measured by using an improved precision semimicro-titration calorimeter. Transfer enthalpies of sodium chloride from water to aqueous saccharide solutions were evaluated as well as enthalpy interaction parameters of sodium chloride with these monosaccharides in water. Combined with Gibbs energy interaction parameters, entropy interaction parameters were also obtained. The results show that interactions of the saccharides with sodium chloride depend on the stereochemistry of saccharide molecules. These interaction parameters can identify stereochemical structure of saccharide molecules.     

Trace analysis of sugars by HPLC and post-column derivatization

Summary A HPLC system with post-column derivatization for the quantitative analysis of sugars in complex matrices is described. As reagent a 0.2% solution of thymol in concentrated sulfuric acid has been used. The reaction is sensitive with reducing as well as non reducing sugars whereas sugar alcohols are discriminated. With this reagent and separation of sugars at high pH values with an anion exchange column it is possible to detect sugars in the ng range. Hence, it is possible to characterize wines not only by their fructose and glucose content but also by differences in the distribution of the other not fermentable sugars like trehalose, arabinose, galacturonic and glucuronic acid.