离子排斥色谱法同时测定生物质液体燃料发酵液中的有机酸、糖、醇

建立了离子排斥色谱法同时分析生物质燃料乙醇发酵液中糖、酸和醇的方法。使用Bio-Rad Aminex HPX–87H离子排斥色谱柱,以5 mmol/L H2SO4为流动相,柱温为65℃,流量为0.6 m L/min,用示差折光检测器对玉米秸秆发酵液中的纤维二糖、葡萄糖、木糖、阿拉伯糖、甲酸、乙酸、丁酸、乙醇进行定量分析。方法的加标回收率为97.5%~107.4%,相对标准偏差为0.27%~2.19%(n=6),线性相关系数均大于0.999。该方法适用于生物质发酵制乙醇过程中发酵糖、有机酸和乙醇的测定。     

高效液相色谱法测定1,3-丙二醇发酵液中的有机酸

采用高效液相色谱法在Kromasil C18色谱柱(5 μm,250 mm×4.6 mm i.d.)上测定了1,3-丙二醇发酵液中的有机酸,流动相为0.2%(V/V)磷酸和乙腈混合溶液(体积比为96.53.5),发酵液经氯仿处理后直接分离定量,8 min内可将发酵液中的甲酸、乳酸、乙酸、琥珀酸、柠檬酸及延胡索酸完全分离定量.流动相流速为1.0 mL/min,紫外检测波长为214 nm,柱温为20℃.方法的回收率为97.7%～100.5%;RSD为0.98%～2.35%.实验结果表明,该法是测定发酵液中有机酸的快速、有效的定量分析方法.     

高效液相色谱法测定菌群降解纤维素产物中的糖、有机酸和醇

采用硫酸除钙和调节pH的样品预处理方法,利用高效液相色谱对菌群降解纤维素发酵液中的糖、有机酸和醇3类物质进行分析,待测组分与培养基成分能够得到有效分离。从菌群降解纤维素发酵液中检出纤维二糖、葡萄糖、乙醇、丁醇、甘油、乙酸与丁酸并进行了定量分析,7种组分的检出限范围为0.10~2.00 mg/L,线性相关系数均大于0.9996,线性范围为0.020~1.000 g/L,回收率为85.41%~115.60%,相对标准偏差(RSD)为0.22%~4.62%(n=6)。该方法准确可靠,可实现对菌群降解纤维素发酵液中糖、醇和有机酸的同时准确测定。     

基于96孔板与拉曼光谱的发酵乙醇高通量快速检测

发酵液中乙醇含量是实验室研究和工业生产的必检项目.应用拉曼光谱在倒置显微镜上建立一种用96孔板高通量快速检测发酵液乙醇含量的新方法,通过最小二乘法拟合标准乙醇溶液与内标物的拉曼信号比值,得到回归方程,根据回归方程计算乙醇溶液和发酵液中的乙醇含量,与气相色谱法的检测结果进行对比.用本方法检测了菌株筛选、三角瓶发酵和500 L发酵罐发酵过程的乙醇含量.t-检验表明,与气相色谱法结果吻合较好(p=0.05).本方法只需要10～15 s的拉曼光谱收集时间,应用自编程序实时读取检测值,准确度高;结合96孔板可以实现大量样品的实时快速检测.     

纤维素水解液厌氧发酵产丁二酸发酵液中有机酸和混合单糖的测定

对于以纤维素类原料(玉米皮)水解糖液作碳源厌氧发酵制备丁二酸的发酵液,利用Aminex HPX-87H(300 mm×7 8 mm i.d., 5 μm)离子排斥色谱柱及折光示差检测器检测,以0 005 mol/L H2SO4溶液(pH 2 0)作流动相,在流速为0 6 mL/min,柱温为55 ℃时对发酵液进行检测,16 min内能将发酵液中甲酸、乙酸、丁二酸、葡萄糖、木糖、阿拉伯糖完全分离定量.6种物质线性相关系数均大于0 999,方法的回收率为99 3%～102 1%;RSD为0 6%～1 6%.本方法能够简便、快速测定丁二酸发酵体系中有机酸及单糖的含量.     

HPLC法检测丁二酸发酵液中的有机酸和水溶性维生素

采用高效液相色谱法(HPLC)同时检测丁二酸发酵液中的有机酸和水溶性维生素。以RP-HPLC为分离模式,选用Hedera ODS-2色谱柱(5μm,4.6×250 mm),20 mmol/L的磷酸盐缓冲溶液(pH2.9)和乙腈为流动相,梯度洗脱,检测波长为210 nm,建立了同时测定分析8种水溶性维生素和3种有机酸的方法,15 min内所有组分都洗脱完全。8种水溶性维生素和3种有机酸在线性范围内峰面积与浓度呈良好的线性关系,相关系数为0.9989~0.9997;加标回收率在92.5%~100.3%之间;RSD(n=5):0.9%~1.9%。本方法采用同一种流动相既可以测定发酵液中的有机酸又可以测定水溶性维生素的含量。     

离子排斥色谱法同时测定2,3-丁二醇发酵液中的葡萄糖和木糖及各种代谢产物

针对2,3-丁二醇发酵体系,以高交联度磺化苯乙烯-二乙烯基苯共聚物多孔微球为固定相的Aminex HPX-87H离子色谱柱为分析柱,利用示差折光检测器对该体系中的6种代谢产物(2,3-丁二醇、3-羟基丁酮、乙醇、乙酸、甲酸和乳酸)以及2种残留底物葡萄糖和木糖进行了分离.在65 ℃柱温下,以5 mmol/L H2SO4作为流动相,发酵液样品中底物葡萄糖和木糖及2,3-丁二醇等各种代谢产物的线性相关系数均在0.9990～0.9999之间,回收率为98.8%～103.2%,精密度为0.3%～2.1%.在最佳色谱条件下,能够同时测定2,3-丁二醇发酵体系中的残留底物和各种代谢产物的含量,适合于实时定量监测2,3-丁二醇发酵过程.     

高效液相色谱法同时测定生物质乳酸发酵液中有机酸及糖类化合物

建立了高效液相色谱(HPLC)同时测定生物质乳酸发酵液中有机酸及糖类的分析方法。使用Bio-Rad Aminex HPX-87H色谱柱,以5 mmol/L的H2SO4为流动相,在柱温55 ℃,流速0.6 mL/min条件下,采用示差折光检测器进行检测。结果表明,该方法可在17 min内实现发酵液中各种有机酸和糖类化合物等的完全分离与定量,6种有机酸和3种糖类化合物在0.15～5.19 g/L范围内的线性关系良好,回归方程的线性相关系数在0.9998以上。将该法用于米根霉发酵液的检测,两个水平的加标回收率为96.91%～103.11%,相对标准偏差(n=6)为0.81%～4.61%。该法适用于微生物发酵液中多种有机酸和糖类的快速、高效分离和定量测定。     

反相高效液相色谱法测定丙酸发酵液中的有机酸

对于生物法制备丙酸的微生物发酵体系,利用Waters Atlantis dC18反相色谱柱,以0.01mol/L KH2PO4缓冲液(pH2.8)-乙腈(95∶5,V/V)作流动相,在流速为1.0mL/min,柱温为25℃时,于紫外波长215nm处检测,9min内发酵液中的草酸、甲酸、乙酸、乳酸、琥珀酸和丙酸能得到良好分离。6种有机酸线性相关系数均在0.9992~1.0000之间;方法的回收率为99%~102%;RSD为0.56~1.66。本方法能够简便、快速测定丙酸发酵体系中主产物丙酸与其它有机酸含量,适于指导整个发酵过程条件的优化及发酵产物的监控。     

离子色谱法分析磷脂纯化工艺回收乙醇中的乳酸、甲酸和乙酸

建立了同时分析磷脂纯化工艺回收乙醇中乳酸、甲酸和乙酸的离子交换色谱法。采用阴离子交换柱,以4 mmol/L NaHCO3溶液作流动相,样品中的有机酸(乳酸、甲酸和乙酸)在13 min内达到基线分离。采用抑制型电导检测,有机酸的检出限在0.03～0.04 mg/L之间。加标回收率在87.5%～102.4%之间。方法可用于磷脂纯化工艺监控和产品质量监测。     

Ion-exclusion chromatography determination of organic acid in uridine 5'-monophosphate fermentation broth

Simultaneous determination of organic acids using ion-exclusion liquid chromatography and ultraviolet detection is described. The chromatographic conditions are optimized when an Aminex HPX-87H column (300 × 7.8 mm) is employed, with a solution of 3 mmol/L sulfuric acid as eluent, a flow rate of 0.4 mL/min and a column temperature of 60°C. Eight organic acids (including orotic acid, α-ketoglutaric acid, citric acid, pyruvic acid, malic acid, succinic acid, lactic acid and acetic acid) and one nucleotide are successfully quantified. The calibration curves for these analytes are linear, with correlation coefficients exceeding 0.999. The average recovery of organic acids is in the range of 97.6% ～ 103.1%, and the relative standard deviation is in the range of 0.037% ～ 0.38%. The method is subsequently applied to obtain organic acid profiles of uridine 5'-monophosphate culture broth fermented from orotic acid by Saccharomyces cerevisiae. These data demonstrate the quantitative accuracy for nucleotide fermentation mixtures, and suggest that the method may also be applicable to other biological samples.     

Evaluation and Optimization of Organic Acid Pretreatment of Cotton Gin Waste for Enzymatic Hydrolysis and Bioethanol Production

This paper investigates the efficiency of the organic acids on the pretreatment of an industrially generated cotton gin waste for the removal of lignin, thereby releasing cellulose and hemicellulose as fermentable sugar components. Cotton gin waste was pretreated with various organic acids namely lactic acid, oxalic acid, citric acid, and maleic acid. Among these, maleic acid was found to be the most efficient producing maximum xylose sugar (126.05?±?0.74 g/g) at the optimum pretreatment condition of 150 °C, 500 mM, and 45 min. The pretreatment efficiency was comparable to the conventional dilute sulfuric acid pretreatment. A lignin removal of 88% was achieved by treating maleic acid pretreated biomass in a mixture of sodium sulfite and sodium chlorite. The pretreated biomass was further evaluated for the release of sugar by enzymatic hydrolysis and subsequently bioethanol production from hydrolysates. The maximum 686.13 g/g saccharification yield was achieved with maleic acid pretreated biomass which was slightly higher than the sulfuric acid (675.26 g/g) pretreated waste. The fermentation of mixed hydrolysates(41.75 g/l) produced 18.74 g/l bioethanol concentration with 2.25 g/l/h ethanol productivity and 0.48 g/g ethanol yield using sequential use of Saccharomyces cerevisiae and Pichia stipitis yeast strains. The production of bioethanol was higher than the ethanol produced using co-culture in comparison to sequential culture. Thus, it has been demonstrated that the maleic acid pretreatment and fermentation using sequential use of yeast strains are efficient for bioethanol production from cotton gin waste.     

Comprehensive DFT calculations on organic sulfuric acid derivatives to design of powerful neutral organic superacids

In order to examine the acidity of organic sulfuric acid derivatives in gas phase, comprehensive density functional theory (DFT) calculations at B3LYP/6-31++G(d,p) level have been undertaken. In the title compounds, one of the oxygen atoms is substituted by an 1,3-cyclopentadiene group. The focus of this paper is on DFT studies of two classes of sulfuric acid derivatives: dithionic and peroxydisulfuric acids. Tautomers of proposed organic sulfuric acids are also investigated. DFT calculations indicate that the acidity of the proposed acids without any electron withdrawing groups on the ring was more than sulfuric acid.

     

Spectroscopic interferences in Fourier transform infrared wine analysis

Fourier transform infrared (FTIR) spectrometry has brought many advantages to wine analysis, such as fast analysis and good precision and accuracy for a great number of parameters. This technology has to be cautiously applied, therefore the need for analytical validation. Recovery results of several current wine control parameters using a FTIR wine analyser were determined. Good results were obtained for ethanol (addition of ethanol), total acid (addition of tartaric acid), total sugars in sweet wines (addition of glucose) and sulfate (addition of sulfuric acid). On the contrary, worse results were obtained for total acid (addition of acetic and sulfuric acids), volatile acid (addition of acetic acid) and total sugars in dry wines (addition of glucose). These findings can be explained by spectroscopic interferences that were also a subject of analysis in this work. In fact, ethanol, organic acids and other compounds, present in high concentrations in wine, can produce major interferences in the analysis for compounds such as volatile acid and sugars in dry wines, when their strong infrared absorption bands do not differ significantly from other abundant compounds.     

Determination of organic acids in the presence of inorganic anions by ion chromatography with suppressed conductivity detection

Simultaneous separation of 19 organic acids and 10 inorganic anions has been demonstrated using ion chromatography with a high capacity anion exchange column and the suppressed conductivity detector under an auto-suppression external sulfuric acid mode. Quantitative merits of this method were examined for analysis of nine organic acids of potential significance in cell culture broth. External calibration curves for these analytes were linear with correlation coefficients exceeding 0.999, and the relative standard derivations of observed analyte concentrations were less than 3.0% in both inter- and intra-day evaluations of aqueous standards. Developed methodology was subsequently applied to obtain organic acid profiles of Luria-Bertani liquid media, yeast extract, peptone, and the culture broth of a mutant Escherichia coli strain. Analytes recoveries observed for triplicate analysis of LB media spiked at two concentration levels ranged from 88% to 105% with less than 7% RSD. These data demonstrate quantitative accuracy for LB media and suggest that the report method may also be applicable to complex samples such as fermentation mixture and lignocellulose hydrolysate.     

Uptake and dissolution of gaseous ethanol in sulfuric acid

The solubility of gas-phase ethanol (ethyl alcohol, CH3CH2OH, EtOH) in aqueous sulfuric acid solutions was measured in a Knudsen cell reactor over ranges of temperature (209-237 K) and acid composition (39-76 wt % H2SO4). Ethanol is very soluble under these conditions: effective Henry's law coefficients, H, range from 4 x 10(4) M atm(-1) in the 227 K, 39 wt % acid to greater than 10(7) M atm(-1) in the 76 wt % acid. In 76 wt % sulfuric acid, ethanol solubility exceeds that which can be precisely determined using the Knudsen cell technique but falls in the range of 10(7)-10(10) M atm(-1). The equilibrium concentration of ethanol in upper tropospheric/lower stratospheric (UT/LS) sulfate particles is calculated from these measurements and compared to other small oxygenated organic compounds. Even if ethanol is a minor component in the gas phase, it may be a major constituent of the organic fraction in the particle phase. No evidence for the formation of ethyl hydrogen sulfate was found under our experimental conditions. While the protonation of ethanol does augment solubility at higher acidity, the primary reason H increases with acidity is an increase in the solubility of molecular (i.e., neutral) ethanol.     

Effect of diluents on the extractive capacity of organophosphoric acids in vanadium(V) recovery from sulfuric acid solutions

The extractive capacity of di(2-ethylhexyl)phosphoric and di(2,4,4-trimethylpentyl)phosphinic acids for vanadium(V) in its extraction from individual sulfuric acid solutions with the use of kerosene, a number of aliphatic alcohols, and octanone as diluents was studied. The most effective organic mixtures for extraction of vanadium(V) were determined in relation to the concentration of sulfuric acid.     

Reversed phase liquid chromatographic determination of organic acids using on-line complexation with copper(II) ion

We describe a simple and sensitive liquid chromatographic method for the analysis of organic acids using on-line complexation with copper(II) ion. Organic acids complexed with copper(II) ion were separated on a reversed-phase C18 column and detected by UV absorption at 240 nm. The copper(II) ion concentration in the mobile phase had a great influence on separation and sensitivity. A mobile phase consisting of 10 mM copper(II) sulfate in 5 mM sulfuric acid (pH 2.3) was used to separate nine organic acids (tartaric, malic, malonic, lactic, acetic, citric, maleic, succinic and fumaric acids). The detection limits of the examined organic acids calculated at S/N = 3 ranged from 0.6 to 100 μM. The detector signal was linear over three orders of magnitude of organic acid concentration. The method successfully measured organic acids in juice and vinegar samples.