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1.
A new, high performance liquid chromatography method has been developed for the separation of monovinyl- and divinyl-protochlorophyllides, using commercially available, C30 reverse phase column and isocratic elution. This method can be used both for analytical applications and preparative scale purification of monovinyl- and divinyl-protochlorophyllides using the same column where submilimolar concentrations of the crude protochlorophyllide extract can be separated in one run. The purity of the obtained protochlorophyllides was demonstrated by spectroscopic methods, as well by the formation of aggregates in toluene. 相似文献
2.
运用灰色系统理论中的关联度分析方法,研究了人体血清微量元素与土壤,水、辕食(小麦)中微量元素关联度的大小.结果表明,血清微量元素与土壤中微量元素的关联程度最大. 相似文献
3.
A kinetic method for the determination of selenium(IV) traces is proposed, based on its inhibitory action on the oxidation of Nile Blue A by hydrogen peroxide in phosphate buffer (pH 10.5). A linear dependence was established between the rate of the proposed indicator reaction and selenium concentration in the range 9.5 × 10–2-1.58 ng cm–3. The experimental conditions of maximal selenium effect were established. Selenium, determined by the tangent method, was determined at concentrations over the range 0.22–1.26 ng cm–3, with relative standard deviations up to 4.5%. The reaction rate was followed spectrophotometrically. The effect of foreign ions on the accuracy of this method was also investigated. The method was applied to the determination of selenium in pharmaceutical preparations and wheat flour. 相似文献
4.
Neutral hydroxylamine extracts of wheat contained a product that was colourless at pH<5 (λmax 340 nm) and yellow at pH>9 (λmax 400 nm). ESI-MS showed a major ion m/z 184.0 and a possible parent ion m/z 367.2 (MH+) suggesting that the product resulted from the reaction of 2,6-dimethoxy-p-quinone with hydroxylamine. However, mass spectral and other spectroscopic data indicated that the compound was neither of the 2,6-dimethoxy-p-quinone oximes. A product with identical absorbance, mass spectrum, electrophoretic mobility and HPLC retention time as the pigment from hydroxylamine extracts of flour was observed amongst the reaction products of hydroxylamine and 1,4-dihydroxy-2,6-dimethoxybenzene. The structure of this product was identified by NMR, 2D NMR and IR as 4,4′-dihydroxy-3,3′,5,5′-tetramethoxyazodioxybenzene. 相似文献
5.
Five cassava flour wastewater (manipueira) preparations were tested as culture media for biosurfactant production by a wild-type Bacillus sp. isolate. No-solids (F), no-solids diluted (F/2), natural (I), natural diluted (I/2), and decanted (IPS) were the tested
manipueira media. The microorganism was able to grow and to produce biosurfactant on all manipueira preparations. The media whose solids were removed (F and F/2) showed better results than preparations with the presence of
solids (I, I/2, and IPS). No-solids medium (F) showed a surface tension of 26,59 mN/m and reciprocal of critical micelle concentration
of over 100 and was selected as a potential substrate for biosurfactant production. 相似文献
6.
刘晓庚 《理化检验(化学分册)》2006,42(10):809-812
联合应用BPO与KIO3(在KI存在下)的倍增反应和光度滴定数据的二阶导数法处理,使面粉中微量BPO测定的灵敏度较常规碘量法提高了200倍,方法的检出限可达0.1 mg.L-1。在面粉实样分析中,测定结果的RSD值在1.3%~2.8%之间,加标回收率在98.6%~102.2%之间。提出的方法所得测定结果与国标法(GB/T 18415-2001)所得结果一致。 相似文献
7.
Ethanol production from steam-explosion pretreated wheat straw 总被引:1,自引:0,他引:1
Ignacio Ballesteros Ma José Negro José Miguel Oliva Araceli Cabañas Paloma Manzanares Mercedes Ballesteros 《Applied biochemistry and biotechnology》2006,130(1-3):496-508
Bioconversion of cereal straw to bioethanol is becoming an attractive alternative to conventional fuel ethanol production
from grains. In this work, the best operational conditions for steam-explosion pretreatment of wheat straw for ethanol production
by a simultaneous saccharification and fermentation process were studied, using diluted acid [H2SO4 0.9% (w/w)] and water as preimpregnation agents. Acid-or water-impregnated biomass was steam-exploded at different temperatures
(160–200°C) and residence times (5, 10, and 20 min). Composition of solid and filtrate obtained after pretreatment, enzymatic
digestibility and ethanol production of pretreated wheat straw at different experimental conditions was analyzed. The best
pretreatment conditions to obtain high conversion yield to ethanol (approx 80% of theoretical) of cellulose-rich residue after
steam-explosion were 190°C and 10 min or 200°C and 5 min, in acid-impregnated straw. However, 180°C for 10 min in acid-impregnated
biomass provided the highest ethanol yield referred to raw material (140 L/t wheat straw), and sugars recovery yield in the
filtrate (300 g/kg wheat straw). 相似文献
8.
Schultz J Gottlieb DM Petersen M Nesic L Jacobsen S Søndergaard I 《Electrophoresis》2004,25(3):502-511
Methods for classification of two-dimensional (2-DE) electrophoresis gels based on multivariate data analysis are demonstrated. Two-dimensional gels of ten wheat varieties are analyzed and it is demonstrated how to classify the wheat varieties in two qualities and a method for initial screening of gels is presented. First, an approach is demonstrated in which no prior knowledge of the separated proteins is used. Alignment of the gels followed by a simple transformation of data makes it possible to analyze the gels in an automated explorative manner by principal component analysis, to determine if the gels should be further analyzed. A more detailed approach is done by analyzing spot volume lists by principal components analysis and partial least square regression. The use of spot volume data offers a mean to investigate the spot pattern and link the classified protein patterns to distinct spots on the gels for further investigation. The explorative approach in analysis of 2-D gels makes it possible, in a fast and convenient way, to screen many gels in order to determine the protein patterns that form clusters and could be selected for further examination. 相似文献
9.
Katalin Mészáros Szécsényi I. Esztelecki G. Pokol 《Journal of Thermal Analysis and Calorimetry》2007,89(3):829-833
In order to increase the nutrition value of bread, one of the most commonly used foodstuff all over the world, different additives
are used in bread processing. In this paper we describe the thermal changes in bread and that of with 0.5% crude soybean lecithin
additive. Their thermal stability has been investigated by TG, DSC and EGD methods. The thermal changes were also followed
of soy products, lecithin and lysine, ingredients used as bread additives in order to check if they may suffer any thermal
degradation during the baking process. The data obtained can be of use only for qualitative conclusions. According to the
obtained data at the usual bread baking temperature only the additives in crust may partly decompose while in the crumb, at
lower temperatures the additives, due to baking, are not damaged. The thermal methods give a possibility for rapid estimation
of processes induced by heat effects in additives during the baking, and they are suitable to detect the changes during the
bread-making procedure. However, they are neither suitable to provide any quantitative data on these changes nor facts affecting
the nutrition value and of the bread. 相似文献
10.
《Analytical letters》2012,45(15):2478-2490
Water-soluble carbohydrate (WSC) reserved in stem is an important agronomic trait for crop improvement. The intact samples and pieces of chipped samples were employed to determine WSC content by near-infrared reflectance spectroscopy (NIRS). Three NIRS models were developed to predict WSC content in wheat stem lower internode, upmost internode, and wheat glume, respectively. Moreover, a mixed model was developed for WSC quantitative analysis in the mixed sample of the three wheat organs. Statistics analysis indicated that the four models showed a high determination coefficient (R2 ≥ 0.97) and ratio of standard deviation to RMSECV (RPD ≥ 5.99). The NIRS models would allow rapid and high throughout assessments and selections of WSC contents in wheat genetics and breeding programs. 相似文献