共查询到20条相似文献,搜索用时 0 毫秒
1.
Solange I. Mussatto Giuliano Dragone Marcela Fernandes Adriane M. F. Milagres Inês C. Roberto 《Cellulose (London, England)》2008,15(5):711-721
Brewer’s spent grain components (cellulose, hemicellulose and lignin) were fractionated in a two-step chemical pretreatment
process using dilute sulfuric acid and sodium hydroxide solutions. The cellulose pulp produced was hydrolyzed with a cellulolytic
complex, Celluclast 1.5 L, at 45 °C to convert the cellulose into glucose. Several conditions were examined: agitation speed
(100, 150 and 200 rpm), enzyme loading (5, 25 and 45 FPU/g substrate), and substrate concentration (2, 5 and 8% w/v), according
to a 23 full factorial design aiming to maximize the glucose yield. The obtained results were interpreted by analysis of variance
and response surface methodology. The optimal conditions for enzymatic hydrolysis of brewer’s spent grain were identified
as 100 rpm, 45 FPU/g and 2% w/v substrate. Under these conditions, a glucose yield of 93.1% and a cellulose conversion (into
glucose and cellobiose) of 99.4% was achieved. The easiness of glucose release from BSG makes this substrate a raw material
with great potential to be used in bioconversion processes. 相似文献
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Chunbo Liu Zhihua Liu Meng Wang Yaling Yang 《Journal of the Iranian Chemical Society》2018,15(7):1561-1568
A novel and simple two-step micro-extraction technique combining surfactant-assisted dispersive liquid–liquid micro-extraction and magnetic solid-phase extraction prior to high-performance liquid chromatography was established for analysis of polyphenols including chlorogenic acid, caffeic acid, and scopoletin in tobacco samples. In the developed system, Fe3O4 nanoparticles were synthesized by a one-step chemical co-precipitation method and used to remove hydrophobic substances in tobacco samples by physical adsorption. Low-density solvent (1-heptanol) and cationic surfactant cethyltrimethyl ammonium bromide were employed as extraction solvent and disperser agent, respectively. Under the optimized experimental conditions, a good linearity of the method was obtained over the concentration range from 0.1 to 1000 ng mL?1 for target analytes. The limits of detection (S/N?=?3) were 0.05 ng mL?1 for CGA, 0.10 ng mL?1 for CFA, and 0.12 ng mL?1 for SP, respectively. Finally, the applicability of the developed method was evaluated by extraction and determination of these three phenolic compounds in tobacco samples and satisfactory average recoveries of spiked samples were between 96.6 and 102.7%. 相似文献
4.
Aso Kaboodi Hamid Mirzaei Farzad Katiraee Afshin Javadi Mohammad Reza Afshar Mogaddam 《Journal of separation science》2023,46(16):2300068
In this study, for the first time, a deep eutectic solvent-based microwave-assisted extraction was combined with ionic liquid–based temperature controlled liquid phase microextraction for the extraction of several aflatoxins from cheese samples. Briefly, the analytes are extracted from cheese sample (3 g) into a mixture of 1.5 mL choline chloride:ethylene glycol deep eutectic solvent and 3.5 mL deionized water by exposing to microwave irradiations for 60 s at 180 W. The liquid phase was taken and mixed with 55 μL 1-hexyl-3-methylimidazolium hexafluorophosphate. By cooling the solution in the refrigerator centrifuge, a turbid state was obtained and the analytes were extracted into the ionic liquid droplets. The analytes were determined by high-performance liquid chromatography equipped with fluorescence detector. Low limits of detection (9–23 ng kg–1) and quantification (30–77 ng kg–1), high extraction recovery (66%–83%), acceptable enrichment factor (40–50), and good precision (relative standard deviations ≤ 5.2%) were obtained using the offered approach. These results reveal the high extraction capability of the method for determination of aflatoxins in the cheese samples. In this method, there was no need for organic solvents and it can be considered as green extraction method. 相似文献
5.
Bogar B Szakacs G Tengerdy RP Linden JC Pandey A 《Applied biochemistry and biotechnology》2002,102(1-6):453-461
Ten Aspergillus oryzae strains were screened in solid substrate fermentation for α-amylase production on spent brewing grain (SBG) and on corn fiber.
SBG proved to be a better substrate for enzyme production than corn fiber. A Plackett-Burman experimental design was used
to optimize the medium composition for the best strain. Solid substrate fermentation on optimized medium with A. oryzae NRRL 1808 (=ATCC 12892) strain in stationary 500-mL Erlenmeyer flask culture yielded 4519 U of α-amylase/g of dry matter
substrate in 3 d. The whole solid substrate fermentation material (crude enzyme, in situ enzyme) may be considered a cheap biocatalytic material for animal feed rations and for bioalcohol production from starchy
materials. 相似文献
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Arshia Alizadeh Panahi Afshin Javadi Mohammad Reza Afshar Mogaddam 《Journal of separation science》2023,46(10):2200893
In the present work, a combination of microwave-assisted extraction with magnetic ionic liquid–based dispersive liquid–liquid microextraction was developed for the extraction of chloramine–T from fish samples. In this method, the sample was mixed with a hydrochloric acid solution and exposed to microwave irradiations. By doing so, chloramine–T was converted to p–toluenesulfonamide and extracted from the sample into an aqueous phase. Then, a mixture of acetonitrile (as a dispersive solvent) and magnetic ionic liquid (as an extraction solvent) was rapidly injected into the obtained solution. In the following, the magnetic solvent droplets including the extracted analytes were isolated from the aqueous solution in the presence of an external magnetic field and after diluting with acetonitrile injected into high-performance liquid chromatography equipped with a diode array detector. Under the optimum extraction conditions, high extraction recovery (78%), low limits of detection (7.2 ng/g) and quantification (23.9 ng/g), good repeatability (relative standard deviations ≤5.8 and 6.8% for intra– and inter-day precisions, respectively), and wide linear range (23.9–1000 ng/g) were obtained. Finally, various fish samples marketed in Tabriz city (East Azarbaijan, Iran) were analyzed with the suggested method. 相似文献
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Kristina Kotnik Tina Kosjek Uroš Krajnc Ester Heath 《Analytical and bioanalytical chemistry》2014,406(13):3179-3190
This study describes a procedure for determining eight benzophenone-derived compounds in surface waters and sediments. These include the pharmaceutical ketoprofen, its phototransformation products 3-ethylbenzophenone and 3-acetylbenzophenone, and five benzophenone-type ultraviolet (UV) filters. The proposed analytical method involves the pre-concentration of water samples by solid-phase extraction (SPE) and microwave-assisted extraction (MAE) of sediment samples followed by derivatization and analysis by gas chromatography–mass spectrometry. Different parameters were investigated to achieve optimal method performance. Recoveries of 91 to 96 % from water samples were obtained using HLB Oasis SPE cartridges, whereas MAE of sediments (30 min at 150 °C) gave recoveries of 80 to 99 %. Limits of detection were between 0.1 and 1.9 ng L?1 for water samples and from 0.1 to 1.4 ng g?1 for sediment samples. The developed method was applied to environmental samples and revealed the presence of UV filters in the majority of the surface waters with up to 690 ng L?1 of 2-hydroxy-4-methoxybenzophenone. By contrast, ketoprofen (≤2,900 ng L?1) and its degradation products (≤320 ng L?1) were found in only two rivers, both receiving wastewater treatment plant effluents. Sediment analysis revealed benzophenone to be present in concentrations up to 650 ng g?1, whereas concentrations of other compounds were considerably lower (≤32 ng L?1). For the first time, quantifiable amounts of two ketoprofen transformation products in the aqueous environment are reported. 相似文献
10.
LI An-Rong CHEN Qing-Yun Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai China 《中国化学》1997,15(2):154-159
The reaction of difluorodiiodomethane with alkynes (4a-e) in the presence of hydrogen peroxide afforded the corresponding β-iodo-α,β-unsaturated carboxylic acids.When propargylic alcohol was used as the substrate,β-iodo-α,β-unsaturated γ-butyrolactone (5f) was produced.The mechanism of the reaction was suggested. 相似文献
11.
Carmona P Molina M Calero M Bermejo-Pareja F Martínez-Martín P Alvarez I Toledano A 《Analytical and bioanalytical chemistry》2012,402(6):2015-2021
Peripheral mononuclear leukocytes from Alzheimer’s disease (AD) patients were analyzed by infrared spectroscopy and their
spectroscopic properties were compared with those from age-matched healthy controls. Two-dimensional correlation analysis
of mean spectra measured at various disease stages shows that the protein secondary structure from AD patients involves β-sheet
enrichment and carbonyl intensity increase relative to healthy controls. The area percentages of β-sheets, which were obtained
by using a peak ratio second-derivative spectral treatment, were used for receiver operating characteristic (ROC) analysis
to distinguish between patients with AD and age-matched healthy controls. The critical concentration and area under the curve
(AUC) were determined by this curve analysis which showed a good performance for this quantitative assay. The results were
90% sensitivity and 90.5% specificity for determinations involving mild and moderate AD patients, and 82.1% sensitivity and
90.5% specificity for determinations involving patients at the three AD stages (mild, moderate, and severe). The AUC was greater
than 0.85 in both scenarios. Taken together these results show that healthy controls are distinguished from mild and moderate
AD patients better than from patients with severe disease and suggest that this infrared analysis is a promising strategy
for AD diagnostics. 相似文献
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Herbert P Morais S Paíga P Alves A Santos L 《Analytical and bioanalytical chemistry》2006,384(3):810-816
A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace
solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, α- and γ-chlordane, p,p′-DDT, heptachlor, heptachlor epoxide isomer A, γ-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The
HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present
analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized
conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36%
(as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence
of the selected pesticides, and was applied to landfill soil samples. 相似文献
14.
《Tetrahedron: Asymmetry》1998,9(10):1779-1787
C1-Symmetric phosphino-oxazolines, (S,S)- and (S,R)-2-[4-(isopropyl)oxazol-2-yl]-2′-diphenylphosphino-1,1′-binaphthyl, which possess both phosphine and oxazoline moieties, were prepared from racemic binaphthol and enantiomerically pure (S)-(+)-2-amino-3-methyl-1-butanol in high yields. Reaction of 1,3-diphenyl-2-propenyl acetate with dimethyl sodiomalonate in the presence of 2 mol% of palladium catalysts bearing the new chiral ligands proceeded with high enantioselectivity to give allylic alkylation products of up to 91% ee. 相似文献
15.
A new type of metal-oxide-coated magnetic nanoparticles (NPs)—tantalum-oxide-coated magnetic iron oxide (Fe3O4@Ta2O5) NPs—which are used as affinity probes for selectively trapping phosphopeptides from complex samples, is demonstrated in
this study. In this approach, phosphopeptide enrichment was achieved by incubating the NPs with sample solutions under microwave
heating within 1 min. The NP–target species conjugates were readily isolated from samples by magnetic separation followed
by matrix-assisted laser desorption/ionization (MALDI) mass spectrometric analysis. When using human serum as the sample,
phosphorylated fibrinopeptide-A-derived ions are the only ions observed in the MALDI mass spectra after enrichment by the
Fe3O4@Ta2O5 NPs. Furthermore, only phosphopeptides appear in the MALDI mass spectra after using the affinity probes to selectively trap
target species from the tryptic digest of a cell lysate and milk sample. The results demonstrated that the Fe3O4@Ta2O5 NPs have the capability of selectively trapping phosphorylated peptides from complex samples. The detection limit of this
approach for a phosphopeptide (FQpSEEQQQTEDELQDK) was ~10 fmol.
Figure For the first time, tantalum oxide-coated magnetic iron oxide (Fe3O4@Ta2O5) NPs were demonstrated as suitable affinity-probes for selectively trapping phosphopeptides from complex samples. To shorten
the analysis time, phosphopeptide enrichment was achieved by incubating the NPs with sample solutions under microwave-heating
within 1 min. MALDI MS was employed for characterization of the species trapped by the NPs. 相似文献
16.
L. Kh. Faizullina D. M. Faizullina Yu. S. Galimova Sh. M. Salikhov V. A. Shamukaev R. L. Safiullin F. A. Valeev 《Russian Journal of Organic Chemistry》2015,51(12):1725-1728
Cycloaddition of levoglucosenone to 7-methoxy-4-vinyl-1,2-dihydronaphthalene has been studied under different conditions, including heating under atmospheric pressure, in a sealed ampule, and under high pressure, as well as under microwave irradiation and in the presence of various catalysts. The chiral Diels–Alder adduct thus obtained can be used in the synthesis of estrone and its analogs. 相似文献
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One-step preparation of sulfonated carbon-based solid acid from distillers’ grain for esterification
Liu Xiguang Zhang Lei Sun Wu Zhang Man Yu Shaoming 《Research on Chemical Intermediates》2017,43(10):5917-5932
Research on Chemical Intermediates - A carbon-based solid acid catalyst was prepared by simultaneous carbonization and sulfonation of distillers’ grain with concentrated sulfuric acid.... 相似文献
19.
Ionic liquids have many unique properties as a new and remarkable class of environmental benign solvents,which promises widespread applications in industry and other areas. However,the ionic liq-uids with surface activity are rarely reported. In this work,a series of novel ionic liquids was synthe-sized by using N-methyl-2-pyrrolidone and alkyl bromide. The physical properties of this family of ionic liquids have been characterized,which shows that these compounds have ionic liquids characteristics,surface activity and biocompatibility. 相似文献