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1.
Luís C. Duarte Florbela Carvalheiro Joana Tadeu Francisco M. Gírio 《Applied biochemistry and biotechnology》2006,130(1-3):461-475
The combined effects of inhibitors present in lignocellulosic hydrolysates was studied using a multivariate statistical approach.
Acetic acid (0–6 g/L), formic acid (0–4.6 g/L) and hydroquinone (0–3 g/L) were tested as model inhibitors in synthetic media
containing a mixture of glucose, xylose, and arabinose simulating concentrated hemicellulosic hydrolysates. Inhibitors were
consumed sequentially (acetic acid, formic acid, and hydroquinone), alongside to the monosaccharides (glucose, xylose, and
arabinose). Xylitol was always the main metabolic product. Additionally, glycerol, ethanol, and arabitol were also obtained.
The inhibitory action of acetic acid on growth, on glucose consumption and on all product formation rates was found to be
significant (p≤0.05), as well as formic acid inhibition on xylose consumption and biomass production. Hydroquinone negatively affected biomass
productivity and yield, but it significantly increased xylose consumption and xylitol productivity. Hydroquinone interactions,
either with acetic or formic acid or with both, are also statistically signficant. Hydroquinone seems to partially lessen
the acetic acid and amplify formic acid effects. The results clearly indicate that the interaction effects play an important
role on the xylitol bioprocess. 相似文献
2.
Doran Joy Bethune Cripe Jennifer Sutton Misty Foster Brian 《Applied biochemistry and biotechnology》2000,84(1-9):141-152
Pectin-rich residues from sugar beet processing contain significant carbohydrates and insignificant amounts of lignin. Beet
pulp was evaluated for conversion toethanol using recombinant bacteria as biocatalysts. Hydrolysis of pectin-rich residues
followed by ethanolic fermentations by yeasts has not been productive because galacturonic acid and arabinose are not ferm
entable toethanol by these organisms. The three recombinant bacteria evaluated in this study, Escherichia coli strain KO11, Klebsiella oxytoca strain P2, and Erwinia chrysanthemi EC 16 pLOI 555, ferment carbohydrates in beet pulp with varying efficiencies. E. coli KO11 is able to convert pure galactu ronic acid to ethanol with minimal acetate production. Using an enzyme loading of 10.5
filter paper un its of cellulase, 120.4 polygalactu ronase units of pectinase, and 6.4 g of cellobiase (per gram of dry wt
sugar beet pulp), with substrate addition after 24 h of fermentation, 40 g of ethanol/L was produced. Other recombinants exhibited
lower ethanol yields with increases in acetate and succinate production. 相似文献
3.
The conversion of monosaccharides in organe peel hydrolysates to ethanol by recombinantEscherichia coli KO11 has been investigated in pH-controlled batch fermentations at 32 and 37°C. pH values and concentration of peel hydrolysate
were varied to determine approximate optimal conditions and limitations of these fermentations. Very high yields of ethanol
were achieved by this microorganism at reasonable ethanol concentrations (28–48 g/L). The pH range between 5.8 and 6.2 appears
to be optimal. The microorganism can convert all major monosaccharides in organe peel hydrolysates to ethanol and to smaller
amounts of acetic and lactic acids. Acetic acid is coproduced in equimolar amounts with ethanol by catabolism of salts of
galacturonic acid.
South Atlantic Area, Agricultural Research Service, US Department of Agriculture. Mention of a trademark or proprietary product
is for identification only, and does not imply a guarantee or warranty of the product by the US Department of Agriculture.
All programs and services of the US Department of Agriculture are offered on a nondiscriminatory basis without regard to race,
color, national origin, religion, sex, age, marital status, or handicap. 相似文献
4.
The economics of large-scale production of fuel ethanol from biomass and wastes requires the efficient utilization of all
the sugars derived from the hydrolysis of the heteropolymeric hemicellulose component of lignocellulosic feedstocks. Glucuronic
and 4-0-methyl-glucuronic acids are major side chains in xylans of the grasses and hardwoods that have been targeted as potential
feedstocks for the production of cellulosic ethanol. The amount of these acids is similar to that of arabinose, which is now
being viewed as another potential substrate in the production of biomass-derived ethanol.
This study compared the end-product distribution associated with the fermentation of D-glucose (Glc) and D-glucuronic acid
(GlcUA) (as sole carbon and energy sources) byEscherichia coli B (ATCC 11303) and two different ethanologenic recombinants—a strain in whichpet expression was via a multicopy plasmid (pLOI297) and a chromosomally integrated construct, strain KO11. pH-stat batch fermentations
were conducted using a modified LB medium with 2% (w/v) Glc or GlcUA with the set-point for pH control at either 6.3 or 7.0.
The nontransformed host culture produced only lactic acid from glucose, but fermentation of GlcUA yielded a mixture of ethanol,
acetic, and lactic acids, with acetic acid being the predominant end-product. The ethanol yield associated with GlcUA fermentation
by both recombinants was similar, but acetic acid was a significant by-product. Increasing the pH from 6.3 to 7.0 increased
the rate of glucuronate fermentation, but it also decreased the ethanol mass yield from 0.22 to 0.19 g/g primarily because
of an increase in acetic acid production. In all fermentations there was good closure of the carbon mass balance, the exception
being the recombinant bearing plasmid pLOI297 that produced an unidentified product from GlcUA. The metabolism of GlcUA by
this metabolically engineered construct remains unresolved. The results offered insights into metabolic fluxes and the regulation
of pyruvate catabolism in the wild-type and engineered strains. End-product distribution for metabolism of glucuronic acid
by the nontransformed, wild-typeE. coli B and recombinant strain KO11 suggests that the enzyme pyruvate-formate lyase is not solely responsible for the production
of acetylCoA from pyruvate and that derepressed pyruvate dehydrogenase may play a significant role in the metabolism of GlcUA. 相似文献
5.
Fábio C. Sampaio Paolo Torre Flávia M. Lopes Passos Célia Alencar de Moraes Patrizia Perego Attilio Converti 《Applied biochemistry and biotechnology》2007,136(2):165-181
To obtain in-depth information on the overall metabolic behavior of the new good xylitol producer Debaryomyces hansenii UFV-170, batch bioconversions were carried out using semisynthetic media with compositions simulating those of typical acidic
hemicellulose hydrolysates of sugarcane bagasse. For this purpose, we used media containing glucose (4.3–6.5 g/L), xylose
(60.1–92.1 g/L), or arabinose (5.9–9.2 g/L), or binary or ternary mixtures of them in either the presence or absence of typical
inhibitors of acidic hydrolysates, such as furfural (1.0–5.0 g/L), hydroxymethylfurfural (0.01–0.30 g/L), acetic acid (0.5–3.0
g/L), and vanillin (0.5–3.0 g/L). D. hansenii exhibited a good tolerance to high sugar concentrations as well as to the presence of inhibiting compounds in the fermentation
media. It was able to produce xylitol only from xylose, arabitol from arabinose, and no glucitol from glucose. Arabinose metabolization
was incomplete, while ethanol was mainly produced from glucose and, to a lesser less extent, from xylose and arabinose. The
results suggest potential application of this strain in xyloseto-xylitol bioconversion from complex xylose media from lignocellulosic
materials. 相似文献
6.
Lawford Hugh G. Rousseau Joyce D. Tolan Jeffrey S. 《Applied biochemistry and biotechnology》2001,91(1-9):133-146
Iogen Corporation of Ottawa, Canada, has recently built a 50 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme
production facility. Iogen has partnered with the University of Toronto to test the C6/C5 cofermentation performance characteristics
of National Renewable Energy Laboratory's metabolically engineered Zymomonas mobilis using its biomass hydrolysates. In this study, the biomass feedstock was an agricultural waste, namely oat hulls, which was
hydrolyzed in a proprietary two-stage process involving pretreatment with dilute sulfuric acid at 200–250°C, followed by cellulase
hydrolysis. The oat hull hydrolysate (OHH) contained glucose, xylose, and arabinose in a mass ratio of about 8:3:0.5. Fermentation
media, prepared from diluted hydrolysate, were nutritionally amended with 2.5 mL/L of corn steep liquor (50% solids) and 1.2
g/L of diammonium phosphate. The estimated cost for large-scale ethanol production using this minimal level of nutrient supplementation
was 4.4c/gal of ethanol. This work examined the growth and fermentation performance of xyloseutilizing, tetracycline-resistant,
plasmid-bearing, patented, recombinant Z. mobilis cultures: CP4:pZB5, ZM4:pZB5, 39676:pZB4L, and a hardwood prehydrolysate-adapted variant of 39676:pZB4L (designated asthe
“adapted” strain). In pH-stat batch fermentations with unconditioned OHH containing 6% (w/v) glucose, 3% xylose, and 0.75%
acetic acid, rec Zm ZM4:pZB5 gave the best performance with a fermentation time of 30h, followed by CP4:pZB5 at 48h, with
corresponding volumetric productivities of 1.4 and 0.89 g/(L·h), respectively. Based on the available glucose and xylose,
the process ethanol yield for both strains was 0.47 g/g (92% conversion efficiency). At 48 h, the process yield for rec Zm
39676:pZB4L and the adapted strain was 0.32 and 0.34 g/g, respectively. None of the test strains was able to fermentarabinose.
Acetic acid tolerance appeared to be a major determining factor in cofermentation performance. 相似文献
7.
Acid-pretreated biomass contains various compounds (acetic acid, etc.) that are inhibitory to fermentative microorganisms.
Removing or deactivating these compounds using detoxification methods such as overliming or ammonium hydroxide conditioning
(AHC) improves sugar-to-ethanol yields. In this study, we treated the liquor fraction of dilute-acid-pretreated corn stover
using AHC and a new reactive membrane extraction technique, both separately and in combination, and then the sugars in the
treated liquors were fermented to ethanol with the glucose–xylose-fermenting bacterium, Zymomonas mobilis 8b. We performed reactive extraction with mixtures of octanol/Alamine 336 or oleyl alcohol/Alamine 336. The best ethanol
yields and rates were achieved for oleyl alcohol-extracted hydrolysates followed by AHC hydrolysates, while octanol-extracted
hydrolysates were unfermentable because highly toxic octanol was found in the hydrolysate. Adding olive oil significantly
improved yields for octanol-extracted hydrolysate. Additional work is underway to determine if this technology is a cost-effective
alternative to traditional hydrolysate conditioning processes. 相似文献
8.
E. V. Tatarnikova V. V. Sizov A. V. Aleksandrov I. V. Tselinskii 《Russian Journal of Organic Chemistry》2009,45(10):1523-1527
N-Nitrobenzimidazol-2-ones readily undergo rearrangement to C-nitro derivatives on heating in various solvents (ethyl acetate, butyl acetate, acetonitrile, acetone, dioxane, o-dichlorobenzene, anisole, acetic acid). This rearrangement was used to develop a procedure for the synthesis of 4,5,6,7-tetranitro-1,3-dihydrobenzimidazol-2-one
in high yield (90–96%) by nitration of 1,3-dihydrobenzimidazol-2-one, as well as of 5,6-dinitro- and 4,5,6-trinitro-1,3-dihydrobenzimidazol-2-ones,
with a small excess of concentrated nitric acid in a mixture with acetic anhydride and acetic acid at 50–60°C. 相似文献
9.
L. N. Yang F. Xu L. X. Sun Z. C. Tan H. D. Tan Z. B. Zhao J. G. Liang 《Journal of Thermal Analysis and Calorimetry》2006,85(3):807-810
A microcalorimetric
technique based on the bacterial heat output was applied to evaluate the influence
of antibiotics PIP (Piperacillin Sodium)
and composite preparation of PIP and SBT (Sulbactam
Sodium) on the growth of E. coli
DH5α. The power–time curves of the growth metabolism of E. coli DH5α were studied using a TAM Air Isothermal
Microcalorimeter at 37°C. By analyzing the power–time curves, the
parameters such as growth rate constants (k),
inhibitory ratio (I), the maximum heat
power (P
m) and the
time of the maximum heat power (t
m)
were obtained. The results show that different concentrations of antibiotics
affect the growth metabolism of E. coli
DH5α. The PIP in the concentration range of 0–0.05 μg mL–1
has a stimulatory effect on the E. coli
DH5α growth, while the PIP of higher concentrations (0.05 –0.25
μg mL–1) can inhibit its growth. It seems
that the composite preparation composed of PIP and SBT cannot improve the
inhibitory effect on E. coli DH5α
as compared with the PIP. 相似文献
10.
Donnelly Mark I. Millard Cynthia Sanville Clark David P. Chen Michael J. Rathke Jerome W. 《Applied biochemistry and biotechnology》1998,(1):187-198
Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate:
formate lyase and the fermentative lactate dehydrogenase, gave rise spontaneously to a chromosomal mutation that restored
its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor,
strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol
in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1
mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence
in E.coli of a novel succinic acid:acetic acid:ethanol fermentation pathway. 相似文献
11.
A pretreatment method using aqueous ammonia was investigated with the intent of minimizing the liquid throughput. This process
uses a flow-through packed column reactor (or percolation reactor). In comparison to the ammonia recycle percolation (ARP)
process developed previously in our laboratory, this process significantly reduces the liquid throughput to one reactor void
volume in packed bed (2.0–4.7 mL of liquid/g of corn stover) and, thus, is termed low-liquid ARP (LLARP). In addition to attaining
short residence time and reduced energy input, this process achieves 59–70% of lignin removal and 48–57% of xylan retention.
With optimum operation of the LLARP to corn stover, enzymatic digestibilities of 95, 90 and 86% were achieved with 60, 15,
and 7.5 filter paper units/g of glucan, respectively. In the simultaneous saccharification and fermentation test of the LLARP
samples using Saccharomyces cerevisiae (NREL-D5A), an ethanol yield of 84% of the theoretical maximum was achieved with 6% (w/v) glucan loading. In the simultaneous saccharification
and cofermentation (SSCF) test using recombinant Escherichia coli (KO11), both the glucan and xylan in the solid were effectively utilized, giving an overall ethanol yield of 109% of the
theoretical maximum based on glucan, a clear indication that the xylan content was converted into ethanol. The xylooligomers
existing in the LLARP effluent were not effectively hydrolyzed by cellulase enzyme, achieving only 60% of digestibility. SSCF
of the treated corn stover was severely hampered when the substrate was supplemented with the LLARP effluent, giving only
56% the overall yield of ethanol. The effluent appears to significantly inhibit cellulase and microbial activities. 相似文献
12.
Gutiérrez Tony Buszko Marian L. Ingram Lonnie O. Preston James F. 《Applied biochemistry and biotechnology》2002,98(1-9):327-340
The ethanologenic bacteria Escherichia coli strains KO11 and LYO1, and Klebsiella oxytoca strain P2, were investigated for their ability to metabolize furfural. Using high performance liquid chromatography and 13C-nuclear magnetic resonance spectroscopy, furfural was found to be completely biotransformed into furfuryl alcohol by each
of the three strains with tryptone and yeast extract as sole carbon sources. This reduction appears to be constitutive with
NAD(P)H acting as electron donor. Glucose was shown to be an effective source of reducing power. Succinate inhibited furfural
reduction, indicating that flavins are unlikely participants in this process. Furfural at concentrations >10 mM decreased the rate of ethanol formation but did not affect the final yield. Insight into the biochemical nature of this furfural
reduction process may help efforts to mitigate furfural toxicity during ethanol production by ethanologenic bacteria. 相似文献
13.
Foster A. Agblevor Sandra Batz Jessica Trumbo 《Applied biochemistry and biotechnology》2003,105(1-3):219-230
Cotton gin residue (CGR) collected from five cotton gins was fractionated and characterized for summative composition. The
major fractions of the CGR varied widely between cotton gins and consisted of clean lint (5–12%), hulls (16–48%), seeds (6–24%),
motes (16–24%), and leaves (14–30%). The summative composition varied within and between cotton gins and consisted of ash
(7.9–14.6%), acid-insoluble material (18–26%), xylan (4–15%), and cellulose (20–38%). Overlimed steam-exploded cotton gin
waste was readily fermented to ethanol by Escherichia coli KO11. Ethanol yields were feedstock and severity dependent and ranged from 58 to 92.5% of the theoretical yields. The highest
ethanol yield was 191 L (50 gal)/t, and the lowest was 120 L (32 gal)/t. 相似文献
14.
In pH-controlled batch fermentations with pure sugar synthetic hardwood hemicellulose (1% [w/v] glucose and 4% xylose) and
corn stover hydrolysate (8% glucose and 3.5% xylose) lacking acetic acid, the xyloseutilizing, tetracycline (Tc)-sensitive,
genomically integrated variant of Zymomonas mobilis ATCC 39676 (designated strain C25) exhibited growth and fermentation performance that was inferior to National Renewable
Energy Laboratory's first-generation, Tc-resistant, plasmid-bearing Zymomonas recombinants. With C25, xylose fermentation following glucose exhaustion wasmarkellyslower, and the ethanol yield (based
on sugars consumed) was lower, owing primarily to an increase in lactic acid formation. There was an apparent increased sensitivity
to acetic acid inhibition with C25 compared with recombinants 39676:pZB4L, CP4:pZB5, and ZM4:pZB5. However, strain C25 performed
well in continous ferm entation with nutrient-rich synthetic corn stover medium over the dilution range 0.03–0.06/h, with
a maximum provess ethanol yield at D=0.03/h of 0.46 g/g and a maximum ethanol productivity of 3 g/(L·h). With 0.35% (w/v) acetic acid in the medium, the process
yield at D=0.04/h dropped to 0.32 g/g, and the maximum productivity decreased by 50% to 1.5 g/(L·h). Under the same operating conditions,
rec Zm Zm 4:pZB5 performed better; however, the medium contained 20 mg/L of Tc to constantly maintain selective pressure.
The absence of any need for antibiotics and antiboitic resistance genes makes the chromosomal integrant C25 more com patible
with current regulatory specifications for biocatalysts in large-scale commercial operations. 相似文献
15.
Dien Bruce S. Nichols Nancy N. O'Bryan Patricia J. Bothast Rodney J. 《Applied biochemistry and biotechnology》2000,84(1-9):181-196
Two new ethanologenic strains (FBR4 and FBR5) of Escherichia coli were constructed and used to ferment corn fiber hydrolysate. The strains carry the plasmid pLO1297, which contains the genes
from Zymomonas mobilis necessary for efficiently converting pyruvate into ethanol. Both strains selectively maintained the plasmid when grown anaerobically.
Each culture was serially transferred 10 times in anaerobic culture with sugar-limited medium containing xylose, but noselective
antibiotic. An average of 93 and 95% of the FBR4 and FBR5 cells, respectively, maintained pLO1297 in anaerobic culture. The
fermentation performances of the repeatedly transferred cultures were compared with those of cultures freshly revived from
stock in pH-controlled batch fermentations with 10% (w/v) xylose. Fermentation results were similar for all the cultures.
Fermentations were completed within 60 h and ethanol yields were 86–92% of theoretical. Maximal ethanol concentrations were
3.9–4.2% (w/v). The strains were also tested for their ability to ferment corn fiber hydrolysate, which contained 8.5% (w/v)
total sugars (2.0% arabinose, 2.8% glucose, and 3.7% xylose). E. coli FBR5 produced more ethanol than FBR4 from the corn fiber hydrolysate. E. coli FBR5 fermented all but 0.4% (w/v) of the available sugar, whereas strain FBR4 left 1.6% unconsumed. The fermentation with
FBR5 was completed within 55 h and yielded 0.46 g of ethanol/g of available sugar, 90% of the maximum obtainable.
Author to whom all correspondence and reprint requests should be addressed.
Names are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard
of the product, and the use of the name by USDA im plies no approval of the product to the exclusion of others that may also
be suitable. 相似文献
16.
Pretreatment of corn stover by soaking in aqueous ammonia 总被引:1,自引:0,他引:1
Soaking in aqueous ammonia (SAA) was investigated as a pretreatment method for corn stover. In this method, the feedstock
was soaked in aqueous ammonia over an extended period (10–60 d) at room temperature. It was done without agitation at atmospheric
pressure. SAA treatment removed 55–74% of the lignin, but retained nearly 100% of the glucan and 85% of the xylan. The xylan
remaining in the corn stover after SAA treatment was hydrolyzed along with the glucan by xylanase present in the Spezyme CP
enzyme. In the simultaneous saccharification and fermentation (SSF) test of SAA-treated corn stover, using S. cerevisiae (D5A), an ethanol yield of 73% of theoretical maximum was obtained on the basis of the glucan content in the treated corn stover.
The accumulation of xylose in the SSF appears to inhibit the cellulase activity on glucan hydrolysis, which limits the yield
of ethanol. In the simultaneous saccharification and co-fermentation (SSCF) test, using recombinant E. coli (KO11), both the glucan and xylose were effectively utilized, resulting in on overall ethanol yield of 77% based on the glucan
and xylan content of the substrate. When the SSCF process is used, the fact that the xylan fraction is retained during pretreatment
is a desirable feature since the overall bioconversion can be carried out in a single step without separate recovery of xylose
from the pretreatment liquid. 相似文献
17.
Preparation of γ-aminobutyric acid using E. coli cells with high activity of glutamate decarboxylase
A. Yu. Plokhov M. M. Gusyatiner T. A. Yampolskaya V. E. Kaluzhsky B. S. Sukhareva A. A. Schulga 《Applied biochemistry and biotechnology》2000,88(1-3):257-265
γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter synthesized in the central nervous system from glutamate
by glutamate decarboxylase (GAD). It has applications in the production of many drugs. The technology of GABA synthesis by
treating L-glutamic acid with the cells of the gene-engineered GAD superproducer strain of Escherichia coli GAD K10 was developed. Cell growing in the presence of 0.02 mM pyridoxal phosphate (PLP) causes the 2- to 2.5-fold increase of total productivity of the cells. The best way to prepare
the cells for the reaction was their thermal activation by pretreatment for 1 h at 53°C. The optimal conditions for this reaction
were 37°C and pH 4.6. The rate of the enzymatic reaction is the function of acetate concentration with the maximum at 0.5
M acetate. The total amount of GABA synthesized using 1 g of wet cells reached 23–25 g. The final concentration of GABA in
the reaction medium was 280–300 g/L. The yield of the product was about 99%. 相似文献
18.
X-ray crystal structures of two calix[4]arenes are reported. They feature aside from two distal n-propyl units, two ethyl acetate or mixed ethyl acetate and acetic acid groups as the characteristic substituents of the lower
rim hydroxylic hydrogens. The structures are compared by making use of isostructurality calculations. In case of the semi-ester,
solvates with methanol and ethanol as the guest solvents are involved. The carboxy function of the semi-ester does not form
a dimer but an intramolecular hydrogen bond to a propoxy group. The solvates can be described as isostructural in spite of
the different solvent molecules.
Original Russian Text Copyright ? 2009 by T. Gruber, P. Bombicz, W. Seichter, and E. Weber
The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 544–552, May–June, 2009. 相似文献
19.
A new bicyclo[3.2.1]octanoid neolignan rel-(7S,8R,1′S,2′R,3′S)-Δ8′-2′-hydroxy-5,1′,3′-trimethoxy-3,4methylenedioxy-7,3′,8,1′-neolignan (1) was isolated from ethanol extract from the fruit of Ocotea heterochroma Mez & Sodiro ex Mez as well as the known compounds β-friedelanol (2), meso-dehydroguaiaretic acid (3), and yangambin (4), whose structures were elucidated on the basis of their comprehensive spectroscopic analysis including 2D NMR data. Lethality
bioassay using brine shrimp (Artemia salina Leach) was evaluated with the ethanol extract from the Ocotea heterochroma’s fruit. The toxicity of this extract was greater than the toxicity of those fractions obtained in a first solvent partition
(benzene, ethyl acetate, and butanol subfractions) and that of a mixture of acetylated 2′-epimers from the new neolignan 1.
Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 158–160, March–April, 2009. 相似文献
20.
5,10,15,20-tetrakis(phenoxy acetic acid) porphyrin (PAAP) was covalently linked to Merrifield chloromethylated resin. Characterization
of PAAP and the modified polymeric matrix were performed by 1H NMR, FTIR and elemental analysis. The sorbent was used for the separation and enrichment of the d-electron metals (Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) at pH 6–8 and of the f-electron metals U(VI) and Th(IV) at pH 4–5. The metals ions were preconcentrated with a concentration factor range of 115–215
and then determined by flame atomic absorption spectrometry or visible spectrophotometry using Arsenazo(III). The retained
metals were eluted with 2.0 mol L−1 HNO3 in the case of the d-electron metals and 0.1/0.25 mol L−1 HCl in the case of the f-electron metals. The procedure was validated by analyzing the NIST standard reference material 2709 (San Joaquin Soil).
Correspondence: Melek Merdivan, Chemistry Department, Faculty of Arts and Sciences, Dokuz Eylul University, 35160 Buca, Izmir,
Turkey 相似文献