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1.
Aman CS Pastor A Cighetti G de la Guardia M 《Analytical and bioanalytical chemistry》2006,386(6):1869-1879
A sensitive, specific and selective multianalyte GC–MS/MS method has been developed for the determination of 11 anabolic hormones
in bovine urine. After adjusting the urine pH to 4.8, the samples were spiked with deuterated internal standards and submitted
to enzymatic hydrolysis with β-glucuronidase/arylsulfatase. Hormones were eluted with methanol through a C18 solid phase cartridge
and submitted to a liquid–liquid extraction. Analytes were derivatized by adding N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane and GC–MS data were obtained in the positive
electron impact tandem mass mode. Under these conditions, no matrix effects were observed and limit of detection values were
in the range of 0.005 ng/mL (diethylstilbestrol) to 0.38 ng/mL (17α-methyltestosterone and 17α-ethynylestradiol). Recoveries
from 81% (α-zeranol) to 149% (17α-methyltestosterone) were found under the selected conditions. These results were better
than those found using heptafluorobutyric anhydride (HFBA) as derivative reagent and those measured in full scan and selective
ion monitoring modes. 相似文献
2.
Galesio M Mazzarino M de la Torre X Botrè F Capelo JL 《Analytical and bioanalytical chemistry》2011,399(2):861-875
A comparison between ultrasonication and microwave irradiation as tools to achieve a rapid sample treatment for the analysis
of banned doping substances in human urine by means of gas chromatography–mass spectrometry (GC–MS) was performed. The following
variables were studied and optimised: (i) time of treatment, (ii) temperature, (iii) microwave power and (iv) ultrasonic amplitude.
The results were evaluated and compared with those achieved by the routine method used in the World Anti-Doping Agency (WADA)
accredited Antidoping Laboratory of Rome. Only under the effect of the ultrasonic field was it possible to enhance the enzymatic
hydrolysis reaction rate of conjugated compounds. Similar reaction yield to the routine method was achieved after 10 min for
most compounds. Under microwave irradiation, denaturation of the enzyme occurs for high microwave power. The use of both ultrasonic
or microwave energy to improve the reaction rate of the derivatisation of the target compounds with trimethyliodosilane/methyl-N-trimethylsilyltrifluoroacetamide (TMSI/MSTFA/NH4I/2-mercaptoethanol) was also evaluated. To test the use of the two systems in the acceleration of the reaction with TMSI,
a pool of 55 banned substances and/or their metabolites were used. After 3 min of ultrasonication, 34 of the 55 compounds
had recoveries similar to those obtained with the classic procedure that lasts for 30 min (Student’s t test, n = 5), 18 increased to higher silylation yields, and for the compounds 13β,17α-diethyl-3α,17β-dihydroxy-5α-gonane (norboletone
metabolite 1), metoprolol and metipranolol the same results were obtained increasing the ultrasonication time to 5 min. Similar
results were obtained after 3 min of microwave irradiation at 1,200 W. In this case, 30 of the 55 compounds had recoveries
similar to the classic procedure (Student’s t test, n = 5) whilst 18 had higher silylation yields. For the compounds 3α-hydroxy-1α-methyl-5α-androstan-17-one (mesterolone metabolite
1), 17α-ethyl-5β-estrane-3α,17β,21-triol (norethandrolone metabolite 1), epioxandrolone, 4-chloro-6β,17β-dihydroxy-17α-methyl-1,4-androstadien-3-one
(chlormetandienone metabolite 1), carphedon, esmolol and bambuterol the same results were obtained after 5 min under microwave
irradiation. 相似文献
3.
Sarah Combalbert Marie-Laure Pype Nicolas Bernet Guillermina Hernandez-Raquet 《Analytical and bioanalytical chemistry》2010,398(2):973-984
Hormones are among the highest-impact endocrine disrupters affecting living organisms in aquatic environments. These molecules
have been measured in both wastewater and sewage sludge. Analytical techniques for such matrices are well described in the
literature. In contrast, there is little information about the analysis of hormones in animal waste. The objectives of this
study were, first, to propose a method for conditioning swine manure samples (addition of formaldehyde, separation of the
solid and liquid phases, and duration of storage) in order to determine hormones in the liquid fraction of manure by solid-phase
extraction (SPE) coupled with gas chromatography–mass spectrometry (GC–MS). Our results showed that analysis of hormones was
affected by matrix changes which occurred during freezing and thawing and after addition of formaldehyde, an additive frequently
used to preserve environmental samples. Thus, our results argue for the conditioning of samples without formaldehyde and for
separating the solid and liquid fractions of manure before freezing. Second, this study reports on the use of a liquid extraction
method coupled with SPE and GC–MS analysis for determination of hormones in the solid fraction of manure. Under the conditions
selected, hormone recoveries were between 80 and 100%. Finally, the optimized method was used to quantify hormones in both
liquid and solid fractions of swine manure from different breeding units. High levels of estrone and α-estradiol were found
in samples whereas β-estradiol was detected in smaller amounts. Estriol and progesterone were mainly found in manure from
the gestating sow building whereas testosterone was detected in manure from male breeding buildings. 相似文献
4.
Hájková K Pulkrabová J Schůrek J Hajslová J Poustka J Nápravníková M Kocourek V 《Analytical and bioanalytical chemistry》2007,387(4):1351-1363
A wide range of estrogenic contaminants has been detected in the aquatic environment. Among these, natural and synthetic steroid
estrogens, typically present in municipal sewage-treatment plant (STP) effluents, are the most potent. In this study a new
GC–MS method has been developed for direct analysis of five major steroid estrogens (estrone, 17β-estradiol, 17α-ethinylestradiol,
dienestrol, and diethylstilbestrol) in river sediments. Four GC–MS systems used for analysis of underivatized analytes in
purified extracts were compared. Relatively low detection limits (1.5–5 ng g−1 dried sediment) and good repeatability of GC splitless injection (RSD 1–2%) were achieved by use of a system combining low-pressure
gas chromatography with a single-quadrupole mass analyzer (LP-GC–MS). Use of orthogonal gas chromatography (GC×GC) hyphenated
with high-speed time-of-flight mass spectrometry (HSTOF-MS) enabled not only significantly better resolution of target analytes,
and their unequivocal identification, but also further improvement (decrease) of their detection limits. In addition to these
outcomes, use of this unique GC×GC–TOF-MS system enabled identification of several other non-target chemicals, including pharmaceutical
steroids, present in purified sediment extracts. 相似文献
5.
Farré M Brix R Kuster M Rubio F Goda Y López de Alda MJ Barceló D 《Analytical and bioanalytical chemistry》2006,385(6):1001-1011
In this work four different commercially available enzyme-linked immunosorbent assays (ELISA) (from Japan EnviroChemicals,
Ltd., Tokyo, Japan) were evaluated in terms of performance for the rapid screening of estrogens in different water matrices,
including natural and spiked samples from urban wastewater, river water and ground water. All four test kits are based on
monoclonal antibodies. The compounds detected by these immunoassays are (1) 17-β-estradiol, (2) estrone, (3) 17-α-ethynyl
estradiol and (4) estrogens in general, with high recognition properties for 17-β-estradiol, estrone and estriol. Standards
were prepared in water containing 10% (v/v) methanol. The IC
50 (corresponding to the 50% of the effective concentration) values, the dynamic ranges, and the limits of detection of the
ELISA kits were 0.060–0.304 μg/L, 0.05–5 μg/L and 0.05 μg/L, respectively. All samples were extracted by solid-phase extraction
(SPE) beforehand, and the evaluation was carried out by comparing the results obtained by ELISA with those obtained by HPLC–MS/MS
using a triple quadrupole (QqQ) instrument. In addition, two different solid-phase extraction procedures were carried out
and compared. Except for moderate overestimation in the results observed with the ELISA kits in the analysis of complex wastewater
samples, the results obtained using all of the tested techniques were generally in very good agreement.
相似文献
6.
Sargaeva NP Lin C O'Connor PB 《Journal of the American Society for Mass Spectrometry》2011,22(3):480-491
Ion-electron reaction based fragmentation methods (ExD) in tandem mass spectrometry (MS), such as electron capture dissociation
(ECD) and electron transfer dissociation (ETD) represent a powerful tool for biological analysis. ExD methods have been used
to differentiate the presence of the isoaspartate (isoAsp) from the aspartate (Asp) in peptides and proteins. IsoAsp is a
β3-type amino acid that has an additional methylene group in the backbone, forming a Cα–Cβ bond within the polypeptide chain. Cleavage of this bond provides specific fragments that allow differentiation of the isomers.
The presence of a Cα–Cβ bond within the backbone is unique to β-amino acids, suggesting a similar application of ExD toward the analysis of peptides
containing other β-type amino acids. In the current study, ECD and ETD analysis of several β-amino acid containing peptides
was performed. It was found that N–Cβ and Cα–Cβ bond cleavages were rare, providing few c and z type fragments, which was attributed to the instability of the Cβ radical. Instead, the electron capture resulted primarily in the formation of a and y fragments, representing an alternative fragmentation pathway, likely initiated by the electron capture at a backbone amide
nitrogen protonation site within the β amino acid residues. 相似文献
7.
R. Dj. Khachikyan N. V. Karamyan H. A. Panosyan M. H. Injikyan 《Russian Chemical Bulletin》2005,54(8):1982-1986
Reactions of NH2OH·HCl with β-aroylacrylic acids proceed ambiguously: a nucleophile attacks either the carbonyl group or the C=C bond. In
the latter case, the resulting α-hydroxyl-amino derivative converts into enamine, probably via dehydration followed by isomerization. Addition of 1,2,4-triazole to the C=C bond of β-(p-toluyl)acrylic acid followed by refluxing of their adduct with 60% NH2NH2·H2O gave a dihydropyridazinone derivative.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1923–1927, August, 2005. 相似文献
8.
Solfrizzo M Gambacorta L Lattanzio VM Powers S Visconti A 《Analytical and bioanalytical chemistry》2011,401(9):2831-2841
Humans and animals can be simultaneously exposed through the diet to different mycotoxins, including aflatoxins, ochratoxin
A, deoxynivalenol, zearalenone, and fumonisins, which are the most important. Evaluation of the frequency and levels of human
and animal exposure to these mycotoxins can be performed by measuring the levels of the relevant biomarkers in urine. Available
data on the toxicokinetics of these mycotoxins in animals suggest that aflatoxin M1 (AFM1), ochratoxin A (OTA), deoxynivalenol (DON)/de-epoxydeoxynivalenol (DOM-1), alpha-zearalenol (α-ZOL)/beta-zearalenol (β-ZOL),
and fumonisin B1 (FB1) can be used as urinary biomarkers. A liquid chromatographic–tandem mass spectrometric method has been developed for simultaneous
determination of these mycotoxin biomarkers in human or animal urine. Urine samples were purified and concentrated by a double
cleanup approach, using a multitoxin immunoaffinity column and a reversed-phase SPE Oasis HLB column. Separation of the biomarkers
was performed by reversed-phase chromatography using a multi-step linear methanol–water gradient containing 0.5% acetic acid
as mobile phase. Detection and quantification of the biomarkers were performed by triple quadrupole mass spectrometry (LC–ESI-MS/MS).
The clean-up conditions were optimised to obtain maximum analyte recovery and high sensitivity. Recovery from spiked samples
was performed at four levels in the range 0.03–12 ng mL−1, using matrix-matched calibration curves for quantification. Mean recoveries of the biomarkers tested ranged from 62 to 96%
with relative standard deviations of 3–20%. Enzymatic digestion with β-glucuronidase/sulfatase resulted in increased concentrations
of the biomarkers, in both human and pig urine, in most samples containing measurable concentrations of DON, DOM-1, OTA, α-ZOL,
or β-ZOL. A highly variable increase was observed between individuals. Co-occurrence of OTA and DON in human urine is reported
herein for the first time. 相似文献
9.
Sandrine Bourgoin-Voillard Emilie-Laure Zins Françoise Fournier Yves Jacquot Carlos Afonso Claude Pèpe Guy Leclercq Jean-Claude Tabet 《Journal of the American Society for Mass Spectrometry》2009,20(12):2318-2333
The affinity of estradiol derivatives for the estrogen receptor (ER) depends strongly on nature and stereochemistry of substituents
in C(11) position of the 17β-estradiol (I). In this work, the stereochemistry effects of the 11α-OH-17β-estradiol (IIIα) and 11β-OH-17β-estradiol (IIIβ) were investigated using CID experiments and gas-phase acidity (ΔHacid∘) determination. The CID experiments showed that the steroids decompose via different pathways involving competitive dissociations
with rate constants depending upon the α/β C(11) stereochemistry. It was shown that the fragmentations of both deprotonated [IIIα-H]− and [IIIβ-H]− epimers were initiated by the deprotonation of the most acidic site, i.e. the phenolic hydroxyl at C(3). This view was confirmed by H/D exchange and double resonance experiments. Furthermore, the ΔHacid∘ of both epimers (IIIα and IIIβ), 17β-estradiol (I), and 17-desoxyestradiol (II) was determined using the extended Cooks’ kinetic method. The resulting values allowed us to classify steroids as a function
of their gas-phase acidity as follows: (IIIβ)≫(II)>(I)>(IIIα). Interestingly, the α/β C(11) stereochemistry appeared to influence strongly the gas-phase acidity. This phenomenon could be explained through stereospecific
proton interaction with π-orbital cloud of A ring, which was confirmed by theoretical calculation. 相似文献
10.
Huang Yun Cui Lijian Zhan Wenhong Dou Yuhong Wang Yongli Wang Qiang Zhao Ding 《Chemistry of Natural Compounds》2007,43(6):672-677
A novel steroidal saponin, along with 12 known steroidal compounds, was isolated from the rhizomes of Paris polyphylla var. chinensis. Spectral data, including two-dimensional NMR, showed that the structure of the novel saponin was 3β,21-dihydroxypregnane-5-en-20S-(22,16)-lactone-1-O-α-L-rhamnopyranosyl(1→2)-[β-D-xylopyranosyl(1→3)]-β-D-glucopyranoside. The isolated steroidal compounds were evaluated for their cytotoxic activity on human gastric cancer cell
line HepG2, SGC7901, BxPC3. Diosgenin-3-O-α-L-rhamnopyranosyl(1→2)[α-L-rabinofuranosyl(1→4)]-β-D-glucopyranoside exhibited the most potent cytotoxic activity among the isolated steroids.
Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 556–560, November–December, 2007. 相似文献
11.
Synthesis of 6α-methyl-16α,17α-cyclohexano-19-norprogesterone from a 19-methyl-6-desmethyl precursor
After prolonged refluxing of 19-tosyloxy-16α,17α-cyclohexanopregn-5-en-3β-ol-20-one (3) with NaI in 2-propanol, the initially formed 19-iodo derivative (4) undergoes supraface migration of the CH2I group from the C(10) atom to the C(6) atom, probably through involvement of a homoallyl cation. The resulting 6β-iodomethyl-16α,17α-cyclohexano-19-norpregn-5(10)-en-3β-ol
(5) was transformed in three steps into 6α-methyl-16α,17α-cyclohexano-19-norprogesterone (6α-methyl-19-nor-D′
6-pentarane,8). The transformation of compound5 into the target product8 also gave a side product, a pentarane with aromatic ringA (10), which was isolated and characterized by spectroscopic methods.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1688–1691, September, 1997. 相似文献
12.
Abul K. Mallik Kaori Shingo Usha Ghimire Gautam Tsuyoshi Sawada Makoto Takafuji Hirotaka Ihara 《Analytical and bioanalytical chemistry》2010,397(2):623-629
Poly(2-N-carbazolylethyl acrylate) with terminal trimethoxysilyl groups was prepared as an organic phase and immobilized onto silica.
The retention behavior of the column packed with this carbazole-based polymer-immobilized silica (Sil-CEA) was investigated
by using various estrogenic steroids and corticoids in both reversed-phase and normal-phase liquid chromatography. As a result,
complete separation was confirmed for eight kinds of steroids with Sil-CEA. The most specific separation with Sil-CEA can
be emphasized by the high separation factor (e.g., α = 1.39 in methanol–water (7:3, v/v) at 35 °C) for 17α and 17β-estradiols, one of the most difficult pairs of isomers in chromatographic separation, whereas
for two kinds of commercially available polymeric ODS columns as references α = 1.01, only, under the same conditions. Because the excellent separation and retention order with Sil-CEA was maintained
even in a normal-phase mobile phase such as a hexane–2-propanol, it is estimated that the CEA phase has multiple interaction
mechanisms through stronger interactions such as dipole–dipole, carbonyl–π, and hydrogen bonding interactions than the hydrophobic
effect expected with ODS. 相似文献
13.
Shibasaki H Okamoto S Inoue R Okita M Yokokawa A Furuta T 《Analytical and bioanalytical chemistry》2012,402(9):2945-2952
The present study developed an high-performance liquid chromatography (HPLC) method for the simultaneous determination of
urinary metabolites of endogenous cortisol, 6α-hydroxycortisol (6α-OHF) and 6β-hydroxycortisol (6β-OHF), in human urine, using
6α-hydroxycorticosterone as internal standard. 6α-OHF and 6β-OHF were extracted from urine with ethyl acetate by using a Sep-Pak
C18 plus cartridge. Separation of the stereoisomers was achieved on a reversed-phase hybrid column by a gradient elution of (A)
0.05 M KH2PO4–0.01 M CH3COOH (pH 3.77) and (B) 0.05 M KH2PO4–0.01 M CH3COOH/acetonitrile (2:3, v/v). 6α-OHF and 6β-OHF were well separated on an XTerra MS C18 5 μm column using two types of stepwise gradient elution program (programs 2 and 3). Resolutions of 6α-OHF and 6β-OHF were
Rs = 4.41 for program 2 and Rs = 4.60 for program 3. The analysis was performed within 23~26 min, monitored by UV absorbance
at 239 nm. The lower limits of detection of 6α-OHF and 6β-OHF were 0.80 ng per injection (s/n = ca. 8), and the lower limits of quantification were 5.02 ng/ml for 6α-OHF and 41.08 ng/ml for 6β-OHF, respectively. The
within-day reproducibilities in the amounts of 6α-OHF and 6β-OHF determined were in good agreement with the actual amounts
added, the relative errors being −5.37% and −3.73% (gradient 2) and −5.69% and −3.96% (gradient 3) for both 6α-OHF and 6β-OHF,
respectively. The inter-assay precisions (RSDs) for 6α-OHF and 6β-OHF were less than 1.99% (gradient 2) and 2.61% (gradient
3), respectively. The present HPLC method was applied to the measurement of 6α-OHF and 6β-OHF in urine to evaluate the time
courses of 6α-hydroxylation and 6β-hydroxylation clearances of cortisol during 40 days for phenotyping CYP3A in a healthy
subject. 相似文献
14.
Horst Fr. Schröder Wilhelm Gebhardt Mario Thevis 《Analytical and bioanalytical chemistry》2010,398(3):1207-1229
Municipal wastewater has been examined for steroids, β2-agonists, stimulants, diuretics, and phosphodiesterase type V inhibitors (PDE type V inhibitors), which are “dual-use-drugs”
applied either as anabolic, doping, and lifestyle drugs or for treatment of diverse diseases. To identify their origin, fitness
centre discharges under suspicion of being point sources and sewage-treatment plant feed and effluents were sampled and concentrations
determined. Sensitive and selective methods for determination and quantification based on solid-phase extraction (SPE) followed
by high-performance liquid chromatography–high resolution mass and tandem mass spectrometry (HPLC–(HR)MS and HPLC–MS–MS) were
developed and established for analysis of these compounds in wastewater and to assess their effect on the environment. The
methods developed enabled quantification at trace concentrations (limit of quantification (LOQ): 5 ng L−1). Of the steroids and stimulants under investigation, testosterone, methyltestosterone, and boldenone or ephedrine, amphetamine,
and MDMA (3,4-methylendioxy-N-methylamphetamine) were observed at up to 5 μg L−1 (ephedrine). Of the β2-agonists salbutamol only, and of the diuretics furosemide and hydrochlorothiazide were confirmed in the extracts. Quite high
concentrations of the PDE type V inhibitors sildenafil, tadalafil, and vardenafil and their metabolites were confirmed in
fitness centre discharges (sildenafil: 1,945 ng L−1) whereas their concentrations in municipal wastewater did not exceed 35 ng L−1. This study identified anabolic and doping drugs in wastewater for the first time. Results obtained from wastewater treatment
plant effluents proved that these “dual-use-drugs”, with the exception of hydrochlorothiazide, were mostly eliminated. 相似文献
15.
Blokland MH Sterk SS Stephany RW Launay FM Kennedy DG van Ginkel LA 《Analytical and bioanalytical chemistry》2006,384(5):1221-1227
An EU project, FAIR5-CT-1997-3443, has been undertaken to distinguish illegal use of zeranol from consumption of food contaminated
with Fusarium spp. toxin. One of the tasks was development of screening and confirmatory methods of analysis. This paper describes a new method
based on two-step clean-up and GC–MS analysis. The first clean-up step is matrix-dependant; the second is applicable to both
urine and meat. The MS is operated in negative chemical ionisation mode. The method is quantitative for zeranol and taleranol,
α- and β-zearalenol, and zearalenone and qualitative for zearalanone. Validation was performed according to the latest EU
performance criteria (Commission Decision 2002/657). For analysis of urine and for the method (μg L−1) were 0.06–0.11 for zeranol, 0.07–0.12 for taleranol, 0.07–0.11 for α-zearalenol, 0.21–0.36 for β-zearalenol, 0.35–0.60 for
zearalenone, and 0.19–0.33 zearalanone. Within-laboratory reproducibility was 16.2, 11.2, 31.9, 30.1, 26.6, and 54.2% for
zeranol, taleranol, α-zearalenol, β-zearalenol, zearalenone, and zearalanone, respectively. It was found that all the compounds
are stable in urine at −20°C for at least a year. Part of the validation program was organisation of a small proficiency study
(ringtest) and a correlation study with an LC–MS–MS method developed by the Veterinary Science Division (VSD; Belfast, UK-NI).
This study showed there was good correlation between results from both laboratories. The method can be used for quantitative
analysis discriminating illegal use of zeranol from consumption of zearalenone-contaminated food. 相似文献
16.
Twelve cardiac glycosides and aglycons were isolated from Strophanthus kombe seeds. Of these, eight were identified as cymarin, K-strophanthin-β, K-strophanthoside, periplocymarin, 17α-strophadogenin, erysimin (= helveticoside), erysimoside, and neoglucoerysimoside.
Four glycosides, preliminarily designated Sk-x, Sk-y, Sk-z, and Sk-20, were new. Their chemical structures were established
as 3β-O-β-D-glucopyranosyl-5β,14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-β-D-glucoside), 3β-O-β-D-cymaropyranosyl-5β,14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-β-D-cymaroside), 3β-O-β-D-cymaropyranosyl-4′-O-β-D-glucopyranosyl-6″-O-β-D-glucopyranosyl-5β, 14β,16β-trihydroxy-19-oxo-17α-card-20(22)enolide (17α-strophadogenin-3-O-strophanthotrioside), and 3-O-β-D-digitoxopyranosyl-4′-O-β-D-glucopyranosyl-6″-O-β-D-glucopyranosyl-5β,14β, 19-trihydroxy-card-20(22)enolide (strophanthidol-3-O-gentiobiosyldigitoxoside), respectively.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 156–159, March–April, 2006. 相似文献
17.
Sergey V. Ushakov Divya Nag Alexandra Navrotsky 《Journal of Thermal Analysis and Calorimetry》2011,104(1):351-356
The severe heating of soil during wildfires and prescribed burns may result in adverse effects on soil fertility due to organic
matter loss. No rapid and reliable procedure exists to evaluate soil organic matter (SOM) losses due to heating. Enthalpy
of SOM combustion correlates with organic matter content. Quartz is a ubiquitous mineral in soils and has a remarkably constant
composition and reversible α–β phase transition at 575 °C. We suggest that SOM content in heated and unheated soils can be
compared using the ratio of SOM combustion enthalpy on heating to the β–α quartz transition enthalpy measured on cooling of
the same sample. This eliminates the need to dry and weigh the samples, making possible field applications of the proposed
method. The feasibility of using the (ΔH
comb SOM)/(ΔH
β–α Qz) ratio was established with experiments on soil samples heated in the laboratory and the method was then used for evaluation
of SOM loss on two pile burn sites at UC Berkeley’s Blodgett Forest Research Station in Georgetown, California. 相似文献
18.
Two new polyhydroxysteroids and five new glycosides were isolated from the starfishCeramaster patagonicus and their structures were elucidated: 5α-cholestane-3β,6α,15β,16β,26-pentol, (22E)-5α-cholest-22-ene-3β,6α,8,15α,24-pentol, (22E)-28-O-[O-(2-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-hydroxymethyl-5α-cholest-22-ene-3β,4β, 6α,8,15β,16β,28-heptol (ceramasteroside C1), (22E)-28-O-[O-(2,4-di-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-hydroxymethyl-5α-cholest-22-ene-3β, 6α,8,15β,16β,28-hexol (ceramasteroside C2), (22E)-28-O-[O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-hydroxymethyl-5α-cholest-22-ene-3β,6α,8,15β,16β 28-hexol (eramasteroside C3), (22E)-28-O-[O-(2-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-galactofuranosyl]-24-methyl-5α-cholest-22-ene-3β,4β,6α,8, 15β, 26-hexol (ceramasteroside C4), and (22E)-28-O-[O-(2-O-methyl-β-d-xylopyranosyl)-(1→2)-β-d-xylopyranosyl]-5α-cholest-22-ene-3β,6α,8,15β,24-pentol (ceramasteroside C5)). Three known polyhydroxysteroids (24-methylene-5α-cholestane-3β,6α,8,15β,16β,26-hexol, 5α-cholestane-3β,6α,8,15β,16β,26-hexol,
and 5α-cholestane-3β,6β,15α,16β,26-pentol) were also isolated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 190–195, January, 1997. 相似文献
19.
Galactomannans with galactose:mannose ratios 1:1.48 and 1:1.33, [α]D +67.9 and +76.4°, [η] 870.3 and 1337.1 mL/g, and molecular weights 999 and 1549 kDa, respectively, were isolated in 0.59
and 4.65% yields (of seed mass) from seeds of Astragalus alpinus and A. tibetanus (Fabaceae). Physicochemical methods (CrO3 oxidation; methylation–GC/MS; IR, NMR, and 13C spectroscopy) found that the main polysaccharide chain consisted of 1,4-β-D-mannopyranose units substituted 67.5% (A. alpinus) and 75.2% (A. tibetanus) at the C-6 position by single α -D-galactopyranose units. The contents of mannobiose blocks Man–Man, (Gal)Man–Man/Man–Man(Gal), and (Gal)Man–Man(Gal) variously
substituted with galactose were according to 13C NMR spectroscopy 15.9, 55.5, and 28.6% in A. alpinus galactomannan and 9.9, 42.3, and 47.8% in A. tibetanus galactomannan. 相似文献
20.
Farré M Asperger D Kantiani L González S Petrovic M Barceló D 《Analytical and bioanalytical chemistry》2008,390(8):1999-2007
In this work, the contributions of triclosan and its metabolite methyl triclosan to the overall acute toxicity of wastewater
were studied using Vibrio fischeri. The protocol used in this paper involved various steps. First, the aquatic toxicities of triclosan and methyl triclosan
were determined for standard substances, and the 50% effective concentrations (EC50) were determined for these compounds. Second, the toxic responses to different mixtures of triclosan, methyl triclosan, and
surfactants were studied in different water matrices, i.e., Milli-Q water, groundwater and wastewater, in order to evaluate
(i) the antagonistic or synergistic effects, and (ii) the influence of the water matrices. Finally, chemical analysis was
used in conjunction with the toxicity results in order to assess the aquatic toxicities of triclosan and its derivative in
wastewaters. In this study, the toxicities of 45 real samples corresponding to the influents and effluents from eight wastewater
treatment works (WWTW) were analyzed. Thirty-one samples were from a wastewater treatment plant (WWTP) equipped with two pilot-scale
membrane bioreactors (MBR), and the influent and the effluent samples after various treatments were characterized via different
chromatographic approaches, including solid-phase extraction (SPE), liquid chromatography coupled to tandem mass spectrometry
(LC–MS/MS), and SPE coupled to gas chromatography–mass spectrometry (GC–MS). The toxicity was determined by measuring the
bioluminescence inhibition of Vibrio fischeri. In order to complete the study and to extrapolate the results to different WWTPs, the toxicity to V. fischeri of samples from seven more plants was analyzed, as were their triclosan and methyl triclosan concentrations. Good agreement
was established between the overall toxicity values and concentrations of the biocides, indicating that triclosan is one of
the major toxic organic pollutants currently found in domestic wastewaters. 相似文献