共查询到20条相似文献,搜索用时 31 毫秒
1.
Reddithota J. Krupadam Bhagyashree Bhagat Muntazir S. Khan 《Analytical and bioanalytical chemistry》2010,397(7):3097-3106
A method based on solid--phase extraction with a molecularly imprinted polymer (MIP) has been developed to determine five
probable human carcinogenic polycyclic aromatic hydrocarbons (PAHs) in ambient air dust by gas chromatography-mass spectrometry
(GC-MS). Molecularly imprinted poly(vinylpyridine-co-ethylene glycol dimethacrylate) was chosen as solid-phase extraction
(SPE) material for PAHs. The conditions affecting extraction efficiency, for example surface properties, concentration of
PAHs, and equilibration times were evaluated and optimized. Under optimum conditions, pre-concentration factors for MIP-SPE
ranged between 80 and 93 for 10 mL ambient air dust leachate. PAHs recoveries from MIP-SPE after extraction from air dust
were between 85% and 97% and calibration graphs of the PAHs showed a good linearity between 10 and 1000 ng L−1 (r = 0.99). The extraction efficiency of MIP for PAHs was compared with that of commercially available SPE materials—powdered
activated carbon (PAC) and polystyrene-divinylbenzene resin (XAD)—and it was shown that the extraction capacity of the MIP
was better than that of the other two SPE materials. Organic matter in air dust had no effect on MIP extraction, which produced
a clean extract for GC-MS analysis. The detection limit of the method proposed in this article is 0.15 ng L−1 for benzo[a]pyrene, which is a marker molecule of air pollution. The method has been applied to the determination of probable carcinogenic
PAHs in air dust of industrial zones and satisfactory results were obtained. 相似文献
2.
Leveriza F. Arenas Benilda S. Ebarvia Fortunato B. Sevilla III 《Analytical and bioanalytical chemistry》2010,397(7):3155-3158
A piezoelectric quartz crystal (PQC) sensor based on a molecularly imprinted polymer (MIP) has been developed for enantioselective
and quantitative analysis of d-(+)-methamphetamine (d(+)-MA). The sensor was produced by bulk polymerization and the resulting MIP was then coated on the
gold electrode of an AT-cut quartz crystal. Conditions such as volume of polymer coating, curing time, type of PQC, baseline
solvent, pH, and buffer type were found to affect the sensor response and were therefore optimized. The PQC-MIP gave a stable
response to different concentrations of d(+)-MA standard solutions (response time = 10 to 100 s) with good repeatability (RSD = 0.03
to 3.09%; n = 3), good reproducibility (RSD = 3.55%; n = 5), and good reversibility (RSD = 0.36%; n = 3). The linear range of the sensor covered five orders of magnitude of analyte concentration, ranging from 10−5 to 10−1 μg mL−1, and the limit of detection was calculated as 11.9 pg d(+)-MA mL−1
. The sensor had a highly enantioselective response to d(+)-MA compared with its response to l(−)-MA, racemic MA, and phentermine.
The developed sensor was validated by applying it to human urine samples from drug-free individuals spiked with standard d(+)-MA
and from a confirmed MA user. Use of the standard addition method (SAM) and samples spiked with d(+)-MA at levels ranging
from 1 × 10−3 to 1 × 10−2 μg mL−1 showed recovery was good (95.3 to 110.9%). 相似文献
3.
A new molecularly imprinted polymer (MIP), selective for major metabolites of quinoxaline-1,4-dioxides was firstly prepared
by combining surface molecular imprinting technique with the sol–gel process. Methyl-3-quinoxaline-2-carboxylic acid (MQCA)
was used as template, 3-aminopropyltriethoxysilane as functional monomer, and tetraethoxysilicane as cross-linker. The MIP
was characterized by Fourier transform infrared and evaluated through static adsorption experiments. The results indicated
that MIP had high adsorption capacity, fast binding kinetics for MQCA, and the polymer showed a high degree of cross-reactivity
for quinoxaline-2-carboxylic acid (QCA). The MIP was then applied as a selective sorbent in an online solid phase extraction
(SPE) coupled with high-performance liquid chromatography (HPLC). For a 50-mL sample solution, enrichment factors of 1,349
and 1,046 for QCA and MQCA, respectively, and limits of detection (S/N = 3) of 0.8 and 2 ng L−1 for QCA and MQCA, respectively, were obtained (corresponding to 0.02 and 0.04 ng g−1 in solid samples for final 100 mL of sample solutions of 5 g of pork). The sample preparation protocol was simplified and
only included one step extraction with acetonitrile (MeCN) after the release of target analytes through acidic hydrolysis
without further sample cleanup. The new MIP-SPE-HPLC method was successfully applied to the quantification of trace QCA and
MQCA in pork muscle with good recoveries ranging from 67% to 80% and RSD below 8%. 相似文献
4.
Guzmán-Vázquez de Prada A Loaiza OA Serra B Morales D Martínez-Ruiz P Reviejo AJ Pingarrón JM 《Analytical and bioanalytical chemistry》2007,388(1):227-234
A molecularly imprinted polymer was developed and used for solid-phase extraction (MISPE) of the antihelmintic fenbendazole
in beef liver samples. Detection of the analyte was accomplished using square wave voltammetry (SWV) at a cylindrical carbon
fibre microelectrode (CFME). A mixture of MeOH/HAc (9:1) was employed both as eluent in the MISPE system and as working medium
for electrochemical detection of fenbendazole. The limit of detection was 1.9 × 10−7 mol L−1 (57 μg L−1), which was appropriate for the determination of fenbendazole at the maximum residue level permitted by the European Commission
(500 μg kg−1 in liver). Given that the SW voltammetric analysis could not be directly performed in the sample extract as a consequence
of interference from some sample components, a sample clean-up with a MIP for selectively retaining fenbendazole was performed.
The MIP was synthesized using a 1:8:22 template/methacrylic acid/ethylene glycol dimethacrylate ratio. A Britton–Robinson
Buffer of pH 9.0 was selected for retaining fenbendazole in the MIP cartridges, and an eluent volume of 5.0 mL at a flow rate
of 2.0 mL min−1 was chosen in the elution step. Cross-reactivity with the MIP was observed for other benzimidazoles. The synthesized MIP
exhibited a good selectivity for benzimidazoles with respect to other veterinary drugs. The applicability of the MISPE-SWV
method was tested with beef liver samples, spiked with fenbendazole at 5,000 and 500 μg kg−1. Results obtained for ten different liver samples yielded mean recoveries of (95 ± 12)% and (96 ± 11)% for the upper and
lower concentration level, respectively. 相似文献
5.
Zhou Y Han L Cheng J Guo F Zhi X Hu H Chen G 《Analytical and bioanalytical chemistry》2011,399(5):1901-1906
A method for analysis of diethofencarb and pyrimethanil in apple pulp and peel was developed by using dispersive liquid–liquid
microextraction based on solidification of a floating organic droplet (DLLME-SFO) and high-performance liquid chromatography
with diode-array detection (HPLC–DAD). Acetonitrile was used as the solvent to extract the two fungicides from apple pulp
and peel, assisted by microwave irradiation. When the extraction process was finished, the target analytes in the extraction
solvent were rapidly transferred from the acetonitrile extract to another extraction solvent (1-undecanol) by using DLLME-SFO.
Because of the lower density of 1-undecanol than that of water, the finely dispersed droplets of 1-undecanol collected on
the top of aqueous sample and solidified at low temperature. Meanwhile, the tiny particles of apple cooled and precipitated.
Recovery was tested for a concentration of 8 μg kg−1. Recovery of diethofencarb and pyrimethanil from apple pulp and peel was in the range 83.5–101.3%. The repeatability of the
method, expressed as relative standard deviation, varied between 4.8 and 8.3% (n = 6). Detection limits of the method for apple pulp and peel varied from 1.2–1.6 μg kg−1 for the two fungicides. Compared with conventional sample preparation, the method has the advantage of rapid speed and simple
operation, and has high enrichment factors and low consumption of organic solvent. 相似文献
6.
Yang Song Yu Ge Yan Zhang Bing Liu Yang Lu Tingting Dong Shuo Wang 《Analytical and bioanalytical chemistry》2009,393(8):2001-2008
In this study, a panel of haptens was synthesized for immunoconjugate preparation, and several haptens for heterologous tracer
conjugates were also prepared. A highly sensitive polyclonal antibody against the organophosphorus insecticide phosmet was
obtained and competitive direct enzyme-linked immunosorbent assays (cd-ELISA) for this pesticide were developed. In the cd-ELISA,
the limit of detection (IC15) was 0.6 μg kg−1 and the sensitivity (IC50) was 20 μg kg−1. The suitability of the ELISA for pesticide quantification in peach, apple, orange juice, and apple juice was also studied.
Good accuracy and precision were obtained with mean recoveries between 78% and 102.3% and mean coefficients of variation below
13.63%. Validation of the ELISA was conducted by high-performance liquid chromatography. The correlation between the data
obtained using the microwell assay and the high-performance liquid chromatography was good (R
2 = 0.9849). The developed immunoassay methods were suitable for the rapid quantitative or qualitative determination of phosmet
in food samples. 相似文献
7.
The synthesis and evaluation of a molecularly imprinted polymer (MIP) used as a selective solid-phase extraction sorbent and
coupled to high-performance liquid chromatography (HPLC) for the efficient determination of sulfamerazine (SMR) in pond water
and three fishes are reported. The polymer was prepared using SMR as the template molecule, methacrylic acid as the functional
monomer and ethylene glycol dimethacrylate as the crosslinking monomer in the presence of tetrahydrofuran as the solvent.
The SMR-imprinted polymers and nonimprinted polymers were characterized by FT-IR and static adsorption experiments. The prepared
SMR-imprinted material showed a high adsorption capacity, significant selectivity and good site accessibility. The maximum
static adsorption capacities of the SMR-imprinted and nonimprinted materials for SMR were 108.8 and 79.6 mg g−1, respectively. The relative selectivity factor of this SMR-imprinted material was 1.6. Several parameters influencing the
solid-phase extraction process were optimized. Finally, the SMR-imprinted polymers were used as the sorbent in solid-phase
extraction to determine SMR in pond water and three fishes with satisfactory recovery. The average recoveries of the MIP-SPE
method were 94.0% in ultrapure water and 95.8% in pond water. Relative standard deviations ranging from 0.3% to 5.2% in MIP
were acquired. The results for the SMR concentrations in crucian, carp and wuchang fish were 66.0, 127.1 and 51.5 ng g−1, respectively. The RSDs (n = 5) were 3.51%, 0.53% and 5.08%, respectively. The limit of detection (LOD) for SMR was 1 ng g−1 and the limit of quantitation (LOQ) was 3.5 ng g−1. 相似文献
8.
Gema Paniagua González Pilar Fernández Hernando Jesús Senén Durand Alegría 《Analytical and bioanalytical chemistry》2009,394(4):963-970
This work reports a comparative study of two automated flow-through fluorosensors for the determination of digoxin in serum
samples: an immunosensor with an anti-digoxin polyclonal antibody as the reactive phase permanently immobilised on controlled-pore
glass and a sensor with a selective reaction system based on a methacrylic molecularly imprinted polymer (MIP) synthesised
by bulk polymerisation. The variables affecting the sensitivity and dynamic range of the sensors (e.g. the carrier and elution
solutions, flow rates, pH and reagent concentrations) were optimized, and the binding characteristics of their reactive phases
were compared in a competitive fluorescent assay. Digoxin was reproducibly determined by both sensors at the milligram per
litre level (detection limit = 1.20 × 10−3 mg L−1 and RSD = 4–7% for the immunosensor; detection limit = 1.7 × 10−5 mg L−1 and RSD = 1–2% for the MIP sensor). No cross-reactivity with digoxin-related compounds was seen for either sensor at a digoxin/interferent
ratio of 1:100. The lifetime of the immunosensor was about 50 immunoassays; its shelf life, when unused, is about 3 months.
The lifetime of the MIP sensor was over 18 months. Both sensors were used to determine the digoxin concentration of human
serum samples with satisfactory results. 相似文献
9.
A novel molecularly imprinted polymer solid-phase extraction (MISPE) with flow-injection chemiluminescence (CL) was developed
for the determination of pazufloxacin mesilate (PZFX). The molecularly imprinted polymer (MIP) was synthesized by using PZFX
as the imprinting molecule. A glass tube packed the particles of the MIP was employed as MISPE micro-column, which was connected
into the sampling loop of the eight-way injection valve for on-line selective preconcentration and extraction of PZFX. The
eluent of acetonitrile:acetic acid (9:1, v:v) was used as carrier for eluting the adsorbed PZFX to react with the mixture
of cerium(IV) and sodium sulfite in the flow cell to produce strong CL. The relative intensity of CL was linear to PZFX concentration
in the range from 2.5 × 10−9 to 2.5 × 10−7 g mL−1. The limit of detection was 7 × 10−10 g mL−1 (3 σ) and the relative standard deviation for 5 × 10−8 g mL−1of PZFX solution was 3.7% (n = 7). This method has been applied to the determination of PZFX in human urine. 相似文献
10.
Preparation of magnetic molecularly imprinted polymer for rapid determination of bisphenol A in environmental water and milk samples 总被引:2,自引:0,他引:2
Yongsheng Ji Juanjuan Yin Zhigang Xu Chuande Zhao Huayu Huang Haixia Zhang Chunming Wang 《Analytical and bioanalytical chemistry》2009,395(4):1125-1133
A magnetic molecularly imprinted polymer (M-MIP) of bisphenol A (BPA) was prepared by miniemulsion polymerization. The morphological
and magnetic characteristics of the M-MIP were characterized by Fourier-transform infrared spectroscopy, transmission electron
microscopy, and vibrating sample magnetometry. The adsorption capacities of the M-MIP and the nonimprinted polymer were investigated
using static adsorption tests, and were found to be 390 and 270 mg g−1, respectively. Competitive recognition studies of the M-MIP were performed with BPA and the structurally similar compound
DES, and the M-MIP displayed high selectivity for BPA. A method based on molecularly imprinted solid-phase extraction assisted
by magnetic separation was developed to extract BPA from environmental water and milk samples. Various parameters such as
the mass of sorbent, the pH of the sample, the extraction time, and desorption conditions were optimized. Under selected conditions,
extraction was completed in 15 min. High-performance liquid chromatography with UV detection was employed to determine BPA
after the extraction. For water samples, the developed method exhibited a limit of detection (LOD) of 14 ng L−1, a relative standard deviation of 2.7% (intraday), and spiked recoveries ranging from 89% to 106%. For milk samples, the
LOD was 0.16 μg L−1, recoveries ranged from 95% to 101%, and BPA was found in four samples at levels of 0.45–0.94 μg L−1. The proposed method not only provides a rapid and reliable analysis but it also overcomes problems with conventional solid-phase
extraction (SPE), such as the packing of the SPE column and the time-consuming nature of the process of loading large-volume
samples. 相似文献
11.
Determination of nine high-intensity sweeteners in various foods by high-performance liquid chromatography with mass spectrometric detection 总被引:1,自引:0,他引:1
Zygler A Wasik A Kot-Wasik A Namieśnik J 《Analytical and bioanalytical chemistry》2011,400(7):2159-2172
An analytical procedure involving solid-phase extraction (SPE) and high-performance liquid chromatography-mass spectrometry
has been developed for the determination of nine high-intensity sweeteners authorised in the EU; acesulfame-K (ACS-K), aspartame
(ASP), alitame (ALI), cyclamate (CYC), dulcin (DUL), neohesperidin dihydrochalcone (NHDC), neotame (NEO), saccharin (SAC)
and sucralose (SCL) in a variety of food samples (i.e. beverages, dairy and fish products). After extraction with a buffer
composed of formic acid and N,N-diisopropylethylamine at pH 4.5 in ultrasonic bath, extracts were cleaned up using Strata-X 33 μm Polymeric SPE column. The
analytes were separated in gradient elution mode on C18 column and detected by mass spectrometer working with an electrospray source in negative ion mode. To confirm that analytical
method is suitable for its intended use, several validation parameters, such as linearity, limits of detection and quantification,
trueness and repeatibilty were evaluated. Calibration curves were linear within a studied range of concentrations (r
2
≥ 0.999) for six investigated sweeteners (CYC, ASP, ALI, DUL, NHDC, NEO). Three compounds (ACS-K, SAC, SCL) gave non-linear
response in the investigated concentration range. The method detection limits (corresponding to signal-to-noise (S/N) ratio
of 3) were below 0.25 μg mL−1 (μg g−1), whereas the method quantitation limits (corresponding to S/N ratio of 10) were below 2.5 μg mL−1 (μg g−1). The recoveries at the tested concentrations (50%, 100% and 125% of maximum usable dose) for all sweeteners were in the
range of 84.2 ÷ 106.7%, with relative standard deviations <10% regardless of the type of sample matrix (i.e. beverage, yoghurt,
fish product) and the spiking level. The proposed method has been successfully applied to the determination of the nine sweeteners
in drinks, yoghurts and fish products. The procedure described here is simple, accurate and precise and is suitable for routine
quality control analysis of foodstuffs. 相似文献
12.
Liu X Xu J Li Y Dong F Li J Song W Zheng Y 《Analytical and bioanalytical chemistry》2011,399(7):2539-2547
A sensitive and effective method for simultaneous determination of triazolopyrimidine sulfonamide herbicide residues in soil,
water, and wheat was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The four
herbicides (pyroxsulam, flumetsulam, metosulam, and diclosulam) were cleaned up with an off-line C18 SPE cartridge and detected
by tandem mass spectrometry using an electrospray ionization source in positive mode (ESI+). The determination of the target
compounds was achieved in <2.0 min. The limits of detection were below 1 μg kg−1, while the limits of quantification did not exceed 3 μg kg−1 in different matrices. Quantitation was determined from calibration curves of standards containing 0.05–100 μg L−1 with r
2 > 0.997. Recovery studies were conducted at three spiked levels (0.2, 1, and 5 μg kg−1 for water; 5, 10, and 100 μg kg−1 for soil and wheat). The overall average recoveries for this method in water, soil, wheat plants, and seeds at three levels
ranged from 75.4% to 106.0%, with relative standard deviations in the range of 2.1–12.5% (n = 5) for all analytes. 相似文献
13.
An approach for rapid quantitation of 5-hydroxymethylfurfural (HMF) in honey using planar chromatography is suggested for
the first time. In high-performance thin-layer chromatography (HPTLC) the migration time is approximately 5 min. Detection
is performed by absorbance measurement at 290 nm. Polynomial calibration in the matrix over a range of 1:80 showed correlation
coefficients, r, of ≥ 0.9997 for peak areas and ≥ 0.9996 for peak heights. Repeatability in the matrix confirmed the suitability of HPTLC–UV
for quantitation of HMF in honey. The relative standard deviation (RSD, %, n = 6) of HMF at 10 ng/band was 2.9% (peak height) and 5.2% (peak area); it was 0.6% and 1.0%, respectively, at 100 ng/band.
Other possible detection modes, for example fluorescence measurement after post-chromatographic derivatization and mass spectrometric
detection, were also evaluated and can coupling can be used as an additional tool when it is necessary to confirm the results
of prior quantitation by HPTLC–UV. The confirmation is provided by monitoring the HMF sodium adduct [M + Na]+ at m/z 149 followed by quantitation in TIC or SIM mode. Detection limits for HPTLC–UV, HPTLC–MS (TIC), and HPTLC–MS (SIM) were 0.8 ng/band,
4 ng/band, and 0.9 ng/band, respectively. If 12 μL honey solution was applied to an HPTLC plate, the respective detection
limits for HMF in honey corresponded to 0.6 mg kg−1. Thus, the developed method was highly suitable for quantitation of HMF in honey at the strictest regulated level of 15 mg kg−1. Comparison of HPTLC–UV detection with HPTLC–MS showed findings were comparable, with a mean deviation of 5.1 mg kg−1 for quantitation in SIM mode and 6.1 mg kg−1 for quantitation in TIC mode. The mean deviation of the HPTLC method compared with the HPLC method was 0.9 mg kg-1 HMF in honey. Re-evaluation of the same HPTLC plate after one month showed a deviation of 0.5 mg kg−1 HMF in honey. It was demonstrated that the proposed HPTLC method is an effective method for HMF quantitation in honey.
相似文献
14.
Benito-Peña E Martins S Orellana G Moreno-Bondi MC 《Analytical and bioanalytical chemistry》2009,393(1):235-245
A novel water-compatible molecularly imprinted polymer (MIP), prepared with enrofloxacin (ENR) as the template, has been optimised
for the selective extraction of fluoroquinolone antibiotics in aqueous media. The results of a morphological characterisation
and selectivity tests of the polymer material for ENR and related derivatives are reported. High affinity for the piperazine-based
fluoroquinolones marbofloxacin, ciprofloxacin, norfloxacin and ofloxacin was observed, whereas no retention was found for
nonrelated antibiotics. Various parameters affecting the extraction efficiency of the polymer have been optimised to achieve
selective extraction of the antibiotics from real samples and to reduce nonspecific interactions. These findings resulted
in a MISPE/HPLC-FLD method allowing direct extraction of the analytes from aqueous samples with a selective wash using just
50% (v/v) organic solvent. The method showed excellent recoveries and precision when buffered urine samples fortified at five
concentration levels (25–250 ng mL−1 each) of marbofloxacin, ciprofloxacin, norfloxacin, enrofloxacin and sarafloxacin were tested (53–88%, RSD 1–10%, n = 3). Moreover, the biological matrix of the aqueous samples did not influence the preconcentration efficiency of the fluoroquinolones
on the MIP cartridges; no significant differences were observed between the recovery rates of the antibiotics in buffer and
urine samples. The detection limits of the whole process range between 1.9 and 34 ng mL–1 when 5-mL urine samples are processed. The developed method has been successfully applied to preconcentration of norfloxacin
in urine samples of a medicated patient, demonstrating the ability of the novel MIP for selective extraction of fluoroquinolones
in urine samples. 相似文献
15.
Hugo M. Oliveira Marcela A. Segundo José L. F. C. Lima Manuel Miró Victor Cerdà 《Analytical and bioanalytical chemistry》2010,397(1):77-86
In the present work, it is proposed, for the first time, an on-line automatic renewable molecularly imprinted solid-phase
extraction (MISPE) protocol for sample preparation prior to liquid chromatographic analysis. The automatic microscale procedure
was based on the bead injection (BI) concept under the lab-on-valve (LOV) format, using a multisyringe burette as propulsion
unit for handling solutions and suspensions. A high precision on handling the suspensions containing irregularly shaped molecularly
imprinted polymer (MIP) particles was attained, enabling the use of commercial MIP as renewable sorbent. The features of the
proposed BI-LOV manifold also allowed a strict control of the different steps within the extraction protocol, which are essential
for promoting selective interactions in the cavities of the MIP. By using this on-line method, it was possible to extract
and quantify riboflavin from different foodstuff samples in the range between 0.450 and 5.00 mg L−1 after processing 1,000 μL of sample (infant milk, pig liver extract, and energy drink) without any prior treatment. For milk
samples, LOD and LOQ values were 0.05 and 0.17 mg L−1, respectively. The method was successfully applied to the analysis of two certified reference materials (NIST 1846 and BCR
487) with high precision (RSD < 5.5%). Considering the downscale and simplification of the sample preparation protocol and
the simultaneous performance of extraction and chromatographic assays, a cost-effective and enhanced throughput (six determinations
per hour) methodology for determination of riboflavin in foodstuff samples is deployed here. 相似文献
16.
Rodrigues TH Rocha MV de Macedo GR Gonçalves LR 《Applied biochemistry and biotechnology》2011,164(6):929-943
In this work, the potential of microwave-assisted alkali pretreatment in order to improve the rupture of the recalcitrant
structures of the cashew able bagasse (CAB), lignocellulosic by-product in Brazil with no commercial value, is obtained from
cashew apple process to juice production, was studied. First, biomass composition of CAB was determined, and the percentage
of glucan and lignin was 20.54 ± 0.70% and 33.80 ± 1.30%, respectively. CAB content in terms of cellulose, hemicelluloses,
and lignin, 19.21 ± 0.35%, 12.05 ± 0.37%, and 38.11 ± 0.08%, respectively, was also determined. Results showed that, after
enzymatic hydrolysis, alkali concentration exerted influence on glucose formation, after pretreatment with 0.2 and 1.0 mo L−1 of NaOH (372 ± 12 and 355 ± 37 mg gglucan−1) when 2% (w/v) of cashew apple bagasse pretreated by microwave-assisted alkali pretreatment (CAB-M) was used. On the other hand, pretreatment
time (15–30 min) and microwave power (600–900 W) exerted no significant effect on hydrolysis. On enzymatic hydrolysis step,
improvement on solid percentage (16% w/v) and enzyme load (30 FPU gCAB-M−1) increased glucose concentration to 15 g L−1. The fermentation of the hydrolyzate by Saccharomyces cerevesiae resulted in ethanol concentration and productivity of 5.6 g L−1 and 1.41 g L−1 h−1, respectively. 相似文献
17.
The worldwide contamination of winery by-products by mycotoxins may present a serious hazard to human and animal health. Mycotoxins
are secondary metabolites of fungi with possible adverse effects on humans, animals, and crops that result in illnesses and
economic losses. Mycotoxins are under continuous survey in Europe, but the regulatory aspects still need to be set up for
winery by-products, which may be used in animal feed. The aim of this study was to implement a simple but reliable analytical
methodology for ochratoxin A (OTA) quantification in grape pomaces in order to perform a survey of samples from the Douro
Demarcated Region, Portugal. The method involved a unique preparation step, solvent extraction, followed by high-performance
liquid chromatography (HPLC) with fluorescence (FL) detection. A comparative study was performed with two extraction solvents
(ethyl acetate and methanol) as well as using extraction on an immunoaffinity column. The linearity range for OTA analysis
was 0.05–23.5 μg L−1 with a detection limit of 0.05 μg L−1 and a precision (expressed by the coefficient of variation under repeatability conditions) of 0.4–14.7%. The percentage of
recovery was on average 23.5 ± 3.6% (extraction with ethyl acetate) or 70.1 ± 2.5% (extraction with 70% methanol). Accounting
for the recovery factor and the chromatographic detection limit, as well as the preconcentration factor, the limit of detection
in grape pomaces is 0.04 μg kg−1 (ethyl acetate extraction) and 0.33 μg kg−1 (methanol extraction). Samples from 12 out of 13 sites in the Douro Demarcated Region showed OTA presence with concentrations
not exceeding 0.4 μg kg−1. Both developed methods for evaluation of OTA in grape pomace are simple but efficient.
Figure Extraction of ochratoxin A (OTA) from grape pomaces allows simple but efficient quantification of OTA in winery by-products
by HPLC-FL 相似文献
18.
Juliana Canto Duarte Rita de Cássia Silva Luz Flavio Santos Damos Adriano Bof de Oliveira Lauro Tatsuo Kubota 《Journal of Solid State Electrochemistry》2007,11(5):631-638
The electrocatalytical oxidation of hydrazine at low potential using tetracyanoquinodimethanide adsorbed on silica modified
with titanium oxide was investigated by cyclic voltammetry and amperometry. The modified electrode was prepared modifying
a carbon paste electrode employing lithium tetracyanoquinodimethanide adsorbed onto silica gel modified with titanium oxide.
This electrode showed an excellent catalytic activity and stability for hydrazine oxidation. With this modified electrode,
the oxidation potential of hydrazine was shifted toward less positive value, presenting a peak current much higher than those
observed on a bare GC electrode. The linear response range, sensitivity and detection limit were, respectively, 2 up to 100 μmol
l−1, 0.36 μA l μmol−1, and 0.60 μmol l−1. The repeatability of the modified electrode evaluated in term of relative standard deviation was 4.2% for 10 measurements
of 100 μmol l−1 hydrazine solution. The number of electrons involved in hydrazine oxidation (4), the heterogenous electron transfer rate
constant (1.08 × 103 mol−1 l s−1), and diffusion coefficient (5.9 × 10−6 cm2 s−1) were evaluated with a rotating disk electrode. 相似文献
19.
Development of a selective molecularly imprinted polymer-based solid-phase extraction for indomethacin from water samples 总被引:1,自引:0,他引:1
A selective molecularly imprinted solid-phase extraction (MISPE) for indomethacin (IDM) from water samples was developed.
Using IDM as template molecule, acrylamide (AM) or methacrylic acid (MAA) as functional monomer, ethylene dimethacrylate (EDMA)
as crosslinker, and bulk or suspension polymerization as the synthetic method, three molecularly imprinted polymers (MIPs)
were synthesized and characterized with a rebinding experiment. It was found that the MIP of AM-EDMA produced by bulk polymerization
showed the highest binding capacity for IDM, and so it was chosen for subsequent experiments, such as those testing the selectivity
and recognition binding sites. Scatchard analysis revealed that at least two kinds of binding sites formed in the MIP, with
the dissociation constants of 7.8 μmol L−1 and 127.2 μmol L−1, respectively. Besides IDM, three structurally related compounds — acemetacin, oxaprozin and ibuprofen — were employed for
selectivity tests. It was observed that the MIP exhibited the highest selective rebinding to IDM. Accordingly, the MIP was
used as a solid-phase extraction sorbent for the extraction and enrichment of IDM in water samples. The extraction conditions
of the MISPE column for IDM were optimized to be: chloroform or water as loading solvent, chloroform with 20% acetonitrile
as washing solution, and methanol as eluting solvent. Water samples with or without spiking were extracted by the MISPE column
and analyzed by HPLC. No detectable IDM was observed in tap water and the content of IDM in a river water sample was found
to be 1.8 ng mL−1. The extraction efficiencies of the MISPE column for IDM in spiked tap and river water were acceptable (87.2% and 83.5%,
respectively), demonstrating the feasibility of the prepared MIP for IDM extraction.
Figure Molecularly imprinted polymer-based solid-phase extraction for indomethacin 相似文献
20.
Moreno M Bermejo E Sánchez A Chicharro M Zapardiel A 《Analytical and bioanalytical chemistry》2008,391(3):867-872
A new method based on matrix solid-phase dispersion (MSPD) extraction was studied for the extraction of amitrole (3-amino-1,2,4-triazole),
and its metabolite urazole (3,5-dihydroxy-1,2,4-triazole), in apple samples. The influence of experimental conditions on the
yield of the extraction process and on the efficiency of the cleanup step was evaluated. Determination was carried out by
capillary electrophoresis (CE) with electrochemical detection, demonstrating the compatibility between MSPD and CE techniques.
The method has been successfully applied to different apple varieties. Recoveries in samples spiked at 1.6 and 1.7 μg g−1 for amitrole and urazole were 88 and 82%, respectively. The limits of detection were 0.4 μg g−1 for both compounds using electrochemical detection. 相似文献