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1.
This work reports the development of a bienzyme system consisting of salicylate hydroxylase (SHL) and nitrate reductase (NaR)
for the electrochemical determination of nitrate. This method measures the concentration of nitrate directly under ambient
air without suffering from oxygen interferences. The determination is based on the detection of NADH consumption, and the
principle is as follows: NADH initiates the irreversible decarboxylation and hydroxylation of salicylate by SHL in the presence
of oxygen to produce catechol, which results in a detectable signal due to its oxidation at the working electrode; the second
enzyme, NaR, in the presence of nitrate, reduced the availability of NADH, and consequently, the current difference after
the injection of nitrate is proportional to its concentration. This method shows high performance characteristics for nitrate
determination with a broad detection range between 10 μM and 1,000 μM, a short measuring time of around 5 min, and a simple
operation without sample pretreatment by inert gas purge or oxygen scavenger.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible to authorized users. 相似文献
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible to authorized users. 相似文献
2.
Patricia W. Stege Lorena L. Sombra Germán A. Messina Luis D. Martinez María F. Silva 《Analytical and bioanalytical chemistry》2009,394(2):567-573
Many aromatic compounds can be found in the environment as a result of anthropogenic activities and some of them are highly
toxic. The need to determine low concentrations of pollutants requires analytical methods with high sensitivity, selectivity,
and resolution for application to soil, sediment, water, and other environmental samples. Complex sample preparation involving
analyte isolation and enrichment is generally necessary before the final analysis. The present paper outlines a novel, simple,
low-cost, and environmentally friendly method for the simultaneous determination of p-nitrophenol (PNP), p-aminophenol (PAP), and hydroquinone (HQ) by micellar electrokinetic capillary chromatography after preconcentration by cloud
point extraction. Enrichment factors of 180 to 200 were achieved. The limits of detection of the analytes for the preconcentration
of 50-ml sample volume were 0.10 μg L−1 for PNP, 0.20 μg L−1 for PAP, and 0.16 μg L−1 for HQ. The optimized procedure was applied to the determination of phenolic pollutants in natural waters from San Luis,
Argentina.
Figure Schematic representation of the cloud point extraction process. 相似文献
3.
The simultaneous determination of three isomers of phenylenediamines (o, m, and p-phenylenediamine) and two isomers of dihydroxybenzenes (catechol and resorcinol) in hair dyes was performed by capillary
zone electrophoresis coupled with amperometric detection (CZE–AD). The effects of working electrode potential, pH and concentration
of running buffer, separation voltage, and injection time on CZE–AD were investigated. Under the optimum conditions the five
analytes could be perfectly separated in 0.30 mol L−1 borate–0.40 mol L−1 phosphate buffer (pH 5.8) within 15 min. A 300 μm diameter platinum electrode had good responses at +0.85 V (versus SCE)
for the five analytes. Their linear ranges were from 1.0 × 10−6 to 1.0 × 10−4 mol L−1 and the detection limits were as low as 10−7 mol L−1 (S/N = 3). This working electrode was successfully used to analyze eight kinds of hair dye sample with recoveries in the range
91.0–108.0% and RSDs less than 5.0%. These results demonstrated that capillary zone electrophoresis coupled with electrochemical
detection using a platinum working electrode as detector was convenient, highly sensitive, highly repeatable and could be
used in the rapid determination of practical samples.
Figure Electropherograms obtained from 10 mg mL−1 hair dye sample solutions at a platinum working electrode under optimum CZE–AD conditions: (a) natural black (I), (b) golden: (1) p-phenylenediamine, (2) m-phenylenediamine, (3) o-phenylenediamine, (4) resorcinol, and (5) catechol 相似文献
4.
A new post-chemiluminescence (PCL) phenomenon was observed when phenothiazine medications were injected into the reaction
mixture after the chemiluminescence (CL) reaction of luminol and potassium ferricyanide had finished. A possible reaction
mechanism was proposed based on studies of the kinetic characteristics of the CL, CL spectra, fluorescence spectra, and on
other experiments. The feasibility of determining various phenothiazine medications by utilizing these PCL reactions was examined.
A molecular imprinting–post-chemiluminescence (MI-PCL) method was established for the determination of chlorpromazine hydrochloride
using a chlorpromazine hydrochloride-imprinted polymer (MIP) as the recognition material. The method displayed high selectivity
and high sensitivity. The linear range of the method was 1.0×10−8∼1.0×10−6, with a linear correlation coefficient of 0.9985. The detection limit was 3×10−9 g/ml chlorpromazine hydrochloride, and the relative standard deviation for a 1.0×10−7 g/ml chlorpromazine hydrochloride solution was 4.0% (n=11). The method has been applied to the determination of chlorpromazine hydrochloride in urine and animal drinking water
with satisfactory results.
相似文献
5.
de Jesus Rodrigues Santos W Lima PR Tarley CR Kubota LT 《Analytical and bioanalytical chemistry》2007,389(6):1919-1929
Despite the increasing number of applications of molecularly imprinted polymers (MIP) in analytical chemistry, the synthesis
of polymers with hemin introduced as the catalytic center to mimic the active site of peroxidase remains as a challenge. In
the current work, a new type of molecularly imprinted polymer (MIP) was synthesized with 4-aminophenol (4-APh) as the template
and two monomers: hemin, which acts as the catalytic center, and methacrylic acid (MAA), which is used to build the active
sites. This work shows that MIP successfully mimics peroxidase. For this purpose, a flow injection analysis system coupled
to an amperometric detector was investigated through multivariate analysis. The determination of 4-APh was not affected by
the equimolar presence of structurally similar phenol compounds, including catechol, 4-chloro-3-methylphenol, 2-aminophenol,
guaiachol, chloroguaiachol and 2-cresol, thus highlighting the good performance of the imprinted polymer. Under the optimized
experimental conditions, an analytical curve covering a wide linear response range from 0.8 up to 500 μmol L−1 (r > 0.999) was obtained, and the method gave satisfactory precisions (n = 8), as evaluated via the relative standard deviation (RSD), of 4.1 and 3.2% for solutions of 4-APh of 50 and 500 μmol L−1, respectively. Recoveries of 96–111% from water samples (tap water and river water) spiked with 4-APh were achieved, thus
illustrating the accuracy of the proposed system.
Figure Schematic presentation of the synthesis of the MIP 相似文献
6.
Pérez-Sirvent C Martínez-Sánchez MJ García-Lorenzo M López-García I Hernández-Córdoba M 《Analytical and bioanalytical chemistry》2007,388(2):495-498
Use of small membrane pumps, instead of peristaltic pumps, to introduce sample and reagent solutions into the spectrometer
has several advantages in atomic fluorescence spectrometric determination of mercury. This simple modification results in
a substantial saving in the time required for the measurements and so 90% of reagent solution volumes and 95% of sample solution
volumes are saved, with a consequent decrease in the volume of waste generated. The sampling frequency is almost tripled,
with no deterioration in sensitivity, which is similar to that obtained by use of peristaltic pumps. The relative standard
deviation for ten consecutive measurements of a 1 μg L−1 mercury solution was approximately 2%.
Figure Small membrane pumps for the atomic fluorescene spectro metric determination of mercury 相似文献
7.
Determining sulfamonomethoxine and its acetyl/hydroxyl metabolites in chicken plasma under organic solvent-free conditions 总被引:1,自引:0,他引:1
Furusawa N 《Analytical and bioanalytical chemistry》2006,385(8):1570-1574
A quantitative technique is described for a sample preparation followed by high performance liquid chromatography method for
the simultaneous determination of sulfamonomethoxine and its metabolites, N
4-acetyl SMM and 2,6-dihydroxy SMM, in chicken plasma. The average recoveries, analytical total time, and limits of quantitation
were ≥80% (relative standard deviations (SD) ≤6%), <30 min sample-1 (12 samples in 2 h), and ≤0.09 μg ml−1, respectively. The procedure, performed under 100% aqueous conditions, uses no organic solvents and toxic reagents at all
and is, therefore, harmless to the environment and humans.
相似文献
8.
Wang JH Wang HQ Zhang HL Li XQ Hua XF Cao YC Huang ZL Zhao YD 《Analytical and bioanalytical chemistry》2007,388(4):969-974
CdTe quantum dots (QDs) were synthesized in aqueous solution with 3-mercaptopropionic acid as the stabilizer. Chemically reduced
bovine serum albumin (BSA) was used to modify the surface of the QDs. Experimental results showed that the denatured BSA (dBSA)
could be effectively conjugated to the surface of CdTe QDs. Column chromatography was used to purify the conjugates and determine
the optimal ratio of dBSA to QDs. Further experimental results showed that the conjugation of QDs by dBSA efficiently improved
the photoluminescence quantum yield, the chemical stability of QDs and their stability against photobleaching. A facile and
sensitive method for determination of silver(I) ions was proposed based on the fluorescence quenching of the dBSA–QDs. Under
the optimal conditions, the relative fluorescence intensity decreased linearly with the concentration of the silver(I) ions
in the range 0.08–10.66 μM. The detection limit was 0.01 μM. This study provides a new method for the detection of metal cations.
Figure In this work, denatured BSA was used to modify the surface of CdTe QDs by a simple and rapid method. And the conjugates of
dBSA-QDs were purified by column of Sephadex G-100. After the purification of the conjugates, the sensitivity was greatly
increased as silver (I) ions probe. 相似文献
9.
Catechol determination in compost bioremediation using a laccase sensor and artificial neural networks 总被引:1,自引:0,他引:1
Tang L Zeng G Liu J Xu X Zhang Y Shen G Li Y Liu C 《Analytical and bioanalytical chemistry》2008,391(2):679-685
An electrochemical biosensor based on the immobilization of laccase on magnetic core-shell (Fe3O4–SiO2) nanoparticles was combined with artificial neural networks (ANNs) for the determination of catechol concentration in compost
bioremediation of municipal solid waste. The immobilization matrix provided a good microenvironment for retaining laccase
bioactivity, and the combination with ANNs offered a good chemometric tool for data analysis in respect to the dynamic, nonlinear,
and uncertain characteristics of the complex composting system. Catechol concentrations in compost samples were determined
by using both the laccase sensor and HPLC for calibration. The detection range varied from 7.5 × 10–7 to 4.4 × 10–4 M, and the amperometric response current reached 95% of the steady-state current within about 70 s. The performance of the
ANN model was compared with the linear regression model in respect to simulation accuracy, adaptability to uncertainty, etc.
All the results showed that the combination of amperometric enzyme sensor and artificial neural networks was a rapid, sensitive,
and robust method in the quantitative study of the composting system.
Figure Structure of the magnetic carbon paste electrode used in the electrochemical biosensor 相似文献
10.
Competitive adsorption on adsorptive solid-phase microextraction (SPME) fibres implies careful determination of operating
conditions for reliable quantitative analysis of VOCs in indoor air. With this objective, two analytical approaches, involving
non-equilibrium and equilibrium extraction, were compared. The average detection limit obtained for GC-MS analysis of nine
VOCs by the equilibrium method is 0.2 μg m−3, compared with 1.9 μg m−3 with the non-equilibrium method. The effect of the relative humidity of the air on the calibration plots was studied, and
shown to affect acetone adsorption only. Hence, the concentrations that can be accurately determined are up to 9 μmol m−3. The methods were then applied to indoor air containing different concentrations of VOCs. The non-equilibrium method, involving
short extraction time, can be used for detection of pollution peaks whereas equilibrium extraction is preferable for measurement
of sub-μg m−3 ground concentration levels.
相似文献
11.
Veronica M. T. Lattanzio Michele Solfrizzo Angelo Visconti 《Analytical and bioanalytical chemistry》2009,395(5):1325-1334
The selective enzymatic deacetylation of T-2 toxin to give HT-2 toxin has been investigated in aqueous crude extracts of different
cereals and exploited to develop an analytical method for the determination of the sum of T-2 and HT-2 toxins. The method
has been validated for the analysis of total T-2 and HT-2 toxins in maize, wheat, and oats, showing recoveries from 72 to
97% for maize, from 67 to 84% for wheat, and from 61% to 87% for oats, at spiking levels of 20–400 μg/kg, with relative standard
deviation lower than 10%. Liquid chromatography-tandem mass spectrometry was used for quantitative toxin determination. The
potential biological role of this enzymatic conversion and its perspectives for application in the development of antibody-based
analytical techniques are discussed.
相似文献
12.
With UV irradiation, Hg2+ in aqueous solution can be converted into Hg0 cold vapor by low molecular weight alcohols, aldehydes, or carboxylic acids, e.g., methanol, formaldehyde, acetaldehyde,
glycol, 1,2-propanediol, glycerol, acetic acid, oxalic acid, or malonic acid. It was found that the presence of nano-TiO2 more or less improved the efficiency of the photo-induced chemical/cold vapor generation (photo-CVG) with most of the organic
reductants. The nano-TiO2-enhanced photo-CVG systems can be coupled to various analytical atomic spectrometric techniques for the determination of
ultratrace mercury. In this work, we evaluated the application of this method to the atomic fluorescence spectrometric (AFS)
determination of mercury in cold vapor mode. Under the optimized experimental conditions, the instrumental limits of detection
(based on three times the standard deviation of 11 measurements of a blank solution) were around 0.02–0.04 μg L−1, with linear dynamic ranges up to 15 μg L−1. The interference of transition metals and the mechanism of the photo-CVG are briefly discussed. Real sample analysis using
the photo-CVG-AFS method revealed that it was promising for water and geological analysis of ultralow levels of mercury.
Image of the photo-CVG instrumentation showing the photoreactor inside the water cooling unit 相似文献
13.
In-torch LA–ICP–MS was implemented into an in-house-built ICP–TOFMS system. The fast data acquisition capabilities of the
new configuration allowed simultaneous multi-element measurement and readout of in-torch LA–ICP–MS signals with 30 μs time
resolution. The measurements confirmed previously observed fine structures of in-torch generated signals and provided new
insights in the dynamic processes in the plasma on a microsecond time scale. The new setup is described in detail and first
figures of merit are given.
Figure Time dependent multi element signal after laser ablation in the torch of an ICP-TOFMS instrument 相似文献
14.
A method based on use of functionalized gold nanoparticles on polyethylenimine film has been developed for colorimetric detection of immunoglobulin G (IgG). The immunogold nanoparticles were immobilized on quartz slides by recognition between antibody and antigen, with the antigen chemically adsorbed on the polyethylenimine film. By measurement of the UV–visible spectra of the immobilized immunogold, detection of h-IgG was achieved. The detection limit for h-IgG by use of this method can be as low as 0.01 μg mL−1. This method is quite promising for numerous applications in immunoassay.
Figure 相似文献
15.
Ortega-Algar S Ramos-Martos N Molina-Díaz A 《Analytical and bioanalytical chemistry》2008,391(2):715-719
A single optosensing device based on lanthanide-sensitized luminescence was developed for determination of p-aminobenzoic acid (PABA). The method is based on the formation of a complex between PABA and Tb(III) immobilized on the solid
phase (QAE A-25 resin) placed inside the flow cell. NaCl (1 M) was used as carrier solution and HCl (0.05 M) as eluent. The
sample solutions of PABA (100 μL) containing Tb(III) and buffered at pH = 6.0 were injected into the carrier stream and the
luminescence was measured at λ
ex = 290 nm and λ
em = 546 nm. The method shows a linear range from 0.2 to 6.0 μg mL−1 with an RSD of 1.2% (n = 10) and a sampling frequency of 22 h−1. A remarkable characteristic of the method is its high selectivity which allows it to be satisfactorily applied to the analysis
of PABA in pharmaceutical samples without prior treatment.
Figure Typical emission bands of Tb(III) in a solid-phase PABA–Tb(III) luminescence spectrum 相似文献
16.
The electrochemical behavior of paracetamol in 0.1 M acetate buffer solution (pH 4.6) was investigated at a traditional carbon
paste electrode (TCPE) and a carbon ionic liquid electrode (CILE) fabricated by replacing nonconductive organic binders with
a conductive hydrophobic room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6). The results showed that the CILE exhibited better reversibility for the electrochemical redox of paracetamol. The oxidation
potential of paracetamol at the CILE is +0.462 V, which is approximately 232 mV lower than that at the TCPE; the oxidation
peak current response is nine times higher than that at the TCPE. The differential pulse voltammetric determination of paracetamol
at the CILE was established based on this behavior. After optimizing several important parameters controlling the performance
of paracetamol at the CILE, the oxidation peak current versus paracetamol concentration at the CILE showed linearity in the
range from 1.0 μM to 2.0 mM (R
2
= 0.9992) with a detection limit of 0.3 μM (S/N = 3). The method has been applied to the determination of paracetamol in
tablets and urine samples and the average recovery of paracetamol was 98.5% and 99.3%, respectively. The proposed CILE showed
good sensitivity and reproducible response without influence of interferents commonly existing in pharmaceutical and urine
samples.
Figure CV curves of paracetamol illustrate the enhanced electrochemical behavior of paracetamol at the CILE (b), which forms the basis for the differential pulse voltammetric determination of paracetamol 相似文献
17.
External μPIXE has been used for characterisation of small samples of varnish from historical violins, and pieces of varnished
wood from historical and modern stringed instruments. To obtain spatially resolved information about the distribution of elements
across the varnish layers single-spot analysis, line-scans, and area-mapping were performed. Local resolution of approximately
20 μm was obtained from the 3 MeV, 1 nA proton micro-probe. Results from simultaneous multi-element determination of Na, Mg,
Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Br, Rb, Sr, Ag, Cd, Sn, Ba, and Pb in historical varnishes are
presented. Semi-quantitative evaluation of line-scans recorded on diverse historical varnishes is reported. The applied method
is discussed in detail and the results obtained are critically reviewed and compared with those in the literature.
相似文献
18.
Ortner K Sivanandam VN Buchberger W Müller N 《Analytical and bioanalytical chemistry》2007,388(1):173-177
Enzymatically cleaved glycans from sub-milligram quantities of erythropoietin (EPO) and ovalbumin have been analyzed, without
further purification, by two-dimensional diffusion-ordered nuclear magnetic resonance spectroscopy. At NMR sample concentrations
below 50 μmol L−1 the major components of the oligosaccharide fractions could be distinguished by their anomeric proton chemical shift and
their size-dependent diffusion coefficients.
Figure
1H NMR diffusion decay curves of anomeric protons in the EPO glycan fraction 相似文献
19.
Lee KC Cheuk MW Chan W Lee AW Zhao ZZ Jiang ZH Cai Z 《Analytical and bioanalytical chemistry》2006,386(7-8):2225-2232
A reversed-phase HPLC method has been developed for determination of twelve intact glucosinolates—glucoiberin, glucocheirolin,
progoitrin, sinigrin, epiprogoitrin, glucoraphenin, sinalbin, gluconapin, glucosibarin, glucotropaeolin, glucoerucin, and
gluconasturtiin—in ten traditional Chinese plants. The samples were extracted with methanol and the extracts were cleaned
on an activated Florisil column. A mobile phase gradient prepared from methanol and 30 mmol L−1 ammonium acetate at pH 5.0 enabled baseline separation of the glucosinolates. Glucosinolate detection was confirmed by quadrupole
time-of-flight tandem mass spectrometric analysis in negative-ionization mode. Detection limits ranged from 0.06 to 0.36 μg
g−1 when 5 g of dried plant was analyzed. Recoveries of the glucosinolates were better than 85% and precision (relative standard
derivation, n = 3) ranged from 5.3 to 14.6%. Analysis of the glucosinolates provided scientific evidence enabling differentiation of three
pairs of easily confused plants.
Figure Glucosinolates Analysis for the Differentiation of Easily-Confusing Herbs 相似文献
20.
Zaher M Ravelet C Baussanne I Ravel A Grosset C Décout JL Peyrin E 《Analytical and bioanalytical chemistry》2009,393(2):655-660
In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new
dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl
anchor system efficiently (1.15 μmol/m2) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting
coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids.
Chromatographic separation of methionine enantiomers using a dinaphtyl neamine-based ligand-exchange chiral stationary phase 相似文献