共查询到20条相似文献,搜索用时 31 毫秒
1.
Shangfen Gao Guangqun Tan Hongyan Yuan Dan Xiao Martin M. F. Choi 《Mikrochimica acta》2006,153(3-4):159-162
A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg2+ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg2+ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly
on exposure to various concentrations of Hg2+ ion. This forms the basis for the determination of Hg2+ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM
with r2 = 0.997 and the limit of detection for Hg2+ ion was 1.3 μM. Ions including Pb2+, Cd2+, Ag+, Zn2+, Co2+, Ni2+, Cu2+, Mg2+, Mn2+, Ru3+, Er3+, K+, Na+, NH4+, Cl−, NO3−, CH3COO− and SO42− did not interfere with the measurement of Hg2+ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can
provide an alternative, sensitive and economical way to determine Hg2+ ion. 相似文献
2.
Label-free aptamer-based colorimetric detection of mercury ions in aqueous media using unmodified gold nanoparticles as colorimetric probe 总被引:2,自引:0,他引:2
We report a simple and sensitive aptamer-based colorimetric detection of mercury ions (Hg2+) using unmodified gold nanoparticles as colorimetric probe. It is based on the fact that bare gold nanoparticles interact
differently with short single-strand DNA and double-stranded DNA. The anti-Hg2+ aptamer is rich in thymine (T) and readily forms T–Hg2+–T configuration in the presence of Hg2+. By measuring color change or adsorption ratio, the bare gold nanoparticles can effectively differentiate the Hg2+-induced conformational change of the aptamer in the presence of a given salt with high concentration. The assay shows a linear
response toward Hg2+ concentration through a five-decade range of 1 × 10−4 mol L−1 to 1 × 10−9 mol L−1. Even with the naked eye, we could identify micromolar Hg2+ concentrations within minutes. By using the spectrometric method, the detection limit was improved to the nanomolar range
(0.6 nM). The assay shows excellent selectivity for Hg2+ over other metal cations including K+, Ba2+, Ni2+, Pb2+, Cu2+, Cd2+, Mg2+, Ca2+, Zn2+, Al3+, and Fe3+. The major advantages of this Hg2+ assay are its water-solubility, simplicity, low cost, visual colorimetry, and high sensitivity. This method provides a potentially
useful tool for the Hg2+ detection. 相似文献
3.
Utilization of a spiropyran derivative in a polymeric film optode for selective fluorescent sensing of zinc ion 总被引:1,自引:0,他引:1
ZHANG Ying SHAO Na YANG Ronghua LI Ke’an LIU Feng CHAN Winghong & MO Tian . College of Chemistry Molecular Engineering Peking University Beijing China . Department of Chemistry Hong Kong Baptist University Hong Kong China 《中国科学B辑(英文版)》2006,49(3):246-255
Spiropyrans are the most studied families of func- tional materials due to their reversible structural con- version in response to external optical, chemical, and thermal stimulation[1]. Irradiation with ultraviolet light causes formation of an extended π-conjugation open form (merocyanine form) by heterolytic cleavage of the C (spiro)-O bond, which generates an intense ab- sorption in the visible region. Under the irradiating of visible light, the opened form will come back to the closed spi… 相似文献
4.
Tripodal chelating ligand-based sensor for selective determination of Zn(II) in biological and environmental samples 总被引:1,自引:0,他引:1
Potassium hydrotris(N-tert-butyl-2-thioimidazolyl)borate [KTtt-Bu] and potassium hydrotris(3-tert-butyl-5-isopropyl-l-pyrazolyl)borate [KTpt-Bu,i-Pr] have been synthesized and evaluated as ionophores for preparation of a poly(vinyl chloride) (PVC) membrane sensor for Zn(II)
ions. The effect of different plasticizers, viz. benzyl acetate (BA), dioctyl phthalate (DOP), dibutyl phthalate (DBP), tributyl
phosphate (TBP), and o-nitrophenyl octyl ether (o-NPOE), and the anion excluders sodium tetraphenylborate (NaTPB), potassium tetrakis(p-chlorophenyl)borate (KTpClPB), and oleic acid (OA) were studied to improve the performance of the membrane sensor. The best
performance was obtained from a sensor with a of [KTtt-Bu] membrane of composition (mg): [KTtt-Bu] (15), PVC (150), DBP (275), and NaTPB (4). This sensor had a Nernstian response (slope, 29.4 ± 0.2 mV decade of activity)
for Zn2+ ions over a wide concentration range (1.4 × 10−7 to 1.0 × 10−1 mol L−1) with a limit of detection of 9.5 × 10−8 mol L−1. It had a relatively fast response time (12 s) and could be used for 3 months without substantial change of the potential.
The membrane sensor had very good selectivity for Zn2+ ions over a wide variety of other cations and could be used in a working pH range of 3.5–7.8. The sensor was also found to
work satisfactorily in partially non-aqueous media and could be successfully used for estimation of zinc at trace levels in
biological and environmental samples.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Ribeiro Guevara S Zizek S Repinc U Pérez Catán S Jaćimović R Horvat M 《Analytical and bioanalytical chemistry》2007,387(6):2185-2197
Mercury tracers are powerful tools that can be used to study mercury transformations in environmental systems, particularly
mercury methylation, demethylation and reduction in sediments and water. However, mercury transformation studies using tracers
can be subject to error, especially when used to assess methylation potential. The organic mercury extracted can be as low
as 0.01% of the endogenous labeled mercury, and artefacts and contamination present during methylmercury (MeHg) extraction
processes can cause interference. Solvent extraction methods based on the use of either KBr/H2SO4 or HCl were evaluated in freshwater sediments using 197Hg radiotracer. Values obtained for the 197Hg tracer in the organic phase were up to 25-fold higher when HCl was used, which is due to the coextraction of 197Hg2+ into the organic phase during MeHg extraction. Evaluations of the production of MeHg gave similar results with both MeHg
extraction procedures, but due to the higher Hg2+ contamination of the controls, the uncertainty in the determination was higher when HCl was used. The Hg2+ contamination of controls in the HCl extraction method showed a nonlinear correlation with the humic acid content of sediment
pore water. Therefore, use of the KBr/H2SO4 method is recommended, since it is free from these interferences. 197Hg radiotracer (T
1/2 = 2.673 d) has a production rate that is about 50 times higher than that of 203Hg (T
1/2 = 46.595 d), the most frequently used mercury radiotracer. Hence it is possible to obtain a similar level of performance
to 203Hg when it is used it in short-term experiments and produced by the irradiation of 196Hg with thermal neutrons, using mercury targets with the natural isotopic composition. However, if the 0.15% natural abundance
of the 196Hg isotope is increased, the specific activity of the 197Hg tracer can be significantly improved. In the present work, 197Hg tracer was produced from mercury 51.58% enriched in the 196Hg isotope, and a 340-fold increase in specific activity with respect to natural mercury targets was obtained. When this high
specific activity tracer is employed, mercury methylation and reduction experiments with minimum mercury additions are feasible.
Tracer recovery in methylation experiments (associated with Me197Hg production from 197Hg2+ spike, but also with Hg2+ contamination and Me197Hg artefacts) with marine sediments was about 0.005% g−1 WS (WS: wet sediment) after 20 h incubation with mercury additions of 0.05 ng g−1 WS, which is far below natural mercury levels. In this case, the amount of Hg2+ reduced to Hg0 (expressed as the percent 197Hg0 recovered with respect to the 197Hg2+ added) varied from 0.13 to 1.6% g−1 WS. Me197Hg production from 197Hg2+ spike after 20 h of incubation of freshwater sediment ranged from 0.02 to 0.13% g−1 WS with mercury additions of 2.5 ng g−1 WS, which is also far below natural levels. 197Hg0 recoveries were low, 0.0058 ± 0.0013% g−1 WS, but showed good reproducibility in five replicates. Me197Hg production from 197Hg2+ spiked in freshwater samples ranged from 0.1 to 0.3% over a period of three days with mercury additions of 10 ng L−1. A detection limit of 0.05% for Me197Hg production from 197Hg2+ spike was obtained in seawater in a 25 h incubation experiment with mercury additions of 12 ng L−1. 相似文献
6.
Pavlína Pelcová Jana Margetínová Tomáš Vaculovič Josef Komárek Vlastimil Kubáň 《Central European Journal of Chemistry》2010,8(1):116-125
Abiotic parameters (pH, temperature, current velocity, mercury species concentration, and sediment and aqueous media composition)
influence mercury species (MeHg+, EtHg+, PhHg+ and inorganic Hg2+) adsorption on river sediments. The highest amount of adsorbed MeHg+ and EtHg+ (82–93% and 85–91% for static and agitated system, respectively) occurred at pH 3–4. For PhHg+ the maximum adsorption (90% and 95% for static and agitated systems) was located over the broad 3–10 pH range, while for
Hg2+ (94% and 97% for static and agitated systems) it was at pH ∼ 3. Temperature (4.5–60°C) influenced the adsorption rate but
not the quantity. Both rate and quantity increased in the order: static < agitated ≤ stirred systems. The aqueous medium composition
affected both rate and quantity. Sulfate caused the largest adsorption decrease for organomercury species (15–25% decrease);
sulfide reduced Hg2+ adsorption about 67%. Cations at pH 5.2 reduced either the adsorption rate (Ca2+, Al3+) or the total adsorption (Zn2+, Fe3+). Positive correlations were found between sediment C, N, S content as well as cation exchange capacity (CEC) with mercury
adsorption (R = 0.45–0.66, 0.56–0.89, 0.45–0.61 and 0.55–0.73, respectively) while negative correlations were observed with
Fe and Al (R = −0.63 to −0.90 and −0.65 to −0.86, respectively). 相似文献
7.
Caglar P Tuncel SA Malcik N Landers JP Ferrance JP 《Analytical and bioanalytical chemistry》2006,386(5):1303-1312
A newly designed glass-PDMS microchip-based sensor for use in the determination of Ca2+ ions has been developed, utilizing reflectance measurements from arsenazo III (1,8-dihydroxynaphthalene-3,6-disulfonic acid-2,7-bis[(azo-2)-phenyl
arsenic acid]) immobilized on the surface of polymer beads. The beads, produced from cross-linked poly(p-chloromethylstyrene) (PCMS), were covalently modified with polyethylenimine (PEI) to which the Arsenazo III could be adsorbed.
The maximum amount of Arsenazo III which could be immobilized onto the PEI-attached PCMS beads was found to be 373.71 mg g−1 polymer at pH 1. Once fabricated, the beads were utilized at the detection point of the microfluidic sensor device with a
fiber optic assembly for reflectance measurements. Samples were mobilized past the detection point in the sensor where they
interact with the immobilized dye. The sensor could be regenerated and re-used by rinsing with HCl solution. The pH, voltage,
linear range, and the effect of interfering ions were evaluated for Ca2+ determination using this microchip sensor. At the optimum potential, 0.8 kV, and pH 9.0, the linear range of the microchip
sensor was 3.57 × 10−5 – 5.71 × 10−4 M Ca2+, with a limit of detection (LOD) of 2.68 × 10−5 M. The microchip biosensor was then applied for clinical analysis of calcium ions in serum with good results.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
8.
Patel-Sorrentino N Benaim JY Cossa D Lucas Y 《Analytical and bioanalytical chemistry》2011,399(3):1389-1392
Total mercury (HgT) determination requires the addition of concentrated hydrochloric acid solution (≥10 mol L−1 HCl) in relatively high amounts to preserve the samples and to prepare reagent solutions. A method for the preparation of
concentrated HCl with HgT concentration of lower than 5 ng L−1 is described in this article. It is based on the well-known chemical reaction: 2 NH4Cl + H2SO4 → (NH4)2SO4 + 2 HCl. This method is validated thanks to the US Environmental Protection Agency method 1631 and standard reference materials
BCR-579 (mercury in coastal seawater). 相似文献
9.
Xiaoying Liu Yonghong Li Xinsheng Liu Xiandong Zeng Bo Kong Shenglian Luo Wanzhi Wei 《Journal of Solid State Electrochemistry》2012,16(3):883-889
A simple sensor based on bare carbon ionic liquid electrode was fabricated for simultaneous determination of dihydroxybenzene
isomers in 0.1 mol L−1 phosphate buffer solution (pH 6.0). The oxidation peak potential of hydroquinone was about 0.136 V, catechol was about 0.240 V,
and resorcinol 0.632 V by differential pulse voltammetric measurements, which indicated that the dihydroxybenzene isomers
could be separated absolutely. The sensor showed wide linear behaviors in the range of 5.0 × 10−7–2.0 × 10−4 mol L−1 for hydroquinone and catechol, 3.5 × 10−6–1.535 × 10−4 mol L−1 for resorcinol, respectively. And the detection limits of the three dihydroxybenzene isomers were 5.0 × 10−8, 2.0 × 10−7, 5.0 × 10−7 mol L−1, respectively (S/N = 3). The proposed method could be applied to the determination of dihydroxybenzene isomers in artificial wastewater and
the recovery was from 93.9% to 104.6%. 相似文献
10.
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
11.
This work reported for the first time the use of flow injection electrochemiluminescence (FI-ECL) sensor for the determination
of durabolin in an aqueous system based on CdTe quantum dot (QD) films. Aqueous CdTe colloidal solutions were prepared using
thioglycolic acid as a capping agent. Zetasizer Nano ZS (Malvern, UK) was employed to characterize the size of CdTe QDs. The
UV–vis and photoluminescence spectra of samples were systematically characterized. Indium tin oxide (ITO) slide glass was
modified with CdTe QDs by layer-by-layer self-assembly. CdTe QD films were packed into a homemade cell and used as a recognizer
of the FI-ECL sensor to determine durabolin. The intensive anodic ECL emission was obtained at a starting potential of +1.3 V
(vs. Ag/AgCl) in a carbonate bicarbonate buffer solution with a pH of 9.93 at an ITO electrode. The ECL intensity was correlated
linearly with the concentration of durabolin over the range of 1.0 × 10−8–1.0 × 10−5 g mL−1, and the detection limit was 2.5 × 10−9 g mL−1. The relative standard deviation for the determination of 1.0 × 10−6 g mL−1 durabolin was 1.04% (n = 11). This simple and sensitive sensor revealed good reproducibility for ECL analysis. As a result, the new FI-ECL sensor
had been successfully applied to the determination of durabolin in food samples. This strategy could be easily realized and
opened new avenues for the applications of QDs in ECL biosensing. 相似文献
12.
The electrode characteristics and selectivities of PVC-based thiocyanate selective polymeric membrane electrode (PME) incorporating
the newly synthesized zinc complex of 6,7:14,15-Bzo2-10,11-(4-methylbenzene)-[15]-6,8,12,14-tetraene-9,12-N2-1,5-O2 (I
1
) and zinc complex of 6,7:14,15-Bzo2-10,11-(4-methylbenzene)-[15]-6,14-diene-9,12-dimethylacrylate-9,12-N2-1,5-O2 (I
2
) are reported here. The best response was observed with the membrane having a composition of I2:PVC:o-NPOE:HTAB in the ratio of 6:33:59:2 (w/w; milligram). This electrode exhibited Nernstian slope for thiocyanate ions over working concentration range of 4.4 × 10−7 to 1.0 × 10−2 mol L−1 with detection limit of 2.2 × 10−7 mol L−1. The performance of this electrode was compared with coated graphite electrode (CGE), which showed better response characteristics
w.r.t Nernstian slope 59.0 ± 0.2 mV decade−1 activity, wide concentration range of 8.9 × 10−8 to 1.0 × 10−2 mol L−1 and detection limit of 6.7 × 10−8 mol L−1. The response time for CGE and PME was found to be 8 and 10 s, respectively. The proposed electrode (CGE) was successfully
applied to direct determination of thiocyanate in biological and environmental samples and also as indicator electrode in
potentiometric titration of SCN− ion. 相似文献
13.
Mohammad Ali Kamyabi Z. Asgari H. Hosseini Monfared 《Journal of Solid State Electrochemistry》2010,14(9):1547-1553
A carbon past electrode modified with [Mn(H2O)(N3)(NO3)(pyterpy)],
( \textpyterpy = 4¢- ( 4 - \textpyridyl ) - 2,2¢:\text6¢,\text2¢¢- \textterpyridine ) \left( {{\text{pyterpy}} = 4\prime - \left( {4 - {\text{pyridyl}}} \right) - 2,2\prime:{\text{6}}\prime,{\text{2}}\prime\prime - {\text{terpyridine}}} \right) complex have been applied to the electrocatalytic oxidation of nitrite which reduced the overpotential by about 120 mV with
obviously increasing the current response. Relative standard deviations for nitrite determination was less than 2.0%, and
nitrite can be determined in the ranges of 5.00 × 10−6 to 1.55 × 10−2 mol L−1, with a detection limit of 8 × 10−7 mol L−1. The treatment of the voltammetric data showed that it is a pure diffusion-controlled reaction, which involves one electron
in the rate-determining step. The rate constant k′, transfer coefficient α for the catalytic reaction, and diffusion coefficient of nitrite in the solution, D, were found to be 1.4 × 10−2, 0.56× 10−6, and 7.99 × 10−6 cm2 s−1, respectively. The mechanism for the interaction of nitrite with the Mn(II) complex modified carbon past electrode is proposed.
This work provides a simple and easy approach to detection of nitrite ion. The modified electrode indicated reproducible behavior,
anti-fouling properties, and stability during electrochemical experiments, making it particularly suitable for the analytical
purposes. 相似文献
14.
Ashok Kumar Singh Ravindra Pratap Singh Sameena Mehtab 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(1-2):9-15
A new polystyrene based membrane electrode of methyl substituted 6,7:13,14-dibenzo-2,4,9,11-tetraphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,6,8,11,13-hexaene
(I) with sodium tetraphenylborate (NaTPB) and dibutyl phthalate (DBP) as anion excluder and plasticizing agent was prepared and
investigated as Hg (II)-selective electrode. The electrode exhibits a Nernstian response for Hg (II) ions over a wide concentration
range of 1.0 × 10−1–8.9 × 10−6 M with a slope of 30 ± 1 mV per decade concentration. It has a response time of 10 s and can be used for at least 4 months
without any divergence in potentials. The membrane works satisfactorily in a partially non-aqueous medium up to a maximum
30% (v/v) content of methanol and ethanol. The proposed sensor revealed good selectivity over a wide variety of other cations
including alkali, alkaline earth, heavy and transition metal ions and could be used in a pH range of 2.5–5.0. Normal interferents
like Ag+, Cd2+ and Pb2+ low interfere in the working of the electrode. The electrode was successfully used in the direct determination of Hg2+ in aqueous solution. 相似文献
15.
E. Tazikeh Lemeski G. Rezaei Behbehani A. A. Saboury M. Monajjemi R. Zafar Mehrabian M. Ahmadi Golsefidi H. Rajabzadeh M. T. Baei S. Hasanzadeh 《Journal of solution chemistry》2011,40(4):575-586
The interaction of human growth hormone (hGH) with the divalent mercury ion was studied by isothermal titration calorimetry
at two temperatures of 27 °C and 37 °C in aqueous solutions. We found that there is a set of two identical and non-interacting
binding sites for Hg2+ ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 4.2 mmol⋅L−1 and −14.8 kJ⋅mol−1 at 27 °C and 5.1 mmol⋅L−1 and −14.2 kJ⋅mol−1 at 37 °C, respectively. The results obtained indicate that the stability of the protein increases due to the binding of mercury
ions using the extended solvation theory. 相似文献
16.
V. V. Sharutin V. S. Senchurin N. N. Klepikov O. K. Sharutina 《Russian Journal of Inorganic Chemistry》2009,54(2):232-238
Mercury complexes [Ph3AlkP]2+[Hg2I6]2− and [Ph3AlkP]2+[Hg4I10]2− (R = Me, Et, Pr, iso-Pr, Bu, iso-Bu) are synthesized by the reactions of triphenylalkylphosphonium Ph3AlkPI with mercury iodide in acetone with the mole ratio 1: 1 and 1: 2, respectively. According to X-ray diffraction data,
the phosphorus atom in the cations of the [Ph3(iso-Pr)P]2+[Hg2I6]2−, [Ph3BuP]2+[Hg2I6]2−, and [Ph3(iso-Pr)P]2+[Hg4I10]2− complexes has a distorted tetrahedral coordination. The CPC bond angles and P-C bond lengths vary within 107.3(4)°-112.0(4)°
and 1.774(8)-1.827(7) ?. In the [Hg2I6]2− centrosymmetric binuclear anions, the mercury atoms of tetrahedral coordination lie in two near-perpendicular Hg2I6planes. Hg4I4 eight-membered cycles of the [Hg4I10]2− tetranuclear anion are joined into polymeric chains through Hg … I coordination bonds (3.334, 3.681 &OA) due to which Hg
atoms have a trigonal bipyramidal coordination.
Original Russian Text ? V.V. Sharutin, V.S. Senchurin, N.N. Klepikov, O.K. Sharutina, 2009, published in Zhurnal Neorganicheskoi
Khimii, 2009, Vol. 54, No. 2, pp. 267–273. 相似文献
17.
Lina Zou Yamin Li Wenjie Zhao Shusheng Zhang Baoxian Ye 《Journal of Solid State Electrochemistry》2012,16(2):505-511
In the present work, a new voltammetric sensor, Langmuir–Blodgett (LB) film of tetraoxocalix[2]arene[2]triazine (TOCT) modified
glassy carbon electrode (LBTOCT-GCE), for trace analysis of copper ion in water samples, was prepared. The morphology of LBTOCT-GCE was characterized by cyclic voltammetric method, electrochemical impedance spectroscopy, and atomic force microscope.
The recognizing mechanism of LBTOCT-GCE for copper ion in aqueous solution was discussed. Under the optimum experimental conditions, using square wave stripping
voltammetry and accumulation time of 300 s, the peak currents were linear relationship with Cu2+ concentrations in the range of 2 × 10−9 to 1 × 10−6 mol L−1, with detection limit of 1 × 10−10 mol L−1. By this method, real samples (lake water, drinking water, and city wastewater) were analyzed with satisfactory results.
In addition, the fabricated electrode exhibited a distinct advantage of simple preparation, non-toxicity, good reproducibility,
and stability. 相似文献
18.
Ying Xu Fei Wang Le Wang Fangyuan Zhao Baocheng Yang Baoxian Ye 《Journal of Solid State Electrochemistry》2012,16(4):1473-1480
A novel voltammetric sensor, based on single-walled carbon nanotubes (SWNT) dispersed in Nafion and modified glassy carbon
electrode (GCE), was fabricated and used to determine the trace amounts of dihydromyricetin (DMY). The electrochemical behavior
of DMY at this sensor was investigated in 0.1 mol L−1 sulfuric acid solutions + 0.1 mol L−1 NaCl by cyclic voltammetry and squarewave voltammetry. Compared with bare GCE, the electrode presented an excellent response
of DMY through an adsorption-controlled quasi-reversible process. Under the optimum conditions, the response peak currents
were linear relationship with the DMY concentrations in the range of 1.0 × 10−7–1.0 × 10−5 mol L−1 with a detection limit of 9 × 10−8 mol L−1. Based on this voltammetric sensor, a simple and sensitive electroanalytical method for DMY was proposed and applied to quantitative
determination of DMY in Ampelopsis grossedentata samples. In addition, the oxidation mechanism was proposed and discussed, which could be a reference for the pharmacological
action of DMY in clinical study. 相似文献
19.
Conducting polymer poly(pyrrole) (PPy) doped with Nafion was successfully used as ion-to-electron transducer in the construction
of a solid-contact Pb2+-selective polymeric membrane electrode. The Nafion dopant can effectively increase the capacitance of the conducting polymer
and improve the mechanical robustness of the coating. The transducer layer, PPy-Nafion, characterized by cyclic voltammetry
and electrochemical impedance spectroscopy, exhibits a sufficiently high bulk (redox) capacitance and fast ion and electron
transport process. The new Pb2+-selective polymeric membrane electrode, based on PPy-Nafion film as solid contact, shows stable Nernstian characteristics
in Pb(NO3)2 solution within the concentration range of 1.0 × 10−7–1.0 × 10−3 M, and the detection limit is 4.3 × 10−8 M. The potential stability of the electrode and the influence of the interfacial water layer were also evaluated by chronopotentiometry
and potentiometric water layer test, respectively. The results show that the solid-contact Pb2+-selective electrode, based on PPy-Nafion film as ion-to-electron transducer, can effectively overcome the potential drift
and reduce the water layer between the PPy-Nafion transducer layer and the ion-selective membrane. 相似文献
20.
Aline Mara B. Pires Silvia Y. Eguchi Maria Helena Andrade Santana 《Applied biochemistry and biotechnology》2010,162(8):2125-2135
This study aimed to evaluate the influence of the culture medium supplementation with mineral ions, focusing on the growth
of Streptococcus zooepidemicus as well as on the production and average molecular weight (MW) of hyaluronic acid (HA). The ions were investigated in terms
of individual absence from the totally supplemented medium (C+) or individual presence in the non-supplemented medium (C−),
where C+ and C− were used as controls. Differences between the effects were analyzed using the Tukey's test at p < 0.05. The adopted criteria considered required the ions, whose individual absence attained at 80% or less of the C+ and
their individual presence was 20% or more than the C−. The supplementation was either inhibitory or acted in synergy with
other ions, when the individual absence or presence was 20% higher than C+ or 20% lower than C−, respectively. Results showed
that the effects of C+ or C− were equal for both the production of HA and its yield from glucose. However, C+ showed to be
beneficial to cell growth while the individual absence of Na+ was beneficial to the production of HA. The highest MW of HA (7.4 × 107 Da) was observed in the individual presence of Na+ in spite of the lowest HA concentration (0.65 g.L−1). These results suggest that the quality of HA can be modulated through the mineral ion supplementation. 相似文献