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1.
Shihui Si Fenglian Ren Wen Cheng Shouzhuo Yao 《Fresenius' Journal of Analytical Chemistry》1997,357(8):1101-1105
To obtain new coatings for the preparation of piezoelectric immunosensors, the anodic polymerization of o-aminophenol (oAP),
o-phenylenediamine (oPD) and m-phenylenediamine (mPD) onto a gold-plated crystal has been studied. The possibility of immobilizing
an antibody (anti-S. paratyphi A) onto the crystal via the electropolymerized films was investigated. The poly-mPD film gave
the best results for immobilizing the antibody. With antibodies crosslinked on the poly-mPD film, a piezoelectric immuno-assay
for the detection of S. paratyphi A was proposed. The shift (ΔF=F20s−F400s, Hz) between the frequency at 20 s after the addition of sample (F20s), and that of 400 s (F400s) was used to construct a calibration graph, and shortening of the assay time was achieved. The S. paratyphi A concentration
in the range of 105–109 cells/ml can be measured by this method.
Received: 9 May 1996/Revised: 6 September 1996/Accepted: 19 September 1996 相似文献
2.
A. Merko?i A. Sastre J. L. Cortina C. Maccà 《Fresenius' Journal of Analytical Chemistry》1997,358(4):489-492
The acidity constant of di(2-ethylhexyl) thiophosphoric acid (DEHTPA) was investigated using potentiometric measurements
with a pH glass electrode. Owing to the low solubility of DEHTPA in pure water, its concentration and acidity constants were
determined by linearised pH-metric titration in 16.7% ethanol. A Ka value of (2.39±0.08)×10-4 was obtained. Quantitative determination of DEHTPA was performed by capillary zone electrophoresis (CZE) with carbonate buffer
(pH 11.0) as a background electrolyte, operating at −20 kV with direct UV detection at 210 nm. The migration time was 8.97 min
and the detection limit was 5 ppm.
Received: 2 September 1996/Revised: 19 November 1996/Accepted: 21 November 1996 相似文献
3.
Mieczysław Korolczuk 《Analytical and bioanalytical chemistry》1997,357(4):389-391
A selective and sensitive method is proposed for the determination of mercury by anodic stripping voltammetry after its preconcentration
from the gas phase. Mercury from the sample solution is reduced to elemental Hg by SnCl2 and volatilized by the bubbles of a carrier gas. The gas containing mercury vapour is dried and passed through a capillary
onto a gold coated graphite electrode. An anodic stripping voltammogram is recorded from 0.1 mol/l HClO4+3×10-3 mol/l HCl solution. The calibration curve is linear from 1×10-9 to 4×10-8 mol/l Hg(NO3)2. The absolute detection limit is 0.46 ng Hg. The relative standard deviations for 4×10-9 mol/l and 2×10-8 mol/l Hg(NO3)2 are 9.8% and 6.1%, respectively (n=5).
Received: 18 December 1995/Revised: 16 April 1996/Accepted: 20 April 1996 相似文献
4.
Adsorption of a well-characterized cationic polyacrylamide (CPAM) onto the surface of a model colloid (monodisperse polystyrene
latex with carboxylic functional groups) was studied over a wide range of pH (4–9) and KCl concentration (c
s
=10-3–0.3 M). The surface charge density of the latex particles with and without adsorbed CPAM was also measured over the same
range of electrolyte compositions. The adsorbed amount of CPAM increases with increase in c
s
and pH. The polyelectrolyte adsorption alters substantially the surface charge density of the latex particles as compared
to the polymer-free case. A large overcompensation of the surface charge by the adsorbed polyelectrolyte is established at
high c
s
and low pH. A qualitative explanation of the observed features is put forward.
Received: 3 December 1996 Accepted: 20 January 1997 相似文献
5.
Francisco Laborda María V. Vicente José M. Mir J. R. Castillo 《Analytical and bioanalytical chemistry》1997,357(7):837-843
Chromatographic effluents were on-line analyzed by Zeeman-ETAAS, using a flow-through cell placed in a graphite furnace autosampler
as interface. To obtain high sampling rates, the use of fast graphite furnace programmes was studied. Conventional programmes
of 96 s were reduced to 18 s by using hot injection (120 °C) and reducing the charring step to 2 s. The increase of the injection
volume from 20 to 60 μl lengthened the programme to 46 s. Nickel had to be added to get a comparable response for both inorganic
and organic selenium species (selenite and selenomethionine) and to reduce the interferent effect produced in presence of
the chromatographic eluent (TRIS 0.01 mol l-1, NH4NO3 0.1 mol l-1, pH 7). The optimized conditions were applied to the speciation of selenium in human erythrocyte lysates by size exclusion
LC-ETAAS. Using a high performance size exclusion column selenium could be assigned to proteins of 100 and 35 kDa. Detection
limits in the range of 1 ng (2 μg l-1 for 500 μl injection volume) were obtained for the combined technique.
Received: 9 October 1996/Revised: 8 July 1996/Accepted: 14 July 1996 相似文献
6.
The characteristics of poly(oxyethylene) hydrogenated caster oil ether (HCO-10) vesicles were studied for the standpoints
of encapsulation efficiency, stability, solubilization and permeability or barrier efficiency. The vesicles of 5% HCO-10 had
6.24% of calcein-entrapment efficiency and 240 nm of mean diameter. The stability of HCO-10 vesicle suspensions was dependent
on their concentrations. In the vesicle suspensions of 10% HCO-10 or more, both the size of the vesicles and the fluidity
of the suspensions obviously varied with incubation time, indicating that a flocculation occurred; whereas, the vesicle suspension
of 5% HCO-10 was relatively stable. The solubilization process of HCO-10 vesicles by SDS was similar to that of EggPC liposomes.
The rate constants for permeation of Cl ion and calcein were 2.46×10-3 s-1 and 5.79×10-5 s-1, respectively, suggesting that HCO-10 vesicles possessed some barrier potential for Cl ion and calcein although they were
smaller than those of liposomes. Furthermore, the efflux of the solute such as calcein from HCO-10 vesicles was maximum at
37 °C, where the vesicle membrane was presumably destabilized by dehydration of EOs in HCO-10 molecules.
Received: 7 May 1996 Accepted: 3 September 1996 相似文献
7.
I. Shimizu H. Okabayashi N. Hattori K. Taga A. Yoshino C. J. O’Connor 《Colloid and polymer science》1997,275(3):293-297
Changes in the 13C and 1H NMR chemical shifts of the silane coupling agent (3-aminopropyltri-ethoxysilane, APTS) in toluene, which were detected as
the concentration of APTS increased, have been interpreted in terms of the formation of micelles and the presence of a critical
micelle concentration (CMC) equal to ca. 0.47 mol 1-1. For the protons of the n-propyl segment, 1H NMR splitting patterns have been analyzed and conformations of the propyl segment have been discussed. Plots of relative
absorbance of the two NH2 stretch IR bands at 3324 and 3384 cm-1 against concentration provided an inflection point (corresponding to the CMC) at a value equal to 0.46 mol 1-1. Thus, consideration of the interaction of APTS with a surface must take into account the presence of both APTS aggregates
as well as APTS monomers.
Received: 16 August 1996 Accepted: 26 September 1996 相似文献
8.
Waxes were separated from needles by chloroform washing, drying and dissolving the residue in tetrahydrofuran (THF). Both
a THF solution of the wax and an aqueous solution of the Pd-Mg matrix modifier were sampled directly into the graphite tube.
The reaction conditions were optimised for the wax concentration of 45 mg ml-1 in THF and the Pd:Mg ratio of 1:1 in the matrix modifier. The atomisation and charring temperatures for As, Cd and Pb were
the same as those recommended for analysis of aqueous solutions except the charring temperature of Cd takes 200 °C lower.
The characteristic masses for As (26 pg), Cd (0.5 pg) and pb (9 pg) are also comparable to published data. The parameters
of calibration curves were identical for all three elements dissolved either in clear THF or in the wax solution. Elemental
concentrations were found to range from 0.1 to 1.0 mg g-1, increasing with needle age for As, Pb but not Cd.
Received: 20 September 1996 / Revised: 14 November 1996 / Accepted: 13 December 1996 相似文献
9.
Traces of uranium and thorium in barium(II), strontium(II) titanate ((Ba, Sr)TiO3) ferroelectric materials were determined by inductively coupled plasma mass spectrometry (ICP-MS). Samples were completely
dissolved by a mixture of 1.4% H2O2 and 1.0 mol⋅l-1 HNO3. For a complete separation of the analytes from the matrix elements, a two step separation technique involving leaching and
anion-exchange was applied. By the leaching step with HNO3 more than 90% of the matrix can be removed whereas the analytes completely remained in the solution. The anion-exchange step
was carried out on a BIO⋅RAD AG1-X8 column with a mixture of 1.0 mol⋅l-1 HF and 0.5 mol⋅l-1 HNO3 as eluent. The content of uranium and thorium was subsequently measured by ICP-MS. The detection limits (D.L.) obtained were
0.043 ng g-1 and 0.035 ng g-1 for U and Th, respectively. The reproducibility was satisfactory with a relative standard deviation of less than 3% (at the
1 ng g-1 level, n=5). The matrix concentrations in the final solution were reduced to the sub-μg ml-1 level which is in the range of the detection limits of USN-ICP-AES (ultrasonic nebulization-ICP-atomic emission spectroscopy).
The method was successfully applied to the determination of uranium and thorium in three synthetic (Ba, Sr)TiO3 samples spiked with the analytes at levels of 1, 5 and 10 ng g-1 and three (Ba, Sr)TiO3 ferroelectric samples containing sub-ng g-1 levels of the analytes.
Received: 26 February 1996/Revised: 28 May 1996/Accepted: 5 June 1996 相似文献
10.
Traces of uranium and thorium in barium(II), strontium(II) titanate ((Ba, Sr)TiO3) ferroelectric materials were determined by inductively coupled plasma mass spectrometry (ICP-MS). Samples were completely
dissolved by a mixture of 1.4% H2O2 and 1.0 mol⋅l-1 HNO3. For a complete separation of the analytes from the matrix elements, a two step separation technique involving leaching and
anion-exchange was applied. By the leaching step with HNO3 more than 90% of the matrix can be removed whereas the analytes completely remained in the solution. The anion-exchange step
was carried out on a BIO⋅RAD AG1-X8 column with a mixture of 1.0 mol⋅l-1 HF and 0.5 mol⋅l-1 HNO3 as eluent. The content of uranium and thorium was subsequently measured by ICP-MS. The detection limits (D.L.) obtained were
0.043 ng g-1 and 0.035 ng g-1 for U and Th, respectively. The reproducibility was satisfactory with a relative standard deviation of less than 3% (at the
1 ng g-1 level, n=5). The matrix concentrations in the final solution were reduced to the sub-μg ml-1 level which is in the range of the detection limits of USN-ICP-AES (ultrasonic nebulization-ICP-atomic emission spectroscopy).
The method was successfully applied to the determination of uranium and thorium in three synthetic (Ba, Sr)TiO3 samples spiked with the analytes at levels of 1, 5 and 10 ng g-1 and three (Ba, Sr)TiO3 ferroelectric samples containing sub-ng g-1 levels of the analytes.
Received: 26 February 1996/Revised: 28 May 1996/Accepted: 5 June 1996 相似文献
11.
Determination of trace elements in AR grade alkali salts after preconcentration by column solid-phase extraction on TiO2 (anatase) 总被引:1,自引:0,他引:1
Column solid-phase extraction using TiO2 (anatase) as a solid sorbent was applied to preconcentrate traces of Cd, Co, Cu, Fe, Mn, Ni and Pb from AR grade alkali salts
prior to their measurements by atomic absorption spectrometry (AAS). Multi-element preconcentration was achieved from NaCl, KCl,
KNO3, NaNO3, CH3COONa, NaHCO3 and Na2CO3 solutions, whereas the sorption of trace elements from phosphates and sulfates is not quantitative. Optimal conditions (recoveries
of the analytes >95%) for solid-phase co-extraction of the most common heavy metal ions are proposed. The conditions for quantitative
and reproducible elution and subsequent AAS are established. A method of determination of trace elements in different salts
is proposed. It is characterized by precision, reproducibility and a high preconcentration factor. The solid-phase extraction
by TiO2, combined with ETAAS allows the determination of 0.1 ng g-1 Cd, 2 ng g-1 Co, 1 ng g-1 Cu and Ni, 0.5 ng g-1 Mn and 0.4 ng g-1 Pb.
Received: 1 April 1996/Revised: 24 June 1996/Accepted: 9 July 1996 相似文献
12.
This study concerns the detection of natural steroid hormones in hair of cattle. Estradiol (E2) and testosterone (T) were chosen as representatives of estrogens and androgens. In particular, the influence of age, sex
and hair pigmentation on the steroid concentrations was investigated. Samples were obtained from numerous steers, cows, bulls,
and female and male calves. The extraction procedure for E2 and T from hair comprised liquid-liquid and solid-phase extraction and was followed by an essential high-performance liquid
chromatography (HPLC) step for further purification of the extracts. Final quantification was performed with specific enzyme
immunoassays (EIA). Lower E2-concentrations were detected in the hair of some steers, cows, and bulls (approximately 1 ng/g), in several of these hair
samples the concentrations of E2 were below the limit of detection. Testosterone was measured in the hair of steers (approximately 3 ng/g), cows (approximately
6 ng/g), and bulls (in average 15 ng/g). There was a significant difference in the testosterone concentrations of white (approximately
8 ng/g) and of black hair (approximately 33 ng/g) of bulls. In hair from all male and female calves, E2 and T were measured. The concentrations amounted approximately to 9 ng E2/g and 3 ng T/g for female calves and to 5 ng E2/g and 7 ng T/g for male calves. There was no significant influence of sex or hair colour on the steroid concentrations in
hair of calves. The results suggest that the method is a powerful means to detect natural steroid hormones in hair of animal
origin.
Received: 2 August 1996/Revised: 30 August 1996/Accepted: 5 September 1996 相似文献
13.
This study concerns the detection of natural steroid hormones in hair of cattle. Estradiol (E2) and testosterone (T) were chosen as representatives of estrogens and androgens. In particular, the influence of age, sex
and hair pigmentation on the steroid concentrations was investigated. Samples were obtained from numerous steers, cows, bulls,
and female and male calves. The extraction procedure for E2 and T from hair comprised liquid-liquid and solid-phase extraction and was followed by an essential high-performance liquid
chromatography (HPLC) step for further purification of the extracts. Final quantification was performed with specific enzyme
immunoassays (EIA). Lower E2-concentrations were detected in the hair of some steers, cows, and bulls (approximately 1 ng/g), in several of these hair
samples the concentrations of E2 were below the limit of detection. Testosterone was measured in the hair of steers (approximately 3 ng/g), cows (approximately
6 ng/g), and bulls (in average 15 ng/g). There was a significant difference in the testosterone concentrations of white (approximately
8 ng/g) and of black hair (approximately 33 ng/g) of bulls. In hair from all male and female calves, E2 and T were measured. The concentrations amounted approximately to 9 ng E2/g and 3 ng T/g for female calves and to 5 ng E2/g and 7 ng T/g for male calves. There was no significant influence of sex or hair colour on the steroid concentrations in
hair of calves. The results suggest that the method is a powerful means to detect natural steroid hormones in hair of animal
origin.
Received: 2 August 1996/Revised: 30 August 1996/Accepted: 5 September 1996 相似文献
14.
Dong-yuan Wang Y. Zhao Jin-gou Xu Xiang-qun Guo 《Fresenius' Journal of Analytical Chemistry》1997,358(4):514-518
A sensitive method using fluorescence quenching for the determination of nucleotides (ATP, ADP, AMP, CTP, UTP) and polynucleotides[poly(A),
poly(I), poly(U)] is proposed. It is based on the ability of nucleotides and polynucleotides to inhibit the formation of a
strongly fluorescent complex of Tb3+ ion with Tiron. The possibilities of spectrofluorimetric measurements of these systems were studied under optimal conditions
(pH 6.9 in hexamethylene tetramine-HCl buffer, 1.2×10-6 mol/L of Tb3+, 4.0×10-6 mol/L of Tiron, λex=317 nm, λem=546 nm). The results showed that the Tb3+-Tiron complex could be used as a fluorescence test for the phosphate moieties of nucleotides and polynucleotides. The detection
limits are 0.3, 1.2, 3.7, 0.2, 0.3, 1.1, 0.6 and 0.9 ng/mL for ATP, ADP, AMP, CTP, UTP, poly(A), poly(I), and poly(U), respectively.
The relative standard deviations (6 replicates) are within 4.0% in the middle of the linear range. The fluorescence quenching
mechanism of these systems is also discussed.
Received: 16 July 1996 / Revised: 13 November 1996 / Accepted: 13 November 1996 相似文献
15.
Sri Juari Santosa S. Tanaka Kazuo Yamanaka 《Fresenius' Journal of Analytical Chemistry》1997,357(8):1122-1127
A sensitive method has been developed for the sequential determination of V, Mn, Fe, Co, Ni, Cu, Zn, Mo and Sb in sea water
using inductively coupled plasma mass spectrometry (ICP-MS) after electrothermal vaporization of their dithiocarbamate complexes
in methyl isobutyl ketone (MIBK). After complexion with sodium diethyldithiocarbamate (NaDDTC), all trace analyte elements
were simultaneously separated from sea water matrix and concentrated 20 fold in a single extract of MIBK, followed by introduction
of 10 μL of the extract into argon plasma using a pyrolytic graphite rod electrothermal vaporizer (ETV). Sensitivity enhancement
due to chemical modification using a mixed modifier of Pd(NO3)2-Mg(NO3)2 was observed for all the elements. The limits of detection ranged from 2 ng/L for Co to 329 ng/L for V. For replicate determinations
of the elements in sea water, the repeatability was within 10% (as a coefficient variation), except for V (12.8%). The recovery
test performed on a sea water sample resulted in a range value from 87% for Sb to 119% for V. The method has been successfully
applied to sea water samples collected from the surface to the depth of 5000 m at a sampling station in the northwest Pacific
Ocean.
Received: 1 July 1996/Revised: 24 September 1996/Accepted: 25 September 1996 相似文献
16.
Sol and Gel state properties of aqueous gelatin solutions of concentrations 4%, 6%, 8% and 10% (w/v) have been investigated
through dielectric relaxation studies done at various temperatures in the range T=20–60 °C carried out over a frequency range f=20 Hz–10 MHz and no relaxation of any nature was observed. The sharp transition observed at the gelation temperature T
gel provided an excellent matching with the same measured through differential scanning calorimetry (DSC). The capacitance (C
p) values above f=100 kHz became increasingly negative as the gel was melted to the sol state. However, in the gel state C
p was found to be almost independent of temperature for frequencies above 100 kHz. At frequencies lower than 10 kHz, C
p measured was ∼105 F, implying pronounced interfacial polarization either due to electro-chemical reaction or because of ions getting trapped
at some interface within the bulk.
Received: 10 February 1997 Accepted: 2 September 1997 相似文献
17.
Sri Juari Santosa S. Tanaka Kazuo Yamanaka 《Analytical and bioanalytical chemistry》1997,357(8):1122-1127
A sensitive method has been developed for the sequential determination of V, Mn, Fe, Co, Ni, Cu, Zn, Mo and Sb in sea water
using inductively coupled plasma mass spectrometry (ICP-MS) after electrothermal vaporization of their dithiocarbamate complexes
in methyl isobutyl ketone (MIBK). After complexion with sodium diethyldithiocarbamate (NaDDTC), all trace analyte elements
were simultaneously separated from sea water matrix and concentrated 20 fold in a single extract of MIBK, followed by introduction
of 10 μL of the extract into argon plasma using a pyrolytic graphite rod electrothermal vaporizer (ETV). Sensitivity enhancement
due to chemical modification using a mixed modifier of Pd(NO3)2-Mg(NO3)2 was observed for all the elements. The limits of detection ranged from 2 ng/L for Co to 329 ng/L for V. For replicate determinations
of the elements in sea water, the repeatability was within 10% (as a coefficient variation), except for V (12.8%). The recovery
test performed on a sea water sample resulted in a range value from 87% for Sb to 119% for V. The method has been successfully
applied to sea water samples collected from the surface to the depth of 5000 m at a sampling station in the northwest Pacific
Ocean.
Received: 1 July 1996/Revised: 24 September 1996/Accepted: 25 September 1996 相似文献
18.
P. Hoffmann V. K. Karandashev T. Sinner H. M. Ortner 《Analytical and bioanalytical chemistry》1997,357(8):1142-1148
Data are reported for a first measurement campaign for a great number of cations (the range of concentrations for main components
is given in ng/mL: Na:<70–880; Mg: 12–160; Al:<7–120; K: 200–1600; NH4
+: 2500–9000; Ca: 300–2500; Fe:<140–1200; Zn: 20–320) and anions (HCOO-: 100–1800; CH3COO-: 400–14500; C2O2-
4: <100–460; NO-
2: <20–55; NO-
3: 660–9900; SO2-
3:<100–1150; SO4
2-: 450–19700; Cl-: 170–3200) in rain and snow samples of the Chernogolovka region 80 km northeast of the centre of Moscow. These data serve
as a first assessment of the situation of the atmosphere in this region. For the determination of fluoride, formate, acetate,
nitrite, bromide, nitrate, sulfite, and sulfate by IC, a relevant development of the method was carried out. For some metallic
cations, a critical quality control was achieved by parallel measurements with ICP-MS, TXRF, and IC. Furthermore, time resolved
measurements were performed for a rain event. Filtration experiments were undertaken to differentiate between the presence
of a series of elements and species in liquid or solid state in the collected aqueous samples.
Received: 25 July 1996 / Revised: 26 September 1996 / Accepted: 13 October 1996 相似文献
19.
A new method for determining the static permittivity (dielectric constant) of extremely thin liquid interlayers is illustrated.
A special condenser, which can be filled with a test liquid, is constructed. Both condenser plates – one planar, the other
spherically curved – are made of vitreous carbon and are supplied with a high-grade politure.
In order to adjust plate separation distances from 10 nm up to about some μm the planar plate can be easily shifted by a piezoelectric
translation stage; the plate separation is monitored by an optical system supported by displacement transducers.
The measuring frequency was kept constant at 1 MHz. Water was chosen as the test liquid. At 19.8 °C thin water layers having
thickness smaller than 0.3 μm exhibit a decrease of the dielectric constant. The experimental data are consistent with a decay
length α-1 of the order of 1 nm which in view of the underlying crude model must be regarded as approximative.
Received: 28 May 1996 Accepted: 30 September 1996 相似文献
20.
P. Hoffmann V. K. Karandashev T. Sinner H. M. Ortner 《Fresenius' Journal of Analytical Chemistry》1997,357(8):1142-1148
Data are reported for a first measurement campaign for a great number of cations (the range of concentrations for main components
is given in ng/mL: Na:<70–880; Mg: 12–160; Al:<7–120; K: 200–1600; NH4
+: 2500–9000; Ca: 300–2500; Fe:<140–1200; Zn: 20–320) and anions (HCOO-: 100–1800; CH3COO-: 400–14500; C2O2-
4: <100–460; NO-
2: <20–55; NO-
3: 660–9900; SO2-
3:<100–1150; SO4
2-: 450–19700; Cl-: 170–3200) in rain and snow samples of the Chernogolovka region 80 km northeast of the centre of Moscow. These data serve
as a first assessment of the situation of the atmosphere in this region. For the determination of fluoride, formate, acetate,
nitrite, bromide, nitrate, sulfite, and sulfate by IC, a relevant development of the method was carried out. For some metallic
cations, a critical quality control was achieved by parallel measurements with ICP-MS, TXRF, and IC. Furthermore, time resolved
measurements were performed for a rain event. Filtration experiments were undertaken to differentiate between the presence
of a series of elements and species in liquid or solid state in the collected aqueous samples.
Received: 25 July 1996 / Revised: 26 September 1996 / Accepted: 13 October 1996 相似文献