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1.
E. Bobrowska-Grzesik Andrzej M. Grossman 《Analytical and bioanalytical chemistry》1997,357(7):1000-1001
Second order derivative spectrophotometry was applied to the determination of nitrite and nitrate ions in bath solutions
for alkaline black-oxidation of steel. The measurements were directly taken after dilution of the samples at λ = 336.4 nm
for NO3
– and λ = 390 nm for NO2
–. The method was checked on artificial mixtures and applied to real samples containing approximately 5.5% NaNO2 and 6% NaNO3. The results agree well with those obtained by the standard manganometric method.
Received: 8 July 1996 / Revised: 24 September 1996 / Accepted: 28 September 1996 相似文献
2.
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
3.
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
4.
P. G. Verschuren Juul L. van der Baan Rolf Blaauw Dirk de Beer Johannes C. van den Heuvel 《Fresenius' Journal of Analytical Chemistry》1999,364(6):595-598
The synthesis of iodo{2,2′-[1,2-octadecanediylbis(nitrilomethylidyne)]diphenolato}cobalt is described. Liquid membrane microelectrodes
based on this carrier exhibit Nernstian behaviour with a selectivity sequence according to the Hofmeister series: I– > NO3
– > NO2
– > Cl– > HCO3
– > AcO–. The selectivity coefficient of nitrate over nitrite and chloride amounts to –1.6 and –2.7, respectively. The detection limit
for nitrate in water amounts to 10–5.2 mol/L. A nitrate profile measured in a nitrifying biofilm is presented as a practical application.
Received: 11 November 1998 / Revised: 22 January 1999 / Accepted: 27 January 1999 相似文献
5.
Jaw-Cherng Hsu Chin-Hung Chang C.-Y. Liu 《Analytical and bioanalytical chemistry》1998,362(6):514-521
A silica based sorbent with an anion complexone polymer coating, [24]ane-N6 macrocycle, was prepared. The chelation properties of this material were investigated by elemental analysis, infrared spectra
and Voige’s method. The polymer-coated silica column (25– 40 μm, 100 × 4.6 mm i.d.) was employed for trace metal analyses.
Oxalic acid, malonic acid, succinic acid, citric acid, phthalic acid and acetic acid were used as mobile phases. Their retention
characteristics were elucidated. Oxalic acid was found to be the most effective eluent. With a mobile phase consisting of
oxalic acid (25 mM) and sodium nitrate (25 mM) at pH 4.2, the separation of copper(II), cadmium(II), cobalt(II) and zinc(II)
in sea water could be achieved. The identification of metal ions was performed at 510 nm using 4(2-pyridylazo)resorcinol (1
× 10–4 M) as post column reagent. The limits of detection were 5 × 10–7 M, 1 × 10–5 M, 3 × 10–5 M and 2 × 10–6 M for copper(II), cadmium(II), cobalt(II) and zinc(II) based on three times the standard deviation of the response for the
lowest concentration (n = 5) in the chromatogram with a sample volume of 50 μL. For evaluation of data reliability, oyster
tissue (NIST SRM 1566 a) was studied with the proposed system.
Received: 9 February 1998 / Revised: 15 May 1998 / Accepted: 16 June 1998 相似文献
6.
Rahmiana Zein Edison Munaf Toyohide Takeuchi Tomoo Miwa 《Analytical and bioanalytical chemistry》1997,357(4):466-468
Microcolumn ion chromatography of inorganic anions has been studied using octadecylsilica immobilized with bovine serum albumin
as a stationary phase. The analytes were monitored with a conductivity detector. The detection limits for chloride, nitrate
and thiocyanate at S/N = 3 were 0.8, 1.0 and 3.0 μmol L–1, respectively. The present system was applied to the determination of inorganic anions in tap water and serum samples.
Received: 29 May 1996 / Accepted: 12 August 1996 相似文献
7.
A new simple, rapid and sensitive spectrophotometric flow injection method for the determination of trace iodide is described
based on an ion associate of iodate (IO3
–) with 2- (3,5-dibromo-2-pyridylazo)-5-diethylamino-phenol (3,5-Br2-PADAP) and thiocyanate (SCN–). In a strongly acidic medium, this unstable violet product was formed with an absorption maximum at 605 nm. Flow injection
is an ideal method to reproducibly monitor the transient signal. Various parameters were optimized using the Super Modified
Controlled Weighted Centroid Simplex Method (SMCWC). Under the optimum experimental conditions, iodide could be determined
in the range of 1.00 × 10–6 and 2.4 × 10–5 mol l–1. The correlation coefficient of the calibration curve is 0.9991. With a sampling frequency of 80 h–1, the detection limit for iodide is 5.0 × 10–7 mol l–1. The proposed method has been applied to the determination of trace iodide after oxidizing I– in table salt or laver to IO3
–. In addition, the mechanisms of the ion association reaction was studied.
Received: 15 August 1996 / Revised: 10 October 1996 / Accepted: 16 October 1996 相似文献
8.
H. Seco-Lago J. Pérez-Iglesias J. M. Fernández-Solís J. M. Castro-Romero V. González-Rodríguez 《Analytical and bioanalytical chemistry》1997,357(4):464-466
The application of derivative spectrophotometry to the simultaneous determination of chromium (III) and copper (II) with
MEDTA is described. The procedure is suitable for concentrations of 0.40–2.60 mg ml–1 of chromium (III) and 0.15–0.60 mg ml–1 of copper (II). The main interferences, both anionic and cationic, are easily eliminated. The method was applied to different
aqueous matrices. It was compared with an atomic absorption method and good results were obtained.
Received: 12 June 1996 / Revised: 30 July 1996 / Accepted: 2 August 1996 相似文献
9.
Je An Lee Jun Young Lee Myung Hyun Ryou Gi-Beom Han Je-Nam Lee Dong-Jin Lee Jung-Ki Park Yong Min Lee 《Journal of Solid State Electrochemistry》2011,15(4):753-757
Anion receptor-coated separators were prepared by coating poly(ethylene glycol) borate ester (PEGB) as an anion receptor and
poly(vinyl acetate) (PVAc) as a good adhesive material towards electrodes onto microporous polyethylene (PE) separators. Gel
polymer electrolytes were fabricated by soaking them in an liquid electrolyte, 1 M LiPF6 in EC/DEC/PC (30/65/5, wt.%). As the weight ratio of PEGB to PVAc in a coating layer increased, gel polymer electrolytes
showed higher cationic conductivity and electrochemical stability. The cationic conductivity and electrochemical stability
of the gel polymer electrolyte based on coated separator with PVAc/PEGB (2/5, weight ratio) could reach 2.8 × 10–4 S cm–1 and 4.8 V, respectively. Lithium-ion polymer cells (LiCoO2/graphite) based on gel polymer electrolytes with and without PEGB were assembled, and their electrochemical performances
were evaluated. 相似文献
10.
S. Z. Qureshi M. I. H. Helaleh N. Rahman R. M. A. Q. Jamhour 《Analytical and bioanalytical chemistry》1997,357(7):1005-1007
A spectrophotometric determination of trimethoprim is described based on the reaction of its amine group with persulfate
which acts as a strong oxidizing agent in alkaline media. The reaction produces a stable yellow colored compound after heating
in a boiling water bath for 30 min. At λmax 355 nm, Beer’s law is obeyed in the concentration range 10–60 μg ml–1 with a molar absorptivity of 2.7 × 103 l mol–1cm–1. The method is applied to formulations with sulfamethoxazole.
Received: 30 July 1996 / Revised: 16 October 1996 / Accepted: 22 October 1996 相似文献
11.
Sérgio L. C. Ferreira Marcus L. S. F. Bandeira Valfredo A. Lemos Hilda C. dos Santos A. C. Spinola Costa Djane S. de Jesus 《Fresenius' Journal of Analytical Chemistry》1997,357(8):1174-1178
A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic
acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP).
The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 105 l mole–1cm–1 and 5.69 × 104 l mole–1cm–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml–1, a calibration sensitivity of 0.744 ml μg–1 at 560 nm and 0.323 ml μg–1 at 748 nm, and a detection limit of 15 ng ml–1 and 44 ng ml–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations.
The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The
Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system.
Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996 相似文献
12.
Sérgio L. C. Ferreira Marcus L. S. F. Bandeira Valfredo A. Lemos Hilda C. dos Santos A. C. Spinola Costa Djane S. de Jesus 《Analytical and bioanalytical chemistry》1997,357(8):1174-1178
A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic
acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP).
The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 105 l mole–1cm–1 and 5.69 × 104 l mole–1cm–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml–1, a calibration sensitivity of 0.744 ml μg–1 at 560 nm and 0.323 ml μg–1 at 748 nm, and a detection limit of 15 ng ml–1 and 44 ng ml–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations.
The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The
Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system.
Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996 相似文献
13.
Victor Pupkevich Vassili Glibin Dimitre Karamanev 《Journal of Solid State Electrochemistry》2007,11(10):1429-1434
Recently, rejuvenated interest to fuel cells has posed a number of problems regarding the polymer electrolyte membrane properties
and their behaviour in different electrolyte solutions. This work was dedicated to study the conductivity of H+-, Fe3+- and mixed H+/Fe3+-forms of cation exchange membranes Neosepta CMS, Nafion 112, 115 and 117 and Selemion HSF under conditions similar to these
in the Fe3+/Fe2+–H2/H+ fuel cell in the range of current densities 0–90 mA/cm2. It was found that the conductivities of these membranes in 1.09 M H2SO4 solution decrease in the following order: Selemion HSF › Nafion 117 ≈ Nafion 115 ≈ Neosepta CMS › Nafion 112. Conductivities
of perfluorinated membranes were discussed in terms of Hsu and Gierke percolation theory [20]. The Fe3+-forms of Nafion membranes studied displayed a monotonous decline in the resistance when current increased, which is a manifestation
of gradual conversion of the Fe3+-form into H+-form of these membranes. Unlike the Nafion membranes, the Fe3+-forms of Neosepta CMS and Selemion HSF membranes exhibited a sharp jump of resistance at relatively high current densities
(more than 70 mA/cm2) that is most probably a result of concentration polarization. 相似文献
14.
The interaction between anionic surfactants and polyvinylpyrrolidone (PVP) are investigated using 13C NMR, ESR spectroscopy and surface tension measurements at the air/water interface. The behavior of single-chained surfactant,
sodium dodecyl sulphonate (AS), is compared with that of the double-chained surfactant, sodium bis(2-ethylhexyl) phosphate
(NaDEHP). The results showed that a surfactant–polymer complex of “necklace and head structure” is formed in AS aqueous solutions
in the presence of PVP due to the hydrophobic interaction between PVP and AS. The AS micelles nucleate on the polymer hydrophobic
sites, and the mobility of the AS head groups is not affected. But, for NaDEHP surfactant, it was found that PVP is little
effective in influencing the monomer–micelle equilibrium and no surfactant– polymer complex formed in the NaDEHP aqueous solution.
Received: 8 May 1996 Accepted: 14 August 1997 相似文献
15.
R. D. Bautista A. I. Jiménez F. Jiménez J. J. Arias 《Analytical and bioanalytical chemistry》1997,357(4):449-456
The performance of two multivariate calibration methods, multiple linear regression (MULTI3) and partial least-square regression
(PLS-2), for the resolution of the ternary mixtures of acetylsalicylic acid-caffeine-codeine and acetaminophen-caffeine-codeine
is compared. The methodologies were checked by applying them to the analysis of two sets of laboratory-prepared mixtures over
the concentration ranges 13.0–19.0, 1.00–3.00 and 0.20–1.00 μg · ml–1 for acetylsalicylic acid-caffeine-codeine and 12.0–22.0, 0.40–2.00 and 0.20–1.00 μg · ml–1 for acetamimophen-caffeine-codeine, respectively. While the results provided by MULTI3 were unacceptable in the majority
of the cases, those obtained by PLS-2 were quite good with considerably diminished errors, as a result of calibration and/or
checking with MULTI3, taking no account of potential interactions between analytes. It was shown that it is possible by using
PLS-2 to resolve complex mixtures of analytes in a highly disparate proportion, even when they have overlapping signals. The
proposed method was successfully demonstrated for pharmaceutical tablets.
Received: 7 February 1996 / Revised: 22 April 1996 / Accepted: 28 April 1996 相似文献
16.
Jason C. Sanchez Antonio G. DiPasquale Anthony A. Mrse William C. Trogler 《Analytical and bioanalytical chemistry》2009,395(2):387-392
The high sensitivity of silole- and silafluorene-containing polymers for detecting organic nitro, nitrate, and nitramine explosives
cannot be solely attributed to favorable analyte–polymer hydrophobic interactions and amplified fluorescence quenching due
to delocalization along the polymer chain. The Lewis acidity of silicon in conjugated poly(silafluorene-vinylene)s is shown
to be important. This was established by examining the 29Si NMR chemical shifts (Δ) for the model trimer fragment of the polymer CH3–silafluorene–(trans-C2H2)–silafluorene–(trans-C2H2)–silafluorene–CH3. The peripheral and central silicon resonances are up-field from a TMS reference at −9.50 and −18.9 ppm, respectively. Both
resonances shift down-field in the presence of donor analytes and the observed shifts (0 to 1 ppm) correlate with the basicity
of a variety of added Lewis bases, including TNT. The most basic analyte studied was acetonitrile and an association constant
(K
a) of 0.12 M−1 was calculated its binding to the peripheral silicon centers using the Scatchard method. Spin-lattice relaxation times (T
1) of 5.86(3) and 4.83(4) s were measured for the methyl protons of acetonitrile in benzene-d
6 at 20 °C in the absence and presence of the silafluorene trimer, respectively. The significant change in T
1 values further supports a binding event between acetonitrile and the silafluorene trimer. These studies as well as significant
changes and shifts observed in the characteristic UV–Vis absorption of the silafluorene group support an important role for
the Lewis acid character of Si in polymer sensors that incorporate strained silacycles. The nitro groups of high explosives
may act as weak Lewis-base donors to silacycles. This provides a donor–acceptor interaction that may be crucial for orienting
the explosive analyte in the polymer film to provide an efficient pathway for inner-sphere electron transfer during the electron-transfer
quenching process.
Figure
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
A new procedure for the field characterization of the available amount of molybdenum in soil extract is described. It is
based on the preconcentration of the Mo(V)-SCN– complex into toluene solution of N-octylacetamide (OAA) and subsequent heating of the extract for ≈ 10 min at 60° C over
a water bath. The molar absorptivity of the complex is (3.50) × 104 1 mole–1 cm–1 at λmax 470 nm. The detection limit of the method is 4 ppb Mo. It provides a significantly increased tolerance limit for iron (up
to 1000 ppm) and is applicable to the field characterization of Mo in soil extracts.
Received: 29 May 1996 / Revised: 17 July 1996 / Accepted: 19 July 1996 相似文献
18.
Fourier transform infrared spectra in the wave number range 450–4500 cm-1 of poly (2-hydroxy-ethyl methacrylate) PHEMA have been studied as functions of water content in the range 38–2.6 wt% and
of temperature in the range 300–373 K. The results show changes in the intensities of the stretching frequencies of the carbonyl
band, H–O–H bending vibration and O–H stretching vibration with a change in water content and temperature. The results confirm
two types of water in the hydrogel polymer system, tightly bound water and loosely bound water. At low concentrations, water
is mainly hydrogen-bonded to the polymer and is described as tightly bound water. However, at water concentrations greater
than 18% by weight, part of the water exists in a different form and behaves as loosely bound water. For concentrations over
30%, there is some evidence that excess water behaves more loosely bound somewhat like bulk water. Infrared spectroscopic
results supplement those obtained by means of NMR by Smyth et al. and by dielectric spectroscopy. Our results also show that
some of the water continues to be hydrogen bonded to the polymer until at least a temperature of 373 K when the bulk water
should have evaporated. FTIR is found to yield greater site-specific insight into the local behaviour of water in hydrated
PHEMA.
Received: 22 August 1996 Accepted: 11 November 1996 相似文献
19.
Rheological properties of starch/bentonite gels (5.3–8.2% solids, 0–100% starch) were investigated at shear rates 0.0083–0.33 s-1 (Brookfield viscometer). Prior to these measurements the strain introduced during preparation of the gel was kept as low
as possible. Under these conditions six different types of structural units could be identified in the gel: bentonite particles
associated in a band-type structure; bands coated with starch polymers; bundles of bands interlaced and enveloped by starch
polymers (strands); individual bentonite platelets dispersed in a polymer matrix; starch polymer networks; and swollen granules.
A power-law model was fitted to the experimental viscosity data: μapp= Kγ
n-1
. In all cases n was found to be less than 0.5. Its value decreased with the ability of the structural components to reorient under applied
shear. K was found to be proportional to the compaction and/or entanglement of the structural units. These trends in K and n were further confirmed by the index of thixotropy (IT) and complex modulus of shear elasticity (G
*
) measurements.
Received: 12 August 1996 Accepted: 7 January 1997 相似文献
20.
Optimised conditions have been found for the separation of 3-carboxy-4-hydroxy-6-acetylaminoazo-benzene derivatives substituted
in the position 4′ (4′-R-CHAAB, where R=–H, –CH3, –OCH3, –Cl, –COCH3, –NO2 and –NHCOCH3) using reversed phase HPLC with a C18 chemically bonded stationary phase. Suitable mobile phases are mixtures of 0.01 mol/L
NaH2PO4 at pH 4 with methanol (1+1), 0.01 mol/L NaH2PO4 at pH 2 with acetonitrile (1+1) or 1% aqueous acetic acid with methanol (4+6). UV photometry is the most universal detection
technique and yields limits of detection around 10-6 mol/L. Direct anodic voltammetry on a glassy carbon fibre array detector yields lower limits of detection for –COCH3 derivatives and higher limits of detection for –NO2 and –NHCOCH3 derivatives. When the analytes are chemically reduced using zinc powder in acetic acid, the voltammetric detection has limits
of detection one order of magnitude lower than those obtained UV photometrically.
Received: 27 June 1996/Revised: 25 October 1996/Accepted: 3 November 1996 相似文献