共查询到20条相似文献,搜索用时 31 毫秒
1.
Y. Jiang N. Lu Feng Yu Qing Li Hongding Xu 《Analytical and bioanalytical chemistry》1999,364(8):786-787
A method for sampling and determination of hydrogen cyanide in cigarette smoke is described. Cigarette smoke is filtered
through a glass fiber filter paper, and only gaseous compounds, such as hydrogen cyanide, are collected in a dilute sodium
hydroxide solution. The cyanide is determined spectrophotometrically at 550 nm by the isonicotinic acid–pyrazolone method.
Maximum absorbance is achieved within 10 min at room temperature, and remains constant for about 20 min. Beer’s law is obeyed
in the range 0.04∼0.80 μg mL–1 cyanide, with a molar absorptivity of 3.48 × 104 L mol–1 cm–1.
Received: 30 November 1998 / Revised: 21 April 1999 / Accepted: 30 April 1999 相似文献
2.
E. Miralles R. Compa?ó M. Granados M. D. Prat 《Fresenius' Journal of Analytical Chemistry》1999,365(6):516-520
Total cyanide species are determined in a flow injection system which includes UV-photodissociation, gas-diffusion separation
and spectrofluorimetric detection. Without the irradiation step, only cyanide easily released in acid medium, i.e. labile cyanide, is determined. Cyanide diffuses through a microporous PTFE membrane from an acid donor stream to a sodium
hydroxide acceptor stream. Then, the transferred cyanide reacts with ?o-phthalaldehyde and glycine to form a highly fluorescent isoindole derivative. Complete cyanide recoveries were obtained for
the most important metal cyanide complexes found in environmental samples, excepting cobaltocyanide. The sampling frequency
for total cyanide was 4 samples h–1 and the detection limit was 0.4 μg L–1. Recoveries of total cyanide from river water obtained with this method are about 90% of those obtained with APHA Method 4500-CN C for total cyanide.
Received: 10 February 1999 / Revised: 7 May 1999 / Accepted: 13 May 1999 相似文献
3.
S. Pozdniakova R. Ragauskas A. Dikčius A. Padarauskas 《Analytical and bioanalytical chemistry》1999,363(1):124-125
A capillary electrophoretic method for the determination of EDTA has been developed. EDTA was converted to Ni(II)-EDTA prior
to separation, separated from Fe(III)-EDTA, thiosulphate, bromide and polythionates using a fused silica capillary (57 cm
× 75 μm I.D.) filled with a borate buffer (50 mmol L–1; pH 8.5; applied voltage, 30 kV) and detected at 214 nm. The separation time is about 6 min. The detection limit achieved
is 2 × 10–6 mol L–1 for EDTA. This method was applied for the determination of free EDTA in used fixing solutions.
Received: 27 February 1998 / Revised: 28 April 1998 / Accepted: 20 May 1998 相似文献
4.
S. Pozdniakova R. Ragauskas A. Dikius A. Padarauskas 《Fresenius' Journal of Analytical Chemistry》1999,363(1):124-125
A capillary electrophoretic method for the determination of EDTA has been developed. EDTA was converted to Ni(II)-EDTA prior
to separation, separated from Fe(III)-EDTA, thiosulphate, bromide and polythionates using a fused silica capillary (57 cm
× 75 μm I.D.) filled with a borate buffer (50 mmol L–1; pH 8.5; applied voltage, 30 kV) and detected at 214 nm. The separation time is about 6 min. The detection limit achieved
is 2 × 10–6 mol L–1 for EDTA. This method was applied for the determination of free EDTA in used fixing solutions.
Received: 27 February 1998 / Revised: 28 April 1998 / Accepted: 20 May 1998 相似文献
5.
B. Wiedemann G. R?dlinger H. Ch. Alt K. G. Heumann K. Bethge 《Fresenius' Journal of Analytical Chemistry》1999,364(8):772-776
The residual or doped element concentration [E] in GaAs measured by SSMS is only accurate with respect to the relative sensitivity
coefficient RSCE. For a trace element concentration, the RSCE = [E]SSMS/[E]TRUE is set to unity, if no reference material or method is available to approximate the concentration to the true value. For
boron a relative sensitivity coefficient of RSCB = 0.94 ± 0.08 was obtained using TI-IDMS as a reference method. RSCN = 1 is used for nitrogen determinations. A boron and nitrogen detection limit of 4.4 × 1013 cm–3 is achieved. SSMS was used as reference method to calibrate the FTIR factor fE = [E] / Iα due to the integrated local vibrational mode absorption Iα of atomic boron and nitrogen in GaAs. A factor of fB = (12.0 × 2.7) × 1016 cm–1 (517 cm–1) and fN = (7.4 ± 0.1) × 1015 cm–1 (472 cm–1) was obtained for a boron and nine nitrogen containing GaAs samples at 77 K and 10 K, respectively.
Received: 15 December 1998 / Revised: 8 April 1999 / Accepted: 13 April 1999 相似文献
6.
B. Wiedemann G. Rädlinger H. Ch. Alt K. G. Heumann K. Bethge 《Analytical and bioanalytical chemistry》1999,364(8):772-776
The residual or doped element concentration [E] in GaAs measured by SSMS is only accurate with respect to the relative sensitivity
coefficient RSCE. For a trace element concentration, the RSCE = [E]SSMS/[E]TRUE is set to unity, if no reference material or method is available to approximate the concentration to the true value. For
boron a relative sensitivity coefficient of RSCB = 0.94 ± 0.08 was obtained using TI-IDMS as a reference method. RSCN = 1 is used for nitrogen determinations. A boron and nitrogen detection limit of 4.4 × 1013 cm–3 is achieved. SSMS was used as reference method to calibrate the FTIR factor fE = [E] / Iα due to the integrated local vibrational mode absorption Iα of atomic boron and nitrogen in GaAs. A factor of fB = (12.0 × 2.7) × 1016 cm–1 (517 cm–1) and fN = (7.4 ± 0.1) × 1015 cm–1 (472 cm–1) was obtained for a boron and nine nitrogen containing GaAs samples at 77 K and 10 K, respectively.
Received: 15 December 1998 / Revised: 8 April 1999 / Accepted: 13 April 1999 相似文献
7.
A direct chemiluminescence method for the determination of nucleic acids has been developed based on the enhancement of
nucleic acids on the chemiluminescence light emission of the reaction between Ru(phen)3
2+(phen = 1,10-phenanthroline) and Ce(IV). Under the optimum conditions, the calibration graphs are linear in the range of 5.0
× 10–8–5.0 × 10–5 g/mL for calf thymus DNA, 8.0 × 10–8–5.0 × 10–5 g/mL for fish sperm DNA and 1.0 × 10–7–3.0 × 10–5 g/mL for yeast RNA, respectively. The limits of detection are 1.0 × 10–8 g/mL for calf thymus DNA, 3.1 × 10–8 g/mL for fish sperm DNA and 5.2 × 10–8 g/mL for yeast RNA, respectively. The final procedure allows the successful determination of calf thymus DNA, fish sperm
DNA and yeast RNA in six synthetic samples. This method is simple, rapid and specific.
Received: 22 January 1999 / Revised: 29 April 1999 / Accepted: 3 May 1999 相似文献
8.
M. R. Ganjali Tahereh Poursaberi Fatemeh Basiripour Masoud Salavati-Niassari Mohammad Yousefi Mojtaba Shamsipur 《Analytical and bioanalytical chemistry》2001,370(8):1091-1095
A PVC membrane electrode based on a cadmium–salen (N,N′-bis-salicylidene-1,2ethylenediamine) complex as an anion carrier is described. The electrode has an anti-Hofmeister selectivity
sequence with a preference for thiocyanate at pH 1.5–11.0. It has a linear response to thiocyanate from 1.0 × 10–6 to 1.0 × 10–1 mol L–1 with a slope of 59.1 ± 0.2 mV per decade, and a detection limit of 7 × 10–7 mol L–1. This electrode has high selectivity for thiocyanate relative to many common organic and inorganic anions. The proposed sensor
has a fast response time of approximately 15 s. It was applied to the determination of thiocyanate in a milk sample.
Received: 1 December 2000 / Revised: 19 April 2001 / Accepted: 30 April 2001 相似文献
9.
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
10.
B. Wiedemann H. Ch. Alt J. D. Meyer R. W. Michelmann K. Bethge 《Fresenius' Journal of Analytical Chemistry》1999,364(8):768-771
An appropriate calibration of the local vibrational mode absorption of carbon in GaAs on arsenic sublattice sites, CAs, at wavenumber 582 cm–1 (77 K) is presented. Integrated absorptions Iα of CAs, the dominant acceptor in undoped monocrystalline GaAs, and calibrated carbon concentrations [C] were measured in single
crystals using the methods FTIR and SSMS, respectively. A calibration factor fC = [C]/Iα of (7.1 ± 0.2) × 1015 cm–1 has been derived for 2.8 × 1014 cm–3≤ [C] ≤ 1.4 × 1016 cm–3 above a SSMS detection limit of [C]DL≅ 1.4 × 1013 cm–3. The carbon concentrations [C] = [C]SSMS/RSCC were calibrated with a relative sensitivity coefficient RSCC = [C]SSMS/ [C]TRUE of 3.1 ± 0.1. CPAA was used as a reference method for [C]CPAA≥ 4.4 × 1014 cm–3 in order to approximate [C]TRUE.
Received: 15 December 1998 / Revised: 8 April 1999 / Accepted: 13 April 1999 相似文献
11.
A. Ruiz Medina M. L. Fernández de Córdova A. Molina Díaz 《Analytical and bioanalytical chemistry》1999,365(7):619-624
A new, sensitive and very simple spectrofluorimetric biparameter sensor is described for the determination of salicylamide
and/or salicylic acid in pharmaceutical preparations. The method integrates the transitory retention and fluorescence detection
of both compounds on Sephadex QAE A-25 resin packed into a conventional flow-through cell. A monochannel manifold with two
alternative carriers is used. At pH 2.0 (first carrier) salicylic acid is selectively retained on the solid support and after
developing the analytical signal it is desorbed. At pH 11.0 (second carrier) both salicylic acid and salicylamide are simultaneously
and transitorily retained on the solid, the analytical signal now corresponding to both analytes. The monochromators were
tuned at 260 (excitation) and 415 (emission) nm, respectively. The calibration graph for salicylamide is linear over the range
0.01 to 0.32 μg mL–1 and for salicylic acid from 0.04 to 1.0 μg mL–1 in the presence of each other. The relative standard deviation and the sampling frequency for the determination of salicylamide
(0.20 μg mL–1) and salicylic acid (0.50 μg mL–1) were 1.1% and 35 h–1, and 0.9% and 45 h–1, respectively. Good results on application to individual determination or mixture resolution in pharmaceutical samples testify
to the usefulness of the proposed sensor.
Received: 20 April 1999 / Revised: 7 June 1999 / Accepted: 12 June 1999 相似文献
12.
Michael Winklmair Andreas J. Schuetz M. G. Weller Reinhard Niessner 《Fresenius' Journal of Analytical Chemistry》1999,363(7):619-624
A new, sensitive and very simple spectrofluorimetric biparameter sensor is described for the determination of salicylamide
and/or salicylic acid in pharmaceutical preparations. The method integrates the transitory retention and fluorescence detection
of both compounds on Sephadex QAE A-25 resin packed into a conventional flow-through cell. A monochannel manifold with two
alternative carriers is used. At pH 2.0 (first carrier) salicylic acid is selectively retained on the solid support and after
developing the analytical signal it is desorbed. At pH 11.0 (second carrier) both salicylic acid and salicylamide are simultaneously
and transitorily retained on the solid, the analytical signal now corresponding to both analytes. The monochromators were
tuned at 260 (excitation) and 415 (emission) nm, respectively. The calibration graph for salicylamide is linear over the range
0.01 to 0.32 μg mL–1 and for salicylic acid from 0.04 to 1.0 μg mL–1 in the presence of each other. The relative standard deviation and the sampling frequency for the determination of salicylamide
(0.20 μg mL–1) and salicylic acid (0.50 μg mL–1) were 1.1% and 35 h–1, and 0.9% and 45 h–1, respectively. Good results on application to individual determination or mixture resolution in pharmaceutical samples testify
to the usefulness of the proposed sensor.
Received: 20 April 1999 / Revised: 7 June 1999 / Accepted: 12 June 1999 相似文献
13.
C. Zucchi M. Forneris L. Martínez R. Olsina E. Marchevsky 《Fresenius' Journal of Analytical Chemistry》1998,360(1):128-130
A selective and precise spectrophotometric determination of vanadium(V) is performed after preceding extraction with N-benzoyl-N-phenylhydroxylamine
(BPHA). The color is developed in a water-ethanol solution with hydrogen peroxide and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol
(5-Cl-DMPAP). The molar absorptivity at 588 nm is (6.57 ± 0.05) × 104 L mol–1 cm–1 at pH 2.1. The method permits the determination of vanadium (V) at trace levels in the presence of large amounts of other
ions. It is applied to the determination of vanadium in aluminium (analytical reagent grade) and in human hair. High accuracy
and precision is obtained.
Received: 18 April 1997 / Revised: 20 June 1997 / Accepted: 25 June 1997 相似文献
14.
Submicron-sized styrene–methacrylic acid copolymer (92/8 molar ratio) particles dissolved in the presence of polyoxyethylene
nonylphenylether nonionic emulsifier under alkaline conditions at 90 °C, resulting in nanoparticles with diameters of about
30 nm. In order to clarify the role of the emulsifier molecules in the dissolution process, 1H NMR measurements were carried out. As the particles swelled, the NMR integrals due to the emulsifier decreased markedly.
This indicates that the emulsifier molecules permeated into the inside of the alkali-swelling particles and were adsorbed
on the polymer molecules, which supports the formation mechanism of nanoparticles by the particle dissolution method proposed
in a previous article.
Received: 10 December 1998 Accepted in revised form: 1 April 1999 相似文献
15.
A continuous flow atomic absorption spectrometric system was used to develop an efficient on-line preconcentration-elution
procedure for the determination of iodide traces. Chromium (VI) is introduced into the flow system and is reduced to chromium
(III) in acid medium proportionally to the iodide present in the sample. The Cr(III) reduced by iodide is retained on a minicolumn
packed with a poly(aminophosphonic acid) chelating resin, while unreduced Cr(VI) is not retained. Reduced Cr(III) is preconcentrated
by passing the sample containing iodide through the system during 3 min, and is then eluted with 0.5 mol L–1 hydrochloric acid and determined by flame atomic absorption spectrometry (FAAS). The detection limit (3σ) obtained is 2.5
μg L–1. Other ions typically present in waters do not interfere. The proposed method allows the determination of iodide in the range
6–220 μg L–1 with a relative standard deviation of 2.7% at a rate of 17 samples h–1. The method has been applied to the determination of iodide in tap and sea waters.
Received: 16 September 1999 / Revised: 15 November 1999 / Accepted: 19 November 1999 相似文献
16.
D. Dobnik M. Kolar J. Komljenovi Nj. Radi 《Fresenius' Journal of Analytical Chemistry》1999,365(4):314-319
The preparation of an ion-selective electrode by chemical treatment of copper wire and its application for the measurements
of copper (II) and iodide ions is described. The proposed reaction mechanism at the sensing surface, which explains the response
of the electrode to Cu2+ and iodide ions, is discussed. The prepared electrode was suitable for direct potentiometric measurements of iodide and copper
(II) in batch experiments down to concentrations of 1 × 10–5 mol L–1. A tubular electrode, prepared in the same way, may be used as a potentiometric sensor in a flow-injection analysis for Cu
(II) and/or iodide determinations.
Received: 4 December 1998 / Revised: 31 March 1999 / Accepted: 6 April 1999 相似文献
17.
Ying Wang Wanhui Liu Kemin Wang Guoli Shen R. Yu 《Fresenius' Journal of Analytical Chemistry》1998,360(6):702-706
A new optical fiber sensor was prepared for the determination of berberine in aqueous solution using a micrometer-sized flow-cell
and a bifurcated optical fiber. The sensing is based on fluorescence quenching of 2-(4-diphenylyl)-6-phenylbenzoxazole (PBBO)
in the PVC membrane. This process is accompanied by non-fluorescent ground-state complex formation. With this sensor, berberine
can be determined in sample solutions from 2.42 × 10–5 mol L–1 to 6.04 × 10–7 mol L–1. Satisfactory reproducibility, reversibility, and short response times of less than 1 min are realized. The sensor also shows
good selectivity over some common pharmaceutical species and alkali and alkali-earth metal salts, and can be used for the
direct assay of berberine in commercial tablets. The results are in correspondence with those obtained by the pharmacopoeia
method.
Received: 4 April 1997 / Revised: 8 August 1997 / Accepted: 12 August 1997 相似文献
18.
The chiral separation of dansyl-amino acids has been performed by capillary zone electrophoresis using ?β-cyclodextrin as
a chiral selector, urea as an additive and 2-propanol and methanol as organic modifiers. The enantiomeric separations of dansyl-amino
acids were investigated in aqueous medium and compared with the separation in mixed aqueous-organic medium as background electrolytes.
The separation conditions, (concentration of buffer, β-cyclodextrin, methanol, urea and the pH value of buffer) were optimized.
In the absence of organic modifier, only five pairs of 8 separated dansyl-amino acids were resolved when run separately. A
mixture of up to eight chiral amino acids can be baseline resolved in less than 19 min by β-cyclodextrin-modified capillary
zone electrophoresis with a buffer of 60 mmol L–1 H3BO3-KCl/40 mmol L–1 NaOH (pH 9.0), 4 mol L–1 urea, 100 mmol L–1β-cyclodextrin and 10% (v/v) methanol.
Received: 15 March 1999 / Revised: 10 May 1999 / Accepted: 12 May 1999 相似文献
19.
A sensitive analytical method was established for the determination of Th and U in activated concrete samples. The method
combines an anion-exchange separation step with an ICP-MS determination technique. In the ICP-MS measurement, a few μg mL–1 of Al and Ca, a few ng mL–1 of Mn, La, Ce, Nd and Pb and pg mL–1 amounts of Li, Zr, Nb and Ba coexisting in the anion-exchange fraction of Th and U did not interfere. No adverse interference
effects were observed in real sample analyses. The obtained detection limits (3σ, n = 10) of Th and U were 2.3 and 1.8 pg mL–1, respectively. The analytical precisions for ca. 5 μg g–1 Th and ca. 1 μg g–1 U in real activated concrete samples were equally less than 7% RSD. The accuracies obtained by the analysis of GSJ rock standard
samples were –18.1 to 0.4% for the Th determination and –14.0 to –5.7% for the U determination. The method uses the conventional
absolute calibration curve. The internal standard calibration is unnecessary.
Received: 14 March 1999 / Revised: 13 July 1999 / Accepted: 15 July 1999 相似文献
20.
Optical fiber sensor for berberine based on fluorescence quenching of 2-(4-diphenylyl)-6-phenylbenzoxazole 总被引:1,自引:0,他引:1
Ying Wang Wanhui Liu Kemin Wang Guoli Shen R. Yu 《Analytical and bioanalytical chemistry》1998,360(6):702-706
A new optical fiber sensor was prepared for the determination of berberine in aqueous solution using a micrometer-sized flow-cell
and a bifurcated optical fiber. The sensing is based on fluorescence quenching of 2-(4-diphenylyl)-6-phenylbenzoxazole (PBBO)
in the PVC membrane. This process is accompanied by non-fluorescent ground-state complex formation. With this sensor, berberine
can be determined in sample solutions from 2.42 × 10–5 mol L–1 to 6.04 × 10–7 mol L–1. Satisfactory reproducibility, reversibility, and short response times of less than 1 min are realized. The sensor also shows
good selectivity over some common pharmaceutical species and alkali and alkali-earth metal salts, and can be used for the
direct assay of berberine in commercial tablets. The results are in correspondence with those obtained by the pharmacopoeia
method.
Received: 4 April 1997 / Revised: 8 August 1997 / Accepted: 12 August 1997 相似文献