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1.
A kinetic spectrophotometric method for the determination of molybdenum is based on its catalytic effect on the oxidation
of pyrogallol red with hydrogen peroxide. The decrease of the absorbance of pyrogallol red in the presence of hydrogen peroxide
with time from 0.5 to 4.5 min is proportional to the concentration of Mo(VI) over the range 0.010–0.500 μg/mL. The limit of
detection is 0.008 μg Mo/mL. The precision and the effect of the presence of more than forty ions on the molybdenum determination
are reported. Probable interferences are completely removed by a cation exchange resin. The procedure was successfully applied
to the determination of molybdenum in plant materials and steels.
Received: 28 April 1997 / Revised: 16 June 1997 / Accepted: 18 June 1997 相似文献
2.
Jianguo Hong J. Maguhn Dieter Freitag Antonius Kettrup 《Analytical and bioanalytical chemistry》1998,361(2):124-128
A method for the determination of hydrogen peroxide and several organic peroxides by high-performance liquid chromatography
with post-column UV irradiation, derivatization and fluorescence detection is described. By means of post-column UV irradiation
in the presence of water organic peroxides are converted into hydrogen peroxide and organic hydroperoxides, which react rapidly
with the post-column derivatization agent p-hydroxyphenylacetic acid (PHPAA) under catalysis of horseradish peroxidase to
yield the fluorescent PHPAA dimer that is detected at excitation and emission wavelengths of 285 and 400 nm, respectively.
The detection limit for hydrogen peroxide is 14 ng/mL, for organic peroxides between 34 ng/mL and 5 μg/mL. No interference
by other compounds was observed when their concentrations were below 10 mg/mL except ethers and phenols.
Received: 6 August 1997 / Revised: 11 December 1997 / Accepted: 15 December 1997 相似文献
3.
Jianguo Hong J. Maguhn Dieter Freitag Antonius Kettrup 《Fresenius' Journal of Analytical Chemistry》1998,361(2):124-128
A method for the determination of hydrogen peroxide and several organic peroxides by high-performance liquid chromatography
with post-column UV irradiation, derivatization and fluorescence detection is described. By means of post-column UV irradiation
in the presence of water organic peroxides are converted into hydrogen peroxide and organic hydroperoxides, which react rapidly
with the post-column derivatization agent p-hydroxyphenylacetic acid (PHPAA) under catalysis of horseradish peroxidase to
yield the fluorescent PHPAA dimer that is detected at excitation and emission wavelengths of 285 and 400 nm, respectively.
The detection limit for hydrogen peroxide is 14 ng/mL, for organic peroxides between 34 ng/mL and 5 μg/mL. No interference
by other compounds was observed when their concentrations were below 10 mg/mL except ethers and phenols.
Received: 6 August 1997 / Revised: 11 December 1997 / Accepted: 15 December 1997 相似文献
4.
A simple and sensitive flow injection method is described for the determination of trace amounts of hydrazine, based on its inhibitory effect on the reaction between pyrogallol red and iodate in hydrochloric acid media. The reaction was monitored spectrophotometrically by measuring the change in absorbance of pyrogallol red at 470 nm. The calibration graph was linear over the range of 0.050–1.20 g/mL, with a limit of detection of 0.03 g/mL. The relative standard deviation for ten replicate measurements of 0.060 and 0.70 g/mL was 2.2 and 0.50%, respectively. Potential interfering substances were studied in the presence of hydrazine. The proposed method was applied to the determination of hydrazine in water samples. 相似文献
5.
R. Escobar M. S. García-Domínguez A. Guiraúm F. F. de la Rosa 《Fresenius' Journal of Analytical Chemistry》1998,361(5):509-511
A flow injection (FI) chemiluminescence method for the determination of Cr(III) in blood serum, urine and hair samples is
reported. It is based on the chromium-catalyzed light emission from the luminol oxidation by hydrogen peroxide. The apparatus
consists of an FI system with a flow cell formed by a coiled transparent tube suitable for chemiluminescence detection. The
specificity of the method is achieved in presence of EDTA. The detection limit under optimum conditions is 0.01 μg L–1 of Cr(III). Precision and accuracy were evaluated by determining Cr(III) concentrations in urine standards from the National
Institute of Standard and Technology (NIST).
Received: 30 June 1997 / Revised: 16 January 1998 / Accepted: 23 January 1998 相似文献
6.
A method was developed for the chromatographic separation of V(V) and V(IV) based on the different sorption forces of these
vanadium species in C18 columns in presence of KH-phthalate. The vanadium species were detected with a flame atomic absorption
spectrometer with acetylene/N2O flame. The detection limits (3σ) of V(V) and V(IV) were 0.18 μg/mL and 0.15 μg/mL, respectively. The relative standard deviations
(N = 5) are 4.2% and 3.4% for 20–20 μg/mL V(V) and V(IV), respectively. The sampling frequency is 75/h. Because of the special
interaction occurring between phthalate and V(IV) on the C18 column and the acetylene/N2O flame atomic absorption detection, practically no interferences can be detected even in large inorganic matrix.
Received: 20 February 1997 / Revised: 2 June 1997 / Accepted: 7 June 1997 相似文献
7.
This paper reports a simple and sensitive flow-injection method for the spectrophotometric determination of formaldehyde based
on the catalytic effect of formaldehyde on the oxidation of pyrogallol red with bromate in acidic media. The decrease in absorbance
of the reaction mixture was measured at 470 nm. The calibration graph was linear in the range of 0.47 to 40.0 μ/mL formaldehyde
for a sample rate of 30±5 samples per hour. The limit of detection is 0.36 μ/mL. The relative standard deviations for ten
replicate measurements of 2.5, 5.0, and 20.0 μ/mL formaldehyde were 3.9, 2.1, and 0.7%, respectively. The method was applied
to the determination of formaldehyde in river water, shampoo, and melamine-formaldehyde resin.
The text was submitted by the authors in English. 相似文献
8.
L. F. Capitán-Vallvey Mahmoud K. A. Deheidel R. Avidad 《Fresenius' Journal of Analytical Chemistry》1998,362(3):307-312
A phosphorimetric solid phase assay is proposed for the determination of the pesticide carbaryl (CBL) at room temperature.
CBL was spotted on filter paper together with Tl(I) as heavy metal, and dried for 3 min, after which the diffuse transmitted
phosphorescence was measured using two quartz plates to avoid the quenching effect produced by atmospheric oxygen. The linear
dynamic range was 0.5–4.0 μg/mL and the detection and quantification limits were 0.09 and 0.31 μg/mL, respectively. The precision
of the method, expressed as relative standard deviation, was 2.3% for a sample containing 2.0 μg/mL of CBL. The method was
applied to the determination of CBL residues in cereals, potatoes and waters, obtaining recoveries ranging between 92 and
105%.
Received: 10 October 1997 / Revised: 2 February 1998 / Accepted: 7 February 1998 相似文献
9.
A dual stage preconcentration system based on flow injection on-line ion-exchange and solvent-extraction has been developed
for flame atomic absorption spectrometry. Lead is taken as a model trace element. A column packed with Amberlite IRC-718 cation
exchanger is incorporated into the FI manifold. The analyte is retained on the column by time-based sample loading and eluted
by 1 mol/L HNO3. The eluate is subsequently merged with potassium iodide and tetrabutylammonium bromide (TBABr), and isobutyl methyl ketone
(IBMK). Lead is extracted on-line into IBMK as the ion-pair formed between the iodoplumbate anion and tetrabutylammonium cation.
The organic phase is separated from the aqueous phase by a gravity phase separator. 50 μL of concentrate is introduced into
the nebulizer-burner system of the spectrometer. An enhancement factor of 550 is achieved with a 30 mL sample consumption
at a sampling frequency of 30/h. The precision (relative standard deviation) is 2.4% at 10 μg/L level and the detection limit
is 0.3 μg/L (3 σ). The method was successfully applied to the determination of lead in water samples.
Received: 19 March 1997 / Revised: 24 June 1997 / Accepted: 27 June 1997 相似文献
10.
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
11.
A. N. Dimitrov V. D. Lekova K. B. Gavazov B. S. Boyanov 《Journal of Analytical Chemistry》2007,62(2):122-125
The formation of a new tenary complex of molybdenum(VI) with 4-nitrocatechol (NC) and tetrazolium blue chloride (BTC), which
is easily extractable from water into dichloroethane, is reported. The optimum extraction conditions (pH, concentration of
the reagents, extraction time) and composition of the complex (Mo: NC: BTC = 1: 2: 1) were found. The spectrophotometric parameters
of the extract were determined as well. Beer’s law is obeyed for concentrations of Mo ranging from 0.2 to 6.7 μg/mL with the
molar absorptivity λ445 = 2.38 × 104 L mol−1 cm. A precise, sensitive, and simple method for determination of Mo in steels and ferromolybdenum was developed.
The text was submitted by the authors in English. 相似文献
12.
G. Meissner Kari Hartonen M.-L. Riekkola 《Fresenius' Journal of Analytical Chemistry》1998,360(5):618-621
A method is developed for the determination of β-blockers in serum and urine at levels of 0.5 μg/mL. The technique uses a
combination of solid phase extraction (SPE) with in situ derivatization and supercritical fluid extraction (SFE) with subsequent
gas chromatography mass spectrometry. The optimization of the SFE step shows that a static extraction period can be eliminated.
The method gives good linearity (r = 0.991–0.999) and repeatability in the concentration range of 0.5 to 5 μg/mL. Relative
standard deviations for oxprenolol, propanolol and metoprolol were less than 5% in serum and 5–11% in urine.
Received: 23 May 1997 / Revised: 28 July 1997 / Accepted: 5 August 1997 相似文献
13.
A simple and rapid method is proposed for the determination of ultra trace amounts of formaldehyde. It is based on the catalytic
effect of formaldehyde on the oxidation of Brilliant cresyl blue by bromate. The reaction is monitored photometrically by
measuring the decrease in absorbance of the dye. Formaldehyde in the range of 0.005–2.300 μg/mL can be determined with a limit
of detection of 0.003 μg/mL. The relative standard deviation for ten replicate measurements of 1.5 μg/mL formaldehyde is 0.1%.
The method was used for the determination of formaldehyde in real samples with satisfactory results.
Received: 26 May 1998 / Revised: 30 September 1998 / Accepted: 3 October 1998 相似文献
14.
An X-ray fluorescence spectrometric multivariable regression procedure is described for the determination of titanium and
molybdenum in special steels and alloys in the concentration range from 9.41% down to 120 μg/g using Ti Kα1,2 and Mo Kα1,2 analyte lines. In general, better results have been achieved in first order base curve polynomials using LiF (200) crystal
in combination with scintillation counter (SC) or krypton proportional counter (KPC). However, LiF (220)+SC combination also
yields favorable results for Mo. The measured concentrations of Ti and Mo for BAS alloy steel standards agree very well with
their certified values. The automated XRFS method for the determination of Ti and Mo appears to be free from matrix effects
and is suitable for their measurement in special steels and alloys down to 120 μg/g concentration of Ti with a precision of
3.2% and an accuracy of ±2.5% and for Mo down to 350 μg/g with a precision of <1% and an accuracy of ±1.1%. The sensitivities
for these lowest concentrations are calculated to be 5960 counts/mass %/s and 8000 counts/mass %/s for Ti and Mo, respectively. 相似文献
15.
D. Kostova 《Journal of Analytical Chemistry》2011,66(4):384-388
Solvent extraction of molybdenum(VI) ion associate with triphenyltetrazolium chloride (TTC) has been studied. TTC was proposed as reagent for the spectrophotometric determination of micro amounts of molybdenum(VI)
at λmax 250 nm. The optimum conditions for extraction of molybdenum(VI) as an ionassociation complex with TTC has been determined.
Beer’s law is obeyed in the range of 0.5–10 μg/mL molybdenum(VI). The molar absorptivity of the ion-pair is 1 × 106 L/mol cm. The sensitivity of the method is 9.6 × 10−5 μg/cm2. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase are: distribution constant
K
D = 32.64, extraction constant K
ex = 2.19 × 1010 association constant β = 6.71 × 108. The interferences of different cations, anions on molybdenum(VI) determination were also investigated. A sensitive and selective
method for the determination of microquantities of molybdenum(VI) has been developed. The determination was carried out without
preliminary separation of molybdenum. A novel procedure of molybdenum(VI) extraction and spectrophotometric determination
in different plant samples was examined. 相似文献
16.
In-cuvette mixing and titration techniques have been used for the kinetic determination of sulfide based on its inhibition
effect on the oxidation of indigo carmine with hexacyanoferrate(III) in the presence of silver. The reaction was monitored
spectrophotometrically by measuring the decrease in absorbance of indigo carmine at 612 nm. Both initial rate and fixed-time
methods were applied to the in-cuvette technique. Using in-cuvette mixing, sulfide up to 1800 ng was determined and detection
limit and relative standard deviation for the determination of 120 ng of sulfide were calculated as 23.0 ng and 1.59%, respectively.
On the basis of the titration technique, the upper limit of determination was 25 μg of sulfide and detection limit and average
relative standard deviation for the determination of 1 μg of sulfide were 0.025 μg and 4.95%, respectively. The effect of
foreign ions on the sulfide determination was studied. The proposed methods were applied to the determination of sulfide in
water.
Received: 10 March 1999 / Revised: 9 June 1999 / Accepted: 12 June 1999 相似文献
17.
A simple, sensitive and selective method for the extraction and trace determination of molybdenum(VI) has been developed; it is based on its reaction with 3-hydroxy-2-(2-thienyl)-4H-chromen-4-one (HTC) in sulphuric acid medium. The 1:2 Mo (VI)-HTC yellow complex is quantitatively extractable into chloroform (max 420 nm) and is stable for more than 4 h. The procedure eliminates the interference of a large number of metal ions and complexing agents. Beer's law is obeyed in the range of 0–2.85 g Mo/mL with a molar absorptivity, Sandell's sensitivity and standard deviation of 5.28×104 L mol–1 cm–1, 0.0018 g Mo/cm2 and ±0.0054, respectively. The method has successfully been used for the spectrophotometric determination of molybdenum in steel samples. 相似文献
18.
A novel chemiluminescence (CL) flow system has been developed for the sequential determination of Fe(II) and Fe(III) in water.
Fe(II) was detected by its catalytic effect on the CL reaction between luminol immobilized on an anion exchange resin column
and dissolved oxygen; Fe(III) was determined by difference measurement after on-line conversion to Fe(II) in a reducing mini-column
packed with Cu plated Zn granules. For both ions, the calibration graph was linear in the range 1 × 10–9 to 1 × 10–6 g/mL, and the detection limit was 4 × 10–10 g/mL. A complete analysis could be performed in 1.5 min with a relative standard deviation of less than 5%. The system could
be reused for over 200 times and has been applied successfully to the determination of Fe(II) and Fe(III) in natural water
samples.
Received: 13 March 1997 / Revised: 3 June 1997 / Accepted: 6 June 1997 相似文献
19.
Ricardo N. Garavaglia Rubén E. Rodríguez D. A. Batistoni 《Fresenius' Journal of Analytical Chemistry》1998,360(6):683-688
An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils
by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid
and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric
acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations
of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that
matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences
were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5%
for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating
the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference
from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary
B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing
of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil.
Received: 25 June 1997 / Revised: 16 September 1997 / Accepted: 7 October 1997 相似文献
20.
Ricardo N. Garavaglia Rubén E. Rodríguez D. A. Batistoni 《Analytical and bioanalytical chemistry》1998,360(6):683-688
An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils
by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid
and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric
acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations
of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that
matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences
were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5%
for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating
the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference
from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary
B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing
of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil.
Received: 25 June 1997 / Revised: 16 September 1997 / Accepted: 7 October 1997 相似文献