共查询到20条相似文献,搜索用时 31 毫秒
1.
A flow-injection method is proposed for the simultaneous catalytic determination of formaldehyde and methanol on the basis
of the catalytic action of formaldehyde upon the redox reaction between crystal violet and potassium bromate in a phosphoric
acid medium and on-line oxidization of methanol into formaldehyde using a lead dioxide solid-phase reactor. The indicator
reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of crystal violet at the maximum
absorption wavelength of 610 nm. A technique based on three sampling loops with a single injection valve is developed. The
flow-injection system produces a signal of main peak with two shoulders of the same height. The height of the shoulders corresponds
to the formaldehyde concentration, and the height difference between the shoulders and the main peak corresponds to the methanol
concentration. The detection limit is 0.1 μg/mL for formaldehyde and 1.0 μg/mL for methanol with the sampling rate of 10 samples
per hour. The relative standard deviations for 11 replicate determinations of formaldehyde (1.0 μg/mL) and methanol (10 μg/mL)
are 1.1 and 2.1%, respectively. The method has been successfully applied to the simultaneous determination of formaldehyde
and methanol in some gas samples.
The text was submitted by the authors in English. 相似文献
2.
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
3.
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
4.
S. S. Mitić V. V. Živanović G. Ž. Miletić Z. M. Grahovac E. T. Pecev 《Journal of Analytical Chemistry》2012,67(3):284-289
In the present study, a new sensitive and simple kinetic-spectrophotometric method for the determination of the insecticide
dimethoate [O,O-dimethyl-S-(N-methyl-carbomoylmethyl)-phosphoro-dithioate] is developed. The method is based on the inhibition
effect of dimethoate on the oxidation of malachite green (MG) by potassium periodate (KIO4) in the presence of Mn(II) ions. Inhibition kinetics of this catalytic reaction was investigated in the presence of dimethoate
and the possibility of its analytical application was evaluated. The important variables that affected the reaction rate were
investigated and the optimum conditions giving maximum sensitivity were established. Dimethoate was determined with linear
calibration graph in the interval from 4.58 to 41.22 μg/mL. The optimized conditions yielded a theoretical detection limit
of 1.24 μg/mL based on the 3S
b
criterion. The RSDs of the method (n = 5) were 1.2–4.9% for the concentration interval of dimethoate from 4.58 to 41.22 μg/mL. The reaction was monitored spectrophotometrically
by measuring the change in absorbance over time at 615 nm. The method was applied to the determination of dimethoate in waters
and milk, and was compared with the spectrophotometric method. The quantitive method developed on the basis of inhibition
kinetics is practical, fast and economical. For this reason, it is open for new application fields. 相似文献
5.
B. Rezaei 《Journal of Analytical Chemistry》2006,61(11):1074-1078
A simple and selective spectrophotometric method is proposed for the determination of trace amounts of manganese. The method
is based on the extraction of manganese as a MnO2-benzyltriphenylphosphoniumchloride ion pair with chloroform. An artificial neural network (ANN) has been applied to the handling
of the spectrophotometric data of this complex in the organic phase to extend the dynamic range of manganese determination
(0.020–6.0 μg/mL). A three-layer back-propagation network (50:75:1) was used with root-mean-square error (rmse) 0.001 and
momentum (m) 0.8 overall. The application of BP-ANN makes it possible to extend the dynamic range of the determination of
manganese from its narrow linear range of 0.020–2.5 μg/mL to the dynamic range 0.020–6.0 μg/mL.
The text was submitted by the author in English. 相似文献
6.
M. A. Taher A. Mostafavi S. Z. Mohammadi Mobarakeh 《Journal of Analytical Chemistry》2007,62(11):1022-1027
This work assesses the potential of natural analcime zeolite as a sorbent for the preconcentration of palladium. Palladium
is quantitatively retained on modified analcime zeolite loaded with zincon using the column method in the pH range from 2.5
to 3.5 at a flow rate of 1 mL/min. The palladium complex was removed from the column with 5.0 mL of dimethylsulfoxide (DMSO)
and determined by third-derivative spectrophotometry. The detection limit is 0.03 μg/mL (signal-to-noise ratio = 3) in the
final solution. Since it is possible to retain 0.15 μg of palladium from 600 mL of solution passing through the column, elution
with 5.0 mL of DMSO gives a detection limit of 0.25 ng/mL for palladium in the initial aqueous solution. The calibration curve
is linear over the range 0.1 to 5.0 μg/mL of palladium(II) in the final solution with a correlation coefficient of 0.9996.
Seven replicated determinations of 5.0 μg of palladium in 5.0 mL dimethylsulfoxide gave a mean d
3
A/dλ3 (peak-to-peak signal between λ2 = 625 and λ1 = 654 nm) of 0.64 with a relative standard deviation of 1.2%. The sensitivity of the method (d
3
A/dλ3) is 0.5843 mL/μg of palladium(II) from the slope of the calibration curve. The interference of a large number of anions and
cations has been studied and the optimized conditions developed were utilized for the determination of trace palladium in
various synthetic and water samples.
The text was submitted by the authors in English. 相似文献
7.
Summary The optimization of in situ derivatization and preconcentration of formaldehyde in air using solid phase microextraction with
gas chromatographic determination was investigated. A dimethylpolysiloxane coating (7 μm) solid-phase microextraction needle
was used in the final procedure as a support for derivatizing reagents such as 2,4-dinitrophenylhydrazine and acetylacetone.
Standard concentrations of formaldehyde in air were obtained using a headspace technique and equilibrium concentrations of
formaldehyde in air were calculated using Henry's law. After derivatization on the fiber, the derivative was thermally desorbed
in the injector of a gas chromatograph and analyzed using an electron capture detector. A detection limit of 0.17 mg m−3 was obtained. Calibration was done at 296 K. Reproducibility of the method was 9.6%. Some real air samples were also analyzed.
The method is very convenient and ideal for the rapid determination of formaldehyde in air.
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997 相似文献
8.
A rapid, simple, and sensitive kinetic method is developed for the determination of trace amounts of Sb(V). The method is
based on the reaction of Sb(V) with iodide in acidic media in the presence of methylene blue. The reaction was monitored spectrophotometrically
by measuring the decrease in the absorbance at 664 nm by a fixed-time technique of 60 s. The method allowed the determination
of Sb(V) at concentrations between 0.01 and 2.2 μg/mL. The limit of detection was 0.006 μg/mL and the relative standard deviation
for ten replicate measurements of 0.5 μg/mL Sb(V) was 1.2%. The method was applied to the determination of Sb(V) in tap water
and spring water with satisfactory results.
The text was submitted by the authors in English. 相似文献
9.
A simple, economical, and automated spectrophotometric method for the determination of chlorpromazine hydrochloride by sequential
injection analysis using ammonium metavanadate as colorimetric reagent is proposed. The various chemical and physical conditions
that affected the reaction have been thoroughly investigated. The calibration curve was linear within the range 10–100 μg/mL.
The detection limit (S/N = 3) was 0.7 μg/mL and the limit of quantification (S/N = 10) was 2.3 μg/mL. The sampling frequency was 22 h−1. The method has been used for the determination of chlorpromazine hydrochloride in pure form and pharmaceutical formulations.
The t-test has revealed that there is no evidence of significant differences between the obtained results at the 95% confidence
level. The method can be applied to the quantitative determination of chlorpromazine hydrochloride. It is also applicable
in the quality control of chlorpromazine hydrochloride preparations.
The text was submitted by the authors in English. 相似文献
10.
A. Raza 《Journal of Analytical Chemistry》2008,63(3):244-247
The present paper describes an effective and low-cost spectrophotometric method for the determination of mefenamic acid in
its pure form and pharmaceutical preparations. The method is based on the charge-transfer complexation between mefenamic acid
as an n-electron donor and chloranil as a π-acceptor to form a violet chromogen measured at 540 nm. Under the optimum conditions,
a linear relationship with a good correlation coefficient (0.9996) was found between the absorbance and concentration of the
studied drug in the range of 10–60 μg/mL. The optimal reaction conditions such as reagent concentration, heating time, and
stability of the reaction product were determined. The limit of detection (LOD) was 2.16 μg/mL and the limit of quantifycation
(LOQ) was 7.15 μg/mL. The method was successfully applied to the determination of mefenamic acid in pharmaceutical preparations
without any interference from common excipients.
The text was submitted by the author in English. 相似文献
11.
Sayed Zia Mohammadi Daryoush Afzali Davood Pourtalebi 《Journal of Analytical Chemistry》2011,66(7):620-625
In this article, a sensitive cloud point extraction procedure for the preconcentration of trace amounts of palladium, gold
and nickel prior to their determination by flame atomic absorption spectrometry has been developed. The cloud point extraction
method is based on the complexation of Pd(II), Au(II), and Ni(II) ions with 1-(2-pyridylazo)-2-naphthol and entrapping in
non-ionic surfactant Triton X-114. The main factors affecting cloud point extraction efficiency, such as pH of sample solution,
concentration of 1-(2-pyridylazo)-2-naphthol and Triton X-114, equilibration temperature and time, were investigated in detail.
Under the optimized conditions, calibration curves were constructed for the determination of palladium, gold and nickel according
to the general procedure. Linearity was maintained from 0.01 to 1.0 μg/mL for palladium, 10.0 μg/mL to 1.5 μg/mL for gold,
and 10.0 μg/mL to 0.5 μg/mL for nickel. Detection limits based on three times the standard deviation of the blank divided
by the slope of analytical curve (3Sb/m) for Pd(II), Au(III), and Ni(11) ions were 3.4, 3.9, and 2.4 μg/mL, respectively.
Seven replicate determination of a mixture of 0.5 μg/mL palladium and gold and 0.2 μg/mL nickel gave a mean absorbance of
0.174, 0.150, and 0.201 with relative standard deviation ±1.5, ±1.3, and ±1.8%, respectively. The high efficiency of cloud
point extraction to carry out the determination of analytes in complex matrices was demonstrated. The proposed method has
been applied for determination of trace amount of palladium, gold and nickel in certified reference material and water samples
with satisfactory results. 相似文献
12.
Simultaneous determination of arbutin (ART) and l-ascorbic acid (AA) by HPLC with chemiluminescence detection is proposed for the first time. This method is based on the CL
reaction of acidic potassium permanganate with ART and AA in the presence of formaldehyde as enhancer. The separation was
performed on a C18 column with a 90:10 (v/v) mixture of 0.02 M phosphate buffer and methanol as mobile phase. The effects of several conditions on HPLC resolution and
CL emission were studied systematically. The linear ranges were 0.5–50 and 1–200 μg mL−1 for ART and AA, respectively. The detection limits were 0.2 and 0.3 μg mL−1, respectively. The method was successfully applied to the determination of ART and AA in whitening cosmetics. 相似文献
13.
G. A. Shabir 《Journal of Analytical Chemistry》2011,66(10):963-968
A new and simple isocratic high-performance liquid chromatographic method with ultraviolet detection is described for simultaneous
determination of active guaiphenesin and preservative sodium benzoate in Liqufruta garlic cough medicine formulation. The
chromatographic separation was achieved using a Zorbax CN; 150 mm × 4.6 mm and 5 μm particle size column employing acetonitrile
and water (20: 80, v/v) containing 0.1% formic acid (pH 3.5 ± 0.05) as the mobile phase. The method was validated with respect
to linearity, range, precision, accuracy, specificity, limit of detection and limit of quantitation. The both analytes were
detected by UV-Vis detector at 245 nm. The method was linear over the concentration range of 0.2–0.8 mg/mL and 0.02–0.06 mg/mL
for guaiphenesin and sodium benzoate, respectively. The limit of detection was found to be 0.14 μg/mL for GP and 0.06 μg/mL
for SB and the quantification limit was 0.54 μg/mL for GP and 0.22 for SB. Accuracy, evaluated as recovery, was in the range
of 97.8–100.0%. Intra-day precision and intermediate precision showed relative standard deviation <1% in each case. 相似文献
14.
In the present study, a novel, fast and simple liquid chromatographic method was developed and validated for the simultaneous
determination of rosiglitazone and metformin in pharmaceutical preparations. The separation was achieved on a phenyl column
(250 × 4.6 mm i.d., 5 μm) using a mobile phase composed of acetonitrile:10.0 mM phosphate buffer pH 5.5 (70:30, v/v). The flow rate was 1 mL min−1. UV detection was performed at 245 nm and verapamil was used as internal standard. The developed method was validated in
terms of stability, specificity, sensitivity, linearity, accuracy, precision and robustness. The limit of quantification was
0.02 μg mL−1 for both drugs. The method developed was successfully applied to the simultaneous determination of rosiglitazone and metformin
in pharmaceutical preparations. The results were compared to two methods reported in the literature and no significant difference
was found statistically. 相似文献
15.
A simple, reproducible, and sensitive extraction-spectrophotometric method for the determination of fluoxetine (FL) in pharmaceutical formulations is reported. The FLH+ cation, which is formed in an acidic solution, can form an ion-pair with Orange II, (OR II), an anionic dye. The FLH+-OR II− ion pair was quantitatively extracted into dichloromethane solvent and its absorption was measured at 482 nm. The calibration
graph is linear over the FL concentration range of 0.2–9.0 μg/mL and the regression coefficient is 0.9995. The relative standard
deviation (RSD) of ten replicate determinations of 5.0 and 1.4 μg/mL of FL are 0.022 and 0.038, respectively, and the limit
of detection (LOD) of the method is 0.17 μg/mL. The method was successfully applied to the determination of an FL amount in
pharmaceutical formulations (10.0-and 20.0-mg capsules).
The text was submitted by the authors in English. 相似文献
16.
M. C. Yebra M. F. Enríquez A. García A. Moreno-Cid 《Analytical and bioanalytical chemistry》2001,370(1):64-68
A minicolumn packed with poly(aminophosphonic acid) chelating resin incorporated in an on-line preconcentration system for
flame atomic-absorption spectrometry was used to determine ultratrace amounts of lead in mussel samples at μg L–1 level. The preconcentrated lead was eluted with hydrochloric acid and injected directly into the nebulizer for atomization
in an air-acetylene flame for measurement. The performance characteristics of the determination of lead were: preconcentration
factor 26.8 for 1 min preconcentration time, detection limit (3σ) in the sample digest was 0.25 μg g–1 (dry weight) for a sample volume of 3.5 mL and 0.2 g sample (preconcentration time 1 min), precision (RSD) 2.3% for 25 μg
L–1 and 2.0% for 50 μg L–1. The sampling frequency was 45 h–1. The method was highly tolerant of interferences, and the results obtained for the determination of lead in a reference material
testify to the applicability of the proposed procedure to the determination of lead at ultratrace level in biological materials
such as mussel samples.
Received: 1 November 2000 / Revised: 8 January 2001/ Accepted: 11 January 2001 相似文献
17.
A sequential injection analysis (SIA) system is described for the determination of phenoxybenzamine hydrochloride and metoclopramide
using spectrophotometer as detector. The method is based on the detection of an unstable red intermediate compound resulting
from the reaction of phenoxybenzamine hydrochloride or metoclopramide with the diazotizating product of p-phenylenediamine with sodium nitrite in hydrochloric acid medium. The sampling frequency is 69 h−1 and 75 h−1 for phenoxybenzamine hydrochloride and metoclopramide, respectively. The linear range is 10–400 μg/mL for phenoxybenzamine
hydrochloride with a detection limit of 0.081 μg/mL and 20–250 μg/mL for metoclopramide with a detection limit of 0.034 μg/mL.
The RSD is 1.01 and 0.45% for phenoxybenzamine hydrochloride and metoclopramide, respectively. The proposed methods were used
to determine phenoxybenzamine hydrochloride and metoclopramide in pharmaceuticals. The results are compared with those obtained
by pharmacopoeia method.
The article is published in the original. 相似文献
18.
This paper describes a novel method to determine methimazole by spectrophotometry using a potassium ferricyanide-Fe(III) reaction.
The study indicates that at pH 4.0 Fe(III) is reduced to Fe(II) by methimazole and in situ formed Fe(II) reacts with potassium
ferricyanide to give soluble Prussian Blue which is characterized by means of XRD analysis. The absorbance of Prussian Blue
is measured at the absorption maximum of 735 nm, and the amount of methimazole can be determined based on this absorbance.
Beer’s law is obeyed in the range of methimazole concentrations of 0.02–6.00 μg/mL. The equation of the linear regression
is A = −0.0058 + 0.49988c (μg/mL), with a correlation coefficient of 0.9998 and RSD of 0.80%. The detection limit (3σ/k) is 0.015 μg/mL, and the apparent
molar absorption coefficient of indirect determination of methimazole is 5.7 ± 104 L/mol cm. This method has been successfully applied to the determination of methimazole in pharmaceutical, serum and urine
samples, and average recoveries are in the range of 98.6–102.4%. Analytical results obtained with this novel method are satisfactory. 相似文献
19.
A new simple, sensitive and rapid catalytic-spectrophotometric method for the determination of oxalic acid has been described
based on its catalytic effect on the redox reaction between dichromate and Brilliant cresyl blue in acidic media by means
of a flow injection analysis method. The color change of Brilliant cresyl blue due to its oxidation was monitored spectrophotometrically
at 625 nm. The calibration graph was linear in the range of 0.020–4.70 μg/mL oxalic acid with a limit of detection 0.005 μg/mL
of oxalic acid. The relative standard deviation for ten replicate measurements of 0.020 μg/mL and 0.900 μg/mL was 2.2% and
1.7%, respectively. No serious interference was identified. Oxalic acid was determined in wastewater and in spinach by the
proposed method with satisfactory results.
Received: 28 October 1999 / Revised: 13 January 2000 / /Accepted: 20 January 2000 相似文献
20.
Murillo Pulgarín JA Fernández López P Hoyas Nuño P 《Analytical and bioanalytical chemistry》2006,384(2):423-430
A new analytical method is proposed for determination of hydralazine (HZ) in pharmaceuticals—measurement of the chemiluminescence
(CL) emitted after reaction with phosphoric-acidified KMnO4. The novelty of this method is the recording of the whole CL–time profile. Such a recording is possible by use of a CL-detector
operating in tandem which enables the reactants to be mixed in the measurement cell only and, therefore, the CL is reaction
monitored from beginning. At the precise time the pump is stopped signal recording is triggered and so CL evolution is recorded
completely. The optimum chemical conditions for the determination were 0.8 mol L−1 formaldehyde, 0.3 mmol L−1 KMnO4, 4.0 mol L−1 H3PO4, and a total flow of 0.37 mL s−1. Two calibration graphs were plotted, CL intensity and area under the profile curve against HZ concentration. Exhaustive
statistical analysis provided very interesting results, for example, accordance with Clayton’s theory, detection limit below
0.2 μg mL−1, and linear calibration ranges from 0.2 to 5.0 μg mL−1. This method was successfully applied to the determination of HZ in pharmaceuticals. Because they are usually formulated
in association with diuretics and β-blockers, the method was used for analysis of HZ in pharmaceuticals that contained either HZ only or HZ with other hypotensive
substances. Obtained and nominal content were approximately the same and experimental Student t values indicated there were no significant differences between the values. 相似文献