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1.
Direct analysis of polymers containing polymeric hindered amine light stabilizers (HALS) by using pyrolysis coupled to GC-MS is applied successfully for fast and straightforward identification of these HALS additives. Each of the HALS additives shows different pyrolysis gas chromatograms containing characteristic pyrolysis products. As a result, HALS additives with very similar chemical structures, e.g. Chimassorb 944 and Chimassorb 2020, can be distinguished. A HPLC method with both ultraviolet (UV) and evaporative light scattering detection (ELSD) is developed to quantify the various HALS additives in extracts of polymers. The critical factor of the HPLC method is the use of a basic amine, like n-hexylamine, as a solvent additive to facilitate the elution of HALS additives. The various HALS additives can be distinguished according to retention time and peak shape and by using different detection methods. The suitability of the developed methods is demonstrated by the analytical performance of the HPLC method and the identification and determination of the actual content of HALS additives in polyolefines using pyrolysis GC-MS and HPLC. The HPLC method can also be used for the determination of the specific migration of HALS additives from food contact materials. 相似文献
2.
Mir Ali Farajzadeh Mortaza Ebrahimi Ali Ranji Elham Feyz Vali Bejani Amir Abbas Matin 《Mikrochimica acta》2006,153(1-2):73-78
High performance liquid chromatography (HPLC) and gas chromatography (GC) are introduced for analysis of polymer lubricants
(stearamide, oleamide and erucamide). In the HPLC method, a reverse phase octadecylsilane (ODS) column along with acetonitrile/methanol
(60:40) as a mobile phase were used. Detection of analytes was performed by a UV detector at 202 nm. The analysis time was
less than 8 min. In the GC method, polar capillary column and flame ionization detector (FID) were used for separations and
detection, respectively. The analysis time by GC was longer than HPLC and was about 30 min. Limits of detection, linear range
and repeatability of both methods are similar, but determination of oleamide in real samples by HPLC method is difficult due
to complexity of the initial part of HPLC chromatogram in polyethylene samples. That problem is not observed in the GC method.
Detection limits in both methods for all analytes are lower than 0.003% which are much lower than the amount of lubricants
in commercial polymers (0.05–0.2%). 相似文献
3.
《Analytical letters》2012,45(4):617-625
This paper reports the development of a method for the determination of Chimassorb 944 (C944), in polypropylene geotextiles, by high performance liquid chromatography with ultraviolet detection. The C944 was removed from the geotextiles by an ultrasonic extraction and then separated in a NH2 column, followed by UV detection at 244 nm. Analytical validation showed that the method is accurate and precise. The developed methodology was applied for the determination of C944 in geotextiles exposed to artificial UV radiation and to natural weathering. To the best of our knowledge, this is the first method proposed for the determination of C944 in geotextiles. 相似文献
4.
R. C. Díaz M. A. Sarasa C. Ríos J. J. Cuello 《Accreditation and quality assurance》1999,4(11):473-476
The determination of dichlorobenzene and naphthalene in commercial repellents used in Spain has been validated. This was
done using an isocratic regime, to test the reverse -phase HPLC system with acetonitrile: water 65 : 35 (v: v) as the mobile
phase, at 20 °C. This technique is proposed for the modular validation of the HPLC system . The results obtained with this
method show good agreement with the results provided by the manufacturers of the mothrepellents.
Received: 21 December 1998 / Accepted: 4 May 1999 相似文献
5.
Different sample preparation methods on the basis of the oxidation of Irgafos 168 (a phosphite ester used as a secondary antioxidant
in polymers) to phosphate ion are presented for its determination in polymers. Different reagents such as perchloric acid
and sodium hydroxide or heat were used to convert analyte to phosphate ions. In final step, a standard method (vanadomolybdophosphoric
acid method) was used to determine the phosphate ions produced. The method is simple, reliable and relatively rapid. The repeatability
was evaluated using a 20 mg·L−1 solution of analyte and it is found that the relative standard deviation is less than 5% for all procedures. Accuracy of
the method was tested by applying the spectrophotometric method along with gas chromatography to three commercial polymers.
The results in all cases are in good agreement. In nine other polymers Irgafos 168 was not detected using both methods. The
procedure in case of real samples (polyolefins) is: dissolution/precipitation of polymer, filtration, evaporation, dissolving
residue in acetone and performing digestion procedures using HClO4 or NaOH. In the case of the pyrolytic method, the polymer was burned in an electrical furnace at 500 °C and the residue was
dissolved in HCl. 相似文献
6.
Hassan Karami Mir Fazlollah Mousavi Yadollah Yamini Mojtaba Shamsipur 《Mikrochimica acta》2006,154(3-4):221-228
A new simple flow injection analysis (FIA) system is described for on-line preconcentration by solid phase extraction and
simultaneous determination of Hf and Zr in different samples using inductively coupled plasma atomic emission spectroscopy
with a charge coupling detector (CCD). Quinalizarin (QA) was loaded on an octadecyl silica-polyethylene mini-column for the
retention of Hf and Zr ions in complexed form. A 0.3 M ammonium acetate was used as buffer for providing suitable conditions
for complexation and increasing reproducibility. Retained ions on the solid phase were then eluted by a solution containing
3.0 M HCl and 0.5 M HNO3. In this work, for reducing bandwidths of eluted ions, elution of minicolumn was carried out from opposite direction. The
same solution was used as both carrier and eluent, in order to increase the reproducibility. The eluted ions were introduced
into the conventional nebulizer of ICP–AES instrument. Effects of different parameters, including instrumental parameters
of ICP and FIA were optimized. An enrichment factor of 330 for each analyte ion was obtained at a concentration level of 80 ppb.
The detection limits of the proposed method for Hf and Zr were 0.16 ng mL−1 and 0.04 ng mL−1 respectively. The ability of the method for the recovery of Hf and Zr ions was tested in the presence of several diverse
metal ions in a synthetic mixture and some real matrices. It was also applied to the determination of Zr and Hf ions in a
standard soil and in a standard alloy as real samples. 相似文献
7.
A method for the determination of theophylline (TH), without derivatization, in serum by isotope dilution mass spectrometry
using labelled [1, 3-15N2-2-13C]theophylline (LTH) as internal standard is described. After deproteinization, the analyte is directly injected into a high
performance liquid chromatography – mass spectrometer operating with atmospheric-pressure chemical-ionization (APCI HPLC/MS).
The concentrations of TH in sera measured by APCI HPLC/MS are compared with results from gas chromatography – isotope dilution
mass spectrometry (GC-ID/MS), high performance liquid chromatography (HPLC) and fluorescence polarization immunoassay (FPIA).
The accuracy, precision and recovery of the APCI HPLC/MS and GC-ID/MS methods are discussed. The coefficient of variation
(CV) determined from duplicate samples was less than 2%. The detection limit was 10 ng/ml at a signal-to-noise ratio of 3:1.
Received: 17 January 1996/Revised: 26 March 1996/Accepted: 5 April 1996 相似文献
8.
Carlos E. C. Magalhães Éder C. Lima Francisco J. Krug Marco A. Z. Arruda 《Mikrochimica acta》1999,132(1):95-100
A method for direct analysis of tea and coffee samples by using electrothermal atomic absorption spectrometry is described.
Coffee and tea from different sources were analyzed without digestion step. For slurry analyses the samples were ground, sieved
at 105 μm and then suspended in 0.2% v/v HNO3 and 10% v/v Triton X-100 medium. For liquid phase aluminium determination the samples were prepared in the same way and only
the liquid is introduced directly into the graphite furnace. Calibration was performed by aqueous standards for both cases
and the determinations were carried out in the linear range between 50 and 250 μg L−1. The characteristic mass of aluminium and the detection limit were 45 pg and 2 μg L−1, respectively. Using a typical 0.1% m/v coffee slurry sample, the relative standard deviation of measurements (n=15) for
repeatability was about 8.2%.
Received December 27, 1998. Revision March 18, 1999. 相似文献
9.
Dupard-Julien CL Kandlakunta B Uppu RM 《Analytical and bioanalytical chemistry》2007,387(3):1027-1032
A reversed-phase, high-performance liquid chromatography (RP-HPLC) method that allows quantitation of low levels of epoxides
has been described. The method involved derivatization of epoxides using 100- to 1,000-fold excess N,N-diethyldithiocarbamate (DTC) at 60 °C for 20 min at neutral pH. The unreacted DTC was then decomposed to CS2 and diethyl amine by acidification of the reaction mixture to pH 2 using orthophosphoric acid. The first two steps could
be performed in the same reaction vessel by sequential addition of reagents. In the final step, an aliquot (20 μL) of the
derivatized sample was analyzed for the presence of stable esters of DTC by RP-HPLC using a Supelcosil LC-18-S (150 × 4.6-mm)
column and a mobile phase consisting of 40% (v/v) acetonitrile in water at a flow of 1 mL min−1. Using UV detection at 278 nm, the epoxides gave linear responses in the concentration range of 0.25 to 50 μM. The method
is robust, and as low as 5 pmol of the analyte could be successfully detected and quantified with recoveries of ≥94%. Following
a minimal pretreatment such as ultrafiltration (molecular weight cutoff 5,000 Da), the method is suitable for analysis of
epoxides in complex physiological fluids (e.g., fetal bovine serum). The method has been rigorously evaluated and adapted
in our laboratory for routine analysis and determination of stability of epoxides of 1,3-butadiene and other alkenes added
to cell cultures. 相似文献
10.
A new high-performance liquid chromatography assay was developed for the determination of minocycline in plasma and brain.
A solid–liquid extraction procedure was coupled with a reversed-phase HPLC system. The system requires a mobile phase consisting
of acetonitrile:water:perchloric acid (26:74:0.25, v/v/v) adjusted to pH 2.5 with 5 M sodium hydroxide for elution through a RP8 column (250 × 3.0 mm, i.d.) with UV detection set
at 350 nm. The method proved to be accurate, precise (RSD < 20%) and linear between 0.15–20 μg mL−1 in plasma and 1–20 μg mg−1 in brain. The method was successfully applied to a blood-brain barrier minocycline transport study. 相似文献
11.
E.J. Woolf T. Au M. Kasper M. Constanzer B. Matuszewski 《Journal of chromatography. A》1994,660(1-2):307-312
A method for the simultaneous determination of a topical carbonic anhydrase inhibitor, L-693,612, and two of its potential metabolites in human whole blood is described. The analytes are isolated from the matrix via liquid-liquid extraction with a mixture of toluene, ethyl acetate and isopropanol (49:50:1, v/v/v). The analytes are then back extracted into dilute phosphoric acid prior to injection into the HPLC system. A cyano column (Zorbax SB-CN, 150 × 4.6 mm) with a mobile phase of phosphoric acid(0.085%)-acetonitrile (73.5:26.5) containing 10 mM sodium decane sulfonate and adjusted to pH 3 is used for the analysis. Detection is based on UV absorbance at 252 nm. The assay was found to be linear in the concentration range of 5–500 ng/ml for each analyte when 1-ml aliquots of whole blood were extracted. 相似文献
12.
Kishikawa N Ohkubo N Ohyama K Nakashima K Kuroda N 《Analytical and bioanalytical chemistry》2011,400(2):381-385
Ubiquinone is an important biologically active compound in the living body. The determination of ubiquinone in human plasma
is useful for the investigation of bioavailability of ubiquinone and for early diagnosis of several diseases. Therefore, we
developed a high-performance liquid chromatography (HPLC) with chemiluminescence detection method for the analysis of ubiquinone
in plasma samples. The method is based on luminol chemiluminescence detection of super oxide anion that is generated by the
redox cycle reaction between ubiquinone and dithiothreitol. The HPLC system involved an octyl column with a mobile phase of
methanol. Ubiquinone eluted from the column was mixed with dithiothreitol and luminol solutions simultaneously, and generated
chemiluminescence was monitored by chemiluminescence detector. The calibration curve for standard ubiquinone solution was
linear from 0.09 to 43.2 μg/mL (0.45–216 ng on column) with the correlation coefficient of 0.999, and the detection limit
(S/N = 3) was 26 ng/mL (130 pg on column). Using the proposed HPLC method, the peak of ubiquinone in human plasma could be
clearly detected on the chromatogram without any interference from plasma components. 相似文献
13.
A HPLC method with automated column switching was developed and validated for the determination of Ro 63-1908 in rat and cynomolgus monkey plasma. Human plasma was used for calibration and was also included in the validation process. Ro 63-1908 belongs to a class of neuroprotective N-methyl-
-aspartate (NMDA) receptor blockers which were in development for the treatment of stroke and traumatic brain injury. The method involves deproteinisation of plasma samples with ethanol and direct injection of the supernatant (1.4 ml) into the HPLC column-switching system. To prevent a breakthrough of the analyte and the internal standard on the precolumn (Purospher RP-18, 75×4 mm) due to the high ethanol content, the injection solution was diluted, on-line, using an additional pump and a T-piece. 1% ammonium acetate–ethanol (100:2, v/v) was used as mobile phase for injection, as well as for on-line dilution, resulting in pre-concentration of the analyte and the internal standard on the precolumn. As Purospher RP-18 is a non-endcapped stationary phase with a special selectivity for amines, the analyte and the internal standard could then be selectively eluted with 30% acetonitrile (without any buffer in the mobile phase) and transferred to the analytical column [consisting of two coupled columns (125+250×4 mm) packed with Superspher 60 RP-select B], where they were separated by gradient elution and detected by fluorescence detection. Compared to the use of a 125 mm long precolumn and dilution of the supernatant with ammonium acetate prior to injection, the 75 mm precolumn and the on-line dilution procedure allowed about one third shorter run times (21 min) and, therefore, a higher sample throughput. The limit of quantification was 1 ng/ml using 0.4 ml plasma. The method was applied to more than 670 plasma samples from pharmacokinetic and toxicokinetic studies and is also suitable for other matrices and NMDA receptor blockers. 相似文献
14.
A simple flow injection on line separation and preconcentration system coupled to hydride generation atomic fluorescence spectrometry
(HG-AFS) was developed for ultra-trace cadmium determination in seawater. With the sample pH kept at 3.0, the preconcentration
of cadmium on the inner walls of the knotted reactor was carried out based on the retention of cadmium complex with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one.
A 0.2 mol L−1 HCl was introduced to elute the retained analyte complex and merge with KBH4 solution for HG-AFS detection. Under the optimal experimental conditions, an enhancement factor of 12 was obtained with a
sample consumption of 12.0 mL. The limit of detection was 3.2 ng L−1 with a sample frequency of 24 h−1. The developed method was validated by the analysis of cadmium in certified reference materials, and was applied to the determination
of cadmium in four seawater samples with R.S.D. of around 10%.
Correspondence: Hong Wu, Department of Chemistry, Xuzhou Normal University, Xuzhou 221116, P.R. China 相似文献
15.
This study describes the sample preparation and two chromatographic techniques for determination of Tinuvin 622 in polyethylene. The first part of the two methods consisting of dissolving the polyethylene in boiling xylene is followed by addition of a methanolic solution of potassium hydroxide. The polymeric light stabilizer, Tinuvin 622, is thereby saponified to 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (diol). Addition of the methanolic solution of the saponification reagent simultaneously precipitates the polyethylene matrix. Then the diol is quantified using either gas chromatography (GC) or high performance liquid chromatography (HPLC). For GC, a Macherey Nagel Optima-17 capillary column (30m×0.25mm ID, film thickness 0.25µm) is used. Nitrogen is used as carrier gas and make-up gas. The detection system is a flame ionization detector. For HPLC, an octadecyl silane (ODS) column (30cm×4mm, particle size 5µm) and a mobile phase methanol: water mixture (3:97, v/v) are used. Detection of analyte is carried out at 215nm. Both methods can be used to determine Tinuvin 622 in polyethylene in the concentration range of 0.02–1%, which represents the usual application concentration. 相似文献
16.
Comparative study on determination of fumagillin in fish by normal and reversed phase chromatography
Summary Fumagillin is an antibiotic agent mostly used in the veterinary profession. A normal-phase liquid chromatographic method was
developed for the determination of this drug in fish matrices. A hexane-dichloromethanedioxan-2-PrOH-acetic acid (43:43:9:5:0.1
v/v %) eluent was used on a Perkin Elmer silica gel column. For validation of the process a reversed-phase HPLC method was
also developed (eluent: acetonitrile-water-bicyclohyxylamine 70:30:0.05 v/v %, with Spherisorb ODS, as stationary phase).
Recovery is about 100% and the limit of detection is 5 ng g−1 for meat samples.
Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997. 相似文献
17.
Paraskevas D. Tzanavaras Demetrius G. Themelis Anastasios Economou Georgios Theodoridis 《Mikrochimica acta》2003,142(1-2):55-62
Two new simple and rapid methods are reported for the accurate and precise spectrophotometric determination of captopril
(CPL) using flow (FI) and sequential injection (SI) analysis. The methods are based on the fast oxidation of CPL by Fe(III).
The produced Fe(II) reacts with 2,2′-dipyridyl-2-pyridylhydrazone (DPPH) in acidic medium to form a colored complex which
is monitored spectrophotometrically at 535 nm. Both methods allow the determination of the analyte up to 1000 mg L−1 at a sampling rate of 120 and 60 injections per hour for FI and SI, respectively. The methods are very precise [s
r=0.8 and 1.2% at 500 mg L−1 CPL (n=12) for FI and SI, respectively] and the 3σ detection limits (c
L=4.0 and 7.0 mg L1, respectively) are quite satisfactory. Their application to a variety of anti-hypertensive commercial pharmaceutical formulations
showed excellent results (relative errors, e
r, < ± 1.6% in all cases compared to an official HPLC method), while common pharmaceutical excipients were found not to interfere.
Recovery experiments further verified the accuracy of the developed methods, as the percent recoveries were in the range of
98.1–102.5%.
Author for correspondence. E-mail: themelis@chem.auth.gr
Received May 9, 2002; accepted January 8, 2003
Published online May 5, 2003 相似文献
18.
N. Furusawa 《Fresenius' Journal of Analytical Chemistry》1999,364(3):270-272
A method for the determination/identification of residual sulfadimidine (SDD) in milk and eggs by high-performance liquid
chromatography (HPLC) with a photo-diode array detector was developed. The sample preparation was performed by shaking with
a mixture of 20% (w/v) trichloroacetic acid-methanol (4:1, v/v) followed by ultra-filtration using Molcut II?. A LiChrospher? 100 RP-8 (e) column and a mobile phase of 4% (v/v) acetic acid solution-acetonitrile (6:4, v/v) were used. The average recoveries
from spiked SDD samples were 80.8–88.0% with coefficients of variation of 2.8–5.5%. The limits of detection in milk and eggs
were 0.01 μg/mL and 0.01 μg/g, respectively. The total time required for the analysis of one sample was less than 20 min.
Received: 7 October 1998 / Revised: 29 December 1998 / Accepted: 30 December 1998 相似文献
19.
Andrei Blasko Alana Leahy-Dios William O. Nelson Steven A. Austin Robert B. Killion Gary C. Visor Ian J. Massey 《Monatshefte für Chemie / Chemical Monthly》2001,132(7):789-798
Summary. The kinetic and thermodynamic solubilities of Roche (Ro) pharmaceutical compounds were determined by HPLC, titrimetry, and UV/Vis spectroscopy in aqueous buffers and in non-buffered
systems. For kinetic solubility, a turbidimetric method that allows the rapid determination of solubilities using small amounts
of compounds (5–50 mg) was used. Two types of precipitation were observed during the kinetic solubility determinations: i) a disperse precipitation where the solution became foggy with very small particles uniformly distributed in the solution,
and ii) discrete precipitation characterized by formation of crystals that rapidly sediment. The thermodynamic solubility was determined
by shake flask and titrimetrically using a pH-STAT. The pH-STAT titrimetric method for the pH-thermodynamic solubility profile determination eliminates the buffer species and represents a new way to approach the solubility
characterization of pharmaceutical compounds. The strengths of the turbidimetric method for determining the kinetic solubility
are its rapidity, minimal compound requirements, and suitability for high throughput screening. The limitations are that the
maximum solubility is limited to less than 100 mg · cm−3, and the precipitation of trace impurities cannot be distinguished from precipitation of the analyte. The pH-STAT titrimetric approach for the thermodynamic solubility has a lower throughput and is suitable for the characterization
of the lead candidate. It is not limited in its solubility range and provides a common basis for the comparison of the solubility
values at different pH values in contrast to traditional buffered systems.
Received August 21, 2000. Accepted (revised) February 5, 2001 相似文献
20.
M. Colli A. Gironi V. Molina R. Marchetti G. Melzi D'Eril C. Lucarelli 《Chromatographia》1991,32(3-4):113-115
Summary This work describes an HPLC method for the determination of formaldehyde concentration in air. Traps containing 20–40 mesh
silica gel coated with 2,4-dinitrophenylhydrazine (DNPH) are used. After aspiration of air the traps are eluted with methanol.
The hydrazone formed is then separated on a C18 column using a mobile phase of methanolwater (50–50 v/v). The effluent is
monitored with a UV detector at 365 nm.
To calibrate and to compare this method with that of Niosh 2502 (traps coated with 2 benzylamino ethanol on Chromosorb 102),
a mixing chamber that generated atmospheres of known concentration of formaldehyde was used. 相似文献