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1.
Thin-layer chromatography (TLC) of three cationic surfactants was performed on silica TLC plates with various solvent systems.
The mutual separation of cetylpyridinium chloride (CPC), tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium
bromide (DTAB) was achieved on silica TLC plates with ethanol: 1% aqueous ammonium chloride (4:6, v/v) as an eluent. Effects of cations and anions in the mobile phase on mobility and separation of CPC, TTAB and DTAB were examined.
The interference due to the presence of metal cations as impurities on the resolution in the mixture of CPC, TTAB and DTAB
was also examined. The limits of detection of CPC, TTAB and DTAB estimated were 0.015, 0.031 and 0.062 μg zone−1, respectively. The developed method was utilized to identify these surfactants in different spiked water samples after their
preliminary separation. 相似文献
2.
Katrin M. Kirschbaum Susann Finger Friederike Vogel Rainer Burger Manfred Gerlach Peter Riederer Christoph Hiemke 《Chromatographia》2008,67(3-4):321-324
An automated high performance liquid chromatography with column-switching and ultraviolet detection was developed for the
analysis of risperidone and 9-hydroxyrisperidone. The method needs minimum sample preparation and is useful for the detection
down to a limit of 1 ng mL−1. Sample clean-up of serum was carried out on a CN 20 μm SPE-column using 8% (v/v) acetonitrile in water. Chromatographic separation was performed on ODS Hypersil C18 material with 38% (v/v) acetonitrile and 0.4% (v/v) TEMED in water. Application of the method to the analysis of serum samples confirmed its suitability for therapeutic drug
monitoring of risperidone and 9-hydroxyrisperidone. 相似文献
3.
Kiran A. Thabaj Deepak S. Munavalli Shivamurti A. Chimatadar Sharanappa T. Nandibewoor 《Transition Metal Chemistry》2007,32(7):902-912
The micro amounts of iodide (10−7) (mol dm−3) and chloride (10−2) (mol dm−3) mediated oxidation of antimony(III) by cerium(IV) in an aqueous sulphuric acid medium have been studied spectrophotometrically
at 25 °C and μ = 3.10 mol dm−3. The stoichiometry is 1:2 in chloride and iodide mediated reactions. i.e. one mole of antimony(III) requires two moles of cerium(IV). In the case of chloride mediated reaction, the reaction was
first order in cerium(IV) and halide concentrations, whereas in the case of iodide mediated reaction the order with respect
to [cerium(IV)] was unity and with respect to iodide concentrations was more than unity (ca. 1.4). In both chloride and iodide mediated reactions the order with respect to antimony(III) concentrations was less than
unity. Increase in sulphuric acid concentration increased the rate. The order with respect to H+ ion concentration was less than unity. Added products, cerium(III) and antimony(V) did not have any significant effect on
the reaction rate. The active species of oxidant was understood to be
, whereas that of reductant as SbCl3 in the case of chloride and SbI2+ in case of iodide mediated reactions. The possible reaction mechanisms were proposed and the activation parameters were determined
and discussed. 相似文献
4.
M. E-S. Metwally 《Chromatographia》1999,50(1-2):113-117
Summary A high performance liquid chromatographic method has been developed for the simultaneous determination of chlorpheniramine
maleate (CPM), methscoplamine nitrate (MSN) and phenylephrine hydrochloride (PEH) in sustained release capsules. The separation
was carried out on a reverse-phase CN-column with use of a mobile phase consisting of 70% (v/v) solution of acetonitrile in water containing 2% (v/v) acetic acid and 0.005M sodium 1-hepatane sulfonate at a flow rate of 2 mL min−1. The eluted peaks were detected at 262 nm. The method is sensitive, accurate and rapid and can be used in the routine analysis
of the mixture of the three compounds. 相似文献
5.
Simplified liquid-chromatographic determination of residues of tetracycline antibiotics in eggs 总被引:2,自引:0,他引:2
N. Furusawa 《Chromatographia》2001,53(1-2):47-50
Summary A high-performance liquid chromatographic (HPLC) procedure is described for the identification and quantification of residues
of tetracycline antibiotics (TCA) (oxytetracycline, tetracycline, chlortetracycline, and doxycycline), in eggs. Spiked and
blank samples were prepared by homogenization with 1∶1 (v/v) acetonitrile-mixed Mcllvaine buffer and EDTA solution (pH 4.0) then centrifugal ultrafiltration. HPLC was performed on a
reversed-phase column with acetonitrile-5% (v/v) aqueous acetic acid, 35∶65 (v/v), as mobile phase and photo-diode array detection. Average recoveries (each drug spiked at 0.1, 0.2, 0.3, 0.5 and 1.0 μg
g−1) were >-77% with standard deviations (SD) between 1.5 and 3.5%. The inter-assay variabilities and theirSD were <3.4% and <0.7%, respectively, and intra-assay variability was between 2.0 and 3.9%. The limits of quantitation (LOQ) were 0.064 0.087, 0.121, and 0.131 μg g−1 for OTC, TC, CTC, and DC, respectively. The total time required for the analysis of one sample was less than 30 min. 相似文献
6.
Determination of Abamectin Residues in Avocados by Microwave-Assisted Extraction and HPLC with Fluorescence Detection 总被引:1,自引:0,他引:1
Javier Hernández Borges Lidia M. Ravelo-Pérez Estrella M. Hernández-Suárez Aurelio Carnero Miguel Ángel Rodríguez-Delgado 《Chromatographia》2008,67(1-2):69-75
In this article a new analytical method for the confirmation and quantification of abamectin residues in avocados is described.
The method allows a fast analysis of abamectin homologues using microwave assisted extraction (MAE), solid-phase extraction
(SPE) and high-performance liquid chromatography (HPLC) with fluorescence (FL) detection using trifluoroacetic anhydride (TFAA)
and N-methylimidazole (NMIM) as derivatizing agents. The mobile phase consisted of water, methanol and acetonitrile (5:47.5:47.5
v/v/v) and was pumped at a rate of 1.1 mL min−1 (isocratic elution). Homogenized avocado samples were extracted once with 20 mL acetonitrile:water 4:1 (v/v) in a microwave oven for 26 min at 700 W with a maximum temperature of 80 °C. MAE operational parameters were optimized by
means of an experimental design. Extracts were cleaned using C18 SPE cartridges. Average recoveries of the method at four spiked levels (0.005, 0.01, 0.10 and 1.0 mg kg−1) were found to be in the range 90–100% with good precision (RSD < 12%). The limits of detection (LODs) and quantification
(LOQs) of the whole method were 0.001 and 0.003 mg kg−1, respectively, which are lower than the maximum residue limit (MRL) established by the Spanish and the European legislation
in avocados (0.01 mg kg−1). Several avocado samples previously treated with the pesticide were also analyzed. 相似文献
7.
A high performance liquid chromatographic method was developed and validated for the quantitative determination of carbamazepine
in intravenous nanoemulsions. The method validation yielded good results with respect to linearity, specificity, precision
and accuracy. The method was carried out on a RP-18 column with a mobile phase composed of methanol–water (70:30 v/v) subjected to a gradient of acetonitrile after drug elution, and detection at 286 nm. The linearity in the range of 10.0–50.0 μg mL−1 presented a determination coefficient (r
2) of 0.9996, calculated by least-squares regression; the RSD values for intra-day and inter-day precision for % recovered
were <0.44 and <1.21%, respectively; and the recovery of carbamazepine from the sample matrix ranged from 94.3 to 104.9%. 相似文献
8.
The analysis of four nitrofuran veterinary drugs, nitrofurantoin, furazolidone, furaltadone and nitrofurazone, was optimized
using reversed-phase liquid chromatography with a monolithic column and photo-diode array detection. The antibiotics were
extracted from animal feeds by heating with acetonitrile. The isocratic mobile phase consisted of a 8:92 (v/v) acetonitrile/phosphate buffer (pH 4.5) at a flow-rate of 1 mL min−1. Peaks were identified by the retention characteristics and UV spectra. Detection limits in the water samples ranged between
0.21 and 0.27 μg L−1, and in the feed samples between 2.1 and 2.7 μg kg−1, depending on the nitrofuran. The procedure was applied to the control of nitrofuran residues in farm water for poultry and
different animal feeds. 相似文献
9.
A high-performance liquid chromatographic method with triple-quadrupole mass spectrometry detection (LC-MS-MS) was developed
and validated for the first time for the simultaneous quantification of zopiclone and its metabolites in rat plasma samples.
The analytes were isolated from rat plasma by liquid–liquid extraction and separated using a chiral stationary phase based
on an amylose derivative, Chiralpak ADR-H column, and ethanol–methanol–acetonitrile (50:45:5, v/v/v) plus 0.025% diethylamine as the mobile phase, at a flow-rate of 1.0 mL min−1. Moclobemide was used as the internal standard. The developed method was linear over the concentration range of 7.5–500 ng mL−1. The mean absolute recoveries were 74.6 and 75.7; 61.6 and 56.9; 72.5, and 70.7 for zopiclone enantiomers, for N-desmethyl zopiclone enantiomers and for zopiclone-N-oxide enantiomers, respectively, and 75.9 for the internal standard. Precision and accuracy were within acceptable levels
of confidence (<15%). The method application in a pilot study of zopiclone kinetic disposition in rats showed that the levels
of (+)-(S)-zopiclone were always higher than those of (−)-R-zopiclone. Higher concentrations were also observed for (+)-(S)-N-desmethyl zopiclone and (+)-(S)-N-oxide zopiclone, confirming the stereoselective disposition of zopiclone. 相似文献
10.
The use of ion exchangers in flow-injection systems is reviewed briefly. In the method described, halides are separated on a short column of a strongly basic ion-exchange resin (Dowex 1-X8) placed in the flow-injection conduit, with a laboratory-made tubular silver/silver halide ion-selective electrode as potentiometric sensor. The response capabilities of the different halide-selective electrodes to a wide concentration range (20-5000 mg dm?3) of single and mixed halide solutions with and without the incorporated ion-exchange column are compared. By careful selection of suitable concentrations of the potassium nitrate carrier/eluent stream to satisfy the requirements of both the ion-exchange column and the halide-selective electrode, it is possible to separate and determine chloride, bromide and iodide in mixed halide solutions with a detection limit of 5 mg dm?3. The bromide-selective electrode is the most satisfactory detector. 相似文献
11.
《Analytical letters》2012,45(6):513-522
Abstract Bromide, iodide, and chloride are extracted from aqueous solutions into toluene-alcohol solutions of tetraheptyl-ammonium carbonate. The tetraheptylammonium halides undergo thermal degradation to 1-haloheptanes and triheptylamine. On-column preparation of the haloheptanes is achieved above 150°C. The halocarbons produce gas chromatographic peaks which are used for quantitative analysis of bromide, chloride, and iodide at low ppm levels. 相似文献
12.
The corrosion and corrosion inhibition effect of carboxymethyl cellulose (CMC) for mild steel in sulphuric acid medium was
investigated using chemical (weight loss and hydrogen evolution) techniques at 30–60 °C. The effect of addition of halide
ions (Cl−, Br−, and I−) was also studied. It was found that CMC functions as an inhibitor for acid induced corrosion for mild steel. Inhibition
efficiency increases with increase in immersion time but decreases with increase in temperature. Addition of halide ions reveals
that chloride ions (Cl−) antagonize the inhibition process whereas iodide ions (I−) exert synergistic effect on the corrosion inhibition by CMC. Corrosion inhibitive effect was afforded by adsorption of CMC
molecules onto the mild steel surface both in the absence and presence of halide ions which was found to follow Langmuir adsorption
isotherm model. The phenomenon of physical adsorption is proposed from decrease in inhibition efficiency with increase in
temperature. The inhibition mechanism was further corroborated by the values of thermodynamic and kinetic parameters obtained
from the experimental data. 相似文献
13.
A simple, precise, and accurate HPLC method has been developed and validated for assay of ezetimibe in tablets and for determination
of content uniformity. Reversed-phase liquid chromatographic separation was achieved by use of phosphoric acid (0.1%, v/v)–acetonitrile 50:50 (v/v) as mobile phase. The method was validated for specificity, linearity, precision, accuracy, robustness, and solution stability.
The specificity of the method was determined by assessing interference from the placebo and by stress testing of the drug
(forced degradation). Response was a linear function of drug concentration in the range 20–80 μg mL−1 (r = 0.9999). Intraday and interday system and method precision were determined. Accuracy was between 100.8 and 102.7%. The
method was found to be robust, and was suitable for assay of ezetimibe in a tablet formulation and for determination of content
uniformity.
An erratum to this article can be found at 相似文献
14.
Viñas P López-García I Bravo-Bravo M Briceño M Hernández-Córdoba M 《Analytical and bioanalytical chemistry》2012,403(4):1059-1066
A miniaturized dispersive liquid–liquid microextraction (DLLME) procedure coupled to liquid chromatography (LC) with fluorimetric
detection was evaluated for the preconcentration and determination of thiamine (vitamin B1). Derivatization was carried out by chemical oxidation of thiamine with 5 × 10−5 M ferricyanide at pH 13 to form fluorescent thiochrome. For DLLME, 0.5 mL of acetonitrile (dispersing solvent) containing
90 μL of tetrachloroethane (extraction solvent) was rapidly injected into 10 mL of sample solution containing the derivatized
thiochrome and 24% (w/v) sodium chloride, thereby forming a cloudy solution. Phase separation was carried out by centrifugation, and a volume of
20 μL of the sedimented phase was submitted to LC. The mobile phase was a mixture of a 90% (v/v) 10 mM KH2PO4 (pH 7) solution and 10% (v/v) acetonitrile at 1 mL min−1. An amide-based stationary phase involving a ligand with amide groups and the endcapping of trimethylsilyl was used. Specificity,
linearity, precision, recovery, and sensitivity were satisfactory. Calibration graph was carried out by the standard additions
method and was linear between 1 and 10 ng mL−1. The detection limit was 0.09 ng mL−1. The selectivity of the method was judged from the absence of interfering peaks at the thiamine elution time for blank chromatograms
of unspiked samples. A relative standard deviation of 3.2% was obtained for a standard solution containing thiamine at 5 ng mL−1. The esters thiamine monophosphate and thiamine pyrophosphate can also be determined by submitting the sample to successive
acid and enzymatic treatments. The method was applied to the determination of thiamine in different foods such as beer, brewer’s
yeast, honey, and baby foods including infant formulas, fermented milk, cereals, and purees. For the analysis of solid samples,
a previous extraction step was applied based on an acid hydrolysis with trichloroacetic acid. The reliability of the procedure
was checked by analyzing a certified reference material, pig’s liver (CRM 487). The value obtained was 8.76 ± 0.2 μg g−1 thiamine, which is in excellent agreement with the certified value, 8.6 ± 1.1 μg g−1. 相似文献
15.
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
16.
A novel molecularly imprinted polymer solid-phase extraction (MISPE) with flow-injection chemiluminescence (CL) was developed
for the determination of pazufloxacin mesilate (PZFX). The molecularly imprinted polymer (MIP) was synthesized by using PZFX
as the imprinting molecule. A glass tube packed the particles of the MIP was employed as MISPE micro-column, which was connected
into the sampling loop of the eight-way injection valve for on-line selective preconcentration and extraction of PZFX. The
eluent of acetonitrile:acetic acid (9:1, v:v) was used as carrier for eluting the adsorbed PZFX to react with the mixture
of cerium(IV) and sodium sulfite in the flow cell to produce strong CL. The relative intensity of CL was linear to PZFX concentration
in the range from 2.5 × 10−9 to 2.5 × 10−7 g mL−1. The limit of detection was 7 × 10−10 g mL−1 (3 σ) and the relative standard deviation for 5 × 10−8 g mL−1of PZFX solution was 3.7% (n = 7). This method has been applied to the determination of PZFX in human urine. 相似文献
17.
Letícia Flores da Silva Martins Pedro Eduardo Froehlich Ana Maria Bergold 《Chromatographia》2009,69(Z2):109-113
A sensitive and rapid liquid chromatographic method was successfully developed and validated for the determination of sibutramine
hydrochloride in bulk and capsules. Sibutramine in the presence of its degradation products was analyzed using UV detection
at 225 nm. Chromatography was performed on a reversed-phase C8 (150 × 4.0 mm I.D., 5 μm) analytical column under isocratic conditions. The mobile phase was composed of acetonitrile:water
(aqueous phase containing 0.3% triethylamine and pH adjusted to 7.0) (75:25, v/v) at a flow-rate of 1.1 mL min−1. No chromatographic interference was found during the analysis. Light was the stress condition which most contributed to
sibutramine degradation. The method showed a linear response (r > 0.999) from 30 to 90 μg mL−1. The mean recovery for capsules was 101.2%. Inter-day assays showed relative standard deviations of 0.42 and 1.62% for bulk
and capsules, respectively. The developed method is able to separate sibutramine from its major degradation products and it
may be used in the quality control of this active pharmaceutical ingredient in both bulk and capsules. 相似文献
18.
In the present study, a rapid and sensitive LC-ESI-MS/MS method for quantification of (S)-fluoxetine as a native marker in mass spectrometry (MS) binding assays addressing the human serotonin transporter (hSERT)
was developed and validated. The concept of MS binding assays based on mass spectrometric quantification of a nonlabeled marker
recently introduced by us represents a promising alternative to conventional radioligand binding without the drawbacks inherently
connected with radioisotope labeling. For high-performance liquid chromatography (HPLC), a 20 × 2-mm RP-18 column with a mobile
phase composed of acetonitrile and ammonium bicarbonate buffer (5 mmol L−1, pH 9.5) at a ratio of 80:20 (v/v) and a flow rate of 800 μL min−1 in an isocratic mode were used, resulting in a chromatographic cycle time of 60 s. Employing [2H5]fluoxetine as internal standard enabled ESI-MS/MS quantification of (S)-fluoxetine between 3 nmol L−1 and 50 pmol L−1 (LLOQ) in matrix obtained from binding experiments without the need of any sample preparation. Validation of the method showed
that linearity, intra-, and inter-batch accuracy as well as precision meet the requirements of the FDA guidance for bioanalytical
method validation. Considering sensitivity and speed, the established method is clearly superior to those published for biological
matrices so far. Furthermore, the method was transferred to other RP-18 columns of different lengths and respective validation
experiments demonstrated its versatility and chromatographic robustness. Finally, the newly developed method was successfully
applied to MS binding assays for hSERT. The affinity determined for (S)-fluoxetine in saturation experiments was in good agreement with literature data obtained in respective radioligand binding
assays. 相似文献
19.
Summary An improved LC method is described for the separation of oxytetracycline and its impurities. The separation is much better
than that obtained with official pharmacopoeia methods. The method uses XTerra RP-18, 5 μm (25cm×4.6 mm I.D.), a silica-based
stationary phase with methyl end-capping, claimed to reduce silanol activity. The column temperature is set at 30°C and a
UV detection is performed at 280 nm. Mobile phase containing acetonitrile −0.25 M tetrabutylammonium hydrogen sulfate pH 7.5−0.25
M ethylenediaminetetraacetic acid pH 7.5-water (115:360:160:365,v/v/v/v) is used at a flow rate of 1.0 mL.min−1, to separate the impurities present in oxytetracycline base. A central composite experimental design is used to optimize
the separation. A second isocratic method with higher content of acetonitrile is needed to separate the more retained impurities
present only in oxytetracycline hydrochloride. The method is robust and shows good selectivity, repeatability, linearity and
sensitivity. 相似文献
20.
W. Earle Waghorne 《Monatshefte für Chemie / Chemical Monthly》2003,29(2):655-667
The solubilities of the silver halides in three non-aqueous solvents: methanol, acetonitrile, and dimethylsulfoxide, and
in their aqueous mixtures, are reviewed. Values for the solubility product, K
SO
, the enthalpies of solution, Δ
sol
H
o
, and the equilibrium products for AgX
(i−1)−
i
silver halide complexes, β
i
, are listed and, where possible, compared. The solvent systems provide examples for three types of mixed aqueous solvent
system: aqueous alcohol mixtures and aqueous mixtures with dipolar aprotic solvents that are weakly or strongly basic. The
experimental data are discussed in terms of the solvation of the silver and halide ions in the mixed solvents. 相似文献