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1.
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
2.
Capitán-Vallvey LF Valencia MC Arana Nicolás E García-Jiménez JF 《Analytical and bioanalytical chemistry》2006,385(2):385-391
An integrated solid-phase spectrophotometry–FIA method is proposed for simultaneous determination of the mixture of saccharin
(1,2-benzisothiazol-3(2H)-one-1,1-dioxide; E-954) (SA) and aspartame (N-l-α-aspartyl-l-phenylalanine-1-methyl ester; E-951) (AS). The procedure is based on on-line preconcentration of AS on a C18 silica gel minicolumn and separation from SA, followed by measurement, at λ=210 nm, of the absorbance of SA which is transiently retained on the adsorbent Sephadex G-25 placed in the flow-through cell
of a monochannel FIA setup using pH 3.0 orthophosphoric acid–dihydrogen phosphate buffer, 3.75×10–3 mol L−1, as carrier. Subsequent desorption of AS with methanol enables its determination at λ=205 nm. With a sampling frequency of 10 h−1, the applicable concentration range, the detection limit, and the relative standard deviation were from 1.0 to 200.0 μg mL−1, 0.30 μg mL−1, and 1.0% (80 μg mL−1, n=10), respectively, for SA and from 10.0 to 200.0 μg mL−1, 1.4 μg mL−1, and 1.6% (100 μg mL−1, n=10) for AS. The method was used to determine the amounts of aspartame and saccharin in sweets and drinks. Recovery was always
between 99 and 101%. The method enabled satisfactory determination of blends of SA and AS in low-calorie and dietary products
and the results were compared with those from an HPLC reference method. 相似文献
3.
Rajiv Dahiya 《Chemical Papers》2008,62(5):527-535
Plant-originated cyclopolypeptide (XIII) was synthesized by coupling of dipeptide Boc-l-asn(bzh)-l-phe-OH and tetrapeptide gly-l-leu-l-ala-l-tyr-OMe followed by cyclization of a linear hexapeptide segment. Structure elucidation of XIII was done on basis of detailed spectral analysis including FTIR, 1H NMR, 13C NMR, FAB MS and elemental analysis. From the results of pharmacological screening, it was concluded that XIII possesses high cytotoxic activity against DLA and EAC cell lines with CTC50 values of 15.1 μM and 18.6 μM, and potent antimicrobial activity against pathogenic fungi C. albicans with MIC of 6 μg mL−1. Moreover, XIII possesses moderate anthelmintic activity against earthworms M. konkanensis, P. corethruses, and Eudrilus sp. at 2 mg mL−1 dose level. 相似文献
4.
Qing Li Liang Xu Ting-Ting Wang Ying Jia Zhi-Wei Wang Kai-Shun Bi 《Chromatographia》2008,67(7-8):627-631
Aidi injection is a clinical medicine used in China for the treatment of cancer. Calycosin-7-O-β-d-glucoside is the main effective components of the formulas. In this study, a high performance liquid chromatographic (LC)
method was developed to quantify calycosin-7-O-β-d-glucoside in rat plasma using a liquid–liquid extraction and ultraviolet (UV) absorbance detection. LC analysis was performed
on a Diamonsil C18 column (200 × 4.6 mm i.d., 5 μm particle size) with isocratic mobile phase consisting of acetonitrile–0.05% phosphoric acid
(19.5:80.5, v/v) of a flow rate of 1.0 mL min−1. The linear range was 0.11–17.6 μg mL−1 and the low quantification limit was 0.11 μg mL−1 (S/N = 10). The intra- and inter-day relative standard deviations (RSD) in the measurement of quality control (QC) samples
0.11, 0.22, 1.32 and 8.80 μg mL−1 ranged from 4.1 to 6.3 and 4.3 to 6.2%, respectively. The accuracy was from −6.7 to 4.3% in terms of relative error (RE).
Calycosin-7-O-β-d-glucoside was stable in storage at −20 °C for 2 weeks and stable after three freeze–thaw cycles in rat plasma. This method
was validated for specificity, accuracy, precision and was successfully applied to pharmacokinetic study of calycosin-7-O-β-d-glucoside in rat plasma after intravenous administration of Aidi lyophilizer. 相似文献
5.
Summary The effect of perchlorate anion as mobile phase modifier on the separation factor, α, forN-(dansyl)-dl-norvaline andN-(dansyl)-dl-tryptophan on a human serum albumin (HSA) column was studied by varying the concentration,c, of the chaotropic agent and the column temperatureT. Gibbs-Helmholtz parameters Δ(ΔH) and Δ(ΔS) between thed andl enantiomers were determined from linear van't Hoff plots of lnα against 1/T. Thermodynamic results indicated that the enhancement of the separation factor observed asc was increased was enthalpically controlled owing to stereoselective H-bonding interactions. Such behavior was used to optimize
the chromatographic conditions for separation ofN-(dansyl)-amino acids on HSA. 相似文献
6.
Lingli Zhang Yi Chen Mei Lin Guorong Fan Weiquan Zhao Yutian Wu 《Chromatographia》2007,65(5-6):305-311
The quick separation and simultaneous determination of d-amphetamine and diphenhydramine in the quick-acting anti-motion capsules was investigated by capillary zone electrophoresis.
The influence of different parameters (internal standard, injection modes, pH, concentration of the running buffer and applied
voltage) was systematically studied. The two compounds could be well separated within 2.0 min in a 40.2 cm fused-silica capillary
at a separation voltage of 20 kV in a 50 mM phosphate–12.5 mM borate buffer adjusted to pH 5.5. Correlation coefficients for
calibration curves in the range 0.50–1.50 μg mL−1 for d-amphetamine and 2.75–8.25 μg mL−1 for diphenhydramine were higher than 0.999. The limits of detection of d-amphetamine and diphenhydramine were 10.0 and 5.5 ng mL−1 and the recoveries of the compounds in the QAAMC were 99.80 and 99.85%, respectively.
The authors L. Zhang and Y. Chen equally contributed to this work. 相似文献
7.
Summary A sensitive HPLC method with marbofloxacin (MAR) as internal standard and fluorescence detection is described for the analysis
of ofloxacin (OFL) enantiomers in plasma samples. Plasma samples were prepared by adding phosphate buffer (pH 7.4, 0.1m), then extracted with trichloromethane.S-OFL,R-OFL, and the internal standard were separated on a reversed-phase column with water-methanol, 85.5∶14.5, as mobile phase.
The concentrations ofS-OFL andR-OFL eluting from the column (retention times 7.5 and 8.7 min, respectively) were monitored by fluorescence detection withλ
ex = 331 andλ
em = 488 nm. The detection and quantitation limits were 10 and 20 ng mL−1, respectively, forS-OFL and 11 and 21 ng mL−1 forR-OFL. Response was linearly related to concentration in the range 10 to 2500 ng mL−1. Recovery was close to 93% for both compounds. The method was applied to determination of the enantiomers of OFL in plasma
samples collected during pharmacokinetic studies. 相似文献
8.
The polymerization of o-phenylenediamine (OPD) on l-tyrosine (Tyr) functionalized glassy carbon electrode (GCE) and its electro-catalytic oxidation towards ascorbic acid (AA)
had been studied in this report. l-Tyrosine was first covalently grafted on GCE surface via electrochemical oxidation, which was followed by the electrochemical
polymerization of OPD on the l-tyrosine functionalized GCE. Then, the poly(o-phenylenediamine)/l-tyrosine composite film modified GCE (POPD-Tyr/GCE) was obtained. X-ray photo-electron spectroscopy (XPS), field emission
scanning electron microscope (SEM), and electrochemical techniques have been used to characterize the grafting of l-tyrosine and the polymerization and morphology of OPD film on GCE surface. Due to the doping of the carboxylic functionalities
in l-tyrosine molecules, the POPD film showed good redox activity in neutral medium, and thus, the POPD-Tyr/GCE exhibited excellent
electrocatalytic response to AA in 0.1 mol l−1 phosphate buffer solution (PBS, pH 6.8). The anode peak potential of AA shifted from 0.58 V at GCE to 0.35 V at POPD-Tyr/GCE
with a greatly enhanced current response. A linear calibration graph was obtained over the AA concentration range of 2.5 × 10−4–1.5 × 10–3 mol l−1 with a correlation coefficient of 0.9998. The detection limit (3δ) for AA was 9.2 × 10−5 mol l−1. The modified electrode showed good stability and reproducibility and had been used for the determination of AA content in
vitamin C tablet with satisfactory results. 相似文献
9.
L. M. Likhosherstov O. S. Novikova A. O. Zheltova V. N. Shibaev 《Russian Chemical Bulletin》2000,49(8):1454-1459
A convenient preparative procedure was developed for the synthesis ofN-glycyl-β-glycopyranosylamines, derivatives of monosaccharides (d-galactose,d-mannose,l-fucose, andN-acetyl-d-glucosamine) and disaccharides (lactose, melibiose, cellobiose, and maltose). These compounds were demonstrated to be useful
for the preparation of glycoconjugates of biologically active compounds containing the carboxy group (nicotinic, orotic, kynurenic,
and indoleacetic acids). Synthetic pathways were developed for conversions ofN-glycyl-β-glycopyranosylamines into derivatives containing the carboxy group with the use of malonic andl-tartaric acid derivatives.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1461–1466, August, 2000. 相似文献
10.
A kind of erbium hexacyanoferrate (ErHCF)-modified carbon ceramic electrodes (CCEs) fabricated by mechanically attaching ErHCF
samples to the surface of CCEs derived from sol–gel technique was proposed. The resulting modified electrodes exhibit well-defined
redox responses with the formal potential of +0.215 V [vs saturated calomel electrode (SCE)] at a scan rate of 20 mV s−1 in 0.5 M KCl (pH 7) solution. The voltammetric characteristics of the ErHCF-modified CCEs were investigated by voltammetry.
Attractively, the ErHCF-modified CCEs presented good electrocatalytic activity with a marked decrease in the overvoltage about
400 mV for l-cysteine oxidation. The calibration plot for l-cysteine determination was linear at 5.0 × 10−6–1.3 × 10−4 M with a linear regression equation of I(A) = 0.558 + 0.148c (μM) (R
2 = 0.9989, n = 20), and the detection limit was 2 × 10−6 M (S/N = 3). At last, the ErHCF-modified CCEs were used for amperometric detection of l-cysteine in real samples. 相似文献
11.
A stability-indicating reversed-phase liquid chromatographic (RPLC) method has been established for analysis of ramipril (RAM)
and moexipril hydrochloride (MOEX.HCl) in the presence of the degradation products generated in studies of forced decomposition.
The drug substances were subjected to stress by hydrolysis (0.1 m NaOH and 0.1 m HCl), oxidation (30% H2O2), photolysis (254 nm), and thermal treatment (80 °C). The drugs were degraded under basic and acidic conditions and by thermal
treatment but were stable under other stress conditions investigated. Successful separation of the drugs from the degradation
products was achieved on a cyanopropyl column with 40:60 (v/v) aqueous 0.01 m ammonium acetate buffer (pH 6)–methanol as mobile phase at a flow rate of 1 mL min−1. Detection was by UV absorption at 210 nm. Response was a linear function of concentration over the range 5–50 μg mL−1 (r > 0.9995), with limits of detection and quantitation (LOD and LOQ) of 0.04 and 0.09 μg mL−1, respectively, for RAM and 0.014 and 0.32 μg mL−1, respectively, for moexipril. The method was validated for specificity, selectivity, solution stability, accuracy, and precision.
Statistical analysis proved the method enabled reproducible and selective quantification of RAM and MOEX as the bulk drug
and in pharmaceutical preparations. Because the method effectively separates the drugs from their degradation products, it
can be used as stability-indicating. 相似文献
12.
Li C Wen D Zhang J Chen Z Cong W Rao Z Liu H 《Analytical and bioanalytical chemistry》2006,386(7-8):1985-1993
Metabolism of four tobacco-specific N-nitrosamines (TSNAs), N′-nitrosonornicotine (NNN), N′-nitrosoanatabine (NAT), N′-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been studied by solid-phase extraction
(SPE) and liquid chromatography–tandem mass spectrometry (LC–MS–MS). 4-(Methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL)
was used as internal standard. SPE and LC–MS–MS was found to be a rapid, simple, sensitive, and selective method for analysis
of TSNAs in rabbit serum. The relative standard deviation (R.S.D., n = 6) for analysis of 5 ng mL−1 and 0.5 ng mL−1 standards and of serum sample spiked with 5 ng mL−1 standards of five TSNAs was 2.1–11% and recovery of 5 ng mL−1 standards from serum was 100.2–112.9%. A good linear relationship was obtained between peak area ratio and concentration
in the range of 0.2–100 ng mL−1 for NNAL and 0.5–100 ng mL−1 for other four TSNAs, with correlation coefficients (R
2) >0.99 (both linear and log–log regression). Detection limits for standards in solvent were between 0.04 and 0.10 ng mL−1. Doses of TSNAs administered to rabbits via the auricular vein were 4.67 μg kg−1 and 11.67 μg kg−1, in accordance with the different levels in cigarettes. Metabolic curves were obtained for the four TSNAs and for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol
(NNAL), a metabolite of NNK; on the basis of these curves we modeled metabolic kinetic equations for these TSNAs by nonlinear
curve fitting. 相似文献
13.
Summary A method was developed for the separation and quantification of the warfare nerve agent sarin (O-isopropylmethylphosphonoflouridate), its metabolite methylphosphonic acid, the anti nerve agent drug pyridostigmine bromide
(PB;3-dimethylaminocarbonyloxy-N-methyl pyridinium bromide) and its metaboliteN-methyl-3-hydroxypyridinium bromide in rat plasma and urine. The method involved using solid phase extraction and high performance
liquid chromatography (HPLC) with reversed phase C18 column, and UV detection at 280 nm. The compounds were separated using gradient of 1% to 55% acetonitrile in 0.1% triflouroacetic
acid water solution (pH 3.20) at flow rate of 0.9 ml/min in a period of 15 min. The retention times ranged from 4.4–12.1 min.
The limits of detection were 50 ng mL−1 for PB andN-methyl-3-hydroxypyridinium bromide, and 10 μg mL−1 for sarin and methylphosphonic acid, while limits of quantitation were between 100 ng mL−1–12 μg mL−1. Average percentage recovery of five spiked samples from plasma were 84.6±8.4, 86.5±9.0, 76.4±8.5, 81.3±8.2, and from urine
78.5±7.9, 76.4±7.8, 74.4±8.4, 80.6±6.8 for sarin, methylphosphonic acid, pyridostigmine bromide andN-methyl-3-hydroxypyridinium bromide, respectively. This method was applied to analyze the above chemicals and metabolites
following combined administration in rats. 相似文献
14.
A method for the simultaneous determination of N-methyl-2-pyrrolidone (NMP) and its metabolites 5-hydroxyl-N-pyrrolidone (5HNMP), N-methylsuccinimide (MSI) and 2-hydroxy-N-methylsuccinimide (2HMSI) in plasma and urine has been developed. Samples were purified by SPE using an ASPEC XL4. Analysis
was performed using LC–MS equipped with an APCI interface. The analysis provided linear responses in the range of 0.125–12 μg
mL−1 for all of the analytes and up to 150 μg mL−1 for 5HNMP and 2HMSI. The within day precision was in the range of 0.9–19.1% for plasma samples and 1.9–10.4% for urine samples
whereas the between day precisions were 4.5–11.9% and 1.2–17.5%, respectively. The method was deemed to be suitable for monitoring
the levels of NMP and its metabolites in the plasma and urine of occupationally exposed persons. 相似文献
15.
A simple, rapid, and precise reversed-phase high-performance liquid chromatographic method has been developed for simultaneous determination of losartan potassium, ramipril, and hydrochlorothiazide. The three drugs were separated on a 150 mm × 4.6 mm i.d., 5 μm particle, Cosmosil C18 column. The mobile phase was 0.025 m sodium perchlorate–acetonitrile, 62:38 (v/v), containing 0.1% heptanesulphonic acid, pH adjusted to 2.85 with orthophosphoric acid, at a flow rate of 1.0 mL min−1. UV detection was performed at 215 nm. The method was validated for linearity, accuracy, precision, and limit of quantitation. Linearity, accuracy, and precision were acceptable in the ranges 35–65 μg mL−1 for losartan, 1.75–3.25 μg mL−1 for ramipril, and 8.75–16.25 μg mL−1 for hydrochlorothiazide. 相似文献
16.
The synthesis ofN-acetyl-β-l-fucosamine-1-phosphate and uridine 5′-diphospho-N-acetyl-β-l-fucosamine
P. A. Illarionov V. I. Torgov I. Hancock V. N. Shibaev 《Russian Chemical Bulletin》2000,49(11):1891-1894
Uridine 5′-(2-acetamido-2,6-dideoxy-β-l-galactopyranosyl) diphosphate (uridine 5′-diphospho-N-acetyl-β-l-fucosamine) was synthesized. The key intermediate, 3,4-di-O-acetyl-2-azido-2,6-dideoxy-β-l-galactopyranosyl dibenzyl phosphate, was prepared by a previously unknown reaction of cesium dibenzyl phosphate with the
corresponding α-glycosyl nitrate and was then converted into theN-acetylated glycosyl phosphate and nucleoside diphosphate sugarsvia 3,4-di-O-acetyl-2-amino-2,6-dideoxy-β-l-galactopyranosyl phosphate using mildN-acetylation andO-deacetylation as the last synthetic steps.
Published inIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 1919–1923, November, 2000. 相似文献
17.
Application of l-cysteine-capped nano-ZnS as a fluorescence probe for the determination of proteins 总被引:1,自引:0,他引:1
Zhu CQ Zhao DH Chen JL Li YX Wang le Y Wang L Zhou YY Zhuo SJ Wu YQ 《Analytical and bioanalytical chemistry》2004,378(3):811-815
Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With =190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 g mL–1 for bovine serum albumin (BSA), 0.01–6.0 g mL–1 for human serum albumin (HSA), 0.05–8.0 g mL–1 for -globulin (-G), and 0.04–4.0 g mL–1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 g mL–1 BSA, 1.90% for 1.0 g mL–1 HSA, 1.65% for 1.0 g mL–1 -G, and 2.32% for 1.0 g mL–1 ovalbumin. 相似文献
18.
A sensitive and selective HPLC–UV method established for determination of picroside I in dog plasma has been used to study
the pharmacokinetics of the drug after intravenous administration of three different doses. Sample pretreatment consists in
deproteination by addition of acetonitrile; l-ascorbic acid was used to improve the stability of picroside I. The lower limit of quantification of picroside I was 0.05 μg mL−1. The recovery of the method was up to 90%. After intravenous administration to dogs picroside I was mainly distributed in
the central compartment and was rapidly eliminated from the plasma; the mean elimination half-life was 30.54 ± 4.34, 30.20 ± 3.78,
and 34.02 ± 1.88 min for doses of 2.5, 5, and 15 mg kg−1, respectively, and the respective values of AUC
0–∞ were 81.04 ± 19.95, 198.50 ± 27.77, and 586.44 ± 103.08 μg min mL−1. The different doses had no significant effect on the main pharmacokinetic data and the kinetics seemed to be linear in dosage
range 2.5–15 mg kg−1. 相似文献
19.
Summary A reversed-phase ion-pair chromatographic (RPIPC) method withN,N,N′, N′-ethylenediaminetetrakis(methylenephosphonic acid) (EDTMP) as coordinating agent has been developed for simultaneous separation
and detection of Cu(II), Fe(III), and Pb(II) ions. Response is linearly dependent on amount of sample over the range 9.52–50.8
μg mL−1 for Cu(II), 8.31–41.8 μg mL−1 for Fe(III), and 37.3–51.8 μg mL−1 for Pb(II). The method has been applied successfully to an artificial mixed-ore sample. 相似文献
20.
Summary An isocratic, reversed-phase liquid chromatographic (LC) method has been developed for the simultaneous determination of azelaic
and benzoic acids in pharmaceutical creams. The compounds were separated on a C18 column (4 μm particles); the mobile phase was methanolwater, 40∶60, containing 10mm ammonium acetate and with the pH adjusted to 5.0. Detection was performed at 220 nm. The method was validated for accuracy,
linearity, precision, and selectivity. Recoveries at levels corresponding to 80% to 120% of the declared content of the creams
ranged from 99.5 to 101.8% and from 100.4 to 102.1% for azelaic and benzoic acids, respectively. The calibration graphs were
linear in the ranges 20–1400 μg mL−1 for azelaic acid (correlation coefficient,r
1>0.99999), and 0.1–7.0 μg mL−1 for benzoic acid (r>0.99998). 相似文献