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1.
Nine widely used veterinary sulfonamide drugs were baseline separated (R s ≥1.5) in just over 4 min using a 3 × 100 mm, 1.8 μm RX-Sil column, with 9.2 % methanol in carbon dioxide, at 110 bar and 30 °C, with direct UV detection at 260 nm using a 3 mm, 2 μL tapered flow cell. Pressure drop was only 172 bar. Optimization was difficult due to the similarity in structures. Small changes in modifier concentration, temperature and pressure, each tended to improve the resolution of some peak pairs but degraded the resolution of others. There were four critical pairs, each responding differently to changes in conditions. Optimization was performed by plotting resolution between pairs as a function of modifier concentration first, temperature second, and outlet pressure third. Retention time was then minimized by changing flow rate. The estimated limit of quantitation (LOQ, S/N >10), for direct injections, was ≈200–400 ng/g of each, inadequate for regulatory requirements. Solid phase extraction (SPE) attempted to pre-concentrate samples spiked with sulfamethazine by ≈20:1. From water, the limit of detection (LOD) was ≈2.7 ng/mL with LOQ ≈9 ng/mL using UV at 260 nm. The LOD for milk was 6.2 ng/mL, and LOQ was 20.1 ng/mL. A better pre-concentration step or a more sensitive detector such as MS–MS is required. Even with these inadequacies, SFC was shown to be a feasible, faster, “greener” alternative to HPLC for the separation of these drugs. 相似文献
2.
Determination of Baicalin in Traditional Chinese Preparation by High Performance Liquid Chromatography with Chemiluminescence Detection 总被引:5,自引:0,他引:5
Er Bao LIU* Hong Qing WEI Xiu Li ZHAO Xiao Xia LI Feng Xian JIANG School of Chemistry Material Science Shanxi Normal University Linfen 《中国化学快报》2004,15(9):1067-1070
Herbal medicine, a form of complementary and alternative medicine, is becoming increasingly popular in the world1. Scutellariae radix is the root of Scutellariabaica -lensis georgi. The primary active constituent includes baicalin as follows: Clinical studies showed that baicalin exhibited therapeutic functions of antifever, moistening aridity, anti-inflammatory and detoxifying 2 and it is also an anti-abortion agent as well as can scavenge free radicals and against oxidation3. So it is… 相似文献
3.
《液相色谱法及相关技术杂志》2012,35(5):1001-1011
Abstract A rapid, specific and reproducible high-performance liquid chromatographic routine assay with electrochemical detection was developed for the determination of Oxodipine in human plasma. After extraction at alkaline pH by cyclohexane, Oxodipine and its internal standard were chromatographied on a reversed-phase column. Calibration curves were linear over a concentration range of 1–50 ng/ml with relative errors within-day or between-day not exceeding 8% at any level. The limit of detection was 30 pg injected based on a signal-to- noise ratio of 7. However, the reliable limit of quantification was 1 ng/ml using 1 ml of human plasma. A dual-electrode coulometric detector was operated in a screening mode of oxidation, providing a greater specificity and reducing background noise. This method allowed the complete follow-up of clinical pharmacokinetic studies and drug monitoring in patients. 相似文献
4.
V. G. Amelin N. M. Fedina I. V. Podkolzin A. I. Korotkov 《Journal of Analytical Chemistry》2018,73(6):576-585
A rapid screening and determination of 150 veterinary drugs of various classes in milk by UHPLC–high-resolution quadrupole time-of-flight mass spectrometry is proposed. One gram of milk was used for the analysis; the precipitation of proteins and extraction were performed with acetonitrile; the extract was analyzed without purification or preconcentration. Veterinary drugs were identified by accurate masses of analyte ions produced by electrospray ionization, their retention time, and the pattern of ion isotope distribution (mSigma). The quantitative analysis of the detected analytes was carried out by the standard addition method. The limits of detection were 0.1–0.5 ng/g; the analytical ranges were (0.1)1–500 ng/g; the duration of screening was 20–30 min; and the analysis time was 30–40 min. The relative standard deviation of the results for all analytes did not exceed 15%. 相似文献
5.
The binding of psychopharmaceutical drugs by -cyclodextrin (-CD) changed their effective electrophoretic mobilities. Based on this phenomenon the interactions between some psychopharmaceutical drugs and -cyclodextrin were studied and the binding constants of -CD with tiapride, imipramine, clomipramine, amitriptyline, trifluoperazine, perphenazine and carbamazepine were determined by affinity capillary electrophoresis. The presence of -CD improved the separation of these psychopharmaceutical drugs. Organic modifier was used as another kind of additive to be added in the running buffer to improve further the separation. 70 mM pH 7.2 phosphate buffer solution containing 12 mM -cyclodextrin and 15% (v/v) acetone was selected as optimal running buffer for separation by capillary electrophoresis. 相似文献
6.
A simple, rapid and accurate high performance liquid chromatographic (HPLC) technique coupled with chemiluminescence (CL) detection was developed for the simultaneous determination of epinephrine (E), noradrenaline (NA) and dopamine (DA). It was based on the analyte enhancement effect on the CL reaction between luminol and potassium ferricyanide. The effects of various parameters, such as potassium ferricyanide concentration, luminol concentration, pH value and component of the mobile phase on chromatographic behaviors of the analytes (E, NA and DA) were investigated. The separation was carded out on C18 column using the mobile phase of 0.01 mol/L potassium hydrogen phthalate solution and methanol (92 : 8, V/V). Under the optimum condi- tions, E, NA and DA showed good linear relationships in the range of 1 × 10^-8 -5 × 10^-6, 5.0× 10^-9 -1.0× 10^-6 and 5.0×10^-9-1.0× 10^-6 g]mL respectively. The detection limits for E, NA and DA were 4.0×10^-9, 1.0× 10^-9 and 8.0 × 10^-10 g/mL. The proposed method has been applied successfully to the analysis of E, NA and DA in human serum samples. 相似文献
7.
《Analytical letters》2012,45(10):1328-1340
Abstract We report a miniature separator for medical microdevices. The separator uses a size-exclusion chromatography (SEC) mini-column in liquid chromatography (LC). The mini-column is fabricated on a glass slide with polydimethylsiloxane (PDMS) for structure. Polydivinlybenzene nanobeads (5–20 µm in diameter, 100-nm pore size) were used. The SEC mini-column successfully separates α-fetoprotein (AFP) and immunoglobulin G (IgG) at 5 and 9 min, respectively, with 0.86 resolution and 0.06-mm plate height. The mini-column shows potential for use in onboard sample preparation in a total analysis system (µTAS) for a point-of-care testing (POCT) device that could be used effectively in cancer screening, diagnosis, and prognosis. 相似文献
8.
《Analytical letters》2012,45(9):1485-1499
A fast and reliable ultra-high performance liquid chromatography–tandem mass spectrometry method was developed for the determination of aflatoxins B1, B2, G1, and G2 in cereal. The analytes were extracted by accelerated solvent extraction with methanol/water (80:20). A polymeric solid-phase extraction column was used for sample preparation. Under optimum conditions, the analyte recoveries for samples spiked at different concentration levels in rice and maize ranged from 71.2 to 94.0%, with relative standard deviations less than 16.4%. Limits of detection (signal-to-noise ratio, 3:1) for the aflatoxins ranged from 0.25 to 0.93 ng/g. The developed method was applied to the determination of aflatoxins in ten rice and maize samples. One maize sample tested positive with an aflatoxin B1 concentration of 2.7 ng/g. 相似文献
9.
Ahmed M. Hamed Mahmoud Abdel-Hamid Laura Gámiz-Gracia Ana M. García-Campaña 《Analytical letters》2019,52(2):363-372
The consumption of plant-based milk has increased due to their nutritional attributes. However, these products may contain aflatoxins if contaminated raw materials were used, although little concern is present in international regulation regarding this topic. In this work, dispersive liquid–liquid microextraction (DLLME) was used for the determination of the most important aflatoxins (B1, B2, G1, and G2) in oat, rice, coconut, almond, and birdseed plant-based milk and milk-based products enriched with oats, almonds, and walnuts using high-performance liquid chromatography (HPLC) with photochemical derivatization and fluorescence detection. Calibrations in matrix were performed for all of the samples, obtaining satisfactory linearity, with correlation coefficients exceeding 0.994 for all of the aflatoxins. The precision in terms of repeatability and intermediate precision, expressed as the relative standard deviation, was lower than 9.7%, and recoveries ranged between 82 and 104%, fulfilling current legislation for the determination of aflatoxins. In addition, the limits of quantification were 0.5?µg?L?1 for the aflatoxins, allowing the determination of these compounds below the maximum levels established by European Commission in these commodities. Finally, 23 commercial products were analyzed to characterize the presence of these toxins. 相似文献
10.
V. V. Belova 《Russian Journal of Inorganic Chemistry》2018,63(4):473-478
Our computational studies into the separation of two- and three-component mixtures of rareearth salts by recycling liquid–liquid chromatography (RLC) with multiple sample injection show that this method considerably enhances metal separation efficiency and makes it possible to concentrate one of the components of mixture. 相似文献
11.
《Analytical letters》2012,45(1):119-136
Abstract We have developed a solid‐phase microextraction procedure for polycyclic aromatic hydrocarbons. A simplex experimental design was employed to optimize the process. A polydimethylsiloxane/divinylbenzene fiber was selected. The optimum conditions were: an extraction step in the immersion mode, over a period of 60 min at 70°C using high‐speed stirring, and an 8 min desorption step using acetonitrile (90 µl). Linear relationships were obtained for all compounds, except for naphthalene. Our method showed a good precision and accuracy with a detection limit between 0.005 and 0.306 µg l?1. Our method was used to detect PAHs in real water samples. 相似文献
12.
Reported here is the Cr-speciation study by High Performance Liquid Chromatography (HPLC) using precolumn derivatization with ammonium pyrolidinyldithiocarbamate (APDC) and spectrophotometric detection. The rapid and sensitive method has been successfully applied to the analysis of environmental water. The chromatographic behavior of the two Cr-APDC chelates are illustrated with "Solvophobic Theory". 相似文献
13.
In recent years, the synthesis of chiral tetrahedral clusters has been studied extensively and various types are accessible , which are a kind of organometallic compounds with greatly growing interest due to their potential application to asymmetric reaction catalysts. As an efficient 相似文献
14.
Wu Jianfeng Liu Peng Wang Qingwei Chen Hui Gao Peng Wang Li Zhang Shengyong 《Chromatographia》2011,74(11):789-797
The enantiomeric separation of several basic drugs was investigated using copper(II)–clindamycin as a new chiral selector. The results show that the chiral selector allows high-resolution separation of some racemic basic drugs, including tropicamide, propranolol, sotalol, bisoprolol, epinephrine, esmolol, atenolol, and metoprolol. The enantioselectivity was influenced by parameters such as the type of metal ion, ratio of clindamycin and Cu(II), pH of the background electrolyte, clindamycin concentration, applied voltage, and capillary temperature. The optimal separation conditions were determined to be 20 mM clindamycin/10 mM Cu2+, pH 9.06, at 20 kV and 22 °C within 25 min.
相似文献15.
Miriam Russ Lisa Weinheimer Susanne Jauk Michaela Andrä Reinhold Wintersteiger 《Analytical letters》2019,52(6):892-901
Oxidative stress can lead to tissue damage in the body, resulting in conditions that may lead to heart failure. Carbonyl proteins and malondialdehyde are common markers for determining oxidative stress. In this study, a high-performance liquid chromatography with ultraviolet‐visible (HPLC–UV–Vis) method was developed for both carbonyl proteins and malondialdehyde and compared with common spectrophotometric methods. The HPLC–UV–Vis method for determining carbonyl proteins showed a linear correlation in a range of 0.05–1.6 µg.mL?1 (correlation coefficient: 0.9939). The limits of detection and quantitation were determined to be 1.7 and 5.1?pmol on-column, respectively. The HPLC–UV–Vis method for malondialdehyde exhibited a linear correlation in the range of 0.04–13.6 µg.mL?1 (correlation coefficient: 0.9982) with limits of detection and quantitation of 1.5 and 4.5?pmol on-column, respectively. As a proof of concept, the applicability of the methods for both marker substances was investigated in chicken heart tissue as a complex matrix sample. To simulate oxidative stress, the tissue was treated with hydrogen peroxide as the oxidizing agent. Samples prepared with hydrogen peroxide showed increased carbonyl protein and malondialdehyde levels when compared to non-oxidized samples and samples treated additionally with the antioxidant Trolox. Regarding oxidative stress, similar results were achieved when compared with common spectrophotometric methods. However, HPLC–UV–Vis presented higher reproducibility and accuracy. The developed methods for both markers enable rapid and simple investigation of possible antioxidant effects on tissue samples. 相似文献
16.
Piotr Czaja 《Journal of Thermal Analysis and Calorimetry》2013,113(1):91-95
In this paper the technology of producing solid solutions of Csx(NH4)1?xLiSO4 using the slow evaporation method is presented. Appropriate conditions were chosen to grow large samples. The ammonium ion content in the solid solutions was determined using the Kjeldahl method. It was found that the real ammonium ion concentration is twice lower than the one applied in the initial substances. At room temperature, the base crystal, lithium cesium sulfate (CsLiSO4), is paraelastic, whereas lithium ammonium sulfate (NH4LiSO4) is ferroelectric. It is expected that as a result of substituting Cs+ ions with $ N{\text{H}}_{4}^{ + } $ N H 4 + ions, instead of the Cs+ ions, the modification of the ferroic properties of solid solutions of Csx(NH4)1?xLiSO4 will take place. Tests conducted with the use of the differential scanning calorimetry method (DSC) allowed the detection of the ferroelastic phase transition which takes place in these compounds. A gradual increase of temperature transition was observed from 202 K for the pure CsLiSO4 to 203.8 K for Cs0.90(NH4)0.10LiSO4 and 230.1 K for Cs0.85(NH4)0.15LiSO4 with the increase of $ N{\text{H}}_{4}^{ + } $ N H 4 + ions concentration. Using polarized light microscopy, a ferroelastic domain structure was detected in the examined solid solutions, which appeared below the structural phase transition temperature. 相似文献
17.
《Analytical letters》2012,45(2):234-249
An optimized high performance liquid chromatography electrospray ionization/tandem mass spectrometry method was developed and optimized for the determination of seven nucleotides and nucleotide sugars in the extract of Candida albicans. The chromatographic separation was performed on a porous graphitic carbon column with gradient elution using acetonitrile and aqueous ammonia acetate containing 0.1% formic acid adjusted to pH 8.8. Negative-ion mode electrospray ionization mass spectrometry was applied to improve the selectivity and sensitivity of the analysis. The calibration curves showed excellent linearity over approximately three orders of magnitude with correlation coefficients exceeding 0.9946. The relative standard deviations of measurements were smaller than 4% (n = 5) and the accuracy of the intra-day and inter-day measurements were between 95.2% and 106.7%. The extraction recovery of each component was within satisfactory ranges. The validated method was applied to characterize the nucleotides metabolic profiles of the biofilm compared to the planktonic mode to evaluate changes of energy states in different growth modes of C. albicans. The levels of nucleotides and nucleotide sugar in the biofilm model treated with 5-fluoropyrimidine, baicalein, and sodium houttuyfonate were determined to investigate their effects on nucleotide metabolism and the mechanisms of antifungal agents. 相似文献
18.
《Analytical letters》2012,45(1):183-195
Abstract The chromatographic separation of o‐cresol, m‐cresol, and p‐cresol by using β‐cyclodextrin as a chiral reagent has been studied. Conditions for the chromatographic separation of these isomers by using the cyclodextrin in the mobile phase or bonded in the stationary phase were optimized, and both procedures provided good results for the resolution of the chromatographic peaks. The use of fluorimetric detection (λexc 275 nm λem 300 nm) allows detection and quantification limits of the µg/L for eight studied phenols by using both procedures. The determination of volatile phenols in alcoholic beverages must be carried out using the cyclodextrin in the mobile phase because of the co‐elution of phenol and ethylguaiacol with other compounds of some studied matrix. 相似文献
19.
Hydrogen peroxide (HP) in river water was determined using the highly luminescent Eu3+-tetracycline hydrogen peroxide (EuTc-HP) complex. A 15-fold increase in luminescence intensity of Eu3+-tetracycline (EuTc) is observed at 616nm after formation of EuTc-HP. In order to eliminate interferences by other fluorescent substances that exist in river water, a time-resolved scheme is employed: EuTc-HP has a main decay time of 61µs, while background fluorescence decays within a few ns. Thus, by performing measurements after a delay time of typically 30µs, the signal becomes highly specific for EuTc-HP. Under optimized conditions (pH 7 in MOPS buffer), the calibration curve for the determination of HP was linear over the range of 2 to 160µmolL–1. The limit of detection is 1.1µmolL–1 HP. An average recovery of 99.5% was obtained for measurements of river water samples spiked with HP. The relative standard deviation of less than 2% indicates the high accuracy and precision of the method. 相似文献
20.
Ya-Ling Ye Kai-Yun Pan Wen-Lu Wang Dr. Bi-Lian Ni Dr. Wei-Ming Sun 《Chemphyschem》2023,24(8):e202200776
The unique characteristic of superatoms to show chemical properties like those of individual atoms opens a new avenue towards replacing noble metals as catalysts. Given the similar electronic structures of the ZrO superatom and the Pd atom, the CO oxidation mechanisms catalysed by (ZrO)n (n=1–4) clusters were investigated in detail to evaluate their catalytic performance. Our results reveal that a single ZrO superatom exhibits superior catalytic ability in CO oxidation than both larger (ZrO)n (n=2–4) clusters and a Pd atom, indicating the promising potential of ZrO as a “single-superatom catalyst”. Moreover, the mechanism of CO oxidation catalysed by ZrO+/− suggests that depositing a ZrO superatom onto the electron-rich substrates is a better choice for practical catalysis application. Accordingly, a graphene nanosheet (coronene) was chosen as a representative substrate for ZrO and Pd to assess their catalytic performances in CO oxidation. Acting as an “electron sponge”, this carbon substrate can both donate and accept charges in different reaction steps, enabling the supported ZrO to achieve enhanced catalytic performance in this process with a low energy barrier of 19.63 kcal/mol. This paper presents a new realization on the catalytic performance of Pd-like superatom in CO oxidation, which could increase the interests in exploring noble metal-like superatoms as efficient catalysts for various reactions. 相似文献