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A method using high-performance liquid chromatography with diode array detection (HPLC-DAD) as a powerful separation technique has been developed for the simultaneous determination of the four flavonols rutin, quercetin, kaempferol and isorhamnetin in food supplements and pharmaceutical formulations. The chromatographic separation was achieved in 36?min using a Symmetry C18 column (250?×?3?mm; 5?µm) as the stationary phase and a mixture of methanol, acetonitrile, and pH 2.5 aqueous acetic acid as the mobile phase in gradient elution mode. The analytical wavelengths were 256?nm for rutin, quercetin and isorhamnetin, and 368?nm for kaempferol. An ultrasound-assisted extraction protocol was performed using methanol as solvent. The detection and quantification limits were lower than 0.03?µg mL?1 and 0.08?µg mL?1, respectively. The inter-day and intra-day precisions were less than 4.8 and 5.1%, respectively, and the average recoveries were in the range from 96 to 107%. The method was applied for the determination of the studied flavonols in food supplements and pharmaceutical preparations. The satisfactory recovery values demonstrate the potential of the developed method for the determination of the analytes in these samples. In addition, the method is suitable for routine quality control due its ease of operation. 相似文献
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Dr. Mariane Le Fur Nicholas J. Rotile Carlos Correcher Dr. Veronica Clavijo Jordan Alana W. Ross Prof. Ciprian Catana Prof. Peter Caravan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(4):1490-1494
Gadolinium-based contrast agents (GBCAs) are used to provide diagnostic information in clinical magnetic resonance (MR) examinations. Gadolinium (Gd) has been detected in the brain, bone and skin of patients, months and years following GBCA administration, raising concerns about long term toxicity. Despite increased scrutiny, the concentration, chemical form and fate of the retained gadolinium species remain unknown. Importantly, the whole body biodistribution and organ clearance of GBCAs is poorly understood in humans. Gadolinium lacks suitable isotopes for nuclear imaging. We demonstrate that the yttrium-86 isotope can be used as a gadolinium surrogate. We show that Gd and their analogous Y complexes have similar properties both in solution and in vivo, and that yttrium-86 PET can be used to track the biodistribution of GBCAs over a two-day period. 相似文献
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Oxidative Conversion of a Europium(II)‐Based T1 Agent into a Europium(III)‐Based paraCEST Agent that can be Detected In Vivo by Magnetic Resonance Imaging
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Dr. Alexander M. Funk Dr. Veronica Clavijo Jordan Prof. A. Dean Sherry Dr. S. James Ratnakar Prof. Zoltan Kovacs 《Angewandte Chemie (International ed. in English)》2016,55(16):5024-5027
The EuII complex of 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid (DOTA) tetra(glycinate) has a higher reduction potential than most EuII chelates reported to date. The reduced EuII form acts as an efficient water proton T1 relaxation reagent, while the EuIII form acts as a water‐based chemical exchange saturation transfer (CEST) agent. The complex has extremely fast water exchange rate. Oxidation to the corresponding EuIII complex yields a well‐defined signal from the paraCEST agent. The time course of oxidation was studied in vitro and in vivo by T1‐weighted and CEST imaging. 相似文献
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María del Rosario Brunetto Yelitza Delgado Sabrina Clavijo Yaritza Contreras Dina Torres Carlos Ayala Máximo Gallignani Rafael Forteza Víctor Cerdà Martin 《Journal of separation science》2010,33(12):1779-1786
In this paper, a method was described to determine cocaine (COC) and benzoylecgonine (BZE) in human urine samples by GC‐MS detection. The extraction of analytes from urine samples was achieved in an Oasis hydrophilic–lipophilic balance column (20 mm×3.9 mm id, dp=25 μm; Waters, USA), incorporated in a multisyringe flow injection system, used for the sample treatment. Finally, to improve the volatility of the BZE, an in‐line derivatization reaction with N,O‐bis (trimethylsilyl) trifluoroacetamide with 1% trimethylchlorosilane was made microwave‐assisted in order to reduce the reaction time. The results showed that the proposed method is a good alternative for the analysis of COC and BZE in urine samples because it offers advantages compared with those described in the literature, which include simplicity in the sample treatment, the sensitivity and selectivity necessary to determine the analytes of interest at low levels in the urine and high sample throughput. 相似文献
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E. M. A. Clavijo V. R. G. Clavijo M. C. Bandéca M. R. Nadalin M. F. Andrade J. R. C. Saad A. A. Pelegrine 《Laser Physics》2009,19(10):2041-2044
Dentin hipersensitivity (DH) is a relatively common clinical condition, especially in periodontal patients after treatment.
In this study it was evaluated 28 teeth who presented dentin hypersensitivity. The teeth were subjected to clinical and radiographic
exams and were divided into groups following the treatment and the time of examination after application proposed: GI: PO
3% (Potassium Oxalate—group control)/Baseline; GII: PO 3%/3 days after first session; GIII: PO 3%/6 days; GIV: PO 3%/30 days;
GV: PO 3%/60 days; GVI: PO 3%/90 days; GVII: Laser (Low_level diode laser with 110 mW/cm2)/Baseline; GVIII: Laser/7 days after first session; GIX: Laser/14 days; GX: Laser/30 days; GXI: Laser/60 days; and GXII:
Laser/90 days. The groups I–VI, the teeth were subjected to 3 applications (GI–GIII) of desensitizing agent at regular intervals
of seven days. The Groups VII–XI, each tooth was subjected to three applications (GVII–GIX) in three different points (mesial,
meddle and distal surfaces) with an interval of 72 h. The time of application in each point was of 33 s and the patients from
both groups were followed up to 90 days. The nonparametric test Friedman (α = 0.05) was applied and the test of Mann Whitney
(α = 0.05) was used to compare the time of examination between groups. The application of Laser was effective 6 days after
first session and to PO was 30 days. It was observed that both treatments were effective for the reduction of dentin hypersensitivity,
however the laser presented better effectiveness. 相似文献
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Clavijo CF Hoffman KL Thomas JJ Carvalho B Chu LF Drover DR Hammer GB Christians U Galinkin JL 《Analytical and bioanalytical chemistry》2011,400(3):715-728
Opioids such as morphine are the cornerstone of pain treatment. The challenge of measuring the concentrations of morphine
and its active metabolites in order to assess human pharmacokinetics and monitor therapeutic drugs in children requires assays
with high sensitivity in small blood volumes. We developed and validated a semi-automated LC-MS/MS assay for the simultaneous
quantification of morphine and its active metabolites morphine 3β-glucuronide (M3G) and morphine 6β-glucuronide (M6G) in human
plasma and in dried blood spots (DBS). Reconstitution in water (DBS only) and addition of a protein precipitation solution
containing the internal standards were the only manual steps. Morphine and its metabolites were separated on a Kinetex 2.6-μm
PFP analytical column using an acetonitrile/0.1% formic acid gradient. The analytes were detected in the positive multiple
reaction mode. In plasma, the assay had the following performance characteristics: range of reliable response of 0.25–1000 ng/mL
(r
2 > 0.99) for morphine, 1–1,000 ng/mL (r
2 > 0.99) for M3G, and 2.5–1,000 ng/mL for M6G. In DBS, the assay had a range of reliable response of 1–1,000 ng/mL (r
2 > 0.99) for morphine and M3G, and of 2.5–1,000 ng/mL for M6G. For inter-day accuracy and precision for morphine, M3G and
M6G were within 15% of the nominal values in both plasma and DBS. There was no carryover, ion suppression, or matrix interferences.
The assay fulfilled all predefined acceptance criteria, and its sensitivity using DBS samples was adequate for the measurement
of pediatric pharmacokinetic samples using a small blood of only 20–50 μL. 相似文献
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T. Aguayo C. Garrido R. E. Clavijo J. S. Gmez‐Jeria C. Araya Monasterio M. Icaza F. Espinoza Moraga M. M. Campos Vallette 《Journal of Raman spectroscopy : JRS》2013,44(9):1238-1245
The Raman and surface enhanced Raman scattering (SERS) spectra of a black dyed silk sample (BDS) were registered. The spectral analysis was performed on the basis of Raman and SERS spectral data of isolated samples of Bombyx mori silk fibroin, its motif peptide component (GAGAGS) and the synthetic reactive black 5 dye (RB5). The macro FT‐Raman spectrum of the silk sample is consistent with a silk II‐Cp crystalline fraction of Bombyx mori silk fibroin; the SERS spectrum is highly consistent with conformational modifications of the fibroin due to the interactions with the Ag nanoparticles. The GAGAGS peptide sequence dominates the Raman spectrum of the silk. The SERS spectrum of the peptide suggests a random coil conformation imposed by the surface interaction; the serine residue in the new conformation is exposed to the surface. Quantum chemical calculations for a model of the GAGAGS–Ag surface predict a nearly extended conformation at the Ag surface. The Raman spectrum of the dye was analysed, and a complete band assignment was proposed; it was not possible to propose a preferential orientation or organization of the molecule on the metal surface. Quantum chemical calculations for a model of the dye interacting with a silver surface predict a rather coplanar orientation of the RB5 on the Ag metal surface. The Raman spectrum of the BDS sample is dominated by signals from the dye; the general spectral behaviour indicates that the dye mainly interacts with the silk through the sulphone (–SO2–) and sulphonate (–SO2–O–) groups. Besides the presence of dye signals, mainly ascribed to the sulphone and sulphonate bands, the SERS spectrum of the BDS sample also displays bands belonging to the amino acids alanine, glycine, serine and particularly tyrosine. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献