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1.
2.
A capillary zone electrophoresis (CZE) method for the analyses of kaempferol in Centella asiatica and Rosa hybrids and rutin in Chromolaena odorata was developed. The optimization was performed on analyses of flavonoids (e.g., rutin, kaempferol, quercetin, myricetin, and apigenin) and organic carboxylic acids (e.g., ethacrynic acid and xanthene-9-carboxylic acid) by investigation of the effects of types and amounts of organic modifiers, background electrolyte concentrations, temperature, and voltage. Baseline separation (R(s) = 2.83) of the compounds was achieved within 10 min in 20 mM NaH2PO4 - Na2HPO4 (pH 8.0) containing 10% v/v ACN and 6% v/v MeOH using a voltage of 25 kV, a temperature of 30 degrees C, and a detection wavelength set at 220 nm. The application of the corrected migration time (t(c)), using ethacrynic acid as the single marker, was efficient to improve the precision of flavonoid identification (% relative standard deviation (RSD) = 0.65%). The method linearity was excellent (r2 > 0.999) over 50-150 microg/mL. Precision (%RSD < 1.66%) and recoveries were good (> 96% and %RSDs < 1.70%) with detection and quantitation limits of 2.23 and 7.14 microg/mL, respectively. Kaempferol in C. asiatica and R. hybrids was 0.014 g/100 g (%RSD = 0.59%) and 0.044 g/100 g (%RSD = 1.04%), respectively, and rutin in C. odorata was 0.088 g/100 g (%RSD = 0.06%). 相似文献
3.
Na'il Saleh Mohammed A. Meetani Leena Al-Kaabi Indrajit Ghosh 《Supramolecular chemistry》2013,25(9):650-656
The supramolecular interactions of the ocular drug tropicamide (TR) with cucurbit[7]uril (CB7) and cucurbit[8]uril (CB8) were investigated in aqueous solutions by using 1H NMR, ESI-MS and UV–vis spectroscopic techniques. The results indicate a 1:1 binding stoichiometry of TR with CB7 and CB8. The binding constants of TR in its protonated form were higher (e.g. K = 4 × 106 M? 1 with CB8) than in its neutral form (e.g. K = 1.4 × 104 M? 1 with CB8), which led to a complexation-induced increase in its pK a value of ca. 0.5 and 2 units with CB7 and CB8, respectively. In the presence of about 1% (w/v) CB8, the ionisation degree of 0.1% (w/v) TR was increased from 2% to 62% at neutral pH. The increase in the pK a value and thus stabilisation of the protonated TR species at neutral pH is discussed in the context of supramolecular drug delivery of ophthalmologic drugs. 相似文献
4.
Lanthanide chelates are excellent labels in ligand binding assays due to their long lifetime fluorescence, which enables efficient background reduction using time-resolved measurement. In separation-free homogeneous assays, however, some compounds in the sample may cause quenching of the lanthanide fluorescence and extra steps are required before these samples can be measured. In this study we have evaluated whether europium chelates packed inside a polystyrene nanoparticle are better protected from the environment than individual Eu(III)-chelates, and do these particles have higher tolerance against known interfering compounds (bivalent metal ions and variation of pH). We also tested whether metal ions had any effect on a fluorescence resonance energy transfer (FRET) based detection of a bioaffinity binding reaction. The presence of metal ions or variation of pH did not affect the fluorescence of the Eu(III)-chelate dyed nanoparticles, while significant decrease of the fluorescence was detected with a 9-dentate Eu(III)-chelate. Metal ions also decreased the fluorescence lifetime of the 9-dentate Eu(III)-chelate from 0.960 to 0.050 ms. Coloured metal ions caused a minor decrease in sensitised emission generated by FRET when Eu(III)-chelate dyed nanoparticles were used as donor labels. The decreased signal was due to the absorption of the sensitised emission by the coloured metal ions, since the metal ions had no effect on the lifetime of the sensitised emission. Thus the Eu(III)-chelate dyed nanoparticles are preferred labels in homogeneous bioaffinity assays, when interfering compounds are known to be present. 相似文献
5.
Leena Suntornsuk 《Analytical and bioanalytical chemistry》2010,398(1):29-52
This review covers recent advances of capillary electrophoresis (CE) in pharmaceutical analysis. The principle, instrumentation,
and conventional modes of CE are briefly discussed. Advances in the different CE techniques (non-aqueous CE, microemulsion
electrokinetic chromatography, capillary isotachophoresis, capillary electrochromatography, and immunoaffinity CE), detection
techniques (mass spectrometry, light-emitting diode, fluorescence, chemiluminescence, and contactless conductivity), on-line
sample pretreatment (flow injection) and chiral separation are described. Applications of CE to assay of active pharmaceutical
ingredients (APIs), drug impurity testing, chiral drug separation, and determination of APIs in biological fluids published
from 2008 to 2009 are tabulated. 相似文献
6.
2, 3, 4-Trimethoxybenzaldehyde, -acetophenone and -benzoic acid give the corresponding 2, 3-dihydroxy-4-methoxy compounds in good yield on treatment with BCl3. 相似文献
7.
Leena V. Bora Manan Rathod Kush Kapadia Sonal Thakkar R.N. Reddy Sandesh S. Chougule Nisha V. Bora 《印度化学会志》2022,99(7):100560
In this study, we report a waste material-ground granulated blast furnace slag (GGBFS) as a low cost geopolymer, hybridised with ZnO to form a novel and efficient photocatalyst capable of discolouring textile wastewater. GGBFS is a waste material in an iron industry. Methylene blue was used as the probe dye and natural sunlight was used for activation of the photocatalyst. It was observed that under the experimental conditions, ZnGP-40 exhibited twice the discoloration efficiency than conventionally used ZnO or TiO2. This enhanced performance is majorly attributed to increased surface area of ZnO when strewn in the GGBFS matrix. The photocatalysts were characterized by SEM, TEM, PSA, TGA, BET and UV–Vis/NIR. The effect of photocatalyst loading, speed of agitation and solar insolation has also been studied. Since this study has been performed in direct sunlight, it exhibits a realizable application of solar energy in the treatment of wastewater. 相似文献
8.
In the present work, the influence of porosity and boron on shear thickening behavior of hybrid mesoporous silica has been studied. Three different levels of boron modification were performed by varying the molar composition of boric acid viz., 1.5 mmol, 2.5 mmol, and 3.5 mmol in a co-condensation approach. The incorporation of boron in mesoporous silica network was confirmed by various techniques such as Fourier transform infra-red (FTIR), and 11B solid- state nuclear magnetic resonance (NMR) spectroscopy. The morphology and particle size were confirmed by using scanning and transmission electron microscopy. To evaluate the effect of boron and porosity on the shear thickening behavior, dispersions were prepared from mesoporous boron- modified silica (MSiB), control mesoporous silica (MSi), non-porous boron-modified silica (SiB), and control non-porous silica (Si) in polyethylene glycol. The shear thickening behavior was studied using steady shear rheology. The dispersion prepared from different loadings of synthesized MSiB containing 1.5 mmol boron showed more than 16 times increase in viscosity (657.7 Pa.s) compared to that of MSi (39.2 Pa.s) at a fairly low volume fraction (φ = 0.15) of silica. It is expected that the highly ordered mesoporous architecture of hybrid silica has improved the interaction between the particle and the dispersing medium through hydrogen bonding. The porous morphology of the hybrid mesoporous silica as well as the incorporation of boron in the silica network favors the formation of a frictional contact network, and a transition from continuous shear thickening (CST) to discontinuous shear thickening (DST) behavior was observed. Therefore, silica prepared via incorporation of boron as well as porosity can be material of interest in variety of applications, for example, soft body armors, sporting goods, and shear thickening electrolytes for high impact resistant batteries. 相似文献
9.
Noble V. Thomas Vidya Sathi Ani Deepthi Sruthi Sudheendran Leena Sidharth Chopra 《Journal of heterocyclic chemistry》2021,58(1):48-55
A simple and efficient method, proceeding through a new mechanistic pathway, for the synthesis of spiro[indoline-3,4-thiopyrano[2.3-b]indole derivatives have been developed by exploiting the reaction of thieno[2,3-b]indole-2,3-dione with N-substituted isatilidenes. The compounds synthesized have been screened for antibacterial activity. The generality of the reaction and mechanistic rationale are presented. 相似文献
10.
Samuel W. Foster Xiaofeng Xie Michelle Pham Paul A. Peaden Leena M. Patil Luke T. Tolley Paul B. Farnsworth H. Dennis Tolley Milton L. Lee James P. Grinias 《Journal of separation science》2020,43(9-10):1623-1627
A newly developed portable capillary liquid chromatograph was investigated for the separation of various pharmaceutical and illicit drug compounds. The system consists of two high‐pressure syringe pumps capable of delivering capillary‐scale flow rates at pressures up to 10 000 psi. Capillary liquid chromatography columns packed with sub‐2 μm particles are housed in cartridges that can be inserted into the system and easily connected through high‐pressure fluidic contact points by simply applying a specific, predetermined torque rather than using standard fittings and less precise sealing protocols. Several over‐the‐counter analgesic drug separations are demonstrated, along with a simple online measurement of tablet dissolution. Twenty illicit drug compounds were also separated across six targeted drug panels. The results described in this study demonstrate the capability of this compact liquid chromatography instrument to address several important drug‐related applications while simplifying system operation, and greatly reducing solvent usage and waste generation essential for onsite analysis. 相似文献