Development of a selective fluorimetric technique for rapid trace determination of zinc using 3-hydroxyflavone

AbstractA sensitive and a selective spectrofluorimetric method have been developed for the rapid determination of trace levels of zinc. The method is based on complex formation between zinc and 3-hydroxyflavone (3HF), which displays an intense emission signal around 478nm. The analytical performance of the method was examined by considering the factors that affect the complex formation such as pH, mole ratio of the metal and solvent type. The optimum conditions for the complex formation were metal to ligand stoichiometric ratio of 1:1 at pH 7.5 with 0.1M Tris buffer. Under these conditions the detection limit attained was 1.5ppb. The method was appropriately validated and yielded relative standard deviations of less than 2% (n=5), which was considered acceptable. It was successfully applied to the trace determination of zinc in drinking water, hair shampoo and pharmaceutical samples

Characterization of the inclusion complex of zerumbone with hydroxypropyl--cyclodextrin

In this paper we investigated the inclusion complexation between zerumbone (ZER) and hydroxylpropyl- -cyclodextrin (HPCD) at four different temperatures: 293–318 ◦K. The thermodynamic parameters (H, S and G) for the formation of the complex were obtained from the van’t Hoff equation. The complex with HPCD was characterized by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), and molecular modeling using PM6. The solubility of ZER was enhanced >30 fold after complexation. Calculations show that ZER penetrates completely into the cavity of HPCD. The complex retained its cytotoxic activity as shown by in vitro cell survival assay on human cervical cancer (Hela), breast cancer (MCF7 and MDA-MB 231) and human leukemic (CEMss) cell lines. HPCD is, therefore, a suitable encapsular capable of forming thermodynamically stable complex with ZER for save delivery of the compound as an anticancer drug in the future

Liquid chromatography - tandem mass spectroscopic method for the determination Of zerumbone in human plasma and its application to Pharmacokinetics

A rapid, sensitive, specific and selective LC-MS/MS method for the determination of zerumbone (ZER) in human plasma using 2,4-diamino-6-(4-methoxyphenyl)-1,3,5-triazine (DMTZ) as an internal standard (IS) has been developed and validated. ZER was chromatographed on C8 column using a mobile phase of acetonitrile/water (80:20, v/v) at a flow rate of 0.25 ml min(-1) . Quantitation was achieved using ESI+ interface, employing multiple reaction monitoring (MRM) mode at m/z 219 > 81 and 218 > 134 for ZER and IS, respectively. The calibration standards were linear over a range of 5-3000 ng ml(-1) (r(2)=0.9994) with an LLOQ of 5 ng ml(-1) (RSD %; 11.4% and bias%; 9.5%). Intra- and inter-day precision of ZER assay ranged from 0.18 to 3.56% with accuracy (bias) that varied between -5.09 and 4.3%, demonstrating good precision and accuracy. Recoveries of ZER and the IS from human plasma were above 85%. The developed method was validated for the determination of ZER in rat plasma. Linearity, stability of ZER and the ME on rat plasma were discussed. The applicability of the developed method was demonstrated by measuring ZER in rat plasma samples following intravenous and intraperitoneal administration of ZER prepared in hydroxypropyl-β-cyclodextrin (HPβCD) and sodium carboxymethyl cellulose (CMC), respectively, in 20 mg kg(-1) and this study indicated a clear significant difference (p<0.05) in pharmacokinetic parameters of ZER in ZER/HPβCD complex compared with ZER in CMC preparation

Luminol Chemiluminescence Catalyzed by Silver Nanoparticles for the Sensitive Determination of Penicillamine

A sequential injection method for the determination of penicillamine (PA) was developed based on quenching the chemiluminescence generated by oxidation of luminol by hydrogen peroxide in presence of silver nanoparticles (AgNPs). The chemiluminescence (CL) of the reaction was found to greatly enhance in presence of AgNPs due to the increased catalyst surface area. The method was sensitive and found suitable for analysis of penicillamine in pharmaceutical preparations. Linear calibration curve is obtained in the range 0.2-1.0 mg mL-1 with a relative standard deviation less than 2%. A recovery percent of 102.3 ±0.2 was obtained with the tablets matrix indicating reasonable selectivity of the method for PA in tablets. The mechanism of quenching of the CL reaction was investigated by UV-Visible spectroscopy and transmission electron microscopy as well as by theoretical calculations using DFT-B3LYP method. The covalent attachment of PA to the AgNPs triggers aggregation of the particles thereby diminishing the surface significantly. The method was applied for the assay of PA in pharmaceutical preparations

Study on the Reactivity of Amino Acid Chemosensor, NPFNP, with Ethanol: Structural Elucidation through Single Crystal XRD and DFT Calculations

A novel ethoxy derivative of an amino acid chemosensor, 3-naphthyl-1-phenyl-5-(2ʹ-fluoro-5ʹ-nitrophenyl)-2-pyrazoline (NPFNP), has been synthesized and characterized by different spectroscopic methods.  A single crystal of the ethoxy derivative, 3-naphthyl-1-phenyl-5-(2ʹ-ethoxy-5ʹ-nitrophenyl)-2-pyrazoline NPENP, has been obtained and characterized.  The structure holds interest as it carries biologically active pyrazoline as a central ring attaching to electron donating and withdrawing substituents. The major motivation for this work was to gain detailed insight into the structural parameters of this compound for investigating the influence of crystal packing and geometrical dimensions on optical properties. Time-dependent DFT calculations have been employed for comparing the XRD data with theoretical parameters. The results show that the DFT method at B3LYP/6-31G level can well reproduce the structure of the title compound

Synthesis of a Flavone Based Fluorescent Probe Bearing a Nitroolefin Moiety for Selective Detection of Cysteine

 In this paper, we report the synthesis, characterization and investigation of the optical properties of a new fluorescent probe, 4ʹ-nitroolefinylflavone (4ʹ-NOF) 1, based on a flavone skeleton and bearing a nitroolefin moiety. Upon the addition of cysteine, a remarkable fluorescence enhancement (200 fold) was observed for probe 1 accompanied with a slight blue shift from 457 nm to 459 nm.  The prepared probe displays high selectivity and sensitivity towards cysteine over other amino acids. The Michael addition of cysteine to probe 1 was confirmed by 1H-NMR spectroscopy. The detection limit of probe 1 towards cysteine was found to be 1.63 μΜ, a lower concentration than the normal human cysteine level, 30-200 μΜ.

A Terbium Sensitized Luminescence Method for the Assay of Flubiprofen in Pharmaceutical Formulations

A sensitive time-resolved luminescence method for the determination of flubiprofen (FLP) in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb3+ ) by the formation of a ternary complex with FLP in the presence of 4,7 diphenyl 1,10 phenanthroline (DPP) as co-ligand, and Tween-20 as surfactant. The signal for Tb-FLP-DPP was monitored at λex  = 285 nm and λem  = 552 nm. Optimum conditions for the formation of the complex in an aqueous system were TRIS buffer, pH 8.0, DPP (2.5Å~10−7  M), Tween-20 (0.30%) and 4Å~10-5  mol L-1  of Tb3+  which allowed the determination of 20–1000 ng mL-1  of FLP with a limit of detection (LOD) of 10 ng mL-1 . The relative standard deviations of the method ranged between 0.6 and 1.4% indicating excellent reproducibility of the method. The proposed method was successfully applied for the assays of FLP in pharmaceutical formulations and spiked tap water samples with average recoveries of 87% – 95%

Volatile Compounds of the Leaves and Flowers of Lavandula dhofarensis A.G. Miller

The leaves and flowers of Lavandula dhofarensis were collected from the Dhofar region of Oman and hydro-distilled to give low boiling volatiles, which did not condense at 10 oC.  The dichloromethane extract of the hydrosol was analyzed by GC/FID and GC/MS. Sixty four compounds were identified in the volatiles of the leaves, accounting for 78.7% of the total.  The major components were caryophyllene oxide (8.0%), germacrene (7.9%), spathulenol (7.8%), and b-caryophyllene (6.6%). Eighty six compounds were also identified in the volatiles of the leaves plus flowers, comprising 94.5% of the total. The major compounds were camphor (12.9%), viridiflorol (10.5%), a-terpinyl acetate (7.5%), valerenal (7.2%), a-gurjunene (5.6%), and spathulenol (5.5%). Compounds such as linalool, linalyl acetate, 1,8-cineole, and b-ocimene, which are usually found as the major components of lavender oils, were either absent or detected at low levels  (<0.1%) in the hydrosol of L. dhofarensis. This investigation showed that the fragrance essence of L. dhofarensis is different from the other Lavandula species. L. dhofarensisis is regionally endemic to wetter areas of Oman

Spectrofluorimetric determination of aluminium in water samples using N-((2-hydroxynaphthalen-1-yl)methylene) acetylhydrazide

AbstractA sensitive and selective spectrofluorimetric method has been developed for the rapid determination of aluminium. This method is based on the formation of a complex between aluminium and N-((2-hydroxynaphthalen-1-yl)methylene) acetylhydrazide (HNMA). The fluorescence of the complex is monitored at an emission wavelength of 450nm with excitation at 385nm. Optimum complex formation occurred in Tris buffer at pH 6.0. Under the optimum conditions, linear calibration curves were obtained from 50 to 800ppb. The detection limit was 9.2ppb (ngmL−1). The maximum relative standard deviation of the method for an aluminium standard of 200ppb was 2.5%. The effects of surfactants and interference from other ions were studied. The method was successfully applied for the determination of aluminium ions in water samples