Tuning a pyrazoline-based fluorogenic reagent, 3-naphthyl-1-(4-trifluoromethyl)-5-(4-carboxy phenyl)-2-pyrazoline for sensitive precolumn derivatization of aliphatic alcohols and trace analysis by RP-HPLC with fluorescence detection.

A new member of the pyrazoline family, 3-naphthyl-1-(4-trifluoromethyl)-5-(4-carboxy phenyl)-2-pyrazoline has been evaluated as a precolumn derivatization reagent for the analysis of primary alcohols using HPLC. The simultaneous separation of eight alcohol derivatives (C1 -C8 ) within 15 min was achieved on a reverse-phase C8 column with an isocratic elution mode. The derivatives were detected with fluorescence at an emission wavelength of 470 nm when excited at 360 nm. The identification of the corresponding derivatives was carried out by LC-MS/MS and all showed their characteristic parent peak in negative ion mode. The proposed method was validated using normal analytical tools and was found to be excellent. As a preliminary application, our method was used to determine ethanol concentration in alcohol-containing chocolates and cough syrup.

Controlled Microwave-Assisted Synthesis of the 2D-BiOCl/2D-g-C3N4 Heterostructure for the Degradation of Amine-Based Pharmaceuticals under Solar Light Illumination.

Designing efficient 2D-bismuth oxychloride (BiOCl)/2D-g-C3N4 heterojunction photocatalysts by the microwave-assisted method was studied in this work using different amounts of BiOCl plates coupled with g-C3N4 nanosheets. The effects of coupling the 2D structure of g-C3N4 with the 2D structure of BiOCl were systematically examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence (PL), lifetime decay measurement, surface charges of the samples at various pH conditions, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The prepared photocatalysts were used for the degradation of amine-based pharmaceuticals, and nizatidine was used as a model pollutant to evaluate the photocatalytic activity. The UV-vis DRS and other optical properties indicated the major effect of coupling of BiOCl with g-C3N4 into a 2D/2D structure. The results showed a narrowing in the band gap energy of the composite form, whereas the PL and lifetime analysis showed greater inhibition of the electron-hole recombination process and slightly longer charge carrier lifetime. Accordingly, the BiOCl/g-C3N4 composite samples exhibited an enhancement in the photocatalytic performance, specifically for the 10% BiOCl/g-C3N4 sample. Moreover, the zeta potential of this sample at different pH values was evaluated to determine the isoelectric point of the synthesized composite material. Consequently, the pH was adjusted to match the isoelectric point of the complex materials, which further enhanced the activity. Further degradation of pharmaceuticals was studied under solar light irradiation, and 96% degradation was achieved within 30 min.

Cellulose an ageless renewable green nanomaterial for medical applications: An overview of ionic liquids in extraction, separation and dissolution of cellulose.

Cellulose is a renewable natural fiber, which has gained enormous and significant research interest and evolved as the prime and promising candidate for replacing synthetic fibers. The various sources of cellulose, which is one of the world's most ubiquitous and renewable biopolymer resources, include trees, plants, tunicate and bacteria. The renewable biomaterial in the form of nanocellulose and its composites have been included in this review having the broad range of medical applications, viz.; tissue engineering, cardiovascular surgery, dental, pharmaceuticals, veterinary, adhesion barriers and skin therapy. These grafts are being fabricated from biodegradable materials. Bacterial cellulose is also an emerging renewable biomaterial with immense potential in biomedical field. The fabrication methods, characteristic properties and various overwhelming applications of cellulosic composites are explicitly elucidated in this review. The crux of this review is to exhibit the latest state of art, development in the field of cellulosic nanocomposite science and technology research and their applications towards biomedical field. Among the fourteen principle of green chemistry the two key principles i.e. using environmentally preferable solvents and bio-renewable feed-stocks covers in dissolution of cellulose in ionic liquids (ILs). In addition, this review covers about the comprehensive extraction and dissolution of cellulose and nanocellulose using ILs.

Tuning the constrained photophysics of a pyrazoline dye 3-naphthyl-1-phenyl-5-(4-carboxyphenyl)-2-pyrazoline inside the cyclodextrin nanocavities: A detailed insight via experimental and theoretical approach.

The modulation in the photophysics of a pyrazoline dye 3-naphthyl-1-phenyl-5-(4-carboxyphenyl)-2-pyrazoline (NPCP), when it drifts from bulk water into the nanocages of aqueous cyclodextrin solutions was investigated. The intramolecular charge transfer (ICT) fluorescence band intensity was found to increase with a blue shift in the presence of cyclodextrins. The results from 1H NMR and 1HH COSY NMR spectral analysis clearly points out the position of pyrazoline ring inside the cavity and its role in complexation process. A quantitative assessment of the emission intensity data on Benesi-Hildebrand (B-H) equation along with ESI-MS spectra reveals the probable stoichiometry of NPCP-CD complexes. Molecular docking and molecular dynamics studies were conducted for ß/γ cyclodextrin associated inclusion complexes of NPCP. The results obtained by computational studies are in good relation with the data obtained through experimental methods and both ascertain the encapsulation of NPCP into cyclodextrins.

Nanotechnology: a clean and sustainable technology for the degradation of pharmaceuticals present in water and wastewater.

Pharmaceuticals, newly recognized classes of environmental pollutants, are becoming increasingly problematic contaminants of either surface water or ground water around industrial and residential communities. Pharmaceuticals are constantly released into aquatic environments, mainly due to their widespread consumption and complicated removal in wastewater treatment plants. Heterogeneous photocatalysis appear to be one of the most destructive advanced oxidation processes (AOPs) for organic contaminants and are possible to obtain complete mineralization of organic pollutants into eco-friendly end products under visible and solar light irradiation. In this study, flower-like In2S3 hierarchical nanostructures were successfully prepared via a facile solution-phase route, using thioacetamide as both sulfur source and capping agent. X-ray diffractometry (XRD) of the flowers revealed that the cubic structure of In2S3; morphological studies examined by scanning electron microscopy (SEM) showed the synthesized In2S3 nanostructure was flower-like hierarchitecture assembled from nanoscale flakes. X-ray photoelectron spectroscopy (XPS) analysis confirmed the stoichiometry of In2S3 nanoflowers. Furthermore, the photocatalytic activity studies revealed that the prepared indium(III) sulfide(In2S3) nanoflowers exhibit an excellent photocatalytic performance, degrading rapidly the aqueous pharmaceutical solution of Lisinopril under visible light irradiation. These results suggest that In2S3 nanoflowers will be a promising candidate of photocatalyst working in thevisible light range.

Microfluidic Precolumn Derivatization of Environmental Phenols with Coumarin-6-Sulfonyl Chloride and HPLC Separation.

A simple, fast, sensitive and versatile method for the analysis of phenols in water is proposed using microfluidic precolumn derivatization with the fluorogenic label coumarin-6-sulfonyl chloride (C6SCl) and HPLC separation on monolithic columns. Phenols react with C6SCl within 3.0 min in the microreactor at ambient temperature to produce phenol-coumarin sulphonamides derivatives which were separated in reversed phase high-performance liquid chromatography followed by postcolumn ring-opening and fluorescence detection at λexc = 360 nm and λem = 460 nm. The optimum conditions for the derivatization, separation and ring-opening reaction have been established. The calibration curves were linear for the studied phenols in the range of 0.75-12.5 mg L(-1). The application of the method to environmental samples was demonstrated by analyzing tap and fountain water samples spiked with the phenolic compounds.

Determination of the pseudoephedrine content in pharmaceutical formulations and in biological fluids using a microbore HPLC system interfaced to a microfluidic chemiluminescence detector.

A novel automated precolumn derivatization followed by separation using liquid chromatography for the determination of pseudoephedrine (PSE) by a microfluidic chemiluminescence detector has been developed. An on-line derivatization procedure was utilized by converting PSE into a highly light emitting species in a Ru(bipy)3(2+)-peroxydisulphate chemiluminescence (CL) system by derivatizing it with a 1.0 M formaldehyde solution. The derivatized analyte was directly injected into a microbore high-performance liquid chromatography (HPLC) system coupled to an on-chip chemiluminescence detector. The newly developed highly selective, sensitive and fast HPLC-CL method was validated and successfully applied for the analysis of PSE in pharmaceutical formulations and a human urine sample. The selectivity of the method is not only due to the HPLC separation but is also due to the highly selective detection principle of the Ru(bipy)3(2+)-peroxydisulphate CL system used. There was no interference observed from the common preservatives and excipients used in pharmaceutical preparations, which did not show any significant CL signal. The retention time of PSE was less than 3 min, and the detection limits and quantification limits were found to be 5.7 and 26.0 µg L(-1), respectively.

Study on the spectral and inclusion properties of a sensitive dye, 3-naphthyl-1-phenyl-5-(5-fluoro-2-nitrophenyl)-2-pyrazoline, in solvents and ß-cyclodextrin.

3-Naphthyl-1-phenyl-5-(5-fluoro-2-nitrophenyl)-2-pyrazoline (NPFP), a fluorogenic probe and its derivative NPFP-Phenylephrine were synthesized and their absorption and fluorescence properties were recorded in solvents of varying polarity. Spectroscopic studies reveal that, the solvatochromic behavior of the compounds depend not only on the polarity but also on the hydrogen-bonding properties of the solvents. The effects of ß-cyclodextrin on the fluorescence properties of both compounds were studied. It was found that there is an enhancement in the fluorescence intensity of labeled drug (NPFP-Phenylephrine) in the presence of ß-cyclodextrin. In the present study, the molecular motions of NPFP-Phenylephrine embedded in a ß-cyclodextrin cavity have been investigated by fluorescence techniques in steady-state and time resolved modes.

Parallel microdevice for high throughput analysis of levofloxacin using tris (2,2'-bipyridyl) ruthenium (II) and peroxydisulfate chemiluminescence system.

A parallel microdevice has been developed for high throughput analysis using microfluidics. The detection method is based on a chemiluminescence (CL) system based on the oxidation of tris (2,2'-bipyridyl) Ru(ll) [Ru (bipy)3(2+)] by peroxydisulfate. The device consists of a photoreactor chip and two detection chips. The sample throughput can reach up to 720 runs/h with the total reagent consumption of only 2.4 mL. The parallel microdevice was evaluated using levofloxacin (LEVO) in pharmaceutical preparations. The various factors that affect the CL signal were optimized, and the LOD was found to be 30 and 27 microg/L for the two detectors, respectively (S/N = 3), while RSD was 1.1% (n = 15) for 1.0 mg/L LEVO. Two tablet samples that contain LEVO as an active ingredient were successfully analyzed using the proposed parallel microdevice.

Nanotechnology in environmental remediation: degradation of volatile organic compounds (VOCs) over visible-light-active nanostructured materials.

Volatile organic compounds (VOCs) are major pollutants and are considered to be one of the most important contaminants generated by human beings living in urban and industrial areas. Methyl tert-butyl ether (MTBE) is a VOC that has been widely used as a gasoline additive to reduce VOC emissions from motor vehicles. However, new gasoline additives like MTBE are having negative environmental impacts. Recent survey reports clearly show that groundwater is often polluted owing to leakage of petroleum products from underground storage tanks. MTBE is highly soluble in water (e.g., 0.35-0.71 M) and has been detected at high concentrations in groundwater. The presence of MTBE in groundwater poses a potential health problem. The documented effects of MTBE exposure are headaches, vomiting, diarrhea, fever, cough, muscle aches, sleepiness, disorientation, dizziness, and skin and eye irritation. To address these problems, photocatalytic treatment is the preferred treatment for polluted water. In the present work, a simple and template-free solution phase synthesis method has been developed for the preparation of novel cadmium sulfide (CdS) hollow microspheres using cadmium nitrate and thioacetamide precursors. The synthesized products have been characterized by a variety of methods, including X-ray powder diffraction, high-resolution scanning electron microscopy (HR-SEM), X-ray photoelectron spectroscopy, and UV-visible diffused reflectance spectroscopy. The HR-SEM measurements revealed the spherical morphology of the CdS microspheres, which evolved by the oriented aggregation of the primary CdS nanocrystals. Furthermore, studies of photocatalytic activity revealed that the synthesized CdS hollow microspheres exhibit an excellent photocatalytic performance in rapidly degrading MTBE in aqueous solution under visible light illumination. These results suggest that CdS microspheres will be an interesting candidate for photocatalytic detoxification studies under visible light radiation.

Determination of amlodipine using terbium-sensitized luminescence in the presence of europium(III) as a co-luminescence reagent.

A sensitive time-resolved luminescence method for the determination of amlodipine (AM) in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb(3+) ) by formation of a ternary complex with AM in the presence of tri-n-octylphosphine oxide (TOPO) as co-ligand, dodecylbenzenesulfate as surfactant and europium ion as a co-luminescence reagent. The signal for Tb-AM-TOPO is monitored at λex = 242 nm and λem = 550 nm. Optimum conditions for the formation of the complex in aqueous system were 0.015 m Tris (hydroxylmethyl) amino methane buffer, pH 9.0, TOPO (1.0 × 10(-4) m), Eu(3+) (2.0 × 10(-7) m), dodecylbenzenesulfate (0.14%) and 6.0 × 10(-5) m of Tb(3+) , which allows the determination of 10-50 ppb of AM with a limit of detection of 1.2 ppb. The relative standard deviations of the method range between 0.1 and 0.2% indicated excellent reproducibility of the method. The proposed method was successfully applied for the assay of AM in pharmaceutical formulations and in plasma samples. Average recoveries of 98.5 ± 0.2% and 95.2 ± 0.2% were obtained for AM in tablet and plasma samples respectively.

Removal of Cu2+ and Ag+ from aqueous solution on a chemically-carbonized sorbent from date palm leaflets.

A chemically-carbonized sorbent was prepared from date palm leaflets by sulphuric acid treatment at 170 degrees C. Carbonization took place via the dehydration effect of the hot sulphuric acid producing a carbon with reduction property. Sorption of Cu2+ and Ag+ from aqueous solution was investigated in terms of pH, contact time, metal concentration and temperature. A peculiar behaviour was found for the sorption of the two metals on the produced carbon. Sorption of Cu2+ was fast, reaching equilibrium within -2 h, whilst Ag+ sorption was slow and required -60 h to reach equilibrium. Activation energy (E(a)) for Cu2+ sorption was -16.1 kJ/mol indicating a diffusion-controlled ion exchange process; however, E(a) for Ag+ sorption was -44.3 kJ/mol indicating a chemically controlled process. Equilibrium sorption data were tested for the Langmuir and Freundlich equations. Sorption capacity appears to be much higher for Ag+ than for Cu2+ with increased uptake, for both metals, when increasing the temperature (25-45 degrees C). Ag+ was reduced to elemental silver on the sorbent surface and this was confirmed using scanning electron microscopy and x-ray powder diffraction; however, no reduction processes were involved in Cu2+ sorption. This paper discusses the sorption mechanism.

The composition and antimicrobial activities of Cyperus conglomeratus, Desmos chinensis var. lawii and Cyathocalyx zeylanicus essential oils.

The essential oil compositions of the rhizomes of Cyperus conglomeratus (Cyperaceae) collected from Oman and the leaves of two Annonaceae plants, Desmos chinensis var. lawii and Cyathocalyx zeylanicus collected from India were studied by GC, GC-MS and 13C NMR spectroscopy. Twenty-six compounds, representing 84.4% of the oil were identified in C. conglomeratus, where eugenol (31.3%), alpha-cyperone (10.5%) and cyperotundone (8.4%) were the major compounds. Twelve compounds, constituting 100%, were identified in D. lawii oil, of which benzyl benzoate (58.7%), beta-caryophyllene (23.2%), limonene (4.9%) and alpha-humulene (4.0%) were the major constituents. Thirty-two compounds, comprising 98.0%, were identified in C. zeylanicus oil, of which beta-caryophyllene (21.6%), alpha-pinene (20.4%) and E-beta-ocimene (11.8%) were the major components. The antibacterial and antifungal activities of the oils were tested against a panel of five bacterial and two fungal strains. The oils showed moderate activity against all the tested microbial strains. The minimum inhibitory concentrations of the oils were also determined.

Composition and antibacterial activity of the essential oils of four commercial grades of Omani luban, the oleo-gum resin of Boswellia sacra FLUECK.

The essential oil compositions of four botanically certified and commercially available samples of Omani lubans (oleo-gum resins of Boswellia sacra Flueck.), locally known as Hoojri, Najdi, Shathari, and Shaabi in Jibali Arabic, obtained from plants growing in four different geographic locations of the Dhofar region of Oman, were analyzed by GC-FID, GC/MS, and (13) C-NMR spectroscopy. The market price of these four grades of lubans differed considerably, according to their color, clump size, and texture. However, this study revealed that Hoojri, the first grade luban, and Shaabi, the fourth grade luban, which greatly differed in their price, closely resembled each other in their essential oil composition, yield, and physicochemical characteristics, except the color and texture. The composition, yield, and specific rotation of the oils of Najdi and Shathari, the second and the third grade lubans, respectively, were different from those of Hoojri and Shaabi, but they both had high limonene contents. Najdi oil was different from the other three oils in terms of its high myrcene content. α-Pinene was the principal component in all the oils and can be considered as a chemotaxonomical marker that confirms the botanical and geographical source of the resins. All the oils showed pronounced activity against a panel of bacteria, and the trend in their bioactivity and their mode of action are discussed.

Determination of meloxicam using europium sensitized luminescence in the presence of co-luminescence reagents.

A sensitive time-resolved luminescence method for the determination of meloxicam (MX) in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of europium (Eu(3+)) by formation of ternary complex with MX in the presence of 1,10-phenanthroline as coligand, Tween-80 as surfactant and gadolinium ion as a co-luminescence reagent. The signal for Eu-MX-1,10-phenanthroline is monitored at λ(ex) = 360 nm and λ(em) = 620 nm. Optimum conditions for the formation of the complex in aqueous system were 0.01 M TRIS buffer, pH 8.0, 1,10-phenanthroline (6.0 × 10(-6) M), Gd(3+) (7.0 × 10(-6) M), Tween-80 (0.28%) and 1.75 mM of Eu(3+) which allows the determination of 20-800 ppb of MX with limit of detection (LOD) of 7 ppb. The relative standard deviations of the method range between 0.1 and 1.1% indicating excellent reproducibility of the method. The proposed method was successfully applied for the assay of MX in pharmaceutical formulations, plasma and in urine samples. Average recoveries of 99.8 ± 1.1%, 100.2 ± 0.9% and 100.9 ± 1.1% were obtained for MX in tablet, plasma and urine sample respectively.

High throughput method for the analysis of cetrizine hydrochloride in pharmaceutical formulations and in biological fluids using a tris(2,2'-bipyridyl)ruthenium(II)-peroxydisulphate chemiluminescence system in a two-chip device.

A fast, economic and sensitive chemiluminescence (CL) method has been developed for the analysis of cetrizine hydrochloride (CET) in pharmaceutical formulations and in biological fluids. The CL method is based on the oxidation of tris(2,2'-bipyridyl)ruthenium(II) (Ru (bipy)(3)(2+)) by peroxydisulphate in a two-chip device. Up to 180 samples can be analysed per hour, consuming only minute quantities of reagents. Three instrumental setups were tested to find the most economical, sensitive and high throughput setup. In the first setup, a continuous flow of sample and CL reagents was used, whereas in the second setup, a fixed volume (2 µL) of (Ru (bipy)(3)(2+)) was introduced into a continuous infusion of peroxydisulphate and the sample. In the third design, a fixed volume of sample (2 µL) was injected while the CL reagents were continuously infused. Compared to the first setup, a 200% signal enhancement was observed in the third setup. Various parameters that influence the CL signal intensity, including pH, flow rates and reagent concentrations, were optimized. A linear response was observed over the range of 50 µg L(-1) to 6400 µg L(-1) (R(2)=0.9959) with RSD values of 1.1% (n=15) for 1000 µg L(-1). The detection limit was found to be 15 µg L(-1) (S/N=3). The amount of consumed sample was only 2 µL, from which the detected amount of CET was found to be 6.5 × 10(-14)mol. This procedure was successfully applied to the analysis of CET in pharmaceutical formulations and biological fluids.

Analysis of fexofenadine in pharmaceutical formulations using tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate chemiluminescence system in a multichip device.

A simple, rapid and sensitive method has been developed for the analysis of fexofenadine (FEX) in pharmaceutical formulations, using a tris(1,10-phenanthroline)-ruthenium(II) [Ru(phen)(3)(2+)] peroxydisulphate chemiluminescence (CL) system in a multichip device. Various parameters that influence the CL signal intensity were optimized. These included pH, flow rates and concentration of reagents used. Under optimum conditions, a linear calibration curve in the range 0.05-5.0 µg/mL was obtained. The detection limit was found to be 0.001 µg/mL. The procedure was applied to the analysis of FEX in pharmaceutical products and was found to be free from interference from concomitants usually present in these preparations.

Fluorescence quenching studies of nitrated polycyclic aromatic hydrocarbons.

The analysis of nitrated polycyclic aromatic hydrocarbons (NPAHs) is of great importance because of the mutagenicity and possible carcinogenic activity of these compounds, which are distributed widely in the environment. Nitro-substituents in aromatic compounds are known to quench fluorescence and NPAHs have no intrinsic fluorescence, but they can be determined using their quenching effects on other fluorophores. The quenching effects of several important NPAHs on 1,2,3,4- tetrahydro-1-naphthol,5,6,7,8-tetrahydro-1-naphthol,4-(2-hydroxy-4-sulfo-1-naphthylazo)-2-naphthalene carboxylic acid and 7-amino-4-methyl coumarin have been studied. The singlet emission of these fluorophores is efficiently quenched by all the NPAHs, the quenching following the Stern-Volmer relationship. Quenching constants and the limits of detection and linear ranges of the quenchers have been determined in each case: the limits of detection are ca 1 µm.

Spectrofluorimetric determination of aluminium using 2-hydroxy-1-naphthylidene-(8-aminoquinoline).

A sensitive and selective spectrofluorimetric method has been developed for the rapid determination of aluminium. This method is based on the complex formation between aluminium and 2-hydroxy-1-naphthylidene-(8-aminoquinoline) (HNAQ). The optimum conditions for the complex formation were a metal-to-ligand (M : L) stoichiometric ratio of 1:1, a pH of 5.5 and a 0.20 m acetate buffer. The fluorescence of the complex was monitored at an emission wavelength of 502 nm with excitation at 438 nm. Under these conditions, linear calibration curves were obtained in the ranges 0.05-1 and 1-5 ppm. The detection limit was 3.4 ppb for the former and 13.5 ppb for the latter. The maximum relative standard deviation of the method for an aluminium standard of 200 ppb was 1.5% (n = 5). This method was successfully applied for the determination of aluminium in drinking water, pharmaceutical antacid tablets and suspension samples.

Enhancement of on chip chemiluminescence signal intensity of tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate system for analysis of chlorpheniramine maleate in pharmaceutical formulations.

The effect of detection chip geometry on chemiluminescence (CL) signal intensity of tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate system for analysis of chlorpheniramine maleate (CPM) in pharmaceutical formulations was investigated. It was observed that the design of the detection chip is very crucial and can play an important role in enhancing the CL signal intensity in this system. The CL signal intensity was enhanced 250% when a teardrop micromixer chip was used, compared to the commonly used serpentine chip geometry. The study was conducted using a multi-chip device. In this device, chip 1 was used to prepare and pump the reagent mixture, whereas chip 3 was used for pumping the sample. The two chips were connected to the teardrop chip (2) via silica capillary where detection took place. Non-linear regression curve fitting of the calibration data revealed that the calibration curves are best described by third order polynomial equation with excellent correlation coefficients (R(2)=0.9998) for the concentration range 7.69 × 10(-8) to 5.12 ×1 0(-5)mol L(-1). A linear response is also observed over the range 7.69 × 10(-8) to 1.28 × 10(-5)mol L(-1) (R(2)=0.9996) and the detection limit was found to be 5.49 × 10(-8)mol L(-1). The device was successfully used for the analysis of CPM in tablets and a multi-component cough syrup. Results were reproducible with relative standard deviation (RSD) of 0.6-1.1%.