Diphenylcarbazide Research Articles

Spectroscopic investigation on the sonodynamic damage to protein in the presence of eosine B

In this work, bovine serum albumin (BSA) and eosine B (EB) were selected as a model protein and sonosensitizer, respectively. The sonodynamic damage to protein in the presence of EB and its mechanism were studied by means of absorption and fluorescence spectra. The results indicated that the synergistic effects of ultrasound and EB can efficiently damage the BSA molecules, and the damage of protein could be mainly due to the generation of reactive oxygen species (ROS). The damage degree of protein increased with the increase of ultrasonic time and EB concentration because of the increased quantities of ROS. Hydroxyl free radical (OH) was the major mediators of the ultrasound-inducing proteins damage in the presence of EB. In addition, the quantities of ROS from the diphenylcarbazide (DPCI)–EB solutions and the DPCI–fluorescein (FS) solutions with or without ROS scavengers were contrasted, respectively. The results show that FS mainly produce OH, but the quantities of ROS in the presence of FS were lower than those of EB, which indicates that the nitro and bromine substituent groups on the benzene ring of FS increase the quantity of ROS, but do not change the kinds of ROS.

Removal of Chromium(VI) from Industrial Effluents Through Supported Liquid Membrane Using Trioctylphosphine Oxide as a Carrier

The present study describes extraction of chromium(VI) through supported liquid membrane (SLM), Celgard 2400, which was impregnated with trioctylphosphine oxide (TOPO) dissolved in toluene. The stripping phase was comprised of diphenylcarbazide (DPC) in sulfuric acid (H2SO4) whereas the feed phase consists of potassium dichromate (K2Cr2O7) and hydrogen peroxide (H2O2). The effects of concentrations of chromium, TOPO, DPC, and H2SO4 have been studied in order to evaluate the transport efficiency of chromium(VI) ion. The optimum experimental conditions for the chromium(VI) extraction were established as follows: 19.2 × 10−4 mol L-1 chromium ion, 1.5 mol L-1 H2O2 concentration in the feed phase, 0.1 mol L-1 TOPO concentration in the membrane phase and 0.001 mol L-1 DPC and 1.5 mol L-1 H2SO4 as stripping phase. The measurements of percent recovery, distribution coefficient, flux and permeability were made at the given optimized conditions. The extraction time and membrane stability were also investigated. Extraction efficiency of 80% was recorded in 180 min and the SLM system was found stable up to 10 days. The optimized SLM system was then applied on the paint industry wastewater; about 80% of chromium(VI) was successfully removed from the wastewater.

Extraction of the contribution of kinetic profile for reaction of a chemical species in unknown matrices by standard addition method

A new and simple strategy is applied to resolve kinetic profile for the reaction of an analyte in unknown matrices, using standard addition method (SAM). The proposed method uses kinetic spectrophotometric data obtained by standard addition of analyte into unknown mixtures followed by the reaction of analyte with a proper reagent. The proposed method extracts kinetic profile for the reaction of an analyte by averaging the kinetic profiles obtained by subtraction of kinetic profiles after and before standard addition. The rate constant can be obtained using computational curve fitting. The performance of method was evaluated by using synthetic data as well as several experimental data sets. The proposed method can be applied to obtain kinetic profiles of the reactions in the presence of additive interference as well as multiplicative interferences. Hydroxylation reaction of diphenylcarbazide (DPCI) in the presence of diphenylcarbazone (DPCO) as a real system at various pHs was also studied by the present method. The rate constant and the order of the hydroxylation reaction were determined from extracted kinetic profiles.

Study of a polymer optical microring resonator for hexavalent chromium sensing

This work presents a design method for an Optical Microring Resonator (OMR) dedicated to specific heavy metal species sensing. A Top-Down design approach is used to create an OMR specifically designed for hexavalent chromium sensing, and suitable to a final Lab on Chip integration. Its operating principle is based on optical absorption measurement. This spectral absorption is induced by the colorimetric metallic complexation of hexavalent chromium with 1,5 diphenylcarbazide (DPC).The light enhancement at resonance wavelengths in an OMR allows highly sensitive measurements of the fluid optical absorbance by enhancing the effective path length. Chromate ions react with DPC at visible range. Singular red–violet complex is formed and induce a significant change of light intensity in the transmission spectrum. The intrinsic maximum absorption of metallic complex around 545nm makes the polymer ring resonator parameters changing namely its effective index and attenuation value at resonance. The design considerations of the OMR have been analyzed to optimize critical parameters regarding the polymer ring resonator geometry. Simulations results have been investigated which lead to the geometry of a prototype device.

621 Aryl Hydrocarbon Receptor Is Required for Induction of Apoptosis by the Flavonoid Chrysin in Colon Tumor Cells

As a continuous effort to find new natural products with potential herbicide activity, flavonoids acacetin (1), chrysin (2) and 4′,7-dimethylnarangenin (3) were isolated from a propolis sample collected in the rural area of Mexico City and their effects on the photosynthesis light reactions and on the growth of Lolium perenne, Echinochloa crus-galli and Physalis ixocarpa seedlings were investigated. Acacetin (1) acted as an uncoupler by enhancing the electron transport under basal and phosphorylating conditions and the Mg2+-ATPase. Chrysin (2) at low concentrations behaved as an uncoupler and at concentrations up to 100 μM its behavior was as a Hill reaction inhibitor. Finally, 4′,7-dimethylnarangenin (3) in a concentration-dependent manner behaved as a Hill reaction inhibitor. Flavonoids 2 and 3 inhibited the uncoupled photosystem II reaction measured from water to 2,5-dichloro-1,4-benzoquinone (DCBQ), and they did not inhibit the uncoupled partial reactions measured from water to sodium silicomolybdate (SiMo) and from diphenylcarbazide (DPC) to diclorophenol indophenol (DCPIP). These results indicated that chrysin and 4′,7-dimethylnarangenin inhibited the acceptor side of PS II. The results were corroborated with fluorescence of chlorophyll a measurements. Flavonoids also showed activity on the growth of seedlings of Lolium perenne and Echinochloa crus-galli.

A study of the phase transition of reheated diphenyl carbazide (DPC) by using UV spectroscopy

Phase transition phenomenon in reheated diphenyl carbazide (DPC) is studied here using UV spectroscopy. The optical band gap for reheated DPC is obtained by measuring the optical diffused reflectance (DR) and equals to 3.55eV. Also, the optical band gap is calculated using UV technique and equals to 3.548eV. The absorbance of reheated DPC is studied at some selected temperatures in order to check the presence of phase transitions at 90°C and 125°C. According to the present work, the band gaps are calculated at 80°C, 110°C and 130°C and equal to 3.548eV. But at 100°C, the optical band gap has changed to 4.139eV. It was found that each phase of reheated DPC belongs to a certain definite crystal structure. The presence of the phase transitions are checked and confirmed by scanning electron microscopy (SEM). The structural properties and morphology of reheated diphenyl carbazide are investigated by SEM. The SEM images are taken at some selected temperatures to confirm the presence of phase transitions.

Determination of trace chromium (VI) using a hollow-core metal-cladding optical waveguide sensor

A biosensor capable of highly sensitive detection of trace chromium (VI) with a simple hollow-core metal-cladding waveguide (HCMW) structure is theoretically modeled and experimentally demonstrated. Owing to the high sensitivity of the excited ultrahigh-order modes in the waveguide, a tiny variation of the extinction coefficients in the waveguide guiding layer where the chromate ions reacts with the diphenylcarbazide (DPC) can lead to a significant change of light intensity in the reflection spectrum. The experimental results indicate that using the proposed method, the chromium (VI) sensitivity detection limit can be as low as 1.2 nM, which represents a 16-fold improvement compared to the surface plasmon field-enhanced resonance light scattering (SP-RLS) method, and a 4-fold improvement compared to the flame atomic absorption spectrometry and fluorimetry spectroscopy, respectively.

An Amyloid-Fibril-Based Colorimetric Nanosensor for Rapid and Sensitive Chromium(VI) Detection.

Appearing with a trace! A new colorimetric nanosensor for CrVI from the amyloid fibrils of hen lysozyme has been developed. This nanosensor, which makes use of hen lysozyme fibrils as CrVI binders and acidified diphenylcarbazide (DPC) as the colorimetric probe, can specifically detect CrVI at the ppb level without sample pretreatment and the use of advanced instruments.

Verificación analítica para las determinaciones de cromo hexavalente en aguas por espectrofotometría

En la actualidad la prestación de servicios analíticos de laboratorios, toma de forma ascendente más auge y utilidad. El efecto de un análisis de aguas es forjar resultados correctos y confiables, siendo la verificación de ensayos uno de los aspectos más importantes y factor clave para conseguir este propósito. La determinación de cromo hexavalente en aguas por colorimetría con la difenilcarbazida es la metodología analítica más usada y útil que se conoce en el ámbito científico técnico, principalmente, por su alta selectividad y también debatida por su reacción a las interferencias. En el presente estudio se hizo la valoración analítica del método espectrofotométrico para la determinación de cromo hexavalente en aguas; el objetivo de este trabajo fue confirmar correctamente la aplicación del método para el análisis de aguas. Se trabajaron muestras de diferentes tipos de agua: potable, residual y superficial, siguiéndose estrictamente los protocolos de verificación. Se encontraron resultados satisfactorios en precisión y exactitud con el fin de emitir resultados confiables y reales de la muestra analizada.

IR spectroscopic analysis of the new organic silver complex C13H13N4OAg

IR analysis in the frequency range 400–4000cm−1 is used here to investigate the changes in different modes of thermally treated new metal complex (diphenyl carbazide silver complex DPCAg, C13H13N4OAg) during the glass transition at 91°C and the high temperature phase transition at 167°C. These two phase transitions in this new metal compound are studied here by detecting the changes in some IR spectroscopic parameters (e.g., mode shift, band contour, peak height and peak intensity) during the elevation of temperature. All of the vibrations of DPCAg were found to be due to ionic fundamentals 3311cm−1, 3097cm−1, 3052cm−1, 1677cm−1, 1602cm−1, 1492cm−1, 1306cm−1, 1252cm−1, 887cm−1 and 755cm−1. The results obtained can be considered as the first spectroscopic analysis of this new metal complex. These results strongly confirmed that the thermally treated DPCAg transverse a glass transition at 91°C and a high temperature phase transition at 167°C. Anomalous spectroscopic changes near the glass transition temperature Tg could be recorded. A temperature dependence of peak intensity of the two modes 810cm−1 and 3440cm−1 could be observed beyond Tg. Also, the high temperature phase modification at 167°C showed anomalous change in the spectroscopic parameters before and after the phase transition process. A proposed silver position in the new silver complex DPCAg has been presented.

Removal of Chromium from Electroplating Industry Effluent Using Electrocoagulation

Experiments were performed in batch mode of operation using iron electrodes to remove chromium from effluent by electro- coagulation, and the effect of various operating parameters was investigated. The maximum hexavalent chromium removal efficiency of 100% from a synthetic solution containing hexavalent chromium was obtained for an electrolysis time of 15 min at the optimum current density of 50 mAcm −2 , interelectrode distance 0.5 cm, and solution pH of 4. The real electroplating industry effluent was characterized using the standard diphenylcarbazide (DPC) method. A 100% chromium removal efficiency was obtained for both trivalent and hexavalent chro- mium, for an electrolysis time of 45 min at 4 pH. It was found that Cr(VI) is initially reduced to Cr(III) in the acidic medium. An increase in the pH of the effluent was also noticed in the acidic medium due to the generation of hydroxyl ions. Experiments were performed for the removal of chromium using ferric chloride as the coagulant, and it was found that electrocoagulation is more efficient and relatively faster compared to chemical coagulation. DOI: 10.1061/(ASCE)HZ.2153-5515.0000170. © 2013 American Society of Civil Engineers. CE Database subject headings: Coagulation; Chromium; Iron compounds; Abatement and removal. Author keywords: Electrocoagulation; Electroplating effluent; Hexavalent chromium; Trivalent chromium; Iron.

Influencing Factors of Chromium Ion Stability in Microbe Culture Media

The stability factors for Cr6+ and Cr3+ in microbiological media, including temperature, preservation conditions and medium components were studied in this research project, through potassium permanganate oxidation and DPC (Diphenylcarbazide) spectrophotometry. It shows that the protein component mainly influences Cr6+ content changes at pre- and post- heat sterilization to the chromium ionic liquid medium, other than being impacted basically by inorganic salt ions. It also indicates that the method can be introduced into experiment researches for microbe dechromisation i.e. Chromium ion aqueous solution and fluid medium are sterilized separately, and then are made into the chrome ions liquid as per a certain concentration. The concentration of hexavalent chromium ions is affected by preservation time and temperature also. For this reason, chromium ionic liquid medium is kept at low temperature, and as quickly as possible for the test.

Ultra-trace recognition and removal of toxic chromium (VI) ions from water using visual mesocaptor

The key to designing optical mesocaptors is to construct a chromogenic receptor, namely, diphenylcarbazide (DPC), as a nanoscale platform scavenger with different functional characteristics, such as density, accessibility, and intrinsic mobility. Engineering of optical captors allows facile and reliable signaling in continuous monitoring modes, and enables simple and high-speed removal of toxic chromium (VI) ions. Mesoporous aluminosilica monoliths, with unique morphologies, active surface sites, and physical properties, enhance sensing/removal characteristics in terms of sensitivity, selectivity, and response time. The systematic design of optical mesocaptor is based on a densely patterned selective binding site (DPC) in engineered mesocylinder carriers that have multidirectional pores and microsized particle-like monoliths to control the adsorption/detection assays of Cr(VI) ions. Synthetic mesocaptor can be used for visual removal of Cr(VI) ions even at low concentration levels of 10−10M (i.e., 0.07ppb) with rapid response time in minutes. Moreover, these new classes of design-made hybrid mesocaptor exhibit long-term signaling stability and recognition functionalities that provided extraordinary sensitivity, selectivity, reusability, and fast kinetic detection and quantification of various deleterious metal ions in the environment.

Leaf plasticity to light intensity in Italian cypress (Cupressus sempervirens L.): Adaptability of a Mediterranean conifer cultivated in the Alps

Italian cypress (Cupressus sempervirens L.) is native to the eastern Mediterranean, an area characterised by hot, dry summers and mild winters. Over the centuries, however, the species has been introduced into more northerly regions, a long way from its native range. The current, generally warmer climatic conditions brought about by global warming have favoured its cultivation in even more northerly areas in the Alps and other European alpine regions. Given that not only temperature, but also light availability are limiting factors for the spread of cypress in these environments, it is important to ascertain how this species copes with low light conditions. The photosynthetic characteristics of cypress leaves collected from different portions of the crown with contrasting light availability were evaluated by several methods. Chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoid (Car) content was found to be higher in shade leaves than in sun leaves when measured on a fresh mass basis, although enzymatic activities of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) and nitrate reductase were lower in shade leaves. When the efficiency of PSII was measured by chlorophyll fluorescence, a marked reduction in Fm was found in shade leaves, while Fo remained unchanged. The use of exogenous electron donors diphenyl carbazide (DPC) and NH2OH actually improved the photosynthetic efficiency of shade leaves, and the same effect was found when PSII electron transport activity was measured as O2 evolution. Altogether, these results seem to indicate lesser photosynthetic efficiency in shade leaves, probably an impairment on the donor side of the PSII. At the same time, analysis by SDS–PAGE revealed differences in the polypeptide composition of the thylakoid membranes of sun and shade leaves: the bands corresponding to 23kDa, 28–25kDa and 33kDa polypeptides were less intense in the thylakoid membranes extracted from shade leaves. These results were further confirmed by an immunological study showing that the content of the 33kDa protein, corresponding to the extrinsic PSII protein PsbO, was significantly diminished in shade leaves. The high plasticity of cypress leaves appears to be an advantageous trait in the plant’s response to variations in environmental conditions, including global change. Implications for the management of this Mediterranean species at the northern edge of its distribution are discussed.

Differential effects of UV-B radiation fluence rates on growth, photosynthesis, and phosphate metabolism in two cyanobacteria under copper toxicity

This work was undertaken to ascertain the impact of different fluence rates of ultraviolet-B (UV-B) radiation on two cyanobacterial biofertilizers, Phormidium foveolarum and Nostoc muscorum, growing under copper toxicity. Copper (2 and 5 µmol L−1) and high UV-B fluence rate (UV-BH; 1.0 µmol m−2 s−1) decreased the growth, pigment content, photosynthetic oxygen yield, phosphate uptake, and acid phosphatase activity in both the strains analyzed after 24 and 72 h of experiments, and combined exposure further enhanced the toxic effects. Respiration and alkaline phosphatase activities were stimulated appreciably. The damaging effect was shown on the order on pigments: phycocyanin > chlorophyll a > carotenoids, and on photosystems: whole chain photosynthetic reaction > photosystem II > photosystem I. Partial recovery in the photosystem II activity in the presence of artificial electron donors; diphenyl carbazide (DPC), hydroxylamine (NH2OH), and manganese chloride (MnCl2) pointed out the interruption of electron flow on the oxidation side of photosystem II. Unlike UV-BH, low UV-B fluence rate (UV-BL; 0.1 µmol m−2 s−1), rather than causing damaging effect partially, alleviated the toxic effects of Cu. This study suggests that the cyanobacterium P. foveolarum is less sensitive against UV-BH and excess Cu (2 and 5 µmol L−1), thus P. foveolarum may be used as a biofertilizer for sustainable agriculture.

Sensitive determination of chromium (VI) based on the inner filter effect of upconversion luminescent nanoparticles (NaYF4:Yb3+, Er3+)

A new method was developed for selective and sensitive determination of trace chromium (VI) based on the inner filter effect (IFE) of upconversion luminescent nanoparticles (NaYF4:Yb3+, Er3+) as fluorescence probes. In this study, water-soluble and well dispersible upconversion luminescent nanoparticles (NaYF4:Yb3+, Er3+) were firstly synthesized by hydrothermal method, and characterized by transmission electron microscopy (TEM) and luminescence spectroscopy. And then, the IFE method was established for determination of chromium (VI). The principle of this assay is based on the complementary overlap of the green emission band of nanoparticles (NaYF4:Yb3+, Er3+) with the absorption spectrum of a pink chelate complex (Cr(III)-diphenylcarbazone), which was generated by the quantitative reaction between diphenylcarbazide (DPC) and Cr(VI) in mineral acid solution. Under the optimal condition, the decrease in the upconversion luminescent nanoparticles was proportional to the concentration of chromium (VI) due to IFE. The linear range is 0.070–10.0×10−6molL−1 Cr(VI), and the limit of detection (3σ) is 2.40×10−8molL−1 Cr(VI). The method described here is sensitive than the method of spectrophotometry. This assay was used in the determination of Cr(VI) in water samples.

Stimulatory effect of ascorbate, the alternative electron donor of photosystem II, on the hydrogen production of sulphur-deprived Chlamydomonas reinhardtii

The green alga Chlamydomonas reinhardtii is capable of photoproducing molecular hydrogen following sulphur deprivation, which results in anaerobiosis and a suppression of oxygen evolution and thus an alleviation of the inhibitory effect of oxygen on the hydrogenase. At the same time it transiently maintains a limited supply of electrons arising from photosystem II (PSII) to the hydrogenase (Melis and Happe Plant Physiol 2001; 127:740–748). In this work, using fast chl a fluorescence and P700 measurements, we show that ascorbate (Asc), a naturally occurring PSII alternative electron donor, is capable of donating electrons to PSII in heat-treated and sulphur-deprived cells and this can be significantly accelerated by supplementing the culture with 10 mM Asc. It also enhances, about three-fold, the photoproduction of hydrogen in cells subjected to sulphur deprivation as shown by gas chromatography. Similar stimulation was obtained in the presence of diphenylcarbazide (DPC), an artificial PSII electron donor. Asc and DPC also facilitated the anaerobiosis of cells, probably via super reducing the oxygen evolving complex while feeding electrons to PSII reaction centres and the linear electron transport chain, and ultimately to the hydrogenase – as shown by the significant DCMU-sensitivity of the light-induced Asc- and DPC-dependent re-reduction of P700+ and hydrogen evolution.

Indirect spectrophotometric method for determination of captopril using Cr(VI) and diphenylcarbazide

A spectrophotometric method for the indirect determination of captopril (CP) in pharmaceutical formulations is proposed. The proposed procedure is based on the oxidation of captopril by potassium dichromate and the determination excess oxidant on the basis of its reaction with diphenylcarbazide (DPC). Under the optimum conditions, a good linear relationship (r = 0.9997) was obtained in the range of 0.08-3.5 µg mL-1. The assay limits of detection and quantitation were 0.024 and 0.08 µg mL-1, respectively. The results obtained for captopril determination in pharmaceuticals using the proposed method and those obtained with the US Pharmacopoeia method were in good agreement at the 95% confidence level.

Determination of Cr(vi) in water samples by ICP-OES after separation of Cr(iii) by montmorillonite

In the present work a simple method was proposed for the determination of Cr(VI) in water samples using a previous separation of Cr(III) by the low cost sorbent montmorillonite, followed by separation of the solid phase and subsequent quantification of Cr(VI) employing ICP-OES. A complete Cr(III) removal was observed after only 1 minute of contact time between 25 mg of the clay mineral montmorillonite saturated with potassium ions (MTK) and the aqueous sample. On the other hand, the Cr(VI) remained in solution, yielding a suitable separation of the species. The method presented appropriate accuracy and precision in comparison with the official method of diphenylcarbazide (DPC), showing a good performance for Cr(VI) quantification in effluent water samples, with 0.20 and 0.70 μg L−1 for the Limit of Detection (LOD) and the Limit of Quantification (LOQ), respectively. Based on the experimental results, MTK showed remarkable characteristics to be used as a sorbent phase for an easy and fast separation of chromium species and consequently to provide the speciation analysis.

Photosynthesis-inhibiting effects of 2-benzylsulphanylbenzimidazoles in spinach chloroplasts

AbstractInhibition of photosynthetic electron transport (PET) in spinach chloroplasts by nineteen 2-benzylsulphanylbenzimidazoles (BZA) was studied. BZA were found to inhibit photosynthetic electron transport (PET) and for their inhibitory efficiency, electronic properties of the R substituent on the benzyl moiety are decisive. The PET inhibiting activity of the studied BZA expressed as IC50 varied in the range from 28.5 μM (R = 3,5-(CF3)2) to 394.5 μM (R = 2,4-(NO2)2). For compounds with R = H, 4-CH3, 3-CH3, 3-OCH3, 4-F, 3-F, 4-Cl, 3-Cl, 2-Cl, 4-Br, 3-Br, 3,4-F2, 3,4-Cl2, 3-CF3, 3,5-(CF3)2 linear increase of the inhibitory activity with the increasing value of the substituent’s σ constant up to 0.86 was observed. Further increase of the σ constant resulted in a sharp activity decrease of the corresponding compounds (R = 2-F-6-Cl, 2-NO2, 3,5-(NO2)2, 2,4-(NO2)2). Using EPR spectroscopy and an artificial electron donor diphenyl carbazide it was found that the site of BZA action in the photosynthetic apparatus is situated on the donor side of PS 2, prior to the Z·/D· intermediate.