The Eighth Palestinian International Chemistry Conference (PICC 2015) "Chemical Sciences Towards Knowledge Based Economy "

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Analysis of Pesticide Residues in Tomato and Citrus from The Valley Souss in Morocco.
(2015-04-21) Salghi, R.
Moroccan citrus industry is oriented towards export of high quality fresh fruit worldwide. With an average production of about 1.5 million tons per annum from which 50% is exported mainly to European markets. The quality characteristics of best fruit today in the market are determined by the ‘eye appeal’ and internal organoleptic and sanitary characteristics. Nowadays, there is a growing awareness of the consumer regarding pesticides residues in fresh fruits and vegetables. With the tightening regulations of European Union and the USA markets on fruit safety and Assurance quality, the trend in many exporting countries during the last 5 to 10 years is to monitor the application of pesticides against the major pests of citrus. Morocco with its 75,000 ha of citrus groves is directly concerned with the new legislation and the phytosanitary measures of the importing countries. In southern Morocco in the Agadir region, the cultivation of tomato and citrus occupies a very important place in the national socio-economic context. Exports from the Souss-Massa region exceed 80% of the national export. Citrus fruits are more than 60% of production and over 55% of the country's export.
Antioxidant Activity, Total Phenolic Content, and Total Flavonoids Content of Zizphus Spina-Christi Fruits and Leaves from Palestine
(2015-04-21) Al-Rimawi, Fuad
Different samples of fruits and leaves of Zizphus Spina-Christi (sidr in Arabic) were collected from different areas of West Bank (north, middle, and south) at different maturation stages of the year. The samples were dried at 30 °C, grinded with a blender, and the dried powder was extracted with three different solvents: water, ethanol, and 80% ethanol for one hour. The crude extracts were then analyzed for their total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (AA) using standard assay methods (Folin-Ciocalteau method for TPC, colorimetric assay method for TFC, and ferric ion reducing antioxidant power (FRAP) for AA), and compared with vitamin C which is a known chemical antioxidant. Three samples of leaves and fruits of each treatment were independently analyzed in each sampling, and all of the determinations were carried out in triplicate. The results revealed that the maturation stage affected the composition of the leaves and fruits under investigation in terms of total phenolic, total flavonoid, and antioxidant activity. Additionally it was found that there is a significant difference in TPC, TFC, and AA of the leaves and fruit samples collected from north, middle, and south of the West Bank. Pearson correlation between TPC, TFC, and AA of samples collected from the three areas in the West Bank showed that antioxidant activity is significantly correlated with total phenolic content, and weakly correlated with total flavonoids. It was also found that no significant correlation existed between TPC and TFC in any sample under investigation.
Application of Nano Iron in the Remediation of Cr-Contaminated Soil and its Effect on Plant Growth and Soil Bacteria
(2015-04-21) Zedany, Shireen
Recently, a huge amount of laboratory-scale research and field tests are being carried out internationally in order to assess the effectiveness of iron nanotechnology in environmental cleanup. Published results have shown that nano iron is an effective tool for remediation of water and soil from various kinds of organic and inorganic pollutants. Together with this, increasing attention is also paid to the impact of nano iron on the biosphere. In this research, nano iron will be applied to remediate soil samples contaminated with chromium. Hexavalent chromium is a well-known pollutant in water and soil, particularly in the vicinity of industrial regions. In addition to this, the effect of nano iron on plant growth and soil bacteria will be investigated. Nano iron will be synthesized, and its efficiency toward Cr(VI) removal will be tested using laboratory scale experiments at the department of Chemistry. The experiments will be performed under various experimental conditions. The assessment of nano iron impact on plant growth and soil bacteria will be realized.
Biodiesel Viscosity and Flash Point Determination
(2015-04-21) Ateeq, Eman A.
In this research, biodiesel samples of different percentages of blend biodiesel (Palestinian biodiesel prepared from waste oil) and petro-diesel were studied. The density, refractive index, flash point and viscosity of the samples were measured. The flash points were measured as a function of percentage of biodiesel, the results emphasized that the flash points increase as the percentage of biodiesel increases in the sample. Two equations were proposed to obtain more suitable prediction of the flash point. The values of flash points of biodiesel were compared with the standard value of flash point of biodiesel. The comparison shows that samples containing more than 40% biodiesel coincide with standard values. The values of kinematic viscosity of biodiesel were compared with the Palestinian standard value of biodiesel. The comparison shows that samples containing less than 72% biodiesel coincide with standard value. Taking into consideration results of kinematic viscosity and flash point one can suggest percentage 71% of biodiesel and 29% petro-diesel as the best percentage that the two materials can be mixed according the Palestinian standards.
CdSe Thin Film Photoelectrochemical Electrodes: Combined Electrochemical and Chemical Bath Depositions
(2015-04-21) Nour Nayef, Abdul-Rahman
CdSe thin films have been deposited onto FTO/glass substrates by three different techniques, electrochemical deposition (ECD), chemical bath deposition (CBD) and combined method based on electrochemical deposition (ECD) followed by chemical bath deposition (CBD). The films were comparatively characterized by a number of techniques (photoluminescence spectra, electronic absorption spectra and XRD measurements). Photoelectrochemical (PEC) characteristics of the electrodes including current density-voltage (J-V) plots, conversion efficiency (ƞ) and fill factor (FF) were then studies. The PEC measurements indicate that the CdSe films are n-type in electrical conduction, and optical absorption measurements show that the band gap range for the prepared films is estimated to be 2.06-2.30 eV. XRD results show that the three systems involved nano-sized CdSe particles with cubic type crystals. The new ECD/CBD-CdSe electrode exhibited higher photo-electrochemical conversion efficiency (ƞ% ̴ 4.40) than either ECD- or CBD-CdSe film electrodes. This supports the basic hypothesis of this work where the ECD/CBD film is assumed to combine the advantages of both ECD-CdSe film (good adherence to FTO/glass substrate) and CBD-CdSe film (suitable film thickness) together.
Cellulose Powder from Biomass Waste of Olive Industry
(2015-04-21) Al-Hajj, Nisreen
In the present work cellulose powder was extracted from olive industry solid waste and then converted into cellulose acetate. The cellulose powder was extracted from olive industry solid waste by kraft pulping process and multistep bleaching p sequences. An elemental chlorine-free chemical bleaching sequence chlorine dioxide (D)-cold caustic extraction (E)-hypochlorite (H)- hydrogen peroxide (P) was used. Cellulose powder was obtained in about 35 % yield. The extracted cellulose and cellulose acetate made from thereof were extensively characterized using Fourier transform infrared spectroscopy, electron microscopy sciences, gel-permeation chromatography/high-performance liquid chromatography, and viscometry. Our key finding in this study was that olive industry solid waste is a valuable source of cellulose powder and its derivatives. This is important, since our results show how lignocellulosic agricultural wastes could be utilized and converted into cellulose products with high value.
Characterization of the MgO/GaSe0.5S0.5 Heterojunction Designed for Visible Light Communications
(2015-04-21) Qasrawi, Atef F.
In this study an optoelectronic design is reported and characterized. The device is made of p-type MgO solved in sodium silicate binder and n-type GaSe0.5S0.5 heterojunction. It is described by means of X-ray diffraction, optical absorption and reflection in the incident light wavelength range of 190-1100 nm and by means of dark and 406 nm laser excited current (I)-voltage (V) characteristics. The optical reflectance was also measured as a function of angle of incidence of light in the range of 35-80o. The structural analysis revealed no change in the existing phases of the device composers. In addition, it was observed that for pure sodium silicate and for a 67% content of MgO solved in sodium silicate binder (33%), the heterojunction exhibits a valence band splitting of 0.45 and 0.70 eV, respectively. The painting of MgO improved the light absorbability significantly. On the other hand, the angle-dependent reflectance measurements on the crystal displayed a Brewster condition at 70o. The MgO/ GaSe0.5S0.5 heterojunction exhibited no Brewster condition when irradiated from the MgO side. Moreover, for the crystal and the MgO/GaSe0.5S0.5 heterojunction, the dielectric spectral analysis revealed a pronounced increase in the quality factor of the device. The I V characteristics of the device revealed typical optoelectronic properties with high photoresponse that could amplify the dark current 24 times when irradiated with 5 mW power laser light. The structural, optical, dielectric and electrical features of the MgO/GaSe0.5S0.5 heterojunction nominate it for use in visible light communication technology
Combined Electrochemical and Chemical Bath Deposition Techniques to Prepare CuSe Thin Film Electrodes for Solar Energy Purposes
(2015-04-21) Murtada, Khaled A.Q.
Copper selenide (CuSe) thin films were prepared using electrochemical deposition (ECD), chemical bath deposition (CBD) and combined CBD/ECD preparation techniques on fluorine-doped tin oxide (FTO) coated glass substrates. Enhancement of deposited CuSe thin film characteristics in photo-electrochemical (PEC) systems was investigated. Deposited CuSe thin films were treated by different methods. The films were annealed at 250°C under N2 atmosphere for 1 hour. Cooling of annealed films to room temperature was done using two different methods (slow and fast cooling). K3Fe(CN)6/K4Fe(CN)6/LiClO4 as redox couple was also used in the PEC measurements. The effect of such treatment on electrode PEC characteristics, such as: open-circuit voltage (Voc), short-circuit current density (Jsc), dark current density-potential (J-V) plots, photo J-V plots, conversion efficiency (ɳ), fill factor (FF), Surface Morphology and stability, was studied. The characteristics of CuSe thin films in PEC systems were enhanced by using different experimental conditions, annealing and cooling rates. Improving the stability of the prepared CuSe electrode by cleaning and using suitable redox couple was also achieved. The dark and photo-current density versus potential plots were non-improved by annealing. Cell efficiency (ɳ), fill factor (FF), and short-circuit current densities (Jsc) were enhanced by CuSe films annealing. The best CuSe films are naked and non- annealed CBD/ECD film for which the photo J-V plots and cell efficiency was improved significantly. The effect of coating the CuSe electrodes with MP/polysiloxane (1:4 ratios) was also studied. The (Jsc) values of coated CuSe films were significantly enhanced. The MP/polysiloxane coating introduces a charge-transfer mediator species that enhances current and electrode stability. The PEC studies and characteristics showed that the 2 hr deposition time (prepared by CBD/ECD) gave films with more uniform, smoother, more homogeneous surfaces, higher conversion efficiency (14.6%) than other counterparts.
Concentration and Temperature Dependence of Viscosity in Mode-Coupling Theory of Binary Mixture of Water and Phenol
(2015-04-21) Elayyat, Shadia M.
The dynamic shear viscosity of a binary liquid mixture of water and phenol has been measured at different temperatures (32.0 ℃ ≤ 𝑇 ≤ 75.0 ℃) and different concentrations (0.00% up to 100.00% by weight of phenol) by using glass capillary viscometer and Brookfield viscometer model DV-I+. The critical temperature and critical concentration have been determined to be 67.0 ℃ and 33.90% by weight of phenol respectively. The mode coupling theory (MCT) has been used to calculate the value of background viscosity (noncritical part of shear viscosity) 𝜂0 = 0.684 cP, the Debye momentum cutoff 𝑞𝐷 = 0.786 Å −1 and the MCT constant A = 0.050. The intermolecular force range L of water and phenol molecules in a binary mixture has been calculated to be 11.17 Å. The large value indicates that the mutual force between binary mixture molecules can be considered as a week attractive force. The critical amplitude of specific heat under constant pressure at critical concentration and above critical temperature 𝐶𝑝𝑐 has been found to be 259.16 𝐽 𝑘𝑔.𝐾 by using the two scale factor university.
Critical Behavior of Refractive Index of Binary Mixture Cyclohexane - Phenol
(2015-04-21) Bsharat, Heba Yousef
The dynamic viscosity of binary mixture of cyclohexane - phenol was measured over the entire possible range of concentrations and temperatures. The results above the critical temperature and critical concentration were analyzed by the mode coupling theory of one phase. The anomaly of dynamic viscosity was detected as a function of temperature and concentration. Dynamic viscosity anomaly was clearly observed near the critical temperature Tc = 17.0 ℃ and the critical concentration χc= 2.70% by weight of phenol. The value of noncritical part of refractive index was found to be 𝑛0𝐷= 1.4276. The universal critical exponent for refractive index 𝜒𝑛 is also calculated to be 0.00156. The behavior of refractive index of cyclohexane -phenol obeys power law universality above the phase transition. The isobaric specific heat for the critical binary mixture 𝑐𝑝𝑐 was found to be 106.6 𝐽/𝑘𝑔.𝐾 using two-scale factor universality. Joule`s constant for cyclohexane - phenol binary mixture was found to be 4.1 Calorie/J
Critical Behavior of the Density of Binary Liquid Mixture Cyclohexane – Phenol
(2015-04-21) Hussien, Ghadeer
The dynamic shear viscosity coefficients of the binary liquid mixture cyclohexane - phenol for different temperatures and concentrations are measured using glass capillary viscometer. Dynamic shear viscosity anomaly is observed near the critical temperature 𝑇𝑐 = 17.0℃ and the critical concentration 𝑥𝑐 = 2.70% by weight of phenol. Mode Coupling Theory is used to fit our experimental data above the critical temperature. It is found that the value of noncritical part of the dynamic shear viscosity 𝜂0 = 0.8174 cP. The power law isexpected for the mass density above critical temperature. The value of noncritical part of the mass density is found to be 𝜌0 = 0.7357 gm cm3 . The critical isobaric thermal expansion coefficient αp𝑐 was calculated to be 2.07x10-6 0C-1. The critical isobaric specific heat cp was found to be 106.6 J/kg.K, Joule`s constant.Joule′sconstant was found 4.11180 Calori/joule and pressure derivation of the critical temperature Tc′was also calculated to 1.22x10-4 K/Pa.
Critical Behavior of the Ultrasonic Attenuation for the Binary Mixture of Water – Phenol
(2015-04-21) Reehan, Maryam
The dynamic shear viscosity of the binary liquid mixture water – phenol was measured for different temperatures and concentrations using the glass capillary and digital viscometers. Dynamic shear viscosity anomaly was detected near the critical temperatureTc = 67 °C and the critical concentration xc= 33.9% by weight of phenol. The specific heat at constant pressure was calculated using the two scale factor universality and found to be 241.9 J kg K . The critical and the background isobaric thermal expansion coefficients were determined and found to be 2.729 x10-3 °Cˉ¹ and 22.59 x10-3 °Cˉ¹ respectively. Ultrasonic attenuation data at 9, 15, 30 and 35 MHz were analyzed using the dynamic scaling theory of Ferrell and Bhattacharjee. The values of αc f2 versus fˉ¹˙⁰⁶ yield a straight line as predicted by the theory. The experimental values of α(xc,T) αc(xc,Tc) for water – phenol were compared to the scaling function F(ω*') and showed good agreement with the theory.
Design and Characterization of Al/GaSe/MgO/Ag Hybrid Devices
(2015-04-21) Kmail, Renal R. N.
A new hybrid type device is designed and characterized. The design is actualized in the scope of the theoretically derived band diagrams of Schottky Al/GaSe, the p-n junction n-GaSe/p-MgO and the Schottky Ag/MgO interfaced together. Geometrically two Schottky diodes one of p-type majority and another is of n-type majority are brought together. The total area is ~200  m2, while the height is ~50 m  . The resulting structure is characterized by means of optical spectroscopy, current voltage characteristic curves, capacitance, and resistance and inductance spectra in addition to the microwave power absorption spectra in the frequency range that extends to 3.0 GHz under no biasing conditions. Optically, the energy band gap of the 0.8 m  thick GaSe devices is determined as 1.6 eV. As the MgO energy band gap is 7.8 eV, with the help of the midgap rap rule the valance band splitting is determined to be 3.19 eV. On the other hand, the current voltage characterization of the device is observed to be governed by the electric field assisted thermionic emission for low field values during reverse biasing process and up to 1200 V/cm. The tunneling of charged particles is through a wide barrier of ~670 nm during the forward biasing operation and relatively narrow barrier of 116 nm during the reverse basing operation. The barrier height is ~0.81 eV. In addition, the capacitance frequency dependence spectral analysis in the frequency region of 0-2000 MHz reflects a resonance anti resonance physical phenomena at ~1.0 GHz. The inductive region width during the resonance-antiresonance operation is 134.67 MHz. Moreover, when the hybrid device is inserted between the electrodes of the device the amplitude of the ac signal power shows a sharp decrease with increasing frequency down to 1.5 GHz follow by strong growth with growing frequency. Such behavior indicates the applicability of the device as a band stop filter that can absorb signals with notch frequency of 1.5 GHz. The feather of the Al/GaSe/MgO/Ag device are promising as they appear to be suitable as for use as processor clock controller, microwave band stop filter, and as an effective electronic element in the optoelectronic communication systems including the visible light communication, Wi-Fi and WLAN communications.
Determination and Assessment of Heavy Metals in Tobacco Sold and Smoked In Palestinian Market
(2015-04-21) Jodeh, Shehde
Through smoking, important flux of heavy metals and many other toxins reaches smokers ' lungs. This project reports the heavy metal concentrations in tobacco from samples of 25 cigarette products, sold in Palestine. Cadmium (Cd), lead (Pb), cobalt (Co), nickel (Ni), copper (Cu) and zinc (Zn) contents were determined in 25 brands of tobacco cigarette commonly available in Palestine by flame atomic absorption spectrophotometer. The concentration of trace metals in the cigarettes ranged, Cd: from 0.85 to 2.11 μg/g with mean 1.20±0.15 μg/g, Pb: 2.21 to 5.06 μg/g with mean 3.12±1.33 μg/g, Co: 0.18 to 2.61 μg/g with mean 1.09±0.28 μg/g, Ni: 3.42 to 6.23 μg/g with mean 4.92±0.53 μg/g, Cu: 11.86 to 20.35 μg/g with mean 15.21±0.34 μg/g, and Zn: 30.55 to 114.43 μg/g with mean 51.15±0.14 μg/g. Comparable results of trace metals are obtained in both imported and Palestinian cigarettes. The average trace metal contents of cigarettes available and sold in Palestine are Cd:0.82 μg/cigarette with range (0.60– 1.70) μg/cigarette, Pb: 2.13 μg/cigarette with range (1.41 – 3.54) μg/cigarette, Co: 0.74 μg/cigarette with range (0.12– 2.02) μg/cigarette, Ni: 3.37μg/cigarette with range (2.57– 5.66) μg/cigarette Cu: 10.42 μg/cigarette with range ( 7.80– 20.11) μg/cigarette, Zn: 35.02 μg/cigarette with range (20.10- 88.80) μg/cigarette. The results indicate that smoking and exposure to cigarette smoke is a serious problem to be taken into account when carrying out epidemiological studies on human exposure to trace metals.
Determination of Haloperidol Hydrochloride in Ampoulesandin Urine Samples Using a New Potentiometric Carbon Paste Electrode
(2015-04-21) Abu Shawish, Hazem M.
A novel approach for the determination of haloperidol hydrochloride (HDCl) in pharmaceutical formulations and in urine samples is presented. New carbon paste electrode for HDCl based on Haloperidol-phosphomolybdateas (an ion-exchanger) dissolved in plasticizer DBP and their potentiometric characteristics were discussed. The electrode exhibited a good Nernstian slope of 56.9±0.3 mV/decade with a linear concentration range from 3.5 × 10-6 - 1.0 × 10-2 M for the haloperidol ion. The limit of detection was 1.6 × 10-6 M. It had response time of 5-8 sec, useable in pH range of 6.2–8.6 and temperature of 20–60o C. The electrode shows clear discrimination of haloperidol hydrochloride from several inorganic ions, sugars and some common drug excipients. The sensor was applied for determination of haloperidol hydrochloride in urine and in pharmaceutical formulations using potentiometric determination, standard addition and the calibration curve methods. The results are satisfactory with excellent percentage recovery comparable or better than those obtained by other routine methods.
Determination of Some Metallic Elements and their Effect on Physical Properties of Edible Olive Oil in Palestine
(2015-04-21) Fuqha, Estiklal
The physical properties: density, refractive index, viscosity, and acidity of samples of olive oil from different geographical location and heights in Palestine were measured. The measured physical properties agreed with International and local standards. The concentration of Al, Cd, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn elements of olive oil are measured by inductively coupled plasma mass spectrometry ICP-MS. Magnesium (Mg) is the most concentrated metal detected (294.738 - 782.968μg/g), followed by concentration of sodium (Na) (73.401 390.699 μg/g ) and potassium (K) (18.473 -168.883 μg/g). Concentrations of iron, copper and lead in Palestinian olive oil don’t agree with concentration of International Olive Council (IOC). The differences of concentration of metals of olive oil depend on the type of olive oil tree, storage age, height and geographical location. There is a positive relation between the concentration of metals of olive oil and physical properties: density, refractive index, viscosity, and acidity. The daily intake rate of these metals shows no risk to human health according to US Environmental Protection Agency (US EPA).
Effect of Ca2+ on Adsorption and Desorption of Chromium (VI) by "Greener" Iron Nanoparticles
(2015-04-21) Aabed, Isra’a
Cr (VI) compounds are utilized in a variety of industrial applications, and the hexavalent specie of Cr has been detected in many types of industrial wastewater. These ions are well known for their environmental hazards, and therefore their removal from water is essential. Iron nanomaterials has been reported by many researchers to be very effective in sequestration of Cr (VI) ions over a wide range of experimental studies. In this study, Fe NPs produced by reducing Fe2+ ions with green tea extract has been used in the removal of Cr (VI) ions. Adsorption and desorption studies were performed in the presence of Ca2+ ions at different concentrations and time periods. All measurements were obtained using direct UV-Vis spectrophotometric determination. The results showed that proper concentrations of Ca2+ ions can enhance the adsorption Cr(VI) ions and at the same time inhibit their desorption.
Elemental Background and Anthropogenic Pollution of Heavy Metals in the Top Soil of Al-Qilt Catchment, Palestine
(2015-04-21) Harb, Hanan
Heavy metals pollution in Palestine soils was ignored for decades; anthropogenic pollution of soil has negative effect on the environment and human life. Determination of elemental background for anthropogenic pollution in Palestine soils will help in screening the anthropogenic metal-based pollution. The objective of this research was to study the pollution origin in soil of Al-Qilt catchment. Soil samples from pristine areas of Al-Qilt catchments was analyzed for the assessment for heavy and trace metals mainly those considered as anthropogenic sources for pollution in the area. Sources and impact of anthropogenic pollution in Al-Qilt catchment soils were also discussed. Samples along Al-Qilt catchment were collected on monthly bases. Soil samples were digested by aqua regia, and analyzed by using BCR fractionation method for Al, Ti, Mn, Fe, Cr, and Bi. Data analysis by computing the relation coefficient of heavy and trace metals, Heavy and trace metals were graphed with Al and Fe as reference elements to facilitate the comparison between Al-Qilt sites and we chose the best correlated metals with elemental normalizers or reference element, depending on the correlation factors (R2) , The normalization is a way to compensate for the natural variability of trace metals in soils, so that any anthropogenic metal contributed may be detected and quantified by reducing the natural effect of grain size. This allows to identify the trace metal as a man-made pollutant, then the Enrichment Factor (EF) was computed as first step to relate between a metal and its best nomalizer, this lead to identify anomalous metal concentrations that may have an anthropogenic source; then we can specify the enriched site. The elemental background for anthropogenic pollution in the soil of Al-Qilt catchment was made and compared with continental crust value. Results showed that metal/Al and metal/Fe normalization for Ti, V, Mn, Co, Rb, Ag, Li, B and Be were used as anthropogenic pollutants for most of Al-Qilt sites, As comparison the Fe was found to be the best elemental normalizer since it has the highest R2 values compared to Al, The EF calculation showed that Pb had the highest value of trace metals in Al-Qilt catchment, and there was a moderate values for Sn and Ag in some site in Al-Qilt catchment, this results show no anthropogenic sources for pollution in Al-Qilt catchment, therefore these metal can considered as elemental background for another researcher in the future.
Energy Band Gap and Dispersion Parameters in Ga2S3 Thin Films
(2015-04-21) Kmail, Bayan H.
The optical properties of the vacuum deposited transparent Ga2S3 thin films are investigated by means of X-ray diffraction and UV-visible spectrophotometry in the incident light wavelength of 200-1100 nm. The X-ray diffraction revealed no patterns indicating the amorphous nature of the films. The Ga2S3 thin layers are observed to exhibit a direct allowed electronic transitions energy band gap of 3.2 eV. The energy band gap contained a set of tail statesarises from defects and structural deformations. In additions , the analysis of the dielectric spectra which is calculated from the reflection spectra permitted determination of the dielectric loss tangent, the oscillator and dispersion energies as well as the static and lattice dielectric constants .The difference between the mechanical lattice and static dielectric parameter is assigned to the free charge densities associated with the incident electric field excitation and due to the lattice mismatch between the sulfur and the gallium atoms in the Ga-S bond.The specified parameters are found to be sensitive to tetrahertz frequencies in the visible region of light which make it attractive for visible light communications.
Field Method for Estimation of Fuoride in Drinking Groundwater by Photometric Measurement of Spot on Impregnated Reagent Paper
(2015-04-21) Barghouthi, Zaher
Few years ago WHO decided to make mandatory the determination of fluorine and arsenic in drinking water. The reason is that in large parts of the world the population is exposed to these elements at toxic levels, more than 100 million are exposed to arsenic and about 62 million to fluorine, and in some parts like Inner Magnolia, people are exposed to high levels of both elements. Because most of the countries with such health problems belong to third world, the number of existing laboratories is not sufficient to control the amount of these elements. Therefore, simple field method are favored to allow a reliable determination right at the source. To determine arsenic a small handheld instrument based on a photometric measurements of reagent paper was developed and now is available. There is an urgent need to expand the functionality of this small instrument to analyze fluorine too. Through the search for the best fluoride reagent, 94 possible ligands containing groups capable of holding metals in stable combination were examined. These ligands belong to the main types of dyes: triphenylmethane, azo, and anthraqunion dyes. For an optimal result it turned out new prepared a polymeric aluminum complex of 5-(2-carboxyphenylazo)-8-hydroxyquinoline (LH2), and aluminumquinalizarine 2:1 complex. The reagent reacts on an impregnated paper in the following way: AlLH2(yellow) + 6F-→ AlF6-3(colorless)+ LH2 (red) Al2 [quinalizarin](pink) + + 6F-→ AlF6-3(colorless)+ [quinalizarin](orange) The molar absorptivity of the complex formation of the above two reagents is 8.48 ˣ 103 L mol-1 cm-1 at 410 nm and 4.41 L mol-1 cm-1 at 553 nm respectively. For the field instrument the analytical range from 0.0 to 2.0 μg ml-1 is linear. The limit of determination is 0.3 μg ml-1. The recovery of 1.0 μg ml-1 is 96.2% and 104.7% respectively. There is no interference by nitrate or chloride. Sulfate interfered with the measurement, but at high concentrations which are not expected in drinking water. An interesting results were obtained with aluminum complexes of Triphenylmethane dyes, Flavonoid Chrysin, and Resocrin Blue. However, these complexes can be recommended as spectrophotometric reagent for fluoride determination in water.

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