- Monday, January 1, 2007
- Published at:Not Found
- Anatase TiO2 surfaces have been treated with 2,4,6-triphenylpyrilium hydrogen sulfate (TPPHS) dye to yield the modified TiO2/TPPHS surface. The modified TiO2/TPPHS surface was then supported onto activated carbon (AC) surfaces to yield a new class of catalytic system AC/TiO2/TPPHS. The catalytic activities of naked TiO2, TPPHS solution, TiO2/TPPHS and AC/TiO2/TPPHS systems were examined in photo-degradation of phenol and benzoic acid in water, using both UV and visible regions. All studied systems showed low catalytic activity when used in the visible region. In UV, the AC/TiO2/TPPHS showed highest activity, whereas the naked TiO2 and TPPHS solutions were the least active systems. The dye role, in enhancing activity of modified surfaces in UV degradation of contaminants, is understandable by a charge-transfer catalytic effect rather than a sensitizing effect. AC role is explainable by its ability to adsorb contaminant molecules and bringing them closer to catalytic sites.
Solid State Sciences, Vo
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- Monday, January 1, 2007
- Published at:Journal of Food Technology 5 (3): 220-224, 2007
- A selective gradient ion-pair reversed-phase high-performance liquid chromatographic method for the simultaneous quantitative determination of seven synthetic water-soluble food colorants (Tartrazine E102, Quinoline Yellow E104, Sunset Yellow E110, Carmoisine E122, Ponceau 4R E124, Erythrosine E127, Carmine E132 and Brilliant Blue FCF E133) was developed. Analysis were performed on 125×4.6 mm i.d. Merck Lichrosher 100 RP C-18 (5 µm ) column. The flow rate of the mobile phase was 1.0 mL min 1 and the injection volume was 50 µL. The mobile phase consisted of water:acetonitrile (50:50 v v 1) Containing 0.35 M (1-Hexadecyl) Trimethylammonium Bromide (CTAB) and buffered to pH 7.5 (mobile phase A) and water acetonitrile (50:50 v v 1) (mobile phase B). Successful separation and quantitative determination was obtained for all the colorants using an optimized gradient elution program. Detection limits were 1.59 (E142) and 22.1 (E124) ppm, with relative standard deviations in the range 0.37%. The meth
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- Thursday, January 1, 2004
- Published at:Not Found
- Differential-pulse adsorptive cathodic stripping voltammetric (DP-AdCSV) and high performance liquid chromatography (HPLC) techniques were developed for quantitative determination of Reactive Blue 19, Reactive Red 198 and Reactive Orange 107 textile dyes. The calibration curves using the DP-AdCSV method were found to be linear over the ranges 0.05-1.0 ppm, 0.10-1.10 ppm and 0.05-1.0 ppm, respectively. The HPLC method is based on using a mobile phase consisting of acetonitrile:water (60:40, v/v) containing 0.45 M N-Cetyl-N,N,N-trimethylammonium bromide (CTAB) and buffered to pH 7.92. Reverse phase RP C18 column was used with a flow rate of 0.6 ml/minute. The retention times for Reactive Blue 19, Reactive Red 198 and Reactive Orange 107 were found to be 5.4 min, 7.8 min and 2.3 min, respectively. The calibration curves were found to be linear over the ranges 0.1-5.0 ppm, 0.1-1.2 ppm and 0.05-1.5 ppm, respectively.
An-Najah University Journal for Research - Natural Sciences (A) ISSN: 1727-21
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- Monday, January 1, 2001
- Published at:Not Found
- Two spectrophotometric methods are described for the determination of tiopronin in pharmaceuticals. They are based on the oxidation-reduction reaction between tiopronin and iron (III), then forming a complex between iron (II) and ferrozine or di-2-pyridyl ketone-2-thiophenoylhydrazone. The produced colored iron (II)-ferrozine complex [system I] absorbs at 562 nm, while the iron (II)-di-2-pyridyl ketone-2-thiophenoylhydrazone complex [system II] absorbs at 656 nm. The effect of different factors such as: pH, reagent concentration, time of reaction, temperature and the tolerance amount of the common excipients have been studied. Applying the optimum working conditions, tiopronin can be determined over the range 0.2-8.6 and 0.5-17.0 ppm and with molar absorptivities of 2.0x104 and 1.0x104 l mol-1cm-1 for systems I and II, respectively. Both methods offer high selectivity, sensitivity and accuracy with a relative standard deviation (RSD) of less than 1.1% for five measurements. The proposed methods were applied s
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- Tuesday, August 1, 2000
- Published at:Not Found
- Two methods are described for quantitative determination of nizatidine. The first is a cathodic stripping voltammetric method which is based on the accumulation of the compound at the hanging mercury drop electrode. The adsorptive stripping response was evaluated with respect of accumulation time, potential, concentration, pH and other variables. A linear calibration graph was obtained over the range 3.0×10−8–1.0×10−6 M with a detection limit 3.0×10−8 M after a 20s accumulation time at −0.2 V accumulation potential. On the other hand, it was found that the detection limit could be lowered to 1.0×10−8 M after 180s accumulation time at −0.2 V accumulation potential. The relative standard deviation was in the range 1.2−2.0% for six measurements. The tolerance amounts of the common excipients have also been reported.
The second is a spectrophotometric method which is based on the formation and extra
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RSS
Nidal Abdul-Jabbar Mohammd Zatar