VOLUME 23, NO4, DEC 2001

Solvent Extraction Properties of Aminophthalic - Anhydride (APA) and Mono-methyl Phthalate-2-Potassium Hydroxamate (MMPPH) Towards Some Metal Ions

The aim of this work is to study the extractive ability of hydroxamic acids derived from phthalic acid (an aromatic l,2dicarboxylic acid). Thus mono - and di-esters of this acid were synthesized and employed for the preparation of the corresponding hydroxamic acids. Compounds prepared are aminophthalic - anhydride (APA) and mono methyl phthalate 2­potassium hydroxyamate (MMPPH) were characterized with different physical and chemical tools. The extractive ability of these compounds towards V(V), Cu(ll), Fe(1I1), Cd(11), Mo(V) and U(VI) were studied under different pH values and the stripping of these metal ions with 2.0M H2S04 is also studied.read more

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A E HAMED ELNIEL ,T M A ISMAIL ,

Modeling the Solubility of Aliphatic Alcohols via Molecular Descriptors

We compare several QSPR models for predicting the aqueous solubility of aliphatic alcohols on the basis of physical (structural and electronic) descriptors. Results are compared with previously published data obtained from topological descriptors and with available experimental results. It is noted that there is a remarkable improvement on going from linear models in one variable to the quadratic equations in several variables. Some further possible  extensions are discussed.read more

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E A CASTRO ,C M MARTINO ,G P ROMANELLI ,

Dilute Solution Properties of Phenolphthalein Poly(aryl ether ketone)

Five narrow molecular weight distributed fractions of Phenolphthalein poly (aryl ether ketone) were studied in chloroform by static laser light scattering (LLS) and viscometry at 25°C. From static LLS, the weight-average molecular weights (Mw), z-average radii of gyration; <Rg2>z1/2 (or written as <Rs> and second virial coe1licients, A2 of the PEK-C fractions were determined. Our results showed that <Rg2>z1/2 = 3.50 x 10-2 Mw0.54. From viscometry, the reduced and inherent viscosities of all the fractions were measured and the corresponding intrinsic viscosities were determined. The intrinsic viscosities scaled with the molecular weights obtained through static LLS yielding a Mark-Houwink equation of [ h] = 4.42 x 10-2 Mw0.686.The exponent values indicate that PEK-C in CHCl3 at 25°C has a coil chain conformation.read more

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MOHAMMAD SIDDIQ ,KHALID MAHMOOD ,BAKHTIAR MOHAMMAD ,MUSA KALEEM BALOCH ,MOHSIN NAWAZ ,CHI WU ,

Catalyzed Organosolv Delignification of an Indigenous Wood - Partal (Picea morinda)

Partal (Picea morinda) wood in particle size of 0.315 - 1.00 nun was subjected to acid catalyzed organosolv delignification with acetic, formic and propionic acids. The effect of different process variables like concentration of acid, concentration of catalyst and solid-liquor ratio on the yield and quality of delignified products along with the kinetic of the reactions involved was also studied. It was thereafter found that along lower aliphatic organic acids, only acetic and propionic acids could sufficiently delignify this particular species. However. propionic acid had proven to be better of the two. as it gave a good quality product in lesser time (90 minutes) and higher yield (67%). Further. formic acid was not found to be an appropriate medium for delignification of this particular raw material.read more

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TANZIL H USMANI ,MOHAMMAD TAHIR ,SOFIA KHALIQUE ALVI ,MOHAMMAD ALEEM AHMED ,

A Study of the Molar Absorptivity and Structure of Vitamin B2 Relationship

Molar absorptivity (e) and E(1%, 1 cm) values have been obtained at different pH of the medium containing vitamin B2 in the solution. s-values ranged from 12000-26000 when the measurement was made at 265 nm  at different pH. E(1%, 1 cm) values ranged from 323-710, increasing from lower to higher values as the pH of the medium was changed from 2.6-7.8. read more

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KARAMAT MAHMOOD ,MUNAWAR HUSSAIN ,M AMINUDDIN ,

Effect of Temperature on the Adsorption Behavior of Copper onto Carbonaceous Substrate

The adsorption of Cu (II) from aqueous solutions on the surface of activated charcoaI was investigated as a function of shaking time, concentration of adsorbate, and shaking temperatures of 25°C, 30°C, 35°C, °C 40°C, 45°C and 50°C. For this purpose, high purity CuCl2 was used as the heavy metal source and commercial activated charcoal was used as the adsorbent Adsorption equilibrium was attained within 20 minutes. The adsorption was lower at higher temperatures and vice versa, due to the exothermic nature of the process. Accordingly the energy of activation is small, and thus these reaction are favorable at lower as compared to high temperatures. Freundlich and Langmuir adsorption isotherms were applied to the data and it was found that both equation fitted the data well. The rate constants of adsorption were determined by the first order kinetic equation which provided best fit to the data, indicating that the kinetics of the surface adsorption process are directly proportional to the adsorbate concentration. The adsorption isotherm data was also used for computing the thermodynamic parameters like DG¹, DH¹and DS¹. Negative value of these parameters show that the interaction of the adsorbate with the adsorbent is spontaneous.read more

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MANZOOR IQBAL ,SULTAN ALAM ,FAZLULLAH KHAN BANGASH ,

Determination of Cadmium in Root Vegetables after Activated Carbon Enrichment by Flame Atomic Absorption Spectrometry

Enrichment of trace levels of cadmium in vegetable materials by flame atomic absorption spectrometry has been carried out using anthranilic acid on activated carbon at pH 7. Up to hundred fold enrichment has been achieved by this reagent. Interferences due to matrix components are minimized by their addition at higher level to the standards and blank. Calibration curve is linear in 1–7 ppb range of cadmium. The relative standard deviation for 7 ppb of cadmium is found to be 3.5%. The observed cadmium level in root vegetables is 0.09-0.20ppm. read more

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SHAHIDA B NIAZI ,M YOUNAS KHOKHAR ,RANA LIAQAT ALI ,F MAHMOOD ,

Indirect Determination of Mefenamic acid by Atomic Absorption Spectrometry

A method is described  based on the complexation of mefenamic acid with copper(II) amine sulpahte and extraction of complex in chloroform. The copper is back extracted with nitric acid. The copper content in aqueous phase is determined by flame atomic absorption spectrometry (FAAS). The concentration of copper is proportional to mefenamic acid. The linear calibration curve was obtained with 30-241 ug\ml, with detection limit S ug/ml. The method was applied for the determination of mefenamic acid in pharmaceutical preparations. read more

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F M A RIND ,T M JEHANGIR ,M Y KHUHAWAR ,

Analytical Application of Immobilised Enzymes

Enzymes bound on solid supports have number of advantages over their soluble counterparts e.g. high stability, no purification, easy handling, economicity and high yield of product. Immobilised enzymes have gained increased signifinance in several areas of analytical chemistry. The use of immobilised enzymes is not only limited for the determination of their substrates but is also gaining attention for the determination of many enzyme inhibitors. This paper gives brief description about the introduction of immobilised enzymes, methods of immobilisation and their analytical applications particularly in connection with flow injection analysis (F.I.A.).read more

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TAHSEEN GHOUS ,

Elution of Copper (II), Nickel(II), Cobalt(II) and Zinc (II) and the Separation of Nickel(II), Palladium(II) and Platinum(II) Complexes of Quinoxaline-2,3-Dithiol, Using Reserved Phase Ion-pair HPLC.

The anionic complexes of Cu(II), Ni(II), Co(II), Zn(11), Pd(Il) and Pt(ll) with quinoxaline-2,3-dithiol (qdt) were successfully eluted as ion-pair  with quaternary ammonium cations on the revened phase 1Uchrosorb RP-18 (ISO nun x 4.6 nun) column. The eluent UIed was ethanol:wala" (80:20) containing each in turn, tetrabutyl ammonium (TBA), tctraheptyl ammonium (fHA'1 and cetyltrimllthyl ammonium (CT A'1 •• their bromide salta in concentrations ransina (O.OS% to 0.2% wlv) at dilfereot pH.The Ni(ll) , Pd(I1) or Pt(ll)-qdt complexes were ICplIIaled &om Cu(ll) or Zn(11) or Co(U)-qdt complexes using THA+ ,or CTA+ at pH 8.4 ±. 0.1. The separation of Ni(ll), Pd(11) and Pt(ll) -qdt complexes was achieved using (fHA+) at pH 9.0:i: 0.1 with the cation salt concentration of 0.1% in ethanol: water (80:20) eluenl The detection limits were at ng levels per injection. read more

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J A W DALZIEL ,S A MEMON ,