VOLUME 15, NO1, MAR 1993

DETERMINATION OF TRACE-METALS IN KARACHI COASTAL WATERS USING ATOMIC-ABSORPTION SPECTROMETRY

Trace metal (Co, Cu, Fe, Pb and Zn) concentrations were determined in Karachi coastal waters (Bath Island, Keamari and Korangi) using atomic absorption spectrometric technique. These metals have been quantitatively separated from sea water matrices as metal-APDC complex using MIBK as an extractant. The extract was directly aspirated into atomic absorption spectrometer and a reproducible signal was obtained. The results showed prominent variations in metal concentration with distance and also from one sampling area to another. Seasonal variations were also monitored.read more

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IFTIKHAR IMAM NAQVI ,AMJAD ALI MAHMOOD ,ITRAT ZEHRA ,SHEHLA HABIB ,ZEBRA GUL ,

ADSORPTION FROM AQUEOUS-SOLUTIONS OF DYES ON ACTIVATED SILICA-GEL

Adsorption behaviour of aqueous solutions of acid red-4, acid green-25 and sulphorhodamine-B on activated silica gel in relation to shaking time and solution pH has been studied. It is observed that the dyes are chemisorbed on the surface of silica gel. The effect of pH has been explained in terms of protonation of the dyes.read more

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MAQSOOD HUSSIAN ,MUHAMMAD JAVED IQBAL ,

THERMOGRAVIMETRIC STUDIES OF HYDRATED ZEOLITE TYPE-A - EFFECT OF TRANSITION-METAL ION-EXCHANGE ON ZEOLITIC WATER

The crystal structure of fully hydrated synthetic zeolite type A has been described. Co2+, Ni2+, Cu2+ and Mn2+ ions have been exchanged to different extents (from 16.6% up to 81. 6%) into zeolite A and their zeolitic water contents have been measured thermogravimetrically. The gravimetric studies showed complete loss of water molecules in dynamic vacuum (10(-6) torr) at 623 K. Turnover numbers for H2O increase smoothly with increasing transition metal divalent ions in the zeolite framework. The water content is closely related to the nature and number of the cations incorporated into the zeolite lattice. The sequence of the number of water molecules per unit cell was Ni A> Co A> Cu A> Ma A> Na A. Thus the water content increases with decreasing ionic radius of the cation, from 27 for Na+ (r = 0.98 A-degrees) to 47.8 for Ni2+ (r = 0.69 A-degrees)read more

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SHER AKBER ,

EVALUATION OF ADSORBENT SUPPORTED METAL NITRATES FOR HETEROGENOUS CATALYTIC-OXIDATION OF ISOPROPANOL TO ACETONE

Catalytic effects of several solid adsorbents on the adsorbed metal nitrates towards oxidation (dehydrogenation) of isopropanol to acetone in the absence of any co-solvent have been studied. The efficacies of some commercial adsorbents as well as some indigenously available natural clays as catalytic supports have been evaluated. Transition metal nitrates have been found to be better supported oxidizing reagents than the alkali and alkaline-earth metal nitrates. A simple spectrophotometric method has been developed to monitor the amount of acetone formed during isopropanol oxidation.read more

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HANIF UR REHMAN ,MOHAMMAD ARFAN ,

THE EFFECT OF BIVALENT-METAL IONS ON TANNIN FORMALDEHYDE REACTION

The catalytic influence of bivalent metal ions on tannin formaldehyde reaction has been investigated, wing three different methods (1): Hydroxylamine hydrochloride (2), Viscometry and (3) IR Spectroscopy. The results obtained from the first and third methods are comparable, while a slight deviation in the order of effectivity was observed in the case of second method due to die stability of the intermediate complexes. It was also observed that transition metals catalysed the reaction more effectively than alkaline earth metals.read more

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SABINA NAZLI ,MANSOOR AHMAD ,

DETERMINATION AND COMPARISON OF STABILITY CONSTANT, ENTHALPY AND ENTROPY OF FORMATION OF IRON(III) COMPLEXES OF GALLIC ACID AND METHYL-ESTER OF GALLIC ACID

Stability constant of Iron(III) gallic acid complxes had been measured potentiometrically. The experimental results of these potentiometric titrations were treated by well known computer program ''Best''. The values were further refined till least sigma fit i.e. 0.02. For thermodynamic study the change in log beta values at different temperatures were also examined and entropy and enthalpy of these reactions were determined. Iron(III) complexes of gallic acid methyl ester were prepared in the same way, and the above results were compared with this new complex. The role of carboxylate group on the complex were noted. The beta values of these two complexes were then compared with other iron complexes and their biological importance were also discussed.read more

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S ARIF KAZMI ,ZAHID T MAQSOOD ,

SYNTHESIS AND SPECTROSCOPIC STUDIES OF MOLYBDENUM (0) AND RUTHENIUM(II) COMPLEXES OF 2,2'-DIPYRIDYLAMINE(+)

The reaction between neutral electron donor ligand 2,2'-dipyridylamine (dpa) with Mo(CO)6 or [Ru Cl2(CO)2]n in (1:1) molar ratio in refluxing THF affords Mo(CO)4 dpa and Ru Cl2(CO)2 dpa complexes in high yields. On the basis of spectroscopic studies it is suggested that the ligand (dpa) in these complexes acts as bidentate and coordinates to the metals through pyridine-N atoms rather than with the amino group. The complex Mo(CO)4 dpa reacts with iodine to give seven coordinated Mo(CO)3 dpaI2 complexes. All the complexes were characterised by their H-1-NMR, IR and elemental analyses.read more

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Y AL ANQUARY ,M ISHAQ ,M I AL KHATERY ,A O BAGHLAF ,

SPECTROPHOTOMETRIC DETERMINATION OF DIPHENHYDRAMINE HYDROCHLORIDE USING CARMOISINE BY SOLVENT-EXTRACTION

Carmoisine (chromotrope FB, C.I. 14720, acid red 14) has been used for the determination of diphenhydramine.read more

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M M ABDEL BADEI ,

IMPACT OF DRINKING, SURFACE AND UNDERGROUND WATER ON UROLITHIASIS

Sixty two drinking water samples (39 from underground and 23 from surface water sources) from six districts of Sindh were chemically analysed for pH, sodium, potassium, calcium. magnesium, phosphate and silicate contents. Samples from the same sources were also analysed for total bacterial count and total and differential coliform densities. Results show that the total alkalinity, total hardness and mineral contents of underground waters were significantly (P<0.001) higher than the surface waters while reverse was true for the pH and phosphate Surface water was also found to be highly contaminated by faecal coliforms. Although no direct relationship between microbial contamination of surface water and urinary stone disease was observed, low calcium intake alongwith increased ingestion and excretion of oxalate and phosphate due to faulty dietary habits might be a possible cause of higher incidence of urolithiasis in surface water users.read more

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T U KHAND ,F D KHAND ,A F ANSARI ,M S SHAIKH ,A Q SOOMRO ,

SYNTHESIS AND SPECTROSCOPY OF NOVEL-ALPHA-PYRAZOLYLGLYCINE DERIVATIVES

The synthesis of alpha-pyrazolylglycine derivatives (7a-j) with different substituents, starting from glycine have been prepared. The spectroscopy of intermediate compounds and the final amino acids has been discussed.read more

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ZIA UL HAQ ,ROSHAN AHMAD ,