VOLUME 21, NO2, JUN 1999

Beneficiation of silica sand for the manufacturing of optical glass

Representative samples of silica sand collected from various sand deposits available in Pakistan were chemically analyzed Most of the samples contained 90 - 99% silica (SiO2), 0.05 - 0.81% iron oxide (Fe2O3) and 0.55 - 1.0%(TiO2). The other oxides were present in minute amounts. The iron contents were reduced by sulfite method to bring the samples into the specification for colorless glass. The trace metals present in the upgraded samples in ppm were determined by atomic absorption Spectrophotometric method keeping in view weather the silica sand deposits in Pakistan meet the requirements for the manufacturing of optical glass.read more

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SHAKILA BEGUM ,M A QAISAR ,FARID ULLAH KHAN ,M ALLAHUDIN ,

Kinetics of the thermal gas-phase decomposition of 2-butoxypropene

The kinetics of the thermal gas phase decomposition of 2-butoxypropene has been studied over the temperature range 640-680 K at pressure between 10 and 50 torr. 1-Butene and acetone were the only products and accounted for 63% of butoxypropene decomposition. These products are formed by homogeneous, unimolecular pathways with high pressure first order rate constant given by the equation: k(d)/S-1 = 10(10.80+/-0.24) exp(-171.3 +/- 2.9 KJ mol(-1)/RT) A six membered polar transition state is consistent with the kinetics data.read more

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I A AWAN ,T MAHMOOD ,

Circular dichroism studies of formation of complexes of oxovanadium(IV), cobalt(II) and nickel(II) with (+)-6-aminopenicillanic acid in aqueous solution

The complex forming ability of (+)-6-aminopenicillanic acid with oxovanadium(IV), cobalt(II) and nickel(II) in aqueous solution maintained at 35 degreesC is studied through circular dichroism spectra In these systems, complexation is indicated with the development of well defined CD bands in crystal field region between 18,349-24, 691 cm(-1). The optimum conditions of pH, stoichiometry, time for attaining maximum complexation and formation constants are reported for these complex ions. The CD bands are assigned to electronic transitions.read more

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NASIR AHMAD ,TASMIM AKHTAR ,CHRISTY MUNIR ,

Impact of industrial discharges on the quality of Kabul River water at Amangarh, Nowshera (Pakistan)

Samples of effluents from different industries at Amangarh, Nowshera and receiving Kabul River water were analysed for various parameters like; pH, D.O. suspended solids, electrical conductivity, alkalinity, hardness, COD, NO2-N, NO3-N, chlorides, sulphates, Na+, K+ etc. The results indicate localized pollution within half kilometer after the confluence point where the quality of the river water is being deteriorated The data suggest that the river water in comparison to US rivers and Indus River at Kalabagh and at Tarbella Dam is more saline. Industrial effluents contribute towards increase in the salinity of river water. Presence of appreciable amount of oxygen demanding waste in effluents and in the downstream of the river create a suffocating environment to fish crop.read more

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M AKIF ,M RIAZ ,A R KHAN ,

Quality characteristics of potable water from different sources of district Bannu (Pakistan) and their possible health impacts

The quality of potable water samples collected from 8 tube wells, 8 hand pumps, 15 wells and 4 surface water sources in Bannu District were investigated and compared with international standards. It was observed that water form wells and hand pumps seemed to be more polluted than those from other sources due to high nitrite levels. Similarly the oxygen demanding content was higher in 88% hand pump, 60% wells and 25% surface water, whereas the magnesium level was higher in almost all the samples. The synergetic effect of magnesium and sulphate concentrations has suggested that all hand pumps, 73% well water and the stream wats were unfit for drinking due to their laxative nature. It concludes that all hand pump water and 73% of all well water were not potable. The stream water was found to be laxative in nature due to higher concentration of both magnesium and sulphate. Na+, K+ and chloride concentrations in all the samples were found to be within the permissible limits. The tube well water appeared to be comparatively safer, compared to other sources, due to lower COD and NO2- concentrations. Due to the presence of NO2-, 88% samples of well waters, 50% surface waters, 38% hand pump waters and only 13% tube well water were not potable. Overall, the water of Bannu District has been found to be unsuitable for drinking purposes and are considered to be harmful to humans which may adversely affect the overall health of the people on prolonged usage of these substandard waters.read more

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FARRUKH HUSSAIN ,SHAHID ULLAH ,A R KHAN ,MUMTAZ KHAN ,M RIAZ ,

Bovine pancreatic lipase: Purification and applications in immobilized form for transesterification reactions

The purification of lipase from bovine pancreas is described The final product was homogeneous as determined by electrophoresis in denaturing polyacrylamide gels showing a single protein band with a molecular weight of 47 kDa The procedure involves the preparation of acetone powder from fresh pancreas, ammonium sulphate precipitation, chromatography on DEAE-Sephadex and gel filtration on Sephadex G-100. Optimal activity occurred at pH 9.0 using p-nitrophenyl laurate as a substrate emulsified with polyvinylalcohol for the assay of enzyme activity. The purified lipase is immobilized on phenolic resin and utilized for transesterification reactions in dry pyridine.read more

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MOHAMMAD MASOOM YASINZAI ,MOHAMMAD YAQOOB ,ABDUL NABI ,

A dead-stop amperometric method for the estimation of iodine in iodized salt

A dead-stop amperometric method based on electroactive equilibrium I-2 reversible arrow 21(-) redox couple is developed for the estimation of iodine in iodized salts locally marketed in Pakistan Twenty iodized salt samples. procured from local retailers were subjected to estimation of iodine content by the method The iodine concentrations in the samples were found to be very divergent, ranging from as low as 4.97 mg/kg to as high as 446.38 mg/kg. Parallel estimations. using simple thiosulphate-based titrimetric method, were conducted and the accuracy and precision of the proposed method is discussed The lower detection limit goes to close 1 mg/kg for the proposed method and the present study indicated that the method is quantitatively reliable, as determined by its application on synthetic samples of salt containing a broad range of iodine concentration, between 2.5 mg/kg to 120 mg/kg, with an overall percent error in the range of 0.5 to 4.4%.read more

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M JAFFAR ,M A MINHAS ,KHALID MAHSUD ,

Role of anions (sulphate, nitrate, oxalate and acetate) on the antibacterial properties of cobalt(II), copper(II), nickel(II) and zinc(II) complexes with ONO, NNO and SNO donor pyrazinoylhydrazine-derived ligands

Some biologically active complexes of cobalt(II), copper(II), nickel(II) and zinc(II) with pyrazinoylhydrazine-derived ONO, NNO and SNO donor Schiff-base ligands having the same metal ion but different anions such as sulphate, nitrate, oxalate and acetate have been synthesised and characterised on the basis of their physical spectral and analytical data. In order to evaluate the role of anions on their antibacterial properties, these ligands and their synthesised metal complexes with various anions have been screened against bacterial species Escherichia coli. Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumonge. The title studies have proved a definative role of anions in increasing the antibacterial properties.read more

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M PARVEEN ,SYED K A SHERAZI ,ZAHID H CHOHAN ,

Applications of a functionalised XAD-2 sorbent: Enrichment and HPLC determination of six phenols in tap water

Applications of 1,2-diaminobenzene (1,2-DAB) functionalised XAD-2 sorbent (XAD-2/ 1,2-DAB) have been tested for the enrichment of six phenolic compounds from tap and river water. Phenols enriched on this resin were desorbed with methanol and analyzed by HPLC at 228 nm UV detection. The recovery of phenols studied here, except beta -naphthol, ranges between 90-100 % with a relative standard deviation of 0.01-0.09 %. The performance of the resin was checked on indus river water and it enabled phenolic compounds at levels of 0.01 mug L-1 to be determined in real samples.read more

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U M ABBASI ,M I BHANGER ,SAMINA ABBASI ,S W SHAH ,M A ARAIN ,

Liquid chromatographic determination of selenium in vegetables and tea leaves as 2,1,3-benzoselenasiazole

Derivatization and liquid chromatographic determination of selenium in vegetables and tea leaves have been performed. The samples were digested with (i) nitric acid or (ii) sulfuric acid - nitic acid - hydrogen peroxide mixture, followed by treatment with hydrochloric acid to reduce selenium(VI) to (IV). The resulting solution was treated with 1,2-diaminobenzene, at pH 1- 2 and the product, 2,1,3-benzoselenadiazole was extracted with toluene. RP-HPLC analysis was carried out on a ODS Lichrosorb C-18, 5 mum, (150 x 4 mm, i.d.) with methanol - water (1: 1) as mobile phase, and UV detection at 332 nm. The detector response was linear in the range of 0 - 15 mug / ml with regression coefficient 0. 998. The limit of detection was found to be 0.2 mug / 10 muL injection. Results shows the level of selenium in vegetables and tea leaves to be in the range of 0.11 to 1.75 and 0.52 to 1.08 mug / g, respectively. The coefficient of variation was within 5 %.read more

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M Y KHUHAWAR ,M AMIR ARAIN ,M I BHANGER ,