VOLUME 16, NO3, SEPT 1994

CHARGE PLATE TECHNIQUE IN RECOIL STUDY .3. (N,GAMMA) ACTIVATION OF DIBROMOMETHANE IN 2-NITROTOLUENE

Solutions of dibromomethane (DBM) in 2-nitrotoluene (2-NT) have been irradiated for 30 hours using a 1.11 x 10(10) Bq (Ra-Be) neutron source. Charged radioactive bromine species viz Br-80m, Br-80 and Br-82 of either sign were collected on charged plates kept at 175 V cm(-1) (D.C) during the end - 3 hours of irradiation. The anodic yields are invariably greater than the cathodic yields. All the anodic radiobromine activities increase first with increasing mole fraction (mf.) of 2-NT whereas the cathodic bromine:activities decrease and then reach plateau values. The cationic deposition was almost zero above 0.37 mf. of 2-NT. The results indicate that internal Conversion (I.C) and Auger processes are responsible for the formation of charged bromine species and that 2-NT plays an essential role in the electron picking up process leading to me creation of extra anionic bromine activities.read more

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S P MISHRA ,M R ZAMAN ,

CORRELATION BETWEEN IRON AND SODIUM-OXIDE CONTENTS OF ALUMINUM HYDROXIDE SAMPLES

It is necessary to consider carefully the economy of alumina production due to different chemical and mineralogical properties of aluminum hydroxide. A significant amount of cost can be saved by reducing the number of aluminum hydroxide sample analysis. For this purpose, a linear relationship has been developed between the contents of sodium and, iron oxide in the aluminum hydroxide. The main benefit from such a relationship is to predict the aluminum hydroxide content from rather cheaply obtainable sodium contents. The application of this relationship has been demonstrated for alumina production at Seydisehir Alumina Plant in Turkey.read more

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S SAHIN ,

SORPTION OF HEXANE AND CYCLOHEXANE LIQUIDS IN HIGH-SILICA ZEOLITE AND BORON-ZEOTYPE MATERIALS

Pentasil high silica zeolites (ZSM-5, ZSM-11) and their structural analog boron-zeotypes (ZSM5-B, ZSM11-B) and Al-free silicalites have been examined for the sorption of liquid n-hexane and cyclohexane by thermogravimetric constant coverage method. Effect of adsorbates on the framework topology and unit cell dimensions were also studied. The cell volume of boron-substituted samples were found to be significantly smaller than Al-substituted. Crystallinity of the samples were estimated from framework IR spectroscopy, differential thermal analysis, X-ray diffraction and adsorption of n-hexane techniques.read more

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R BLACKBURN ,S K DURRANI ,A DYER ,S AMIN ,

MEASUREMENT OF GAMMA-ACTIVITY IN SOIL SAMPLES OF CHARSADDAH DISTRICT OF PAKISTAN

Gamma activity of soil samples, collected from agricultural lands of Chrsaddah district of North West Frontier Province (N.W.F.P., Pakistan), have been determined using gamma-ray spectrometry. The average values of the measured activities in Bq.kg(-1) were 57.1 +/- 9.2 (radium-226), 60.1 +/- 9.9 (thorium-232), 387.4 +/- 49.4 (potassium-40) and 7.1 +/- 2.0 (cesium-137). The common index of these radionuclides in terms of radium equivalent activity was 170.8 +/- 22.3 Bq.kg(-1), which is comparable with the values for other countries of the world. The external and internal hazards due to gamma-rays from radium-226, thorium-232 and potassium-40 were found to be less than unity and the concentration of cesium-137 was also very nominal. Thus these radioactivity levels in soil samples do not pose any environmental health problem, however, the presented data provide a general background of the detectable radionuclides for the surveyed area and call be helpful in any radiological emergency.read more

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F JAN ,M A ATTA ,K KHAN ,H M KHAN ,

ANALYSIS OF DOPING SUBSTANCES BY GAS-CHROMATOGRAPHY WITH MASS SELECTIVITY DETECTOR

An analytical method for doping control analysis has been studied. Twenty nine drugs including eighteen narcotic analgesic, nine beta-blockers, one stimulant and one standard were analyzed simultaneously by gas chromatography equipped with nitrogen phosphorous detector and gas chromatography combined with mass selective detector after derivatization of the drugs.read more

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M A CHIPPA ,S A ARBANI ,G A QURESHI ,M Y KHUHAWAR ,A R SAMO ,

EXTRACTION - SPECTROPHOTOMETRIC DETERMINATION OF MICROAMOUNT OF TUNGSTEN(VI) IN THIOCYANATE SYSTEM

Investigations were carried out to develop a sensitive and modified method for the determination of micro-amount of tungsten (VI) in presence of other trace elements. The yellow coloured tungsten (VI) Sn(II)-SCN complex formed between tungsten, thiocyanate and stannous chloride in presence of HCl is quantitatively extractable from the aqueous phase into the organic phase containing tricaprylamine (high molecular weight amine). The complex gives maximum absorption at 420 nm, and is stable upto 72 hours. nle system obeys Beer's law in the range 0.1-8.0 mg of tungsten in the solution, and the molar absorptivity at 420 nm is 7.8 x 10 (-1) mol(-1) cm(-1). The extractability of the complex into tricaprylamine suggests that the coloured species is anionic in nature. Most of the common cations and anions do not interfere.read more

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K KHAN ,M MUMTAZ ,M AMIN ,

INDIRECT DETERMINATION OF MALATHION USING ATOMIC-ABSORPTION

The organophosphate pesticide malathion is hydrolysed in alkaline medium to dimethyl dithiophosphate (DMDSP) sodium fumarate and ethanol. The DMDSP reacts with bismuth (III) to form a complex which is extracted in methyl isobutyl ketone (MIBK). The bismuth is determined in organic phase using air acetylene ne flame atomic absorption. The concentration of bismuth is proportional to malathion in solution. The linear calibration range and detection limits for DMDSP were evaluated. Finally a commercial sample of malathion was analysed for the contents of malathion.read more

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I A QAZI ,M Y KHUHAWAR ,A H CHANAR ,

ANALYSIS OF ROCK SAMPLES BY ATOMIC-ABSORPTION AND X-RAY-FLUORESCENCE

Geological investigations are usually made by a number of techniques. The purpose of present work was to explore the chemical composition of the samples under study and also to see the reliability of the different instrumental techniques used for rock and mineral analysis. Chemical tests were performed prior to the use of any other technique in order to determine the nature of these rocks. The chemical analysis indicated the silica dominance in the rock composition, hence the acidic nature of the rock. The major, minor and trace elements were determined by employing X-ray fluorescence and atomic adsorption spectroscopic methods.read more

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Z AKHTER ,M IKRAM ,M A RAUF ,

ORGANIC-REACTIONS IN THE AQUEOUS-MEDIUM .5. SPECTROSCOPIC AND CHROMATOGRAPHIC EVIDENCE FOR THE FORMATION OF TAUTOMERIC DIHYDROPYRIDINES IN THE REACTIONS OF BETA-DIKETO COMPOUNDS AND HEXAMETHYLENE TETRAMINE (HMTA)

Hexamethylene tetramine (HMTA) on reaction with beta-diketo compounds (ethyl acetoacetate, acetylacetone and dimedone) yielded corresponding dihydropyridine derivatives in the aqueous medium. The formation of these tautomeric analogues has been established on the basis of spectroscopic and chromatographic evidence.read more

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A EHSAN ,M YOUNUS ,S S ALI ,C M ASHRAF ,

REACTIVITY RATIOS FOR THE COPOLYMERIZATION OF STYRENE AND GLYCIDYL METHACRYLATE BY NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

Polymers and copolymers of styrene and glycidyl methacrylate have been prepared. Reactivity ratios for the copolymer system have been determined by using nuclear magnetic resonance spectroscopy. Results obtained by two different methods are in good agreement with each other.read more

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S ZULFIQAR ,M ZULFIQAR ,A PARACHA ,