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1

Reactive extraction of lactic acid using alamine 336 in MIBK: equilibria and kinetics.  

PubMed

Lactic acid is an important commercial product and extracting it out of aqueous solution is a growing requirement in fermentation based industries and recovery from waste streams. The design of an amine extraction process requires (i) equilibrium and (ii) kinetic data for the acid-amine (solvent) system used. Equilibria for lactic acid extraction by alamine 336 in methyl-iso-butyl-ketone (MIBK) as a diluent have been determined. The extent to which the organic phase (amine +MIBK) may be loaded with lactic acid is expressed as a loading ratio, z=[HL](o)/[B](i,o). Calculations based on the stoichiometry of the reactive extraction and the equilibria involved indicated that more lactic acid is transferred to the organic phase than would be expected from the (1:1) stoichiometry of the reaction. The extraction equilibrium was interpreted as a result of consecutive formation of two acid-amine species with stoichiometries of 1:1 and 2:1. Equilibrium complexation constant for (1:1) and (2:1) has been estimated. Kinetics of extraction of lactic acid by alamine 336 in MIBK has also been determined. In a first study of its kind, the theory of extraction accompanied by a chemical reaction has been used to obtain the kinetics of extraction of lactic acid by alamine 336 in MIBK. The reaction between lactic acid and alamine 336 in MIBK in a stirred cell falls in Regime 3, extraction accompanied by a fast chemical reaction occurring in the diffusion film. The reaction has been found to be zero order in alamine 336 and first order in lactic acid with a rate constant of 1.38 s(-1). These data will be useful in the design of extraction processes. PMID:12052683

Wasewar, Kailas L; Heesink, A Bert M; Versteeg, Geert F; Pangarkar, Vishwas G

2002-07-17

2

Linear solvation energy relationship modeling and kinetic studies on reactive extraction of succinic acid by tridodecylamine dissolved in MIBK.  

PubMed

Equilibrium and kinetic studies for the extraction of succinic acid from aqueous solution with tridodecylamine diluted in MIBK are reported. All measurements were carried out at 298.15 K. The extent to which the organic phase may be loaded with succinic acid is expressed as a loading ratio, Z. The equilibrium data were also interpreted by a proposed mechanism of three reactions of complexation by which (1:1) and (2:1) acid-amine complexes are formed. Kinetics of extraction of succinic acid by tridodecylamine in MIBK has also been determined. Kinetic studies for the extraction of succinic acid from aqueous solution with tridodecylamine diluted in MIBK were carried out using a stirred cell for kinetic studies. The results of the liquid-liquid equilibrium measurements were correlated by a linear solvation energy relationship (LSER) model, which takes into account physical interactions. From the regression coefficients, information on the solvent-solute interaction is obtained and solvation models are proposed. PMID:17803280

Inci, Ismail

2007-01-01

3

[{sup 14}C]pyrene bound residue evaluation using MIBK fractionation method for creosote-contaminated soil  

SciTech Connect

The fate of [{sup 14}C]pyrene was evaluated in creosote-contaminated soil undergoing remediation in a prepared bed system at the Champion International Superfund site in Libby, MT. {sup 14}C-bound residue formation was evaluated using the methyl isobutyl ketone (MIBK) humic fractionation procedure, and it increased through 294 days of incubation in biologically active microcosms for humic acid, fulvic acid, bound humic acid, and mineral-associated organic carbon fractions. The relative affinity of the added pyrene and transformation products was highest for the humic acid fraction. Bound residue formation in PAH-contaminated soil was observed to be an important fate mechanism in the prepared bed system and may be an acceptable end point in the remediation of contaminated soil.

Nieman, J.K.C.; Sims, R.C.; Sims, J.L.; Sorensen, D.L.; McLean, J.E. [Utah State Univ., Logan, UT (United States)] [Utah State Univ., Logan, UT (United States); Rice, J.A. [South Dakota State Univ., Brookings, SD (United States). Dept. of Chemistry and Biochemistry] [South Dakota State Univ., Brookings, SD (United States). Dept. of Chemistry and Biochemistry

1999-03-01

4

Comparison of MIBK\\/IPA and water\\/IPA as PMMA developers for electron beam nanolithography  

Microsoft Academic Search

In electron beam lithography, resist behavior, such as sensitivity, contrast, exposure dose latitude, roughness and resolution, are influenced by the nature of the resist, the developer type and composition, and the development technique. In earlier work, ultrasonically assisted development was used to improve resolution and line edge roughness. Here we investigate the influence on resist behavior of an unconventional developer

Shazia Yasin; D. G. Hasko; H. Ahmed

2002-01-01

5

Methyl isobutyl ketone as a solvent for wax deoiling  

SciTech Connect

The solvency of methyl isobutyl ketone (MIBK) for use in deoiling and cold-fractionation of solid paraffin waxes is investigated by a visual polytherm method in the temperature interval 0-36 C. The capability of MIBK for precipitating solid hydrocarbons from solution was found to be greater than acetone/toluene or MEK/toluene, with only MEK better in this respect than MIBK. The quantity of wax remaining in the filtrate is examined. The critical solution temperatures are investigated and it is shown that MIBK surpasses MEK. The results obtained indicate that MIBK is extremely promising for use in processes of deoiling and cold fractionation of waxes.

Larikov, V.I.; Pereverzev, A.N.; Roshchin, Y.N.; Sokolova, S.P.

1983-09-01

6

Integration of pervaporation for the removal of water in the production process of methylisobutylketone  

Microsoft Academic Search

Results of pervaporation experiments are reported for the dehydration of two different mixtures: a ternary synthetic mixture containing acetone, methylisobutylketone (MIBK) and water and a so-called product mixture consisting of 50–60 wt% acetone 40-30 wt% MIBK 7–8 wt% water and 3-2 wt% by-products as directly obtained from a MIBK production plant. The pervaporation experiments have been carried out with PVA

Claudia Staudt-Bickel; Rüdiger N. Lichtenthaler

1996-01-01

7

Methyl isobutyl ketone as a solvent for wax deoiling  

Microsoft Academic Search

The solvency of methyl isobutyl ketone (MIBK) for use in deoiling and cold-fractionation of solid paraffin waxes is investigated by a visual polytherm method in the temperature interval 0-36 C. The capability of MIBK for precipitating solid hydrocarbons from solution was found to be greater than acetone\\/toluene or MEK\\/toluene, with only MEK better in this respect than MIBK. The quantity

V. I. Larikov; Yu. N. Roshchin; S. P. Sokolova; A. N. Pereverzev

1983-01-01

8

The removal of volatile ketone mixtures from air in biofilters  

Microsoft Academic Search

The work reported concerns the removal of mixtures of two ketones, methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), which find wide application as industrial solvents, from effluent air streams in downward flow biofilters operating at relative humidities in excess of 95 percent. The inlet concentrations of the two pollutants were 300 mg m-3MEK and 330 mg m-3MIBK. Maximum

M. A. Deshusses; G. Hamer

1993-01-01

9

40 CFR Table 7 to Subpart Vvvvvv... - Partially Soluble HAP  

Code of Federal Regulations, 2010 CFR

...4-Methyl-2-pentanone (MIBK) 108101 13. Acetaldehyde 75070 14. Acrolein 107028 15. Acrylonitrile 107131 16. Allyl chloride 107051 17. Benzene 71432 18. Benzyl chloride 100447 19. Biphenyl 92524 20. Bromoform...

2010-07-01

10

Extracao por solventes de niobio e tantalo. (Solvents Extraction of Niobium and Tantalum).  

National Technical Information Service (NTIS)

The separation process of niobium and tantalum using solvent extraction is evaluated. The use of methyl isobutyl ketone (MIBK) e tributyl phosphate (TBP), and the distribution of two elements between aqueous and organic phases in function of the fluoridri...

P. R. G. Santos O. C. Cunha

1982-01-01

11

Removal of Methyl Isobutyl Ketone From Contaminated Air by Trickle-Bed Air Biofilter  

Microsoft Academic Search

A laboratory-scale trickle-bed air biofilter was evaluated for the removal of methyl isobutyl ketone MIBK from a waste gas stream. Six-millimeter 6m m Celite pellets R-635 were used as the biological attachment medium. Effects of MIBK volumetric loading rates on removal efficiency, biofilter reacclimation, biomass growth, and removal kinetics were studied under three different operating conditions, namely, backwashing and two

Zhangli Cai; Daekeun Kim; George A. Sorial

2005-01-01

12

Bifunctionalized hollow nanospheres for the one-pot synthesis of methyl isobutyl ketone from acetone.  

PubMed

Pd-doped propyl sulfonic acid-functionalized hollow nanospheres proved to be efficient bifunctionalized catalysts for the one-pot synthesis of methyl isobutyl ketone (MIBK) from acetone and hydrogen in liquid phase. These hollow nanospheres exhibited a higher activity than their bulk mesoporous counterparts (SBA-15 or FDU-12), mainly due to the short diffusion resistance of hollow nanospheres. Hollow nanospheres with silica frameworks showed higher activity and selectivity for MIBK than those with ethane-bridged frameworks, suggesting that hollow nanospheres with hydrophilic surface properties favor the formation of MIBK. This is probably due to the increased affinity of the hydrophilic surface towards acetone and its decreased affinity towards MIBK, which precludes deep condensation of MIBK with acetone. Under optimal conditions, up to 90 % selectivity for MIBK can be obtained with conversions of acetone as high as 43 %. This result is among the best reported so far for mesoporous silica-based catalysts. The control/fine-tuning of morphology and surface properties provides an efficient strategy for improving the catalytic performance of solid catalysts. PMID:23132691

Wang, Peng; Bai, Shiyang; Zhao, Jiao; Su, Panpan; Yang, Qihua; Li, Can

2012-12-01

13

Solvent extraction of phenols from water  

SciTech Connect

Methyl isobutyl ketone (MIBK) and diisopropyl ether (DIPE) have been evaluated as solvents for extraction of phenols, at high dilution, from water. Equilibrium distribution coefficients (K/sub D/) have been measured for phenol, dihydroxybenzenes and trihydroxybenzenes in both solvents as a function of pH. Particularly for the multihydric phenols, MIBK gives substantially higher values of K/sub D/ than does DIPE. The effect of pH can be described quantitatively through a simple ionization model, using published values of dissociation constants for the various phenols. Some method for removal of residual dissolved solvent must ordinarily be included in any extraction process for phenols. Possibilities include atmospheric-steam or inert-gas stripping, vacuum-steam stripping, and extraction with a second solvent. Vacuum-steam stripping is a particularly attractive choice for removal of MIBK; this reinforces the utility of MIBK as a solvent. The optimal temperature for vacuum stripping is generally the temperature of the extraction operation, which in turn is related to the effect of temperature on K/sub D/. Values of K/sub D/ for phenol-water-MIBK were determined at 30, 50, and 75/sup 0/C, and were found to decrease with increasing temperature at all concentrations.

Greminger, D.C.; Burns, G.P.; Lynn, S.; Hanson, D.H.; King, C.J.

1980-02-01

14

Determination of silver in soils, sediments, and rocks by organic-chelate extraction and atomic absorption spectrophotometry  

USGS Publications Warehouse

A useful method for the determination of silver in soil, sediment, and rock samples in geochemical exploration has been developed. The sample is digested with concentrated nitric acid, and the silver extracted with triisooctyl thiophosphate (TOTP) in methyl isobutyl ketone (MIBK) after dilution of the acid digest to approximately 6 M. The extraction of silver into the organic extractant is quantitative and not affected by the nitric acid concentration from 4 M to 8 M, or by different volumes of TOTP-MIBK. The extracted silver is stable and remains in the organic phase up to several days. The silver concentration is determined by atomic absorption spectrophotometry. ?? 1971.

Chao, T. T.; Ball, J. W.; Nakagawa, H. M.

1971-01-01

15

The determination of aluminum, copper, iron, and lead in glycol formulations by atomic absorption spectroscopy  

NASA Technical Reports Server (NTRS)

Initial screening tests and the results obtained in developing procedures to determine Al, Cu, Fe, and Pb in glycol formulations are described. Atomic absorption completion was selected for Cu, Fe and Pb, and after comparison with emission spectroscopy, was selected for Al also. Before completion, carbon, iron, and lead are extracted with diethyl dithio carbamate (DDC) into methyl isobutyl ketone (MIBK). Aluminum was also extracted into MIBK using 8-hydroxyquinoline as a chelating agent. As little as 0.02 mg/l carbon and 0.06 mg/l lead or iron may be determined in glycol formulations. As little as 0.3 mg/l aluminum may be determined.

1977-01-01

16

40 CFR Appendix B to Part 80 - Test Methods for Lead in Gasoline  

Code of Federal Regulations, 2012 CFR

...lead compounds are stabilized by reaction with iodine and a quarternary ammonium salt. The lead...Aliquat 336 with MIBK to one liter. 4.6 Iodine Solution—Dissolve and dilute 3.0 g iodine crystals with Toluene to 100 ml. 4.7...

2012-07-01

17

40 CFR Appendix B to Part 80 - Test Methods for Lead in Gasoline  

Code of Federal Regulations, 2011 CFR

...lead compounds are stabilized by reaction with iodine and a quarternary ammonium salt. The lead...Aliquat 336 with MIBK to one liter. 4.6 Iodine Solution—Dissolve and dilute 3.0 g iodine crystals with Toluene to 100 ml. 4.7...

2011-07-01

18

Determination of traces of copper, nickel and cobalt by solvent extraction and atomic absorption spectrophotometry  

Microsoft Academic Search

A new method for the determination of Cu, Ni and Co is proposed. It involves extraction of the metal 2-nitroso-l-naphtholates by MIBK from a citrate medium and atomic absorption measurement in the organic phase. The extraction eliminates the matrix effects and background fluctuations usually observed when concentrated solutions are directly aspirated into the flame. The procedure has been applied to

A. N. Chowdhury; D. K. De; A. K. Das

1977-01-01

19

Evaluation of solvent selectivity in dewaxing and deoiling  

Microsoft Academic Search

Previous literature on the efficiency of solvents used in removing paraffin wax by decrystallization is insufficient. A method for evaluating selectivity and mixtures of solvents is offered. General solvents MEK, acetone, MIBK are tested in various raw materials, then graphed. It is found that the ratio of the slope of the curve for the temperature of equal solubility (TES) as

N. V. Alperovich; A. N. Leonidov; S. P. Sokolova

1983-01-01

20

Determination of gas phase adsorption isotherms—a simple constant volume method  

Microsoft Academic Search

Single and ternary solute gas phase adsorption isotherms were conducted in this study to evaluate the effectiveness of a simple constant volume method, which was utilized by using Tedlar gas sampling bags as a constant volume batch reactor. For this purpose, gas phase adsorption of toluene, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) on two types of activated

Daekeun Kim; Zhangli Cai; George A. Sorial

2006-01-01

21

Manganese dioxide causes spurious gold values in flame atomic-absorption readings from HBr-Br2 digestions  

USGS Publications Warehouse

False readings, apparently caused by the presence of high concentrations of manganese dioxide, have been observed in our current flame atomic-absorption procedure for the determination of gold. After a hydrobromic acid (HBr)-bromine (Br2) leach, simply heating the sample to boiling to remove excess Br2 prior to extraction with methyl-isobutyl-ketone (MIBK) eliminates these false readings. ?? 1981.

Campbell, W. L.

1981-01-01

22

Stabilizing Agents for Calibration in the Determination of Mercury Using Solid Sampling Electrothermal Atomic Absorption Spectrometry  

PubMed Central

Tetramethylene dithiocarbamate (TMDTC), diethyldithiocarbamate (DEDTC), and thiourea were investigated as stabilizing agents for calibration purposes in the determination of mercury using solid sampling electrothermal atomic absorption spectrometry (SS-ETAAS). These agents were used for complexation of mercury in calibration solutions and its thermal stabilization in a solid sampling platform. The calibration solutions had the form of methyl isobutyl ketone (MIBK) extracts or MIBK-methanol solutions with the TMDTC and DEDTC chelates and aqueous solutions with thiourea complexes. The best results were obtained for MIBK-methanol solutions in the presence of 2.5?g?L?1 TMDTC. The surface of graphite platforms for solid sampling was modified with palladium or rhenium by using electrodeposition from a drop of solutions. The Re modifier is preferable due to a higher lifetime of platform coating. A new SS-ETAAS procedure using the direct sampling of solid samples into a platform with an Re modified graphite surface and the calibration against MIBK-methanol solutions in the presence of TMDTC is proposed for the determination of mercury content in solid environmental samples, such as soil and plants.

Zelinkova, Hana; Cervenka, Rostislav; Komarek, Josef

2012-01-01

23

SML resist processing for high-aspect-ratio and high-sensitivity electron beam lithography  

NASA Astrophysics Data System (ADS)

A detailed process characterization of SML electron beam resist for high-aspect-ratio nanopatterning at high sensitivity is presented. SML contrast curves were generated for methyl isobutyl ketone (MIBK), MIBK/isopropyl alcohol (IPA) (1:3), IPA/water (7:3), n-amyl acetate, xylene, and xylene/methanol (3:1) developers. Using IPA/water developer, the sensitivity of SML was improved considerably and found to be comparable to benchmark polymethylmethacrylate (PMMA) resist without affecting the aspect ratio performance. Employing 30-keV exposures and ultrasonic IPA/water development, an aspect ratio of 9:1 in 50-nm half-pitch dense grating patterns was achieved representing a greater than two times improvement over PMMA. Through demonstration of 25-nm lift-off features, the pattern transfer performance of SML is also addressed.

Mohammad, Mohammad Ali; Dew, Steven K.; Stepanova, Maria

2013-03-01

24

Flame and flameless atomic-absorption determination of tellurium in geological materials  

USGS Publications Warehouse

The sample is digested with a solution of hydrobromic acid and bromine and the excess of bromine is expelled. After dilution of the solution to approximately 3 M in hydrobromic acid, ascorbic acid is added to reduce iron(III) before extraction of tellurium into methyl isobutyl ketone (MIBK). An oxidizing air-acetylene flame is used to determine tellurium in the 0.1-20 ppm range. For samples containing 4-200 ppb of tellurium, a carbon-rod atomizer is used after the MIBK extract has been washed with 0.5 M hydrobromic acid to remove the residual iron. The flame procedure is useful for rapid preliminary monitoring, and the flameless procedure can determine tellurium at very low concentrations. ?? 1978.

Chao, T. T.; Sanzolone, R. F.; Hubert, A. E.

1978-01-01

25

SML resist processing for high-aspect-ratio and high-sensitivity electron beam lithography.  

PubMed

A detailed process characterization of SML electron beam resist for high-aspect-ratio nanopatterning at high sensitivity is presented. SML contrast curves were generated for methyl isobutyl ketone (MIBK), MIBK/isopropyl alcohol (IPA) (1:3), IPA/water (7:3), n-amyl acetate, xylene, and xylene/methanol (3:1) developers. Using IPA/water developer, the sensitivity of SML was improved considerably and found to be comparable to benchmark polymethylmethacrylate (PMMA) resist without affecting the aspect ratio performance. Employing 30-keV exposures and ultrasonic IPA/water development, an aspect ratio of 9:1 in 50-nm half-pitch dense grating patterns was achieved representing a greater than two times improvement over PMMA. Through demonstration of 25-nm lift-off features, the pattern transfer performance of SML is also addressed. PMID:23531370

Mohammad, Mohammad Ali; Dew, Steven K; Stepanova, Maria

2013-01-01

26

Acetone transformation over Pt\\/H[Al]ZSM5 and Pt\\/H[Ga]ZSM5 catalysts  

Microsoft Academic Search

Acetone transformation into methyl–isobutyl ketone (MIBK) under hydrogen atmosphere, using bifunctional catalysts of the platinum supported over medium-pore zeolites (MFI)-type, was studied. This methodology offers a number of advantages; however, since it implies working at low hydrogen pressure (PH2 ) with respect to the acetone pressure (PAc), a rapid catalyst deactivation is observed. Therefore, to minimize deactivation of bifunctional catalysts,

L. Melo; A. Llanos; M. Mediavilla; D. Moronta

2002-01-01

27

Studies on the extraction and determination of metals-I Extraction of hafnium into methyl isobutyl ketone and tributyl phosphate.  

PubMed

The effect of various factors on the distribution of hafnium ( 5.60 x 10(-4)M) between different acids and methyl isobutyl ketone (MIBK) or tributyl phosphate (TBP) was studied by using (176 + 181) Hf as a tracer, when the extraction is made from 7.5-11M hydrochloric acid with an equal volume of IM TBP in benzene, hafnium is extracted quantitatively (>99%). The hafnium can be stripped with 1-3M hydrochloric acid. PMID:18961225

Ichinose, N

1972-12-01

28

Fourth derivative spectrophotometric determination of fungicide thiram (tetramethyldithiocarbamate) using sodium molybdate and its application  

Microsoft Academic Search

A procedure has been developed for the direct fourth derivative spectrophotometric determination of tetramethyldithiocarbamate by converting it into its molybdenum complex, which is then extracted in to methyl isobutyl ketone (MIBK). Beer’s law is obeyed over the concentration range 24?gmL?1 in the final solution. The analytical sensitivity is calculated to be 0.004(d4A\\/d?4) ?g?1mL?1 from the slope of the calibration curve.

Vaneet Kumar Sharma; J. S. Aulakh; A. K. Malik

2005-01-01

29

Comparative Efficiencies of Trace Metal Extraction from Municipal Incinerator Ashes  

Microsoft Academic Search

Five laboratory solvent extraction methods for the determination of leachable trace metals from municipal incinerator fly and bottom ashes are evaluated. The trace elements of interest were cadmium, chromium, copper, manganese and lead. Five different extractants, 0.1NHCl, 1.0 N ammonium acetate, methyl isobutyl ketone (MIBK), chloroform and hexane were used on each ash to determine comparative extraction efficiencies.Extraction efficiencies of

C. A. Cahill; L. W. Newland

1982-01-01

30

An insitu study of dissolution and swelling behavior of poly-(methyl methacrylate) thin films in solvent\\/nonsolvent binary mixtures  

Microsoft Academic Search

A single-element rotating-polarizer ellipsometer (psi-meter) was used for insitu characterization of the thermodynamic and kinetic behavior of poly-(methyl methacrylate), PMMA, thin films (1.2 ?m) in solvent\\/nonsolvent binary mixtures of methyl ethyl ketone\\/isopropanol (MEK\\/IPA) and methyl isobutyl ketone\\/methanol (MIBK\\/MeOH). Thermodynamic effects were inferred from equilibrium behavior by the degree of swelling and polymer-solvent solubility. A sharp transition between complete solubility and

J. Manjkow; J. S. Papanu; D. S. Soong; D. W. Hess; A. T. Bell

1987-01-01

31

SPE–GC\\/FTD determination of N-methyl-2-pyrrolidone and its metabolites in urine  

Microsoft Academic Search

An analytical method using a combination of solid-phase extraction (SPE) and gas chromatography with a flame thermionic detector (GC\\/FTD) was developed for determination of N-methyl-2-pyrrolidone (NMP), N-methylsuccinimide (MSI), and 2-hydroxy-N-methylsuccinimide (2-HMSI) in human urine. The SPE cartridge of poly(divinylbenzene\\/hydroxymethacrylate) used was directly loaded with urine sample, followed by elution with methyl isobutyl ketone (MIBK) and subsequent centrifugation, and the supernatant

Ryuichi Kubota; Yoko Endo; Akito Takeuchi; Yoshinori Inoue; Hiroko Ogata; Masanori Ogawa; Tomoo Nakagawa; Nobuhiko Onda; Ginji Endo

2007-01-01

32

Time evolution of developed contours in poly-(methyl methacrylate) electron resist  

Microsoft Academic Search

The time evolution of exposure contours in poly-(methyl methacrylate) (PMMA) electron resist is calculated for several time-dependent developers comprised of various proportions of methyl isobutyl ketone (MIBK) and isopropyl alcohol (IPA). Contours are calculated for a line of charge incident on 4000 Å of resist coated on a low-atomic-number substrate. Parameters such as beam energy, incident charge per unit length,

James S. Greeneich

1974-01-01

33

Wet-process phosphoric acid obtained from Kola apatite. Purification from sulphates, fluorine, and metals  

Microsoft Academic Search

The purification of pre-concentrated up to 80 wt.% H3PO4 phosphoric acid (PA) obtained from Kola apatite in one of the Polish plants by the wet processing route was carried out by sulphate precipitation, desorption of volatile components (SiF4, HF) and liquid–liquid extraction method using 4-methyl-2-pentanone (MIBK). The experiment was carried out on a laboratory scale. The effects of the reagent

R Kijkowska; D Pawlowska-Kozinska; Z Kowalski; M Jodko; Z Wzorek

2002-01-01

34

Determination of Ultra Trace Amounts of Cobalt in Fish by Graphite Furnace Zeeman Effect Atomic Absorption Spectrometry  

Microsoft Academic Search

A method is described for determining stable cobalt concentrations in fish flesh and bone using polarized Zeeman effect graphite furnace atomic absorption spectrometry (ZAAS). Cobalt analysis on freshwater fish flesh samples (log dry weight) required predigestion and wet-ashing at 70–80°C. Cobalt is chelated with ammonium pyrrolidine dithiocarbamate (APDC) extracted with methyl isobutyl ketone (MIBK) and analysed by ZAAS. The mean

J. W. McMahon; A. E. Docherty; J. M. A. Judd; S. R. Gentner

1986-01-01

35

Energy transfer kinetics in irradiated tributyl phosphate to diphenyl sulfoxide and methyl isobutyl ketone  

NASA Astrophysics Data System (ADS)

Both diphenyl sulfoxide (DPSO) and methyl isobutyl ketone (MIBK) are able to inhibit ?-radiolysis of tributyl phosphate (TBP) efficiently. They have a two-fold effect of energy transfer on excited TBP, i.e. not only can they take away the energy of excited TBP of the first kind, but also can remove that of the second kind. By making distinctions among the different excited stated of TBP, the theoretical values calculated from derivated kinetic equations agree well with the experimental results.

Lan, Wu Ji; Xian, Fu Ying; Qing, Wang Wen

36

Severe cutaneous reaction to CS gas.  

PubMed

Tear gas is used throughout the World for control of riots and civil disobedience. CS gas as used by the UK police force is issued as a 'spray' and is 5% CS in methylisobutylketone (MIBK), a potent irritant. Assaults on police officers in forces issued with CS spray have fallen significantly over the past 3 years, whilst having risen in areas without it. Thus, CS gas appears to be an effective deterrent. However, significant cutaneous reactions can occur as a result of exposure. We report a severe contact dermatitis to CS gas to highlight the clinical features. The nature of CS gas and potential cutaneous adverse reactions are discussed. PMID:11422166

Varma, S; Holt, P J

2001-05-01

37

Evaluation of solvent selectivity in dewaxing and deoiling  

SciTech Connect

Previous literature on the efficiency of solvents used in removing paraffin wax by decrystallization is insufficient. A method for evaluating selectivity and mixtures of solvents is offered. General solvents MEK, acetone, MIBK are tested in various raw materials, then graphed. It is found that the ratio of the slope of the curve for the temperature of equal solubility (TES) as a function of the content of the solvent (that is, the solubility curve) to the slope of the corresponding denormalization curve is constant. This ratio gives a formula, and is therefore a criterion for selectivity. The greater the ratio, the higher the selectivity. The ratio is also generalized to solvents of any composition.

Al'perovich, N.V.; Leonidov, A.N.; Sokolova, S.P.

1983-05-01

38

A comparative study in treating two VOC mixtures in trickle bed air biofilters.  

PubMed

Two independent parallel trickling bed air biofilters (TBABs) ("A" and "B") with two different typical VOC mixtures were investigated. Toluene, styrene, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) were the target VOCs in the mixtures. Biofilter "A" was fed equal molar ratio of the VOCs and biofilter "B" was fed a mixture based on EPA 2003 emission report. Backwashing and substrate starvation operation were conducted as biomass control. Biofilter "A" and "B" maintained 99% overall removal efficiency for influent concentration up to 500 and 300 ppmv under backwashing operating condition, respectively. The starvation study indicated that it can be an effective biomass control for influent concentrations up to 250 ppmv for biofilter "A" and 300 ppmv for "B". Re-acclimation of biofilter performance was delayed with increase of influent concentration for both biofilters. Starvation operation helped the biofilter to recover at low concentrations and delayed re-acclimation at high concentrations. Furthermore, re-acclamation for biofilter "B" was delayed due to its high toluene content as compared to biofilter "A". The pseudo first-order removal rate constant decreased with increase of volumetric loading rate for both biofilters. MEK and MIBK were completely removed in the upper 3/8 media depth. While biofilter depth utilization for the removal of styrene and toluene increased with increase of influent concentrations for both biofilters. However, toluene removal utilized more biofilter depth for biofilter "B" as compared to biofilter "A". PMID:17349673

Cai, Zhangli; Kim, Daekeun; Sorial, George A

2007-06-01

39

Nitrogen utilization and biomass yield in trickle bed air biofilters.  

PubMed

Nitrogen utilization and subsequent biomass yield were investigated in four independent lab-scale trickle bed air biofilters (TBABs) fed with different VOCs substrate. The VOCs considered were two aromatic (toluene, styrene) and two oxygenated (methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK)). Long-term observations of TBABs performances show that more nitrogen was required to sustain high VOC removal, but the one fed with a high loading of VOC utilized much more nitrogen for sustaining biomass yield. The ratio N(consumption)/N(growth) was an effective indicator in evaluating nitrogen utilization in the system. Substrate VOC availability in the system was significant in determining nitrogen utilization and biomass yield. VOC substrate availability in the TBAB system was effectively identified by using maximum practical concentrations in the biofilm. Biomass yield coefficient, which was driven from the regression analysis between CO(2) production rate and substrate consumption rate, was effective in evaluating the TBAB performance with respect to nitrogen utilization and VOC removal. Biomass yield coefficients (g biomass/g substrate, dry weight basis) were observed to be 0.668, 0.642, 0.737, and 0.939 for toluene, styrene, MEK, and MIBK, respectively. PMID:20609512

Kim, Daekeun; Sorial, George A

2010-10-15

40

Identification and separation of the organic compounds in coal-gasification condensate waters  

SciTech Connect

A substantial fraction of the organic solutes in condensate waters from low-temperature coal-gasification processes are not identified by commonly employed analytical techniques, have low distribution coefficients (K/sub D/) into diisopropyl ether (DIPE) or methyl isobutyl ketone (MIBK), and are resistant to biological oxidation. These compounds represent an important wastewater treatment problem. Analytical techniques were developed to detect these polar compounds, the the liquid-liquid phase equilibria were measured with several solvents. A high-performance liquid chromatography (HPLC) technique was employed to analyze four condensate-water samples from a slagging fixed-bed gasifier. A novel sample-preparation technique, consisting of an azeotropic distillation with isopropanol, allowed identification of compounds in the HPLC eluant by combined gas chromatography and mass spectrometry. Solvents containing trioctyl phosphine oxide (TOPO) have high K/sub D/ values for phenol and dihydroxy benzenes. A fraction of the compounds which are not removed by MIBK may be Lewis acids, because some of them were extracted by the strong Lewis bases, TBP and TOPO.

Mohr, D.H. Jr.

1983-01-01

41

Determination of tellurium in geochemical materials by flameless atomic-absorption spectroscopy.  

PubMed

A method is described for the determination of tellurium at nanogram levels in rocks and in other complex materials by the use of flameless atomic-absorption spectroscopy. A very selective organic extraction procedure is applied to avoid matrix interference effects during extraction of Te and the atomization stage in the graphite furnace. Prior separation of iron and other interfering elements is achieved by a combined cupferron-ethyl acetate extraction. Tellerium is extracted from 6M hydrochloric acid with MIBK and stripped into aqueous medium. Pipetting of the aqueous extract into the graphite furnace gives fairly good instrumental reproducibility (2-3% error). Detection limits of about 10 ppM Te for a 0.5-g sample have been achieved with the medium-performance apparatus used. Results for Te in some geochemical reference materials are reported. Indications are given for the determination of Sb and Mo in the same solutions. PMID:18962397

Sighinolfi, G P; Santos, A M; Martinelli, G

1979-02-01

42

The determination of vanadium in brines by atomic absorption spectroscopy  

USGS Publications Warehouse

A standard addition method is described for the determination of vanadium in brines by atomic absorption spectroscopy with a nitrous oxide-acetylene flame. Sample pH is adjusted to 1.0 with concentrated hydrochloric acid and the vanadium is directly extracted with 5% cupferron in methyl isobutyl ketone (MIBK). The ketone layer is then aspirated into the flame and the recorded absorption values are plotted as a function of the concentration of the added metal. As little as 2.5 ??g l-1 of vanadium can be detected under the conditions of the procedure. Tungsten and tin interfere when present in excess of 5 and 10 ??g ml-1, respectively. The concentrations of the two interfering ions normally found in brines are well below interference levels. ?? 1971.

Crump, Wiesner, H. J.; Feltz, H. R.; Purdy, W. C.

1971-01-01

43

Evaluation of performance impairment by spacecraft contaminants  

NASA Technical Reports Server (NTRS)

The environmental contaminants (isolated as off-gases in Skylab and Apollo missions) were evaluated. Specifically, six contaminants were evaluated for their effects on the behavior of juvenile baboons. The concentrations of contaminants were determined through preliminary range-finding studies with laboratory rats. The contaminants evaluated were acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), trichloroethylene (TCE), heptane and Freon 21. When the studies of the individual gases were completed, the baboons were also exposed to a mixture of MEK and TCE. The data obtained revealed alterations in the behavior of baboons exposed to relatively low levels of the contaminants. These findings were presented at the First International Symposium on Voluntary Inhalation of Industrial Solvents in Mexico City, June 21-24, 1976. A preprint of the proceedings is included.

Geller, I.; Hartman, R. J., Jr.; Mendez, V. M.

1977-01-01

44

A Bio-Catalytic Approach to Aliphatic Ketones  

PubMed Central

Depleting oil reserves and growing environmental concerns have necessitated the development of sustainable processes to fuels and chemicals. Here we have developed a general metabolic platform in E. coli to biosynthesize carboxylic acids. By engineering selectivity of 2-ketoacid decarboxylases and screening for promiscuous aldehyde dehydrogenases, synthetic pathways were constructed to produce both C5 and C6 acids. In particular, the production of isovaleric acid reached 32 g/L (0.22 g/g glucose yield), which is 58% of the theoretical yield. Furthermore, we have developed solid base catalysts to efficiently ketonize the bio-derived carboxylic acids such as isovaleric acid and isocaproic acid into high volume industrial ketones: methyl isobutyl ketone (MIBK, yield 84%), diisobutyl ketone (DIBK, yield 66%) and methyl isoamyl ketone (MIAK, yield 81%). This hybrid “Bio-Catalytic conversion” approach provides a general strategy to manufacture aliphatic ketones, and represents an alternate route to expanding the repertoire of renewable chemicals.

Xiong, Mingyong; Deng, Jin; Woodruff, Adam P.; Zhu, Minshan; Zhou, Jun; Park, Sun Wook; Li, Hui; Fu, Yao; Zhang, Kechun

2012-01-01

45

Rapid determination of antimony in steel by flameless atomic-absorption.  

PubMed

A method for the determination of 1-30 ppm or more of Sb in steel by using flameless atomic absorption has been developed. The sample was dissolved in aqua regia and 10 mul were pipetted into the Massmann-type furnace. It was shown that interferences from HCl, HNO(3), Ni and Fe could be eliminated if oxygen was excluded and the heating rate was sufficiently high. Chromium was added to the samples and standards to compensate for its influence. Cu, Co, Mn, Ti and Sn did not interfere. An intercomparison with other laboratories showed that this method gives the same result as extraction with TOPO in MIBK. The time for a complete analysis including dissolution was 15 min. PMID:18961492

Frech, W

1974-06-01

46

Determination of silver, bismuth, cadmium, copper, lead, and zinc in geologic materials by atomic absorption spectrometry with tricaprylylmethylammonium chloride  

USGS Publications Warehouse

Interferences commonly encountered in the determination of silver, bismuth, cadmium, copper, lead, and zinc at crustal abundance levels are effectively eliminated using a rapid, sensitive, organic extraction technique. A potassium chlorate-hydrochloric acid digestion solubilizes the metals not tightly bound in the silicate lattice of rocks, soils, and stream sediments. The six metals are selectively extracted into a 10% Aliquat 336-MIBK organic phase in the presence of ascorbic acid and potassium iodide. Metals in the organic extract are determined by flame atomic absorption spectrometry to the 0.02-ppm level for silver, cadmium, copper, and zinc and to the 0.2-ppm level for bismuth and lead with a maximum relative standard deviation of 18.8% for known reference samples. An additional hydrofluoric acid digestion may be used to determine metals substituted in the silicate lattice.

Viets, J. G.

1978-01-01

47

Determination of gold, indium, tellurium and thallium in the same sample digest of geological materials by atomic-absorption spectroscopy and two-step solvent extraction  

USGS Publications Warehouse

A rock, soil, or stream-sediment sample is decomposed with hydrofluoric acid, aqua regia, and hydrobromic acid-bromine solution. Gold, thallium, indium and tellurium are separated and concentrated from the sample digest by a two-step MIBK extraction at two concentrations of hydrobromic add. Gold and thallium are first extracted from 0.1M hydrobromic acid medium, then indium and tellurium are extracted from 3M hydrobromic acid in the presence of ascorbic acid to eliminate iron interference. The elements are then determined by flame atomic-absorption spectrophotometry. The two-step solvent extraction can also be used in conjunction with electrothermal atomic-absorption methods to lower the detection limits for all four metals in geological materials. ?? 1985.

Hubert, A. E.; Chao, T. T.

1985-01-01

48

Determination of trace amounts of tin in geological materials by atomic absorption spectrometry  

USGS Publications Warehouse

An atomic absorption method is described for the determination of traces of tin in rocks, soils, and stream sediments. A dried mixture of the sample and ammonium iodide is heated to volatilize tin tetraiodide -which is then dissolved in 5 % hydrochloric acid, extracted into TOPO-MIBK, and aspirated into a nitrous oxide-acetylene flame. The limit of determination is 2 p.p.m. tin and the relative standard deviation ranges from 2 to 14 %. Up to 20 % iron and 1000 p.p.m. Cu, Pb, Zn, Mn, Hg, Mo, V, or W in the sample do not interfere. As many as 50 samples can be easily analyzed per man-day. ?? 1976.

Welsch, E. P.; Chao, T. T.

1976-01-01

49

Health hazard evaluation report HETA 93-0448-2407, Thatcher Tubes, Division of Courtaulds US, Muscatine, Iowa  

SciTech Connect

In response to a request from the International Chemical Worker Union, an investigation was begun of exposure in the press area of the plastic tube department at Thatcher Tubes, Muscatine, Iowa, a division of Courtaulds US. The request has been prompted by worker complaints of skin and respiratory sensitization to emissions from the plastic tube printing and curing operations. The company manufactured plastic squeeze tubes, employing about 300 workers over three shifts. Ultraviolet (UV) cured inks were used in the press area. Levels of methyl-ethyl-ketone (MEK) were well below recommended limits, ranging from 7.2 to 18.5 parts per million (ppm). Levels of methyl isobutyl ketone (MIBK), ethanol, isopropanol, and tolune were also below the suggested limits. Ozone and trimethylolpropane triacrylate (TMPTA) were not detected. The authors conclude that no specific exposure in the UV coating process clearly accounted for reported symptoms.

Parker, M.G.; Buchta, T.M.

1994-03-01

50

The determination of specific forms of aluminum in natural water  

USGS Publications Warehouse

A procedure for analysis and pretreatment of natural-water samples to determine very low concentrations of Al is described which distinguishes the rapidly reacting equilibrium species from the metastable or slowly reacting macro ions and colloidal suspended material. Aluminum is complexed with 8-hydroxyquinoline (oxine), pH is adjusted to 8.3 to minimize interferences, and the aluminum oxinate is extracted with methyl isobutyl ketone (MIBK) prior to analysis by atomic absorption. To determine equilibrium species only, the contact time between sample and 8-hydroxyquinoline is minimized. The Al may be extracted at the sample site with a minimum of equipment and the MIBK extract stored for several weeks prior to atomic absorption analysis. Data obtained from analyses of 39 natural groundwater samples indicate that filtration through a 0.1-??m pore size filter is not an adequate means of removing all insoluble and metastable Al species present, and extraction of Al immediately after collection is necessary if only dissolved and readily reactive species are to be determined. An average of 63% of the Al present in natural waters that had been filtered through 0.1-??m pore size filters was in the form of monomeric ions. The total Al concentration, which includes all forms that passed through a 0.1-??m pore size filter, ranged 2-70 ??g/l. The concentration of Al in the form of monomeric ions ranged from below detection to 57 ??g/l. Most of the natural water samples used in this study were collected from thermal springs and oil wells. ?? 1975.

Barnes, R. B.

1975-01-01

51

Cold-development tool and technique for the ultimate resolution of ZEP520A to fabricate an EB master mold for nano-imprint lithography for 1Tbit/inch2 BPM development  

NASA Astrophysics Data System (ADS)

Cold-development is well-known for resolution enhancement on ZEP520A. Dipping a wafer in a developer solvent chilled by a freezer, such a typical method had been employed. But, it is obvious that the dip-development method has several inferiorities such as developer temperature instability, temperature inconsistency between developer and a wafer, water-condensation on drying. We then built a single wafer spin-develop tool, and established a process sequence, to solve those difficulties. And, we tried to see their effect down to -10degC over various developers. In specific, we tried to make hole patterns in hexagonal closest packing in 40nm, 35nm, 30nm, 25nm pitch, and examined holes pattern quality and resolution limit by varying setting temperature from room temperature to -10degC in the cold-development, as well as varying developer chemistry from the standard developer ZED N-50 (n-amyl acetate, 100%) to MiBK and IPA mixture which was a rinsing solvent mixture originally. We also examined the other developer (poor solvent mixture) we designed, N-50 and fluorocarbon (FC) mixture, MiBK and FC mixture, and IPA+FC mixture. This paper describes cold-development tool and technique, and its results down to minus (-) 10degC, for ZEP520A resolution enhancement to obtain 1Xnm bits (holes) in 25nm pitch to fabricate an EB master mold for Nano-Imprinting Lithography for 1Tbit/in2 bit patterned media (BPM) in HDD development and production.

Kobayashi, Hideo; Iyama, Hiromasa; Kagatsume, Takeshi; Watanabe, Tsuyoshi

2012-11-01

52

Methods for collection and analysis of geopressured geothermal and oil field waters  

USGS Publications Warehouse

Present methods are described for the collection, preservation, and chemical analysis of waters produced from geopressured geothermal and petroleum wells. Detailed procedures for collection include precautions and equipment necessary to ensure that the sample is representative of the water produced. Procedures for sample preservation include filtration, acidification, dilution for silica, methyl isobutyl ketone (MIBK) extraction of aluminum, addition of potassium permanganate to preserve mercury, and precipitation of carbonate species as strontium carbonate for stable carbon isotopes and total dissolved carbonate analysis. Characteristics determined at the well site are sulfide, pH, ammonia, and conductivity. Laboratory procedures are given for the analysis of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, iron, manganese, zinc, lead, aluminum, .and mercury by atomic absorption and flame emission spectroscopy. Chloride is determined by silver nitrate titration and fluoride by ion-specific electrode. Bromide and iodide concentrations are determined by the hypochlorite oxidation method. Sulfate is analyzed by titration using barium chloride with thorin indicator after pretreatment with alumina. Boron and silica are determined colorimetrically by the carmine and molybdate-blue methods, respectively. Aliphatic acid anions (C2 through C5) are determined by gas chromatography after separation and concentration in a chloroform-butanol mixture.

Lico, Michael S.; Kharaka, Yousif K.; Carothers, William W.; Wright, Victoria A.

1982-01-01

53

Electrothermal atomic absorption spectrometric determination of cobalt, copper, lead and nickel traces in aragonite following flotation and extraction separation.  

PubMed

A method of determination of Co, Cu, Pb and Ni in nanogram quantities from aragonite is presented. Flotation and extraction of Co, Cu, Pb and Ni is suggested as methods for elimination matrix interferences of calcium. The method of flotation is performed by iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)(3), as a colloid precipitate collector. The liquid-liquid extraction of Co, Cu, Pb and Ni is carried out by sodium diethyldithiocarbamate, NaDDTC, as complexing reagent into methylisobutyl ketone, MIBK. The electrothermal atomic absorption spectrometry (ETAAS) is used for determination of analytes. The detection limits of ETAAS followed by flotation are: 7.8 ng.g(-1) for Co, 17.1 ng.g(-1) for Cu, 7.2 ng.g(-1) for Pb and 9.0 mug.g(-1) for Ni. The detection limits of ETAAS followed by extraction are found to be: 12.0 ng.g(-1) for Co, 51.0 ng.g(-1) for Cu, 24.0 ng.g(-1) for Pb and 21.0 ng.g(-1) for Ni. PMID:18968235

Zendelovska, D; Pavlovska, G; Cundeva, K; Stafilov, T

2001-03-30

54

Determination of dissolved aluminum in water samples  

USGS Publications Warehouse

A technique has been modified for determination of a wide range of concentrations of dissolved aluminum (Al) in water and has been tested. In this technique, aluminum is complexed with 8-hydroxyquinoline at pH 8.3 to minimize interferences, then extracted with methyl isobutyl ketone (MIBK). The extract is analyzed colorimetrically at 395 nm. This technique is used to analyze two forms of monomeric Al, nonlabile (organic complexes) and labile (free, Al, Al sulfate, fluoride and hydroxide complexes). A detection limit 2 ug/L is possible with 25-ml samples and 10-ml extracts. The detection limit can be decreased by increasing the volume of the sample and (or) decreasing the volume of the methyl isobutyl ketone extract. The analytical uncertainty of this method is approximately + or - 5 percent. The standard addition technique provides a recovery test for this technique and ensures precision in samples of low Al concentrations. The average percentage recovery of the added Al plus the amount originally present was 99 percent. Data obtained from analyses of filtered standard solutions indicated that Al is adsorbed on various types of filters. However, the relationship between Al concentrations and adsorption remains linear. A test on standard solutions also indicated that Al is not adsorbed on nitric acid-washed polyethylene and polypropylene bottle wells. (USGS)

Afifi, A. A.

1983-01-01

55

Metal content and physicochemical parameters used as quality criteria in virgin argan oil: influence of the extraction method.  

PubMed

Metal content was determined in 26 samples of virgin argan oil from Morocco. An ETA-AAS with previous sample dilution with MIBK technique was used. In oil obtained by traditional method, Fe ranged from 0.8 to 4.0 mg/kg, Cu from 160.4 to 695.7 microg/kg, Cr from 10.3 to 55.3 microg/kg, Mn from 18.1 to 70.8 microg/kg, and Pb from 28.5 to 450.0 microg/kg. In oil obtained by a half-industrialized method, Fe ranged from 0.8 to 1.7 mg/kg, Cu from 158.4 to 385.0 microg/kg, Cr from 10.0 to 48.1 microg/kg, Mn from 15.0 to 68.5 microg/kg, and Pb from 32.0 to 100.0 microg/kg. Acidity value, peroxide index, K270 and K232, humidity and sludge volatile, and insoluble sludges in petroleum ether were also determined. A high variability in these quality parameters and a decrease of the quality in the oils obtained by the traditional method were observed. PMID:18662006

Marfil, Rocio; Cabrera-Vique, Carmen; Giménez, Rafael; Bouzas, Paula R; Martínez, Olga; Sánchez, Jose Antonio

2008-08-27

56

Simultaneous determination of trace amounts of chromium, cobalt and lead in waste water and plant materials by extraction -- atomic absorption spectrometry  

SciTech Connect

A simple and rapid procedure has been developed for the determination of Cr, Co and Pb in waste water and plant materials by flame atomic absorption spectrometry (FAAS). In this method the metals are complexed with potassium propyl xanthate and extracted into methyl isobutyl ketone (MIBK) and analyzed. Optimum conditions for quantitative determination of metals viz chromium, cobalt and lead are established by studying various parameters like the percentage of recovery in different solvents like butyl acetate, diisobutyl ketone, methyl isobutyl ketone and ethyl acetate, effect of reagent concentration and effect of pH. The data showed that the method could be employed for the determination of aforesaid metals in waste water and plant materials in the concentration range of 0.06--0.8 {micro}g/ml of cobalt and 0.12--1.6 {micro}g/ml of chromium and lead. The reliability of the method was assured by analyzing the Standard Reference Materials and by inter-comparison of Cr, Co and Pb values using inductively coupled plasma atomic emission spectrometry.

Balaji, T.; Chiranjeevi, P.; Naidu, G.R.K. [Sri Venkateswara Univ., Tirupati (India). Dept. of Chemistry

1998-04-01

57

An investigation into the short term and medium term health impacts of personal incapacitant sprays. A follow up of patients reported to the National Poisons Information Service (London)  

PubMed Central

Objectives: The aim of this study is to describe the pattern of ill health after personal incapacitant spray (PIS) exposures reported to the National Poisons Information Service—London (NPIS-L) and the Chemical Incident Response Service and to evaluate the relation between sub-categories of PIS exposure and adverse health effects. Methods: Case series study of patients reported to the NPIS-L, by attending medical personnel during the period 16 January to 31 September 1998. Data collected by questionnaire sent to these medical personnel. Results: Several "adverse" symptoms, particularly dermatitis and blisters were reported for cases exposed to police PIS. These cases were more frequent than in those people exposed to non-police PIS. Adverse effects occurring more than six hours after exposure were also observed, which is in conflict with the recorded immediate, short lived, and self limiting symptoms that PIS are designed to cause. Most patients with persisting symptoms required further treatment. Conclusions: These findings suggest that the formulation of CS (o-chlorobenzylidine malononitrile) with MiBK (methyl iso-butyl ketone) used by the police is more harmful that has been previously assumed. If confirmed then the continued use of this formulation should be reviewed because of longer duration of adverse effects. Less concentrated formulations may reduce the severity or persistence of the adverse effects.

Euripidou, E; MacLehose, R; Fletcher, A

2004-01-01

58

Synthesis of ultrapure ZBLAN glass for laser refrigeration  

NASA Astrophysics Data System (ADS)

The fluorozirconate glass ZBLAN:1%Yb3+ was synthesized, for the first time, from fluoride precursors that were individually purified by solvent extraction and hydrofluoric (HF) gas treatment. The synthesis used aqueous solutions of high-purity commercial precursors that were subjected to ultra-filtration followed by solvent extraction using ammonium pyrrolidine dithiocarbamate (APDC) and methyl-isobutyl-ketone (MIBK). The purified metal fluorides were precipitated and treated in hot HF gas to remove water, hydroxyl (OH-), and oxide impurities. ZBLAN:1%Yb3+ was fabricated from these precursors by melting under inert atmosphere, yielding glasses with excellent mechanical properties and having a clear, bubble-free, and crystallite-free matrix. The effect of adding 0.5 mol% of In3+ as an oxidizer to suppress the reduction of Zr4+ and the accompanying formation of black precipitates was studied. We found evidence for an oxidizer concentration threshold of ~0.8 mol%. Glasses made from purified fluorides formed black precipitates even with the addition of 0.5 mol% In3+, while glasses made from commercial fluorides did not. In the latter, additional oxidizers were likely present in the form of transition-metal impurities. An In3+ oxidizer concentration of >0.8 mol% is expected to eliminate the black precipitates in purified glasses and to yield ZBLAN:Yb3+ glass for efficient laser cooling.

Hehlen, Markus P.; Epstein, Richard I.; Patterson, Wendy M.

2008-03-01

59

Extraction procedure may not be feasible for cadmium analysis of tissues, such as horse kidney cortex, having a very high cadmium content  

SciTech Connect

In the light of the discrepancy between data on cadmium in horse kidney in the U.S. and what has been reported in Europe the present authors have tested the analytical procedure used by Penumarthy et al. (1980). Cadmium in reference pig kidney and horse kidney cortex was determined by flame atomic absorption spectrophotometry after wet digestion, dissolving of the residue in water, complexing with APDC and extraction into MIBK. The ratio between the measured amount (minus blank) and the calculated amount of cadmium in the samples was 86% for blank with addition of 0.5 ..mu..g cadmium and 91% for low-level pig kidney cortex with or without the addition of 0.5 ..mu..g cadmium. The ratio was unacceptably low for horse kidney cortex having a concentration of greater than or equal to 117 ..mu..g/g dry wt. Concentrations of this magnitude are also found in human kidney and in human and horse liver. Data of Penumarthy et al. (1980) are also unusual in that the average cadmium concentration was 3.4 ..mu..g/g wet wt in horse liver and 2.5 ..mu..g/g in horse kidney. As a rule, cadmium concentration in kidney exceeds that in liver by a factor of 2-15. The capacity of the extraction procedure appears to be insufficient at high and intermediate cadmium levels. 1 table (JMT)

Elinder, C.G. (The Karenlinska Inst., Stockholm, Sweden); Lind, B.; Piscator, M.; Sundstedt, K.; Akerberg, S.

1981-12-01

60

Methods for collection and analysis of geopressured geothermal and oil field waters  

SciTech Connect

Present methods are described for the collection, preservation, and chemical analysis of waters produced from geopressured geothermal and petroleum wells. Detailed procedures for collection include precautions and equipment necessary to ensure that the sample is representative of the water produced. Procedures for sample preservation include filtration, acidification, dilution for silica, methyl isobutyl ketone (MIBK) extraction of aluminum, addition of potassium permanganate to preserve mercury, and precipitation of carbonate species as strontium carbonate for stable carbon isotopes and total dissolved carbonate analysis. Characteristics determined at the well site are sulfide, pH, ammonia, and conductivity. Laboratory procedures are given for the analysis of lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, iron, manganese, zinc, lead, aluminum, and mercury by atomic absorption and flame emission spectroscopy. Chloride is determined by silver nitrate titration and fluoride by ion-specific electrode. Bromide and iodide concentrations are determined by the hypochlorite oxidation method. Sulfate is analyzed by titration using barium chloride with thorin indicator after pretreatment with alumina. Boron and silica are determined colorimetrically by the carmine and molybdate-blue methods, respectively. Aliphatic acid anions (C/sub 2/ through C/sub 5/) are determined by gas chromatography after separation and concentration in a chloroform-butanol mixture.

Lico, M.S.; Kharaka, Y.K.; Carothers, W.W.; Wright, V.A.

1982-01-01

61

An on-line analysis of 7 odorous volatile organic compounds in the ambient air surrounding a large industrial complex  

NASA Astrophysics Data System (ADS)

The concentrations of seven odorous volatile organic compounds (VOCs) including styrene (S), toluene (T), xylene (X), methyl ethyl ketone (MEK), isobutyl alcohol (i-BuAl), methyl isobutyl ketone (MIBK), and butyl acetate (BuAc) were measured continuously at hourly intervals from an on-line odor monitoring station in Ansan city, Korea (August 2005 to December 2007). Their concentration data (ppb) exhibited a narrow range of mean values despite large variabilities: 1.33 ± 8.81, 16.1 ± 96.6, 3.32 ± 11.5, 7.45 ± 10.3, 20.4 ± 2.38, 1.31 ± 1.16, and 2.43 ± 3.02, respectively. However, unlike aromatics, the distribution of other VOCs was characterized by infrequent occurrences, e.g., as large as 97.5% of i-BuAl data below detection limit. Comparison of temporal patterns indicates that aromatic VOCs are the highest in summer, while others tend to peak during fall (or summer). If the relative compositions of these VOCs were compared in terms of odor intensity, their contribution in the study area is unlikely significant as the malodor components. Evaluation of the data suggests that the distribution of the target VOCs should be affected more sensitively by local traffic activities rather than industrial processes in the surrounding area. Nonetheless, the potent roles of these volatile components should not be underestimated with respect to human health.

Kabir, Ehsanul; Kim, Ki-Hyun

2010-09-01

62

Separation and preconcentration in a batch mode of Cd(II), Cr(III, VI), Cu(II), Mn(II, VII) and Pb(II) by solid-phase extraction by using of silica modified with N-propylsalicylaldimine.  

PubMed

The complexes formed between IE11 and Cd(II), Cr(III), Cu(II), Mn(II) and Pb(II) were identified and confirmed by IR, UV and pH-metric titration. The uptake behavior of porous silica modified with N-propylsalicylaldimine (IE11) and these metal ions were studied. Log k(d) was found to be within the range 2.19-5.16 depending on pH and time of stirring. IE11 was used in the separation and preconcentration of Cd(II), Cr(III, VI), Cu(II), Mn(II, VII) and Pb(II) from some natural water samples. Data were compared with those obtained by the solvent extraction method APDC/MIBK. The proposed methodology allows to verify an improvement in the water quality of Nile River probably attributed to high to moderate floods in the last few years. The method was found to be accurate and not subject to random error, i.e. precise. PMID:18968753

Abou-El-Sherbini, Khaled S; Kenawy, I M M; Hamed, Mohammad A; Issa, R M; Elmorsi, R

2002-08-23

63

Study of Development Processes for ZEP-520 as a High-Resolution Positive and Negative Tone Electron Beam Lithography Resist  

NASA Astrophysics Data System (ADS)

ZEP brand electron beam resists are well-known for their high sensitivity and etch durability. The various performance metrics such as sensitivity, contrast, and resolution of ZEP resist depend strongly on the development process. In this work, we investigate the development of ZEP-520 resist through contrast curves, dense gratings, and surface roughness measurements using three different classes of developer systems of varying solvation strength, ZED-N50, methyl isobutyl ketone (MIBK) : isopropyl alcohol (IPA) 1:3, and IPA : H2O 7:3, at the ambient temperature (22 °C) and cold (-15 °C) development conditions. In order to provide a deeper insight into the ZEP development process, we propose a novel kinetic model of dissolution for ZEP, and develop an efficient analytical method that allows determining the microscopic parameters of ZEP dissolution based on experimental contrast curves. We also observe experimentally and characterize the negative tone behavior of ZEP for dense grating patterning and compare its performance with positive tone behavior.

Mohammad, Mohammad Ali; Koshelev, Kirill; Fito, Taras; Zheng, David Ai Zhi; Stepanova, Maria; Dew, Steven

2012-06-01

64

Organic-inorganic hybrid resists for EUVL  

NASA Astrophysics Data System (ADS)

Herein, we describe preliminary results on organic-inorganic hybrid photoresists, capable of showing line patterns up to 16 nm under e-beam exposure studies, prepared by incorporating polyoxometalates (POMs) clusters into organic photoresist materials. Various Mo and W based clusters such as (TBA)2[Mo6O19], (TBA)5(H)[P2V3W15O62] and (TBA)4[P2Mo18O61] (where TBA = tetrabutyl ammonium counter ion) have been incorporated into PMMA matrix by mixing POM solutions and standard PMMA polymer in anisole (MW ~ 95000, MicroChem) in 1:33 w/v ratio. E-beam exposure followed by development with MIBK solutions showed that these new organic-inorganic hybrid photoresists show good line patterns upto 16 nm, which were not observed in the case of control experiments done on pure PMMA polymer resist. The observed enhancement of resist properties in the case of hybrid resists could possibly be due to a combination of features imparted to the resist by the POM clusters such as increased sensitivity, etch resistance and thermal stability.

Singh, Vikram; Kalyani, Vishwanath; Satyanarayana, V. S. V.; Pradeep, Chullikkattil P.; Ghosh, Subrata; Sharma, Satinder; Gonsalves, Kenneth E.

2014-03-01

65

Predicting Optimal Resolving Power for Ambient Pressure Ion Mobility Spectrometry (IMS)  

PubMed Central

Although diffusion theory predicts that IMS resolving power increases with the square root of the voltage applied across the drift tube, in practice there exists an optimum voltage above which resolving power decreases. This optimum voltage was determined to be both compound and initial ion pulse width-dependent. A “conditional” resolving power equation is introduced that can be used to quickly approximate realistic resolving powers for specific instrumental operating parameters and compounds. Using four common environmental contaminants [trichloroethylene (TCE), tetrachloroethylene (PCE), methyl tert-butyl ether (MTBE) and methyl iso-butyl ketone (MIBK)], diffusion-limited (theoretical), Rd, conditional, Rc, and actual (or measured), Rm, IMS resolving powers were determined and compared for a small IMS instrument designed for subsurface measurements. Detection limits determined at the optimal resolving power for the environmental contaminants ranged from 18 parts per trillion volume-to-volume (pptv) to 80 parts per billion volume-to-volume (ppbv). The maximal measured resolving power for our small, ambient-pressure stand-alone IMS ranged from 42 to 54, yielding an IMS resolving power efficiency, defined as Rm/Rc × 100%, of 56 to 74% of the maximal conditional resolving power possible.

Kanu, Abu B.; Gribb, Molly M.; Hill, Herbert H

2010-01-01

66

A rapid, partial leach and organic separation for the sensitive determination of Ag, Bi, Cd, Cu, Mo, Pb, Sb, and Zn in surface geologic materials by flame atomic absorption  

USGS Publications Warehouse

A solution of dilute hydrochloric acid, ascorbic acid, and potassium iodide has been found to dissolve weakly bound metals in soils, stream sediments, and oxidized rocks. Silver, Bi, Cd, Cu, Mo, Pb, Sb, and Zn are selectively extracted from this solution by a mixture of Aliquat 336 (tricaprylyl methyl ammonium chloride) and MIBK (methyl isobutyl ketone). Because potentially interfering major and minor elements do not extract, the organic separation allows interference-free determinations of Ag and Cd to the 0.05 ppm level, Mo, Cu, and Zn to 0.5 ppm, and Bi, Pb, and Sb to 1 ppm in the sample using flame atomic absorption spectroscopy. The analytical absorbance values of the organic solution used in the proposed method are generally enhanced more than threefold as compared to aqueous solutions, due to more efficient atomization and burning characteristics. The leaching and extraction procedures are extremely rapid; as many as 100 samples may be analyzed per day, yielding 800 determinations, and the technique is adaptable to field use. The proposed method was compared to total digestion methods for geochemical reference samples as well as soils and stream sediments from mineralized and unmineralized areas. The partial leach showed better anomaly contrasts than did total digestions. Because the proposed method is very rapid and is sensitive to pathfinder elements for several types of ore deposits, it should be useful for reconnaissance surveys for concealed deposits. ?? 1984.

Viets, J. G.; Clark, J. R.; Campbell, W. L.

1984-01-01

67

In situ atom trapping of Bi on W-coated slotted quartz tube flame atomic absorption spectrometry and interference studies  

NASA Astrophysics Data System (ADS)

Analytical performances of metal coated slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) and slotted quartz tube in situ atom trapping flame atomic absorption spectrometry (SQT-AT-FAAS) systems were evaluated for determination of Bi. Non-volatile elements such as Mo, Zr, W and Ta were tried as coating materials. It was observed that W-coated SQT gave the best sensitivity for the determination of Bi for SQT-FAAS and SQT-AT-FAAS. The parameters for W-coated SQT-FAAS and W-coated SQT-AT-FAAS were optimized. Sensitivity of FAAS for Bi was improved as 4.0 fold by W-coated SQT-FAAS while 613 fold enhancement in sensitivity was achieved by W-coated SQT-AT-FAAS using 5.0 min trapping with respect to conventional FAAS. MIBK was selected as organic solvent for the re-atomization of Bi from the trapping surface. Limit of detection values for W-coated SQT-FAAS and W-coated SQT-AT-FAAS was obtained as 0.14 ?g mL- 1 and 0.51 ng mL- 1, respectively. Linear calibration plot was obtained in the range of 2.5-25.0 ng mL- 1 for W-coated SQT-AT-FAAS. Accuracy of the W-coated SQT-AT-FAAS system was checked by analyzing a standard reference material, NIST 1643e.

K?l?nç, Ersin; Bak?rdere, Sezgin; Ayd?n, F?rat; Ataman, O. Yavuz

2013-11-01

68

Atomic absorption spectrometric determination of copper, zinc, and lead in geological materials  

USGS Publications Warehouse

An atomic absorption spectrometric method is described for the determination of copper, zinc, and lead in geological materials. The sample is digested with HF-HCl-H2O2; the final solution for analysis is in 10 % (v/v) HCl. Copper and zinc are determined directly by aspirating the solution into an air-acetylene flame. A separate aliquot of the solution is used for determination of lead; lead is extracted into TOPO-MIBK from the acidic solution in the presence of iodide and ascorbic acid. For a 0.50-g sample, the limits of determination are 10-2000 p.p.m. for Cu and Zn, and 5-5000 p.p.m. for Pb. As much as 40 % Fe or Ca. and 10 % Al, Mg, or Mn in the sample do not interfere. The proposed method can be applied to the determination of copper, zinc, and lead in a wide range of geological materials including iron- and manganese-rich, calcareous and carbonate samples. ?? 1976.

Sanzolone, R. F.; Chao, T. T.

1976-01-01

69

Flame AAS and UV-VIS determination of cobalt, nickel and palladium using the synergetic effect of 2-benzoylpyridine-2-pyridylhydrazone and thiocyanate ions.  

PubMed

A quantitative synergetic extraction procedure for cobalt, nickel and palladium from thiocyanate aqueous solutions into methyl isobutyl ketone (MIBK), containing 2-benzoylpyridine-2-pyridylhydrazone (BPPH), was studied by flame atomic absorption spectrometry (FAAS) and molecular absorption spectrometry (UV-VIS). Using FAAS, linear calibration graphs were obtained from 0.0-0.5 mg l(-1) Co(II), 0.0-1.5 mg l(-1) Ni(II) and 0.0-2.0 mg l(-1) Pd(II). The reproducibilities were s(r,Co(II))=2.0%, s(r,Ni(II))=1.0% and s(r,Pd(II))=1.3% and the limits of detection were c(L,Co(II))=0.004 mg l(-1), c(L,Ni(II))=0.009 mg l(-1) and c(L,Pd(II))=0.012 mg l(-1). Using UV-VIS method the linear calibration graphs were 0.0-0.5 mg l(-1) for Co(II), 0.0-1.0 mg l(-1) for Ni(II) and 0.0-2.0 mg l(-1) for Pd(II). The reproducibilities were s(r,Co(II))=1.3%, s(r,Ni(II))=1.7% and s(r,Pd(II))=1.0% and the limits of detection were c(L,Co(II))=0.001 mg l(-1), c(L,Ni(II))=0.004 mg l(-1) and c(L,Pd(II))=0.002 mg l(-1). The extraction method is almost free from interferences and has been successfully applied to the determination of cobalt, nickel and palladium in dental alloys. PMID:18967315

Zachariadis, G A; Themelis, D G; Kosseoglou, D J; Stratis, J A

1998-09-01

70

Simulation of the breakthrough behavior of volatile organic compounds against sorbent tube sampler as a function of concentration level and sampling volume.  

PubMed

The breakthrough (BT) properties of Tenax TA sorbent were challenged by gaseous standards containing a suite of 13 volatile organic compounds (VOC): (1) aromatic hydrocarbons: benzene (B), toluene (T), p-xylene (p-X), and styrene (S), (2) aldehydes: acetaldehyde (AA), propionaldehyde (PA), butyraldehyde (BA), isovaleraldehyde (IA), and valeraldehyde (VA), (3) ketones: methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), and (4) two others: isobutyl alcohol (i-BuAl) and butyl acetate (BuAc). To this end, 1-3L of standards (10-50ppb) were loaded on the two sorbent tubes (ST) connected in series at 100mLmin(-1). The front ST-1 was used for calibration purposes, while the ST-2 for breakthrough (recovery criterion of <1% with p-xylene as the key datum point). Although aromatic hydrocarbons generally met such criterion, benzene was readily distinguishable with the maximum BT. The BT for the aldehydes exhibited ?100% (AA)?85% (PA)?45% (BA)?30% (VA and IVA). There is good correlation between ST-2 recovery vs. carbon number for >CO entity (aldehydes, ester, and ketones). As such, BT is essentially concentration independent and relatively predictable across different functional groups and between the homologues. However, the BT behavior of ppb level VOCs is no longer consistent for certain species (like benzene or MEK) relative their ppm counterparts. This variation is explained by the Langmuir equation in which the 1/BTV is proportional to analyte gas-phase concentration, if the gas-phase/sorbent partition coefficient is large. PMID:24952628

Kim, Ki-Hyun; Lee, Min-Hee; Szulejko, Jan E

2014-07-01

71

Mechanism of transport and distribution of organic solvents in blood  

NASA Technical Reports Server (NTRS)

Little is known about the mechanism of transport and distribution of volatile organic compounds in blood. Studies were conducted on five typical organic solvents to investigate how these compounds are transported and distributed in blood. Groups of four to five rats were exposed for 2 hr to 500 ppm of n-hexane, toluene, chloroform, methyl isobutyl ketone (MIBK), or diethyl ether vapor; 94, 66, 90, 51, or 49%, respectively, of these solvents in the blood were found in the red blood cells (RBCs). Very similar results were obtained in vitro when aqueous solutions of these solvents were added to rat blood. In vitro studies were also conducted on human blood with these solvents; 66, 43, 65, 49, or 46%, respectively, of the added solvent was taken up by the RBCs. These results indicate that RBCs from humans and rats exhibited substantial differences in affinity for the three more hydrophobic solvents studied. When solutions of these solvents were added to human plasma and RBC samples, large fractions (51-96%) of the solvents were recovered from ammonium sulfate-precipitated plasma proteins and hemoglobin. Smaller fractions were recovered from plasma water and red cell water. Less than 10% of each of the added solvents in RBC samples was found in the red cell membrane ghosts. These results indicate that RBCs play an important role in the uptake and transport of these solvents. Proteins, chiefly hemoglobin, are the major carriers of these compounds in blood. It can be inferred from the results of the present study that volatile lipophilic organic solvents are probably taken up by the hydrophobic sites of blood proteins.

Lam, C. W.; Galen, T. J.; Boyd, J. F.; Pierson, D. L.

1990-01-01

72

Intractable epilepsy due to angiocentric glioma: A case report and minireview  

PubMed Central

The aim of this case report and minireview was to investigate the diagnosis of and therapeutic approaches for angiocentric glioma (AG) and to summarize the clinical manifestations and the pathological and imaging characteristics of the disease. Intraoperative cortical electroencephalogram (ECoG) monitoring was performed to locate the epileptic foci in a child with AG who presented with intractable epilepsy, prior to the total resection of the tumor being performed under the microscope. The clinical features, imaging characteristics, intraoperative conditions, surgical methods and pathological results were analyzed and compared with the literature. The review revealed that to date, the clinical features of the 52 reported cases of AG (including this case) have been mainly characterized by epilepsy. High T2-weighted image (WI) and fluid-attenuated inversion recovery (FLAIR) signals may be detected with magnetic resonance imaging (MRI) scanning of the cranium; however, no enhancement signals are detected by enhanced scanning. The prognosis following surgical resection is favorable. The lesions in the present case demonstrated clear boundaries with a central cystic affection accompanied by an arachnoid cyst on the left temporal pole. Pathological examination revealed that the lesion was positive for glial fibrillary acidic protein (GFAP), S-100 protein, vimentin, epithelial membrane antigen (EMA), cluster of differentiation 99 (CD99) and D2-40. The Ki-67/MIBk-1 labeling index was ~1%. In conclusion, AG exhibits characteristic features in imaging; however, its diagnosis depends on histopathological examination. The prognosis of total surgical resection is good and intraoperative ECoG may be used to assist positioning.

CHEN, GUOQIANG; WANG, LIN; WU, JINTING; JIN, YONGJIAN; WANG, XIAOSONG; JIN, YULAN

2014-01-01

73

Characterization and treatment of coal-gasification condensate waters  

SciTech Connect

This thesis presents work performed to identify the organic constituents in coal-gasification condensate water, along with consideration of the alternatives for condensate water treatment. The characterization experiments performed were primarily limited to a condensate water received from the Lurgi slagging fixed-bed gasifier at the Morgantown Energy Technology Center; however, the analyses of one condensate water sample from the Grand Forks Energy Technology Center and one sample from the Great Plains Gasification Associates gasifier are also included. The characterization results indicated almost complete identification of the compounds contributing to the chemical oxygen demand (COD), total organic carbon (TOC), organic sulfur, and organic nitrogen measurements in the METC condensate water. Thiocyanate was found to contribute significantly to the COD, organic nitrogen, and oganic sulfur measurements of the condensate sample. In addition, polysulfides were also found to contribute to the COD and the organic sulfur measurements. Low-molecular-weight solutes (acetonitrile, acetone, and methanol) were not found to be appreciable in the METC sample but were found to a much greater extent in the GPGA and GFETC samples. Equilibrium distribution coefficients from water into methyl isobutyl ketone (MIBK) were determined for many of the condesnate water solutes. In addition, other extractants including benzophenone, tributyl phosphate (TBP), tributyrin, furan, and 4-methyl cyclohexanone were investigated. TBP was found to yield the highest distribution coefficients for the condensate solutes. Adsorption experiments revealed that both activated carbon and Amberlite XAD-7 were effective for removal of catechol and 5,5-dimethyl hydantoin from water. Both strong-base and weak-base anion-exchange resins were investigated for thiocyanate recovery. Use of weak-base resin was found to offer potential advantages over the strong-base resin. 23 figs., 36 tabs.

Senetar, J.J.; King, C.J.

1986-01-01

74

Concentration levels of metals in vegetables grown in soils irrigated with river water in Addis Ababa, Ethiopia.  

PubMed

Samples of vegetables, water and soil were collected from four vegetable farms in Addis Ababa to evaluate the extent and trend of metal accumulation in these systems and health risk concerns to consumers. Vegetable samples were digested in HNO(3) and HClO(4), soil samples in Aqua Regia and water samples were pre-concentrated with methyl isobutyl ketone (MIBK) using the chelating agent ammonium pyrrolidine dithiocarbamate (APDC). All the samples were analyzed for Co, Cr, Cu, Mn, Ni, Zn, Cd and Pb with flame atomic absorption spectrophotometer. The concentrations of Cd (0.12-1.13 mg kg(-1)) and Pb (0.11-0.89 mg kg(-1)) in the vegetables surpassed the maximum recommended levels. The total metal concentrations in soils were (mg kg(-1)): Cr, 9.9-22.8; Co, 28.0-47.3; Cu, 25.1-51.4, Mn, 1000-1054; Ni, 16.4-55.8; Zn, 146-149; Cd, 1.4-1.8 and Pb, 22.0-50.7. The trace metals Cd, Co, Cu, Mn and Ni in most of the water samples collected from Goffa, Kera and Akaki farms also surpassed irrigation water guideline limits, which might be a case for high accumulation of metals in the soils. However, the soil pH (6.5-7.6) and high cation exchange capacity (CEC), 38.41-50.18, coupled with high clay content, 37-51%, of the soil seemed to limit metal uptake by the vegetables. The physical parameters, pH (7.43-7.89) and electrical conductivity (0.33-1.54 dS/m) of irrigation waters measured at 25°C were found within the acceptable range. PMID:22062152

Weldegebriel, Yirgaalem; Chandravanshi, Bhagwan Singh; Wondimu, Taddese

2012-03-01

75

The Role of Residual Casting Solvent in Determining the Lithographic and Dissolution Behavior of Poly(methyl Methacrylate), a Positive Electron Beam Resist.  

NASA Astrophysics Data System (ADS)

The effect of the pre-exposure bake and the choice of casting solvent on the sensitivity and contrast of PMMA has been documented to an extent not previously reported in the literature. PMMA films were spin cast onto clean silicon substrates from chlorobenzene and tri-chloroethylene solutions. The temperature of the pre-bake was varied over the range of 59^circ to 170^circC using a convection oven with pre-bake times ranging from 30 to 90 minutes. At the end of the designated bake time, the films were removed from the oven and allowed to cool in a temperature and humidity controlled environment. They were promptly exposed to a 15 KeV electron beam, then developed, with mild agitation, in a 1:1 mixture of MIBK and IPA at 22.5^ circC. Film thickness profiles were determined with an alpha-step profilometer. Films baked at temperatures below T_{rm glass} (the temperature which marks the onset of long-range, coordinated molecular motion), exhibited improved sensitivity and poorer contrast when compared to those baked above T_{rm glass }. Unique to this work is the finding that the lithographic performance depends on the choice of casting solvent, even at pre-bake temperatures significantly above T_{rm glass}. The relative concentrations of the casting solvents remaining in the baked films was determined from UV absorption spectra. The dissolution rates of exposed films were also measured and compared to the fragmented molecular weight model of development. Energy depositions were calculated from the empirical model of Everhart and Hoff. Cross-correlation of these results indicate that the pre-bake temperature more strongly correlates with the observed improvement in sensitivity than the presence of residual casting solvent. Residual casting solvent changes the density of the film, thus changing the energy deposition and dissolution behavior. Calculations based on the aforementioned models indicate that the observed lithographic and dissolution behavior can not be accounted for by this change in density. Arguments are presented to support the conclusion that the observed behavior is associated with film morphology. Comparison of results from films cast from TCE and chlorobenzene and baked above T_{rm glass} further support this conclusion.

Criss, Robert Randolph, Jr.