• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.344-349
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• 2014

BACKGROUND: Purpose of the study was to establish the extinction coefficients of chlorophyll a and b in N,N-dimethylformamide(DMF) and Dimethylsulfoxide(DMSO) solvents and to find out the conditions of optimal extraction temperature and time in citrus leaves. METHODS AND RESULTS: Chlorophyll a and b standards were dissolved in DMF and DMSO. Extinction coefficients of chlorophyll pigments were determined and their contents were quantified using spectrophotometer. Chlorophyllous pigments of citrus(Citrus unshiu Marc. cv. Okitsu wase) leaves were extracted at 25, 40, 60 and $80^{\circ}C$ for 4, 6, 8, 24 and 48 hours to determine the optimal extraction condition. CONCLUSION: The extinction coefficients of chlorophyll a(Chl a) and chlorophyll b(Chl b) of DMF extracts for high extinction wavelength were 663.8 and 647.2 nm. Similarly, the high extinction wavelength of DMSO extracts were 665.8 and 649.0 nm for chl a and b respectively. Chl a, Chl b and total chlorophyll content of DMF extracts were Chl a = $12.10A_{663.8}-2.74A_{647.2}$, Chl b = $21.94A_{647.2}-5.06A_{663.8}$ and total $Chl=19.193A_{647.2}+7.04A_{663.8}$. Similarly, Chl a, Chl b and total Chl of DMSO extracts were Chl a = $14.53A_{665.8}-5.40A_{649.0}$, Chl b = $26.98A_{649.0}-7.11A_{665.8}$ and total $Chl=21.58A_{649.0}+7.43A_{665.8}$. The chlorophyll extracts of DMF and DMSO were very stable in dark. High chlorophyll contents of citrus leaves were found at $80^{\circ}C$ extraction for 6 hours in DMF and at $80^{\circ}C$ extraction for 24 hours in DMSO. However, the chlorophyll content was decreased significantly after 8 hours in DMF extraction while it was remained up to 30 hours in DMSO extraction.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.819-824
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• 1994

A membrane-like $H_3PMo_{12}O_{40}$-polysulfone film was prepared by blending $H_3PMo_{12}O_{40}$ with polysulfone using dimethylformamide as a common solvent. SEM and EDX analysis showed that $H_3PMo_{12}O_{40}$ was uniformly and finely distributed in the film catalyst. The ESCA measurement also revealed that the oxidation state of Mo was not changed. The $H_3PMo_{12}O_{40}$-polysulfone catalyst showed lower activity for acid-catalyzed reaction and higher activity for oxidation reaction than $H_3PMo_{12}O_{40}$ in ethanol conversion reaction. The oxidation activity of the film catalyst was about 10 times higher than $H_3PMo_{12}O_{40}$. The decrease of acidic activity was due to DMF strongly adsorbed in acid sites of $H_3PMo_{12}O_{40}$, whereas the increase of oxidation activity was mainly due to uniform distribution of $H_3PMo_{12}O_{40}$. Adsorption results showed that the surface character of $H_3PMo_{12}O_{40}$ was drastically increased, while the bulk property of that was almost same after blending. It is suggested that the control of surface/bulk property as well as acid/redox property of heteropoly acid would be possible by blending it with a polymer.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.345-352
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• 2014

Objectives: This study is aimed to describe the current situation about urinary biomarker N-methylformamide(NMF) for workers exposed to N,N-dimethylformamide(DMF) according to industrial classification. Materials: Special health examination records of the workers who had undergone urinary biological monitoring in 2013 were collected. The numbers and percentage of workers, whose urinary NMF values were above the limit of detection(LOD) and above the biological exposure index(BEI) were calculated. Health relatedness with DMF as judged by their doctors was also described. All description was classified according to the $9^{th}$ Korean Standard Industrial Classification(KSIC). Results: It appeared that most workers exposed to DMF belong to manufacturing section(80.7%). The geometric mean(GM) values of urinary NMF were 6.25 mg/L, 3.54, and 3.86 for the manufacturing section, professional, scientific and technical activities section, and for the construction section respectively. In detail, it seemed that division of textiles(except apparel) (GM 7.51 mg/L), division of leather, luggage and footwear(11.59 mg/L), and division of rubber and plastic products(6.89 mg/L) were highly exposed to DMF with a high percentage of workers with urinary NMF values above BEI. This was probably due to the effect of skin absorption that the division of leather, luggage and footwear showed the highest urine NMF GM. Conclusions: It seemed that workers in manufacture industries such as textile, leather, luggage, footwear, rubber and plastic products were highly exposed to DMF. So, efforts should be focused on those industries in order to effectively diminish worker's exposure. Further studies to compare DMF air-monitoring with bio-monitoring according to industrial classification should be considered.

• Analytical Science and Technology
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• v.26 no.5
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• pp.315-325
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• 2013

The possibility of acute hepatotoxicity caused by dimethylformamide (DMF) requires regular monitoring of the workers who are using DMF to prevent the occupational disease. The authors performed ambient and biological monitoring of workers involved in synthetic leather manufacturing processes using DMF to assess the correlation between the markers of ambient and biological monitoring of DMF. The authors monitored 142 workers occupationally exposed to DMF from 19 workshops in the synthetic leather and ink manufacturing industries located in northern region of Gyeonggi-do. The subjects answered questionnaire on work procedure and use of personal protective equipment to be classified by exposure type. DMF in air samples collected using personal air samplers, diffusive and active sampler, was analysed using gas chromatograph-flame ionization detector (GC-FID) with DB-FFAP column (length 30 m, i.d. 0.25 mm, film thickness 0.25 ${\mu}m$). Urinary N-methylformamide (NMF) was analysed using gas chromatograph-mass selective detector (GC-MSD) at selected ion monitoring (SIM) mode with DB-624 column (length 60 m, i.d. 0.25 mm, film thickness 1.40 ${\mu}m$). Geometric mean (GM) and geometric standard deviation (GSD) of the ambient DMF was $6.85{\pm}3.43$ ppm, and GM and GSD of urinary NMF was $42.3{\pm}2.7$ mg/L. The ratio of subjects with DMF level over 10 ppm was 44%, and those with urinary NMF over 15 mg/L was 87%. NMF in urine adjusted by DMF in air was $4.61{\pm}2.57$ mg/L/ppm and $9.50{\pm}2.41$ mg/L/ppm, respectively, with or without respirator. There was seasonal differences of NMF in urine adjusted by DMF in air, $7.63{\pm}2.74$ mg/L/ppm in summer and $4.53{\pm}2.29$ mg/L/ppm in winter. The urinary NMF concentration which corresponds to 10 ppm of ambient DMF was 52.7 mg/L (r=0.650, n=128). Considering the difference of the route of exposure which resulted from the compliance of wearing personal protective equipment, the estimated contribution of respiratory and dermal exposure route for DMF was 48.5% vs. 51.5%.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.1
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• pp.104-118
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• 1995

This study was performed to evaluate factors affecting desorption of organic solvents collected on charcoal tube and to find out the optimum condition. Desorption efficiency for polar analytes was improved when several polar desorption solvents such as methanol, dimethylformamide(DMF), 2-(2-butoxyethoxy)ethanol were added to carbon disulfide($CS_2$). The best improvement was achieved when 10% dimethylformamide(DMF) in $CS_2$ was used as desorption solvent. During storage of polar analytes, recovery was greatly reduced. Especially, the recovery of cyclohexanone was decreased to 18.1 % after a month storage at $34^{\circ}C$. After two weeks storage, recovery of polar analytes was sharply decreased. Water adsorbed on charcoal interfered the recovery of polar analytes but didn't interfere that one of nonpolar solvent, toluene. When 10% DMF in $CS_2$ was used as desorption solvent, the effect of water on recovery was decreased, comparing with Desorption efficiency increased when analyte loading increased, and usage of 10% DMF in $CS_2$ decreased the loading effect. Increasing volume of desorption solvent was not effective to improve desorption efficiency of analytes when 10% DMF was used. Continuous shaking and sonication is not helpful to increase the desorption efficiency of analytes except cyclohexanone using 10% DMF. When silica gel used as adsorbent, methanol was better desorbent than dimethylsulfoxide. Analytes adsorbed on silica gel showed high recovery in low concentration and less affected by humidity. On the basis of this study, the following conclusions have been drawn. To improve the recovery of polar organic materials in air samples, it is necessary to analyze samples as soon as possible after they were collected. Otherwise, samples must be stored at low temperature. Using two components of desorption solvents, such as 10% DMF in $CS_2$, the effects of loading and humidity decreased for polar analytes such as methyl ethyl ketone and methyl isobutyl ketone. When work place has high humidity with low concentration of polar organic solvents, silica gel can be used as adsorbent, because it produces quantitative recovery for polar analytes at this condition. But it should be noted that high humidity makes breakthrough easy in silica gel samples.

• YAKHAK HOEJI
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• v.9 no.1_2
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• pp.8-13
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• 1965

The sensitivity on microorganisms of ten sulfa-drugs and their Cu-complexes was observed. Ericsson's disc method and modified tube dilution method were applied. Dimethylformamide was used for solvent of sulfa drugs. In general, original sulfa-drugs showed more sensitive patterns than its Cu-complexes except sulfadimethoxine-Cu complex which showed more sensitive patterns than its original drug with disc method.

• Journal of Pharmaceutical Investigation
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• v.6 no.2
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• pp.83-87
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• 1976

Microanalysis of rodenticide by visible absorption method was attempted. The following procedure was found to be very simple and to give accurate results. RH-28787 was added to dimethylformamide (DMF), and extracted after stirring for about 20 minutes in extractor $(30^{\circ}C)$. After extraction, the absorbance of DMF solution, was measured at 346 nm by using spectrophotometer. The result agrees closely with the experimentally determined value by means of the gas chromatograph.

• YAKHAK HOEJI
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• v.33 no.3
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• pp.206-210
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• 1989

Bromolactonization of 2-Substituted-1-cyclohexenyl-1-acetic acid (1) with 1,3-dibromo-5,5-dimethylhydantoin (dibromantin) in N,N-dimethylformamide gave the corresponding ${\gamma}-bromo-{\beta}-lactone$ (2) and ${\beta}-bromo-{\gamma}-lactone$ (3). The effect of the substituents, the reaction temperature, and the solvent on the regioselectivity was discussed.

• YAKHAK HOEJI
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• v.30 no.3
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• pp.121-127
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• 1986

Three new alkanol esters of d-2-(6-methoxy-2-naphthyl)propionic acid, NAPROXEN were synthesized by esterification of sodium naproxen with chloralcohols, such as 2-chloroethanol, 3-chloro-1, 2-propanediol and $\beta$-chloroethoxyethanol in dimethylformamide. These new esters were obtained with comparably high yield and identified by elemental analysis, UV, IR and NMR techniques.

• Archives of Pharmacal Research
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• v.6 no.1
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• pp.45-53
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• 1983

Novel halactolactonizations using NBS (2), NIS(3), and NSP(4) in dry DMF were found to be the most reasonable and efficient procedures. The participation of X as the cylization initiator could be clarly rationalized by experimental results and the regioselectivities of formed halolactones were reasonably elucidated by weakly bridged carbonium ion intermediate.