• 대한화학회지
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• 제10권3호
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• pp.119-128
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• 1966

The glass electrode was empirically calibrated in methanol-and 2-propanol-water mixed solvents, by means of which the pH-meter reading could be converted to stoichiometric hydrogen ion concentration. The thermodynamic dissociation constants of hydrogen cupferrate in methanol-and 2-propanol-water solution were potentiometrically determined with the changes in composition of organic solvents at 0.01 and 0.05 of the ionic strength and 25$^{\circ}C$. The empirical formula of the constants with mole fraction (n) of the organic solvent are as follow: methanol-water solution $pK_a$= 2.24n + 4.29 at ${\mu}$ = 0.01 n = 0.0476∼0.642 $pK_a$ = 2.35n + 4.38 at ${\mu}$ = 0.05 n= 0.0446~0.642 2-propanol-water solution $pK_a$= 5.50n + 4.48 at ${\mu}$ = 0.05 n = 0.0253~0.259 The relationships between $pK_a$ of acetic acid, propionic acid and HCup and dielectric constant of some mixed solvents were discussed. It would be considered that the factors effecting $pK_a$ value of weak acid in mixed-solvent are not only dielectric constants but acid-base character and solvation effect of the solvent, etc.

• 한국환경보건학회지
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• 제24권2호
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• pp.80-87
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• 1998

To evaluate the effects on health by exposure to low dose organic solvents, the author analyzed the air concentration of mixed organic solvents (toluene, xylene, butylacetate) at worker's breathing zone during painting, some laboratory findings of blood (WBC, RBC, Hb, Hct, SGOT, SGPT, TC, TG, HDL-C, LDL-C, IgG, IgM, IgA and IgE) and urine (hippuric acid, urinary protein, urobilinogen), surveyed the subjective symptoms those were obtained from 35 male workers exposed to mixed organic solvents, and 25 male workers not exposed to organic solvents who worked in car repair workshops in Taejon area from December 1, 1995, to February 29, 1996. The results were as follows: 1. The mean concentration of urinary hippuric acid of car painting worker group (organic solvent exposure group) was 0.76$\pm$ 0.21 g/l, which is significantly higher than that of non-exposed group. 2. In hematologic findings, the values of RBC, TC, LDL-C, IgG and IgE in the exposure group were significantly lower than those of the nonexposed group, but SGOT and SGPT in the exposure group were significantly higher than those of the non-exposed group. 3. Urinary hippuric acid levels showed positively correlated with toluene, urobilinogen and HDL-C levels, but those were negatively correlated with RBC, LDL-C, IgM levels. 4. Rates of the subjective symptoms such as "dizziness", "appetite loss", "weight loss", "palpitation", "chest tightness", "sore throat and eye discomfort", "tingling sense and acrodynia", "illusion or hallucination" and "decreaased motor power" were significantly higher in the exposure group than those of the non-exposed group.

• Bulletin of the Korean Chemical Society
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• 제26권7호
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• pp.1037-1043
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• 2005

Kinetic study on the cleavage of N-methylphthalamic acid (NMPA) in mixed acidic aqueous-acetonitrile solvent reveals the formation of both phthalic anhydride (PAn) (through O-cyclization) and N-methylphthalimide (NMPT) (through N-cyclization). The formation of NMPT varies from $\sim$20% to $\sim$3% with the increase in the content of acetonitrile from 2 to 70% v/v. Pseudo first-order rate constants for the formation of PAn are more than 4-fold larger than those for the formation of NMPT at 2% v/v $CH_3CN$ in mixed aqueous solvents. Pseudo first-order rate constants for alkaline hydrolysis of NMPT reveal a nonlinear decrease with increase in the content of $CH_3CN$ in mixed aqueous solvents.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.350-353
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• 2004

This study was conducted for a rapid and simple method using GC/FID and SPME to dectermin gasonline and chlorinated solvents simultaneity. A sodium chloride concentration of 25%(vol/w) combined with such as magnetic stirried, an absorption time of 20min, an extraction temperature of 4$0^{\circ}C$, the volume of minimized 50mL of gaseous phase and a desorption time of 5min pleprovided the greatest sensitivity while maintaining analytical efficiency. Analytical parameter such as linearity was also evaluated. The linear range extend from 30 to 500ppb. The results of chlorinated solvents and gasoline mixed samples showed that solvents have been completely removed from the sample preparation step and more accurated than those obtained by the other methods.

• 약학회지
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• 제5권1호
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• pp.20-23
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• 1960

The study of the isolative determination of the mixed weak bases of INAH and NA-Pas potentimetrically considering the properties of solvents for the INAH and Na-PAS, dielectric constant and solvative properties of solvents are described. The methanol: dioxan (4:1) and glacial acetic acid: dioxan (4:1) are studied first as the mixed solvent, using the N/10 perchloric acid and glacial acetic acid solution as the titrant. The authors found that there is no inflection on INAH with the methanol: dioxan solvent system and on Na-PAS at glacial acetic acid dioxan solvent system. By applying methanol glacial acetic acid dioxan (1:1:1) solvent system, Na-PAS and INAH were successfully determined isolatively from the mixed sample, showing the distinguished inflections respectively as shown in the titration curves in figures 3 and 4. It is found that this method could save considerable time for the isolative determination of the mixed sample of week bases as Na PAS and INHA which were quite difficult to be determined by the present routine at control laboratory.

• Journal of Preventive Medicine and Public Health
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• 제24권3호
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• pp.314-327
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• 1991

To evaluate the effects on health by exposure to mixed organic solvents, the author analyzed some labortory findings of blood (hemoglobin, hematocrit RBC, WBC, SGOT, SGPT) and urine (protein, blood, sugar) that were obtained from 722 workers (male:446, female:276) who worked in plywood, painting and shoes factories in Pusan area from January to December, 1990. The result were as follows ; 1. The mean values of each hematologic findings were all within normal limit but there were significant differences at hematocrit, RBC, WBC, SGOT in male and at WBC, SGPT in female at the comparison of the mean values and the distribution according to the normal criteria by type of work. 2. There were no differences in urinalysis(protein, blood, sugar) by type of work. 3. In stepwise multiple regression, analysis of hematologic findings on age, working duration and type of work, regression coefficients on age and type of work were relatively high in male and female sub1, respectively. As a result of this study, it is considered that the measurement of WBC with morphology is significant in hematologic findings and instead of spot urine and urinstix, 24 hours urine and quantitative analysis is required in urinalysis in screening test for healthy status of workers who deal with the organic solvents.

• Korean Chemical Engineering Research
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• 제58권1호
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• pp.92-97
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• 2020

본 연구에서는 제약성분인 니페디핀이 세 종류의 혼합용매에 녹는 용해도를 측정하였다. 또한 용매(아세톤, DMF, 메틸렌클로라이드)에 녹아 있는 니페디핀을 반용매(물, 헥산, 이산화탄소)를 사용하여 결정화하였고, 생성된 결정입자의 외형, 크기, 용융점 등을 측정하였다. 혼합용매로는 아세톤+물, DMF+물, 메틸렌클로라이드+헥산 혼합물이 사용되었으며, 세 혼합용매에서 모두 반용매의 비율이 증가할수록 니페디핀의 용해도가 감소하였다. 아세톤+물의 경우에는 이 혼합물의 밀도 비이상성 현상에 기인한 용해도 최대값을 나타낸 반면, 나머지 두 혼합용매에서는 이 현상이 나타나지 않았다. 반용매 결정화에 의해 생성된 니페디핀 결정의 외형은 용매와 반용매의 종류에 따라 칼날형, 입자형, 프리즘형 등으로 변화하였으며, 입자의 크기는 원재료에 비해 매우 감소하였다. 니페디핀 원재료 입자의 평균크기는 33 ㎛였으며, 결정화된 입자의 평균크기는 11.6~69.8 ㎛의 범위에 있었다. 결정화된 모든 니페디핀 입자는 동일한 열분석 결과를 보여주었으며, 이 결과는 용매와 반용매의 변화에 의해 영향 받지 않았다.

• Bulletin of the Korean Chemical Society
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• 제21권3호
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• pp.351-352
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• 2000

• 한국산업보건학회지
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• 제1권1호
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• pp.8-15
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• 1991

In order to visualize the distribution of workplace of which mixed solvent level in air exceeded the TLV of 1.0 (ACGIH), 17 thinners used in 44 painting workplaces were analysed with gas chromatography, and their levels in air were compaired with. 1. For detection rate of solvents in thinner was highest in case of toluene (76.4%), and decreased in orders of xylene (70.6%), methylisobutyl ketone (35.3%), acetone (35.3%), methyl ethyl ketone (23.5%), isopropylacohol (17.6%), n-hexane (17.6%), styrene (11.8%), and ethylacetate (11.8%). Average number of solvents detected was 3.0. 2. Detection rates of organic solvent by component category was highest in cases of aromatic hydrocarbons (52.9%), and decreased in orders of ketones (31.4%), alcohols (5.9%), n-hexane (5.9%) and esters (3.9%). The rate by regulatory category, the second category component was detected in 93.9% of total. 3. There was significant correlation (r=0.929, p<0.01)between detection rates of solvents in thinner and in air. 4. Among the total of 44 painting workplace, the rate of them of which level of mixed solvents in air was exceeded was highest in case of aromatic hydrocarbons (29.5%), and decreased in orders of ketones (6.8%), alcohol (2.3%), n-hexane (2.3%), and was highest in guitar painting (71.4%) workplace in case of aromatic hydrocarbons by component category.

• 환경위생공학
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• 제13권3호
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• pp.66-71
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• 1998

This study was investigated to evaluate worker exposures to organic solvents by type of print industry. Results were as follows; 1. Workers were exposed to mixture of toluene, isopropyl alcohol(IPA), methyl ethyl ketone(MEK), n-hexane, ethylacetate(EA), acetone. The components of high exposure solvents were toluene, IPA and MEK. 2. Considering additive effects of the compounds, exposure indices(Em) were calculated. The Mean of exposure indices were 1.79 for Gravere, 0.41 for Screen and 0.14 for Opset workplace. The workers of Gravere workplace were estimated to overexpose for solvents. 3. The highest overexposed solvent was toluene for a single component. The rate of overexposed level for toluene was 7.41% for some print workplace and for mixed solvent was 1.85％. 4. Local exhaust systems were inappropriate and respiratory protective devices were not supplied to the workers. 5. Sound level was over 90dB(A) in Opset print workplace and some measures should be performed to get down the sound level.