• Analytical Science and Technology
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• v.13 no.6
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• pp.722-730
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• 2000

The residual concentration and half-life time of synthetic pyrethroid insecticide cyfluthrin in potato and soil were investigated by gas chromatography (GC). The pesticide in potato was extracted with n-hexane, filtered and concentrated. The concentrated phase was transferred to the Sep-Pak silica gel column and purified with acetonitrile and acetone for the analysis by gas chromatography equipped with electron capture detector (GC-ECD). From the standard additional experiments with 0.01 and $0.1{\mu}g$, the recoveries were 85-87% and the detection limit was 0.005 ng. The soil sample was extracted with acetone and dichloromethane. The organic phase was concentrated and redissolved with n-hexane and analyzed with GC-ECD after cleaned with Sep-Pak column. From the standard additional experiments with 0.01 and 0.1 ng, the recoveries were 84-88% and the detection limit was 0.005ng. The half-life time of cyfluthrin in the silty clay was 25 days in the room laboratory and 0.6 days in the fieJd test whereas it was 38 days and 0.5 days for each in case of silty loam.

• Analytical Science and Technology
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• v.17 no.1
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• pp.1-7
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• 2004

The synergistic solvent extraction of Mn(II) by N-nitroso-N-phenylhydroxylamineammonium salt (cupferron) and tetrabutylammonium ion ($TBA^+$) has been studied. In the presence of $TBA^+$, over 95% Mn(II) was extracted from an aqueous solution into chloroform by the cupferron in the pH range of 4 to 10. But a part of Mn(II) was extracted with only cupferron. The ternary complex of Mn(II) was more efficiently extracted into $CH_2Cl_2$ and $CHCl_3$ than other nonpolar solvents. The extracted Mn(II) was determined in the back-extracted $HNO_3$ solution by GF-AAS. This fixed procedure was applied to the determination of trace Mn(II) in tap water samples of pH 5.0. The detection limit equivalent to 3 times standard deviation of the background absorption was 0.37 ng/mL and Mn(II) was determined with the range of 0.4 to 1.01 ng/mL in our laboratory's tap water. And the recovery was 94 to 107% in samples in which 2.0 ng/mL Mn(II) was spiked. The interferences of common concomitant elements such as Cu(II), Ca(II), Fe(III) and so on were not shown up to $10{\sim}20{\mu}g/mL$. From these results, this procedure could be concluded to be applied for the determination of trace Mn(II) in other environmental water samples.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.667-676
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• 2006

The reduction of $Hg^{2+}$ in the aqueous phase results in the production of dissolved gaseous mercury(DGM), and the volatilization of DGM has been identified as an important mechanism for the loss of Hg from waterbodies to the atmosphere. Although mercury emission in the world is known to be mostly from Asia, there have been few studies of measuring DGM concentrations in lakes in Asia. In this study, DGM concentrations were measured at Juam reservoir($35^{\cir}00'N,\;127^{\circ}14'E$), Korea. The results showed that the average concentrations of DGM at the upper and down stream of the lake during summer time were $95{\pm}8\;and\;130{\pm}15$ pg/L, respectively and the concentration of total mercury(TM) at the upper and down stream was $2.1{\pm}0.7,\;1.7{\pm}0.3$ ng/L respectively. Average DGM concentration during summer time($101{\pm}14pg/L$) was approximately 5.5 times higher than that during fall($18{\pm}0.1pg/L$). The DGM concentrations ai the midstream decreased from 32 to 13.7 pg/L during rain event, while the TM concentrations increased from 2.2 ng/L to 2.7 ng/L indicating the deposition of mercury from the atmosphere. Also, the diurnal patterns between DGM concentrations and UV intensities were observed. Water temperatures and DOC concentrations were significantly related to DGM concentrations, while TM concentrations were negatively related to DGM concentrations(p<0.0001). Comparing with the study of Dill et al.,(2006) the average concentrations of DGM $(109{\pm}15pg/L)\;and\;TM(2.2{\pm} 0.4ng/L)$ at Juam reservoir were approximately 3 and 2.2 times higher than those measured in other lakes(DGM: $38{\pm}16pg/L$, TM: $1.0{\pm}1.2ng/L$).

• Journal of The Korean Society of Inherited Metabolic disease
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• v.17 no.2
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• pp.39-47
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• 2017

Purpose: A sensitive gas chromatography mass spectrometry (GC-MS) method was developed for screening of fatty acid oxidation disorders. Methods: The assay utilized a simple protein precipitation with sulfosalicylic acid followed by tert-butyl dimethylsilyl (TBDMS) derivatization of hydroxyl functional group by N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA). Results: Calibration curves of spiked pooled plasma showed a linear relationship in the range of 0.01 ng -2 mg with correlation coefficient value greater than 0.98. Limits of detection (LOD) and limits of quantification (LOQ) were found in the range of 0.9-8.8 ng and 9-88 ng, respectively. Conclusion: The new developed method might be useful for a rapid, sensitive screening of inherited fatty acid oxidation disorders. In addition, the method expected to be one of the alternative method for screening newborns of metabolic disorders in the laboratories where expensive MS/MS is unavailable.

• Journal of Applied Biological Chemistry
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• v.48 no.1
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• pp.16-25
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• 2005

To develop an enzyme-linked immunosorbent assay (ELISA) for the detection of the residues of the acaricide fenazaquin, five haptens were synthesized and assessed. A competitive indirect format was used with polyclonal antibodies. Under an optimized condition using the selected rabbit C antiserum, an $IC_{50}$ of $96.97\;ng{\cdot}ml^{-1}$, the detection range of $14.9{\sim}631\;ng{\cdot}ml^{-1}$, and the lowest detection limit of $8\;ng{\cdot}ml^{-1}$ were obtained. Some structurally related compounds of practical use showed low crossreactivities to the antibody. Highest cross-reactivity observed with hapten IV indicates that the antiserum C recognizes very well quinazoline ring, 4-tert-butylphenyl, and an adequate length of spacer arm. The length of spacer arm affected recognition of quinazoline ring and 4-tert-butylphenyl moieties. When applied to apple and pear, recoveries were within acceptable ranges of $93.18{\sim}104.77%$ (n = 4) and $79.40{\sim}111.95%$ (n = 4), respectively.

• Toxicological Research
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• v.29 no.4
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• pp.293-298
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• 2013

A method of detecting lead was developed using square wave anodic stripping voltammetry (SWASV) with DNA-carbon nanotube paste electrode (CNTPE). The results indicated a sensitive oxidation peak current of lead on the DNA-CNTPE. The curves were obtained within a concentration range of 50 $ngL^{-1}-20mgL^{-1}$ with preconcentration time of 100, 200, and 400 sec at the concentration of $mgL^{-1}$, ${\mu}gL^{-1}$, and $ngL^{-1}$, respectively. The observed relative standard deviation was 0.101% (n = 12) in the lead concentration of 30.0 ${\mu}gL^{-1}$ under optimum conditions. The low detection limit (S/N) was pegged at 8 $ngL^{-1}$ ($2.6{\times}10^{-8}M$). Results showed that the developed method can be used in real-time assay in vivo without requiring any pretreatment and pharmaceutical samples, and food samples, as well as other materials requiring water source contamination analyses.

• Clinical and Experimental Reproductive Medicine
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• v.5 no.1_2
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• pp.1-7
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• 1978

In order to estimate the human placental lactogen levels and its value as an indicator of placental function during the first half of normal pregnancy, we defermined HPL levels. in normal snbjects (No=40) from the 6th week to the 20th week of gestation For the determination of human placental lactogen in serum of normal pregnant women during the first half of prognancy, radioimmunoassay have been performed using Phadebas HPL Test kit. The range of 25ng to 800ng HPL/ml. were determined by the procedures using Phadbas HPL Test kit, which correspond to levels recorded throughout the first half of normal pregnancy. HPL was detected in the earliest pregnancy samples collected at 6 weeks but was generally present in minute amount during the first trimester of pregnancy, when the HPL level ranged from 25 ng/ml. to 0.86 ${\mu}g$/ml. The mean concentration of HPL increased gradually from only 0.03 ${\mu}g$/ml, at 6 weeks to 0.25 ${\mu}g$/ml, at 12 weeks of gestation, Subsequently the mean HPL value rose steeply from 0.25 ${\mu}g$/ml, at 12 weeks to 1.65 ${\mu}g$/ml, at 20 weeks of gestation.

• Mass Spectrometry Letters
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• v.12 no.2
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• pp.31-40
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• 2021

Probable human carcinogenic compounds nitrosamines, have been detected as by-product impurities in sartan pharmaceuticals in recent years which has drawn worries for medication safety. To provide a sensitive and effective method for the quality control of sartan pharmaceuticals, this study established a feasible gas chromatography-tandem mass spectrometry (GC-MS/MS) method for simultaneous determination of 13 nitrosamines. The target analytes were separated on a DB-WAX Ultra Inert column (30 m × 0.25 mm; i.d., 0.25 ㎛) and were then subjected to electron impact ionization in multiple reaction monitoring mode. The established method was validated and further employed to analyze authentic samples. Limits of detection (LODs) and limits of quantification (LOQs) of the 13 nitrosamines were 15-250 ng/g and 50-250 ng/g, respectively, which also exhibited intra-day and inter-day accuracies of 91.4-104.8%, thereby satisfying validation criteria. Five nitrosamines, viz., N-nitrosodiethylamine, N-nitrosodimethylamine, N-nitrosodiphenylamine, N-nitrosomorpholine, and N-nitrosopiperidine were detected at concentrations above their LODs in 68 positive samples out of 594 authentic samples from seven sartans.

• Environmental Analysis Health and Toxicology
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• v.5 no.3_4
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• pp.19-28
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• 1990

Nitroarenes are ubiquitous environmental pollutants displaying potent mutagenicity in bacteria and carcinogenicity in mammal. In this study, the concentration of nitroarenes in coarse and fine particles and mutagenicity of POC$\_$N/ fraction was investigated in suspended particulates at the Shinchon and Bulkwang area of Seoul. The suspended particulates were collected bimonthly by a high volume cascade impactor air sampler from July 1987 to May 1988. Extractable organic matter was obtained by ultrasonic extraction on diethly ether/cyclohexane (8/2, v/v). Neutral fraction was obtained by liquid-liquid extraction. Polar neutral organic compounds (POC$\_$N/) was fractionated by thin-layer chromatography. Finally, the concentrations of nitroarenes in POC$\_$N/ fraction were measured and determined by capillary gas chromatography. Direct and indirect mutagenicity of POC$\_$N/ fraction were measured using Salmonella typhimurium TA 98. The result were as follows: 1) Major nitroarenes at the Shinchon area was 1-nitropyrene and at the Bulkwang area it was 2,7-dinitro-9-fluorenone during the year. 2) Average concentration of total nitroarenes measured was 67.26 ng/m$^3$in fine particles which was 1,3 folds higher that in coarse particle (52.30 ng/m$^3$). 3) Annual pattern of nitroarenes concentrations revealed that concentration during heating season (Feb., Jan., Mar.) was 2.2 folds higher than that in non heating season (May, Jul., Sep.). Concentration of each season has 157.68 ng/m$^3$and 80.39 ng/m$^3$. 4) The mutagenic activity of POC$\_$N/ fraction from fine particles was higher compared to that of coarse particles and was increased when metabolically activated, with 59 mixture. Mutagenicities, Metabolically activated, were significantly different between Shinchon and Bulkwang area, 322.8 rev/250 $\mu\textrm{g}$/plate and 286.8 rev/250 $\mu\textrm{g}$/plate, respectively. 5) Annual pattern of mutagenicity of POC$\_$N/ fraction revealed that mutagenicity during the heating season was 1.7 folds higher at Shinchon area and 1.2 folds higher at Bulkwang than during the non heating season. The variable contents and levels of nitroarenes in suspended particulates may affect human health significantly. Further studies such as risk assessment should be conducted on the basis of these kind of studies.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.1
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• pp.41-44
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• 2007

The callipyge mutation in sheep is a polar overdominant mutation that results in post-natal muscle hypertrophy in the loin and hindquarters of paternal heterozygotes (+/CLPG). Sheep that are homozygous for the callipyge allele (CLPG/CLPG) do not express the muscle hypertrophy phenotype, but serve as carriers for the mutation. Callipyge sheep are characterized by improved feed efficiencies and leaner carcasses. Leptin is a protein hormone secreted from adipose tissue and has been found to affect appetite and serve as an indicator of body fat mass. To date, very little knowledge is available as to the effect of the callipyge mutation on circulating leptin levels. Due to the interaction of leptin with feed intake and energy availability, and the fact that the majority of fetal growth occurs in late gestation, it is important to understand if the callipyge mutation interacts with leptin production in late gestational ewes. Therefore, our objective was to characterize serum concentrations of leptin in late gestational callipyge ewes vs. non-callipyge ewes. We evaluated genetically verified callipyge (n=6), homozygous (n=8) and normal (n=8) ewes weekly during the last eight wks of gestation through one wk post-partum. Weights were taken and body condition scores were assigned by trained personnel weekly. Blood was collected via jugular venipuncture on each sampling date and subjected to an ovine-specific leptin RIA. Genotype influences on peripheral concentrations of leptin were found to be highly significant (p=0.0005). Total leptin means for +/CLPG were 5.41${\pm}$0.40 ng/ml, CLPG/CLPG 8.11${\pm}$0.70 ng/ml, and +/+ 9.13${\pm}$0.93 ng/ml. Sampling date was also significant (p=0.0098) with all ewes showing a decrease in leptin levels throughout gestation and parturition. Using repeated measures, we were able to detect lower levels of plasma leptin in callipyge ewes, which may be indicative of their lower overall body fat content. These results indicate that the callipyge phenotype decreases the levels of adipose tissue and leptin production in gestating ewes.