• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.87-92
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• 1991

A dual capillary column system is described for the simultaneous measurement of retention index (RI) and area ratio (AR) values of each peak on two capillary columns of different polarity, DB-5 & DB-1701. Both capillary columns were connected to a common splitless injector via a deactivated fused-silica capillary tubing of 1 m length and a 'Y' splitter, the dead volume effect of which was found to be negligible. RI and AR were measured with high reproducibility(${\leq}$0.05% RSD) and with high accuracy (<10% RE), respectively. When applied to the test samples of the organic acid mixture, each acid was positively identified by the combined computer RI library search-AR comparison.

• Mass Spectrometry Letters
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• v.14 no.4
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• pp.178-185
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• 2023

QuEChERS is used worldwide as a universal sample preparation method with many benefits, such as being quick, easy, cheap, effective, rugged and safe. This study examined whether QuEChERS can be employed in isotope dilution mass spectrometry (ID-MS) for accurate analysis of pesticides in food. The ratios of fortified values and measured values of malathion and fenitrothion using the QuEChERS method were compared with those using the solid phase extract (SPE) method which was previously used in this laboratory. The separations of the two pesticides on DB-5MS and VF-1701MS columns were compared. Malathion and fenitrothion were fortified into kimchi cabbage and pretreated with the QuEChERS method and the SPE method. The results obtained using the DB-5MS column varied according to the sample preparation method, column and pesticide level. Using the VF-1701 column, ratios were 98-102% by both QuEChERS and Carb/NH₂ SPE method for all fortification level. Malathion and fenitrothion were fortified into strawberry samples for comparison with kimchi cabbage. The results for the strawberry samples indicated that the ratios were not influenced by the sample preparation methods or GC column. The QuEChERS method could be acceptable in the ID-MS method for pesticide residue analysis in food, however other conditions should be carefully considered for accurate determination, such as the column, amount of analyte and food matrix.

• Analytical Science and Technology
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• v.11 no.3
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• pp.222-228
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• 1998

Five kinds of packed column and two kinds of capillary column were used to get optimum condition for ethanol analysis by using fifteen different volatile, low molecular weight organic substances. Only two columns, Gaskuropack 54 and DB-1, showed good separation efficiency. In the adding salt-effect experiment 0.6N - perchloric acid, 1M - meta-phosphoric acid and saturated NaCl solution were used for alcohol concentration measurement of biological fluids and tissue specimens. Among adding salt experiment, adding saturated NaCl solution showed the most stable value of alcohol concentration. This fact might be due to the increased vaporization of alcohol in the saturated NaCl solution. In the time-course of blood alcohol concentration, the alcohol level was lineary decreased to the diameter of vessel containing specimens. This result was interpreted in view of ethanol level, weight, water content, and hematocrit value. The ethanol distribution levels were measured from samples of blood and tissue obtained from 25 postmortems cases investigated by NISI. This study showed that the distribution level was decreased in order of brain, blood, kidney, spleen, liver, and lung.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.3
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• pp.320-324
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• 2003

The protein hydrolysis with 6 M formic acid containing 0.3% tryptamine was a superior method for amino acid analysis of standard amino acid and protein than 6 M HCI containing 0.3% tryptamine. The recoveries of standard amino acid after acid hydrolysis were more accurate in the 6 M formic acid hydrolysis than 6 M HCI hydrolysis, especially recovery of tryptophan showed higher values of 1.5 times than that of 6 M HCI hydrolysis. The results of analysis on the standard protein, bovine serum albumin, showed very similar values compared to the sequence analysis reported in the literature for the 6 M formic acid hydrolysis than 6 M HCI hydrolysis, especially in the tryptophan recovery as standard amino acid recovery. Butylthiocarbamyl - trimethylsilyl (BTC - TMS) derivatives of 22 standard amino acids were successfully resolved DB-17 capillary column. Excellent reproducibility of standard amino acid recovery and composition of bovine serum albumin were obtained with BTC-TMS derivatives.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.997-1001
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• 2000

The organic acids in 3 kinds of medicinal herbal extracts were screened and compared each other according to their organic acid contents by an efficient gas chromatographic method. It involves solid-phase extraction of organic acids using Chromosorb P with subsequent conversion to stable tert-butyldimethysilyl derivatives for the direct analysis by capillary column gas chromatography and gas chromatography-mass spectrometry. Total of 24 organic acids were reproducibly identified from 3 kinds of herbal extracts. When the GC profiles were simplified to their retention index spectra, characteristic patterns were obtained for each herb sample. As expected, three kinds of herbal extracts showed three distinct patterns.

• The Korean Journal of Community Living Science
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• v.23 no.2
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• pp.199-206
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• 2012

In order to evaluate the aroma compounds in Korean traditional alcoholic beverages, volatile compounds of the commercial wines, Makgeolli were analyzed and quantified using the conventional method. Eight volatile compounds including three kinds of alcohols, two kinds of organic acids and three kinds of ether were extracted by Liquid-Liquid Extraction with Dichloromethane. For the separation and quantification, Gas chromatography coupled with mass spectrometry (GC/MS) was used to analyze these compounds. Also, the separation efficiency of these compounds was performed and compared with GC column. The results of this study were as follows ; Eight kinds of volatile compounds were separated well on the HP-88 column better than on the DB-5MS column. Short chain fatty acids, butyric acid and isovaleric acid were not detected in two brands of makgeolli samples. The higher alcohols were detected in the range of 0.86~225.68 ${\mu}g/mL$ and ethyl esters were detected in the range of 0.86~225.68 ${\mu}g/mL$, respectively. There compounds are known to be associated with sensory and odorant.

• Journal of Urban Science
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• v.7 no.2
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• pp.21-27
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• 2018

With the increase of the skyscraper center, the development of large-diameter and high-strength reinforcing bars is being carried out to solve the dense reinforcement. In case of the steel reinforced concrete with a small cross section such as beam-column joints, the development length becomes short when straight bars are used. Therefore, it is possible to solve the problem that the development length becomes short by using the bearing strength of the hooked bar and headed bar. In this study, the exterior beam-column joint test of SD700 hooked bar and headed bar with anchorage length of 20db was conducted to extend the development length limitation of hooked bar and headed bar. As a result of the evaluation of the anchorage strength using the design equation by KCI, the average of the [measured value]/[predicted value] ratio was 1.31 for the hooked reinforcing bars. In the case of headed bars, the average of the [measured value]/[predicted value] ratio was 1.12. In addition, in order to compare the anchorage performance of the hooked bar and the headed bar, the measured values were divided by the square root of the compressive strength of the concrete to compare the anchorage strength. Under the same conditions, the anchorage strength of headed bars was 8.5% higher than the hooked bars.

• Environmental Analysis Health and Toxicology
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• v.21 no.4 s.55
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• pp.365-373
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• 2006

Emission of methyl bromide (MeBr) from soil was implicated in stratospheric ozone depletion. To determine multi analysis of alternatives fumigants for MeBr, this paper describes the methods of analysis in water and soil. The MeBr, methyl iodide (Mel), propargyl bromide (PBr), cis 1,3-dichloropropene (cis 1,3-D), trans 1,3-dichloropropene (trans 1,3-D) and chloropicrin(CP) are separated on the base line on GC-ECD at three column of AT+DB+DB (90m) with temperature programing of $35^{\circ}C{\rightarrow}110^{\circ}C$ on GC-ECD. The relative retention time for MeBr, Mel, PBr, cis 1,3-D, trans 1,3-D and CP is 1.0, 1.4, 2.3, 3.2, 3.6 and 3.7, respertively. The detection limit for MeBr, Mel, PBr, cis 1,3-D, trans 1,3-D and CP is 469 pg, 5 pg, 21 pg, 79 pg, 101 PE and 5pg, respectively. Recovery of MeBr Mel, PBr, cis 1,3-D, trans 1,3-D and CP in water added 150 ppm fumigants were 81%, 96%, 95%, 97%, 98% and 99%, respectively. Recovery of MeBr, MeI, PBr, cis 1, 3-D, trans 1,3-D and CP in soil added 150ppm fumigants were 56%, 84%), 85%, 81%, 87% and 88%, respectively.

• Analytical Science and Technology
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• v.18 no.1
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• pp.13-22
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• 2005

The elution patterns of seventeen 2,3,7,8-substituted PCDDs/Fs and 12 dioxin-like PCBs were studied by both manual open columns and automatic parallel LC columns in cleanup procedure. PCDDs/Fs and non-ortho-PCBs from other mono-ortho-PCBs were separated on automatic LC column, whereas they were not separated on an open manual column. The elution study on two cleanup methods was carried out using the PAR solution of unlabeled congeners and checked the recovery of each congener. Total recoveries of cleanup fractionation were ranged between 61.9 ~ 96.0% for PCDDs/Fs and 70.4 ~ 79.0% for PCBs by manual open columns and 71.8 ~ 104.5% for PCDDs/Fs and 61.3-120.3% for PCBs by automatic parallel LC columns, respectively. Unfortunately, #169-HxCB and 1,2,3,7,8-PeCDD were not separated on DB-5MS capillary column. The ions of 1,2,3,7,8-PeCDD were selected at M/M+2 instead of M+2/M+4 suggested by EPA method 1613. It is possible to discriminate 1,2,3,7,8-PeCDD and PCB #169 in HRGC/HRMS analysis.

• Ocean and Polar Research
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• v.38 no.3
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• pp.195-207
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• 2016

Because the high latitude region in the North Pacific is characterized by high primary production in the surface water enriched with nutrients, it is important to understand the variation of surface water productivity and associated nutrient variability in terms of global carbon cycle. Surface water productivity change or its related nutrient utilization rate during the Northern Hemisphere Glaciation (NHG; ca. 2.73 Ma) has been reported, but little is known about such circumstances under gradual climate cooling since the NHG. Bulk nitrogen isotope (${\delta}^{15}N_{bulk}$) of sedimentary organic matter has been used for the reconstruction of nutrient utilization rate in the surface water. However, sedimentary organic matter experiences diagenesis incessantly during sinking through the water column and after burial within the sediments. Thus, in this study we examine the degree of nitrate utilization rate during the early Pleistocene (2.4-1.25 Ma) since the NHG, using the diatom-bound nitrogen isotope (${\delta}^{15}N_{db}$), which is known to be little influenced by diagenesis, from Site U1343 in the Bering slope area. ${\delta}^{15}N_{db}$ values range from ~0.5 to 5.5‰, which is lower than ${\delta}^{15}N_{bulk}$ values, but they vary with larger amplitude. Variation patterns between ${\delta}^{15}N_{db}$ values and biogenic opal concentration are generally consistent, which indicates that the nitrate utilization rate is closely related to opal productivity change in the surface water. A positive correlation between opal productivity and nitrate utilization rate was observed, which is different from the other high latitude regions in the North Pacific. The main reason for this contrasting relationship is that the primary production in the surface water at Site U1343 is influenced mostly by the degree of sea ice formation. Still, although concerns about diagenetic alteration have been avoided by using ${\delta}^{15}N_{db}$, the effects of the preservation state of biogenic opal and the species-dependent isotopic fractionation on ${\delta}^{15}N_{db}$ should be assessed in the future studies.