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Matrix Enhancement Effect: A Blessing or a Curse for Gas Chromatography?
심재한 ( Jae Han Shim ) 한국환경농학회 2013 한국환경농학회 학술대회집 Vol.2013 No.-
The matrix enhancement effect in gas chromatography (GC) has been a problem for the last decade as it results in unexpected high recovery. Most of the efforts, including the use of different types of injectors/matrix simplification procedure, and further clean-up associated with removing this effect was focused on equalizing the response of the standard in the solvent and matrix. However, after eliminating the matrix enhancement effect, the sensitivity of GC remained unchanged. But, GC sensitivity can be increased by utilizing this matrix effect originating from a matrix matched standard. Very few studies have highlighted utilizing the matrix effect but have rather advocated eliminating it. Analyte protectants (3-ethoxy-1, 2-propanediol, gulonolactone and sorbitol) have been introduced as an alternative for GC-mass spectroscopy (GC-MS) (not examined for other GC detectors), as they equalize the response without removing the matrix effect, and, hence, increase sensitivity. Versatile applications of analyte protectants are not observed in practice. The European guidelines recommend use of matrix matched standard calibration for residue measurements. As a result, numerous applications are available for matrix matched standards that compensate for the matrix effect. Moreover, the matrices (among them pepper leaf matrix) can act as a protectant for thermolabileanalytes in some cases. A lower detection limit should be achieved from the GC detector to comply with the maximum residue limits. Therefore, the matrix enhancement effect, which is considered a problem, can play an important role in lowering the detection limit by increasing the transfer of analyte from the injection port to the detector.
심재한 ( Jae Han Shim ),최청일 ( Chung Il Choi ) 한국하천호수학회 2002 생태와 환경 Vol.35 No.5
1998년 4월부터 1999년 7월까지 총 7차례에 걸쳐서 영월동강 유역일대 조사지역에서 채집 및 관찰된 양서류는 2목 5과 9종이었고, 파충류는 2목 2아목 6과 13종, 총 4목 2아목 11과 22종이 확인되었다. 전체 22종 중에서 환경부에서 고시하여 법적으로 보호하고 있는 멸종위기야생 동물은 구렁이(Elaphe schrenckii) 1종이었고, 보호야생 동물은 까치살모사(Agkistrodon saxatilis)와 남생이(Chinemys reevesii) 2종이었다. 전체 생물다양도 지수와 다른 지역에서 조사된 수치와 비교하였을 때 종풍부도(R`=3.23), 종다양도(D`=2.59) 그리고 종균질도(E`=0.85)가 높게 나타났으며, 결과적으로 영월 동강 유역일대의 양서·파충류상은 Energy이동, 먹이망, 포식관계, 경쟁 그리고 생태적 지위분배 등을 포함한 개체군의 상호작용이 다른 지역보다는 이론적으로 복잡하고 다양하며, 또한 군집의 구성성분이 어떠한 방해에 의해서도 영향을 받지 않는 안정된 군집구조를 가진다고 판단된다. 수식서식처 다양도를 비교한 결과 양서·파충류는 전체 수몰예정지역 중에서 완경사면의 70% 이상이 서식처와 산란장소가 되며, 양서·파충류 서식처와 산란장소가 수몰되어 막대한 생물다양성의 감소가 초래하게 될 것이 예상된다. 위협도 평가 결과, 도마뱀(Scincella laterale laterale)은 관찰/시도(14/15), 확률(93%) 그리고 물두꺼비(Bufo stejnegeri)는 관찰/시도(13/15), 확률(87%)로 영월 동강 유역일대에서는 서식 밀도가 높은 것으로 나타났으며, 꼬리치레도룡뇽(Onychodactylus fisheri)은 60%, 두꺼비(Bufo bufo gargarizans)는 40%, 까치살모사(Agkistrodon saxatilis)는 46%, 능구렁이(Dinodon rufozonatus rufozonatus)는 40%의 출현빈도를 보이고 있어, 여타의 지역에 비하여 희소한 종들의 출현빈도가 높았다. The purpose of this survey was to evaluate herpetofauna biodiversity including the confirmatton of distribution and habitats in the Dong River Valley. The survey was conducted from April 1998 to July 1999. Collected and observed amphibians specimens were classified into 2 orders, 5 families, 9 species with reptiles in 2 orders, 2 suborders, 6 families and 13 species. Among the 22 species of amphibians and reptiles, Elaphe schrenckii is endangered species, whereas, Agkistrodon saxatilis and Chinemys reevesii are designated for protection by the Ministry of Environment. Bio-deveristy indices of hexpetofauna in the Dong River Valley in comparison with other areas were very high (richness=3.23, diversity=2.59, evenness=0.85). These results indicate that this region`s ecological niches are complex and the population structure seems stable. About 70% of low slope area was considered to be biologically important for spawning and establishment of habitats. Loss of herpetofaunal bio-diversity in the region seems obvious with the submergence. An estimation of appearance frequency including rare species was also high.
HPLC 형광분석법을 통한 벼에서 Brassinolide 의 검정
심재한(Jae Han Shim),김인선(In Seon Kim),이강봉(Kang Bong Lee),서용택(Yong Tack Suh),(E . D . Morgan) 한국응용생명화학회 1996 Applied Biological Chemistry (Appl Biol Chem) Vol.39 No.1
To determine brassinolide in rice(Oriza sutiva L.) using HPLC equipped with fluoresence detector, a highly sensitive fluorescence reagent. 1-cyanoisoindole-2-m-phenylboronic acid, was synthesized from the reaction of o-phthaldehyde, m-phenylboronic acid and KCN, then was reacted with brassinolide. The formation ratio of brassinolide boronate exhibited 90% up at the ratio of 20 : 1(㎍/㎍) of 1-cyanoisoindole-2-m-phenylboronic acid and brassinolide respectively. The detection limit of brassinolide boronate with fluoresence detector was 0.16 ng. Brassinolide was detected in heading stage(biomass : 10 g) and panicle formation stage(biomass : 100 g) of the rice(Oryza sativa L.) with quantity of 0.8 ㎍ and 0.2 ㎍ respectively. However, brassinolide was not detected in blooming and elongation stage.
LC-MS/MS를 이용한 배 중 티오파네이트메틸 및 대사체 동시 분석
이한솔 ( Han Sol Lee ),정형석 ( Hyung Suk Chung ),( Musfiqur Rahman ),( Humayun Kabir ),심재한 ( Jae-han Shim ) 한국환경농학회 2017 한국환경농학회 학술대회집 Vol.2017 No.-
Thiophanate-methyl is used as systemic fungicide with broad-spectrum activity, and is used to control various fungal pathogens such as Venturia nashicola and Glomerella cingulate in pear, apple, and paprika. Pear is one of the most common fruits in Republic of Korea and other Asian countries, and in 2016, it is the crop with the highest yields followed by apple and the production amounted to about 23,000 tons in Korea. In the open field, pear fruits can be easily attacked by plant pathogens at a suitable temperature. However it is difficult for farmers to maintain an environment such as temperature and humidity. For this reason, the application of pesticides should be considered to reduce workforce and cut losses in fruit production. For safety of consumers, an analytical method was developed to quantify the residual levels of the thiophanate-methyl and its metabolite in field-incurred pear samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Samples were extracted with methanol and clean-up with C18 QuEChERS bulk sorbent. Linearity of a matrix-matched calibration curve of the thiophanate-methyl and carbendazim over a concentration range of 0.005-0.5 μg/mL and 0.001-0.1 μg/mL, respectively, was excellent, with determination coefficients (R<sup>2</sup>) ≥ 0.9990. The limits of detection (LOD) and quantitation (LOQ) for thiophanate-methyl and carbendazim were 0.0015 and 0.005 mg/kg, and 0.0003 and 0.001 mg/kg, respectively. The average recoveries of two analyte at two spiking levels (10 × LOQ and 50 × LOQ) were between 75.00 to 84.92%, with relative standard deviations (RSDs) ≤ 5.78%. The method was successfully applied to field-incurred samples treated with a commercial pesticide product. The treatments were divided into four treatments according to the days before harvest and sprayed four times following schedule: (treatment 1) 70, 60, 50 and 40 days before harvest; (treatment 2) 60, 50, 40 and 30 days before harvest; (treatment 3) 50, 40, 30 and 21 days before harvest; (treatment 4) 40, 30, 21 and 14 days before harvest. The highest and lowest residues were obtained for treatment 4 and treatment 2, respectively. The developed method is simple and accurate and can be extrapolated to other fruits.