• 분석과학
• /
• 제32권5호
• /
• pp.163-172
• /
• 2019

Methamphetamine (MA) is currently the most abused illicit drug in Korea and its major metabolite is amphetamine (AP). As MA exist as two enantiomers with the different pharmacological properties, it is necessary to determine their respective amounts in a sample. Thus a chiral stationary phase liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of d-MA, l-MA, d-AP, and l-AP in human urine. Urine sample ($200{\mu}L$) was diluted with pure water and purified using solid-phase extraction (SPE) cartridge. A $5-{\mu}L$ aliquot of SPE treated sample solution was injected into LC-MS/MS system. Chiral separation was carried out on the Astec Chirobiotic V2 column with an isocratic elution for each enantiomer. Identification and quantification of enantiomeric MA and AP was performed using multiple reaction monitoring (MRM) detection mode. Linear regression with a $1/x^2$ as the weighting factor was applied to generate a calibration curve. The linear ranges were 25-1000 ng/mL for all compounds. The intra- and inter-day precisions were within 3.6 %, while the intra- and inter-day accuracies ranged from -5.4 % to 11.8 %. The limits of detection were 2.5 ng/mL (d-MA), 3.5 ng/mL (l-MA), 7.5 ng/mL (d-AP), and 7.5 ng/mL (l-AP). Method validation parameters such as selectivity, matrix effect, and stability were evaluated and met acceptance criteria. The applicability of the method was tested by the analysis of genuine forensic urine samples from drug abusers. d-MA is the most common compound found in urine and mainly used by abusers.

• 한국환경농학회지
• /
• 제38권1호
• /
• pp.1-9
• /
• 2019

BACKGROUND: Accurate and simple analytical method determining Fluxametamid residue was necessary in various food matrices. Additionally, fulfilment of the international guideline of Codex (Codex Alimentarius Commission CAC/GL 40) was required for the analytical method. In this study, we developed Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method to determine the Fluxametamid residue in foods. METHODS AND RESULTS: Fluxametamid was extracted with acetonitrile, partitioned and concentrated with dichloromethane. To remove the interferences, silica SPE cartridge was used before LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry) analysis with $C_{18}$ column. Five agricultural commodities (mandarin, potato, soybean, hulled rice, and red pepper) were used as a group representative to verify the method. The liner matrix-matched calibration curves were confirmed with coefficient of determination ($r^2$) greater than 0.99 at calibration range of 0.001-0.25 mg/kg. The limits of detection and quantification were 0.001 and 0.005 mg/kg, respectively. Mean average accuracies were shown to be 82.24-115.27%. The precision was also shown to be less than 10% for all five samples. CONCLUSION: The method investigated in this study was suitable to the Codex guideline for the residue analysis. Thus, this method can be useful for determining the residue in various food matrices as routine analysis.

• 대한수학회지
• /
• 제58권1호
• /
• pp.29-44
• /
• 2021

The set D of column vectors of a generator matrix of a linear code is called a defining set of the linear code. In this paper we consider the problem of constructing few-weight (mainly two- or three-weight) linear codes from defining sets. It can be easily seen that we obtain an one-weight code when we take a defining set to be the nonzero codewords of a linear code. Therefore we have to choose a defining set from a non-linear code to obtain two- or three-weight codes, and we face the problem that the constructed code contains many weights. To overcome this difficulty, we employ the linear codes of the following form: Let D be a subset of ��2n, and W (resp. V ) be a subspace of ��2 (resp. ��2n). We define the linear code ��D(W; V ) with defining set D and restricted to W, V by $${\mathcal{C}}_D(W;V )=\{(s+u{\cdot}x)_{x{\in}D^{\ast}}|s{\in}W,u{\in}V\}$$. We obtain two- or three-weight codes by taking D to be a Vasil'ev code of length n = 2m - 1(m ≥ 3) and a suitable choices of W. We do the same job for D being the complement of a Vasil'ev code. The constructed few-weight codes share some nice properties. Some of them are optimal in the sense that they attain either the Griesmer bound or the Grey-Rankin bound. Most of them are minimal codes which, in turn, have an application in secret sharing schemes. Finally we obtain an infinite family of minimal codes for which the sufficient condition of Ashikhmin and Barg does not hold.

• 분석과학
• /
• 제24권2호
• /
• pp.150-157
• /
• 2011

아플라톡신은 Aspergillus flavus와 A. parasiticus에 의해 생성되는 독소대사산물로 발암물질이며 곡류(옥수수, 쌀, 보리), 땅콩, 과실류 및 종자류의 생산과 저장과정에서 생성된다. 곰팡이가 생성되기 쉬운 조건에서 오랜 기간 저장된 종자류에서 아플라톡신이 생성될 가능성이 있으며 이를 원료로 하여 유지로 가공 할 때도 아플라톡신이 이행될 우려가 있다. 또한 곡류나 두류 등을 가공하여 만든 영유아용식품도 아플라톡신 오염 가능성이 있다. 따라서 본 연구는 식용유지 및 영유아용식품에 대해 액체 추출법의 아플라톡신 시험법 적용가능 여부를 검토하고 필요시 새로운 분석방법을 확립하고자 하였다. 식용유지에 대한 아플라톡신은 MSPD (Matrix Solid Phase Dispersion)법으로 아플라톡신을 추출해 내고 면역친화성 칼럼을 사용해 정제하여 형광검출기가 장착된 고성능액체크로마토그래피(HPLC/FLD)를 이용해 분석하였다. 아플라톡신($B_1$, $B_2$, $G_1$, $G_2$) 검량선의 직선성은 상관계수가 0.999 이상을 나타냈고 회수율은 85.9~93.0%의 양호한 결과를 얻었으며 상대표준편차는 5.7% 이하였다. 식용유지에서 액체 추출법과 비교해 볼 때, MSPD-면역친화성컬럼법을 사용하여 회수율을 향상시켜 시험법을 확립하였다. 영유아용식품에 대한 아플라톡신 분석방법은 액체 추출법이 적합하였으며 아플라톡신($B_1$, $B_2$, $G_1$, $G_2$)에 대한 회수율은 89.5~92.3%로 양호한 결과를 얻었다.

• 한국식품과학회지
• /
• 제40권2호
• /
• pp.123-128
• /
• 2008

GC-${\mu}$ECD 이용한 수삼, 건조인삼, 홍삼 중 DDT(o,p'-DDE, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT, p,p'-DDT)의 효율적인 분석방법을 살펴본 결과는 다음과 같다. 단순하며 소량의 용매를 사용하는 동시분석법을 이용하여 인삼으로부터 DDT(DDD 및 DDE포함)를 추출하고 헥산 및 6% 에테르 함유 헥산으로 SPE-Florisil(500 mg) 정제하는 것이 GC-${\mu}$ECD 크로마토그램에서 인삼고유성분과 DDT(DDD 및 DDE포함) 피크의 분리도와 회수율 측면에서 가장 효율적이었다. 또한 인삼 중 저농도(0.01-0.05 mg/kg) DDT(DDD 및 DDE포함) 이성질체를 SPE-Florisil(500 mg) 정제 전 30% 황산 처리 후 원심분리로 인삼 고유성분을 제거하여 정확성을 높였다. 동시다성분법 추출 후 황산처리 및 SPE-Florisil(500 mg) 정제방법을 이용한 수삼, 건조 인삼분말, 홍삼분말에 DDT(DDD 및 DDE포함) 이성질체 표준용액을 0.01 mg/kg 농도가 되도록 첨가하여 실험한 회수율은 87.9-99.6%이었으며 표준편차는 0.9-5.9%였다. 또한 검출한계(Method Detection Limits)는 0.003-0.009 mg/kg이었다.

• 콘크리트학회논문집
• /
• 제21권3호
• /
• pp.327-335
• /
• 2009

지진이 빈번하게 발생하는 지역에서는 비내진상세구조물은 지진 발생시 연약층을 형성하고 취성적 붕괴를 일으키게 된다. 그러나, 기존 구조물을 해체하고 내진상세 구조물을 신축하는 방법은 건설폐기물, 환경오염 및 민원 등 여러가지 문제들을 가지는 등 비경제적 방법이라 할 수 있다. 따라서 기존 구조물이 내진성능을 만족하도록 내진보강에 관한 많은 연구가 이루어졌으며, 이러한 내진보강방법에는 끼움벽, 철골브레이스, 연속벽, 부벽, 날개벽, 기둥/보의 자켓팅 등이 있다. 이 중 끼움벽 골조는 큰 변형과 접합부에서의 회전이 발생하는 골조와, 비교적 작은 변형에서도 전단파괴를 야기하는 끼움전단벽 등 복합적인 거동특성을 나타낸다. 따라서, 이러한 시스템의 거동특성은 개개의 골조나 벽에서 나타나는 거동특성과 매우 다르게 된다. 본 연구에서는 끼움벽의 내진성능을 평가하고자 하였으며, 손상에너지의 효과적 흡수를 위해 변형경화형 시멘트 복합체 (SHCC)를 사용하였다. 실험은 1/3 축소모형의 끼움벽을 반복가력하는 것으로 계획하였다. 실험 결과, SHCC 끼움벽에서는 섬유의 가교작용을 통해 시멘트 복합체 내 응력을 재분배함으로써 미세균열이 발생하였으며, 강도 및 에너지소산능력이 우수한 것으로 나타났다.

• 한국환경농학회지
• /
• 제38권4호
• /
• pp.321-331
• /
• 2019

BACKGROUND: Pinoxaden is the phenylpyrazoline herbicide developed by Syngenta Crop Protection, Inc. and marketed on 2006. The maximum residue levels for wheat and barley were set by import tolerance. Thus, Ministry of Food and Drug Safety (MFDS) official analytical method determining Pinoxaden residue was necessary in various food matrixes. Satisfaction of international guideline of CODEX (Codex Alimentarius Commission CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2017) are additional pre-requirements for analytical method. In this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was investigated to analyze residue of Pinoxaden (M4), which is defined as pesticide residue in Korea, in foods. METHODS AND RESULTS: Pinoxaden (M4) was extracted followed by acid digestion (2hr reflux with 1N HCl) and pH adjusting (pH 4-5 with 3% ammonium solution). To remove oil, additional clean-up step with hexane saturated with acetonitrile was required to high oil contained sample before purification. HLB cartridge and nylon syringe filter were used for purification. Then, samples were analyzed by LC-MS/MS using reserve phase column C₁₈. Five agricultural group representative commodities (mandarin, potato, soybean, hulled rice, and red pepper) were used to verify the method in this study. The liner matrix-matched calibration curves were confirmed with coefficient of determination (r²) > 0.99 at calibration range 0.002-0.2 mg/kg. The limits of detection and quantitation were 0.004 and 0.01 mg/kg, respectively, which were suitable to apply Positive List System (PLS). Mean average accuracies of pinoxaden (M4) were shown to be 74.0-105.7%. The precision of pinoxaden and its metabolites were also shown less than 14.5% for all five samples. CONCLUSION: The method investigated in this study was suitable to CODEX (CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2017) guideline for residue analysis. Thus, this method can be useful for determining the residue in various food matrixes in routine analysis.

• 한국환경농학회지
• /
• 제35권3호
• /
• pp.166-174
• /
• 2016

농경지 토양에서 대상항생제 6종(amoxicillin, ampicillin, chlortetracycline, enrofloxacin, oxytetracycline, tetracycline을 아세트산 함유 아세토니트릴, Na₂Cit.5H₂O, Na₃Cit.2H₂O과 Na₂-EDTA로 추출 후 C₁₈으로 정제하여 LC-MS/MS로 분석하는 모니터링을 수행하였다. 그 중 2종의 항생제, chlortetracycline과 enrofloxacin이 국내 농경지 토양에서 검출되었다. 제안한 분석법은 토양 중 잔류 항생제 모니터링을 위한 빠르고 간편한 시험법이었고 다양한 활용이 가능할 것으로 보인다.

• 분석과학
• /
• 제31권4호
• /
• pp.171-178
• /
• 2018

Recently, for successful lactation, many breastfeeding mothers seek various products, including herbal medicine, dietary supplements, and prescribed medicines, to improve milk production. As demand for galactogogues grows, it is highly possible that pharmaceutical galactogogues may be adulterated with illegal products to maximize their efficacy. For continuous control and supervision of illegal products, we developed and validated a simple and sensitive LC-MS/MS method capable of simultaneously determining five galactogogues. Chromatographic separation was conducted using an Agilent Poroshell $120SB-C_{18}$ column with a mobile phase consisting of 20 mM ammonium formate (pH 5.4) and 100 % acetonitrile. The total run time was 13 min per analyte. The proposed method was performed according to the guidelines of the International Conference of Harmonization and it produced reliable results. This method showed high sensitivity and specificity, with a limit of detection (LOD) and limit of quantitation (LOQ) of 0.01-0.82 ng/mL and 0.02-2.45 ng/mL, respectively, for the solid- and liquid-type samples. Specificity was evaluated by analyzing matrix-blank samples spiked with the target compounds at LOQ levels, which provided a good separation of all peaks without interference. Additionally, the repeatability and intermediate precision were typically <15 %, whereas the recovery was 80-120 % of the values obtained using blank samples. Thus, we concluded that this method could be used for the identification and quantification of galactogogues in food or herbal products.

• 한국공간구조학회논문집
• /
• 제11권1호
• /
• pp.121-130
• /
• 2011

스페이스 프레임 구조물은 연속체 쉘 구조물의 원리를 이용하여 매우 넓은 공간을 효과적 으로 덮을 수 있는 구조물이지만 뜀좌굴 및 분기좌굴 등과 같은 불안정거동은 돔형 구조물에서는 더욱 복잡하게 나타난다. 또한 붕괴메커니즘의 이론적 연구와 실험적 연구결과들 사이에서도 많은 차이를 보인다. 본 논문에서는 미적 효과가 크며 단층의 대공간을 확보하기에 적합한 돔형 공간 구조물의 구조 불안정 특성을 접선강성방정식을 이용하여 비선형 증분해석을 수행하고, Rise-span(${\mu}$)비 및 하중모드($R_L$)에 따른 임계점과 분기점의 특성을 돔형 공간구조물의 예제를 통해 고찰하였다. 여기서 불안정점은 증분해석과정을 통해서 예측할 수 있었으며, 예제에서 낮은 ${\mu}$에서는 전체좌굴이, 높은 ${\mu}$의 경우는 절점좌굴이 지배적이며, 낮은 $R_L$에서 정점좌굴이, 높은 $R_L$에서는 전체좌굴이 지배적이고, 전체좌굴이 나타나는 경우, 분기좌굴하중은 완전형상의 극한점좌굴하중의 약 50%에서 70%의 분포를 보였다.