• Food Science of Animal Resources
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• v.29 no.4
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• pp.482-486
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• 2009

The aim of this study was to optimize a simple, fast, and economical analysis procedure for the determination of 16 different pesticides in raw milk via GC/MSD. Analyses were performed via gas chromatography with electron impact mass spectrometric detection in the selected ion monitoring mode (GC/MSD-SIM) using Pentachloronitrobenzene as the internal standard. The modified sample preparation methodology was based on the Pesticide Analytical Manual (PAM) of the FDA concerning fat extraction, ACN-ether partitioning, and clean-up of the Sep-Pak florisil cartridge. The modified methodology for the determination of the 16 pesticides was validated. The range of LOQs of the 16 pesticides was likely three times lower than their Maximum Residence Levels (MRLs). The recoveries of most of the pesticides were acceptable at the fortification levels of 0.5 and 1.0 ${\mu}g/mL$ and their RSD (%) level was less than 20%. None of the 16 pesticides were detected in the selected raw milk samples.

• Journal of the Korean Applied Science and Technology
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• v.26 no.3
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• pp.263-268
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• 2009

Superporous Hydrogels (SPHs) have been extensively investigated for various biomedical applications due to their fast swelling and superabsorbent properties. In this study, glycol chitosan that is one of most abundant natural polymers was used as a cross-linking agent instead of bisacrylamide (BIS), which is a broadly used crosslinking agent for preparation of SPHs. Glycol chitosan was modified to have reactive vinyl groups by chemical conjugation with glycidyl methacrylate (GMA). The vinyl group-containing glycol chitosan (GC-GMA) was characterized by FT-IR and $^1H$-NMR measurements. SPHs have been prepared in various synthetic conditions to establish the optimum synthetic process for making superporous structure, where the inner pores are interconnected to each other to form a open channel structure. Various SPHs with different GC-GMA contents have been successfully prepared and have been observed to show faster swelling properties than other conventional SPHs. From the study on the swelling behavior of SPHs, the GC-GMA content is considered to be an important factor for controlling their swelling properties.

• Bulletin of the Korean Chemical Society
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• v.27 no.2
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• pp.231-236
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• 2006

A novel sample pretreatment technique, headspace hanging drop liquid phase microextraction (HS-LPME) was studied and applied to the determination of flavors from solid clove buds by gas chromatography-mass spectrometry (GC-MS). Several parameters affecting on HS-LPME such as organic solvent drop volume, extraction time, extraction temperature and phase ratio were investigated. 1-Octanol was selected as the extracting solvent, drop size was fixed to 0.6 $\mu$L. 60 min extraction time at 25 ${^{\circ}C}$ was chosen. HS-LPME has the good efficiency demonstrated by the higher partition equilibrium constant ($K_{lh}$) values and concentration factor (CF) values. The limits of detection (LOD) were 1.5-3.2 ng. The amounts of eugenol, $\beta$-caryophyllene and eugenol acetate from the clove bud sample were 1.90 mg/g, 1.47 mg/g and 7.0 mg/g, respectively. This hanging drop based method is a simple, fast and easy sample enrichment technique using minimal solvent. HSLPME is an alternative sample preparation method for the analysis of volatile aroma compounds by GC-MS.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.525-532
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• 2000

A new spectroscopic method for pesticide residues detection on agricultural products was developed. The general determination methods are high performance liquid chromatography (HPLC), gas chromatography (GC) or GC-mass spectrometry. They have provided relatively good detection limit and accuracy with complicated and time-consuming (5hrs above) procedures. In addition freshness is very important for evaluating qualities of agricultural products. This requires a simple and fast method for detection of pesticides. Reflectance, transmittance and fluorescence spectrometry of pesticides were tested using UV range because most of pesticides contain conjugation band in the molecular structures. Fluorescence spectrometry showed better sensitive to detect pesticide residues than did reflectance and transmittance spectrometry. Intensity and shape of fluorescence spectra showed different patterns with different structures of pesticides. Detection limit for fluorescence spectrometry was 0.1 ppm to 10 ppm depending on the structures of pesticides. Application of fluorescence spectrometry appears to be an easy method for detection of pesticide residues on agricultural products.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.474-477
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• 2006

유동형 급속열분해기((fluidized bed type fast pyrolyzer, 용량 300g/h)를 이용하여 너도밤나무와 침엽수 흔합재(독일가문비나무/전나무, 50:50)로부터 바이오오일을 생산하였다. 목질바이오매스의 열분해는 약 $470{\pm}5^{\circ}C$에서 1-2초 간 진행되었다. 목질바이오매스의 열분해 생성물의 조성을 살펴보면, 너도밤나무는 바이오오일이 약 60%, 탄이 약 9% 피리 고 가스가 31% 가량 생산되었으며, 침엽수 혼합재는 49%의 바이오오일, 9%의 탄, 그리고 42% 가량의 가스가 생성되었다. 두 종류의 목질바이오매스에서 생산된 바이오오일에는 약 17-22% 가량의 수분이 포함되어 있었으며, 비중은 약 1.2kg/L 이었다. 바이오오일의 원소 조성은 탄소가 45%, 산소가 47% 수소가 7%, 그리 고 질소가 1% 로서 일반적 인 목질바이오매스와 큰 차이는 없는 것으로 나타났다. 그러나 화석자원에서 생산되는 오일류와 비교하여 산소함량은 매우 높았으나 황은 전혀 포함하고 있지 않았다. 바이오오일의 GC분석 결과 총 90여종의 고리형, 또는 비고리형 저분자량 화합물이 검출되었으며 이들의 함량은 바이오오일 전건중량의 31-33% 정도로 측정되었다.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.12 no.1
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• pp.16-26
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• 2006

The purpose of this study was to investigate the influence of the various knee angles and ground state on the muscular activities and fatigue of the ankle muscles by integrated electromyograms (iEMG) and median frequency of tibialis anterior (TA), peroneus longus (PL), flexor digitorum longus (FDL) and gastrocnemius (GC). Ten healthy male subjects were participated into stable and balance ball sessions at four angles of knee joint. The surface electromyograms (sEMG) were recorded from the TA, PL, FDL and GC on stable and balance ball with full weight bearing at four knee angles of $0^{\circ}$, $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$. The time serial data of the surface electromyographic signals were transformed into integrated and frequency serial data by fast fourier transformation. On the stable ground, the iEMG signals of the TA, PL, FDL and GC were significantly higher at $45^{\circ}$ and $30^{\circ}$ of knee angles than $0^{\circ}$ and $15^{\circ}$ of knee flexion (p<0.05). On the balance ball, the iEMG of the TA, PL, FDL and GC were significantly higher at $45^{\circ}$ and $30^{\circ}$ of knee angles than $0^{\circ}$ and $15^{\circ}$ of knee flexion (p<0.05). The median frequency of the TA, PL, FDL and GC were significantly lower at $45^{\circ}$ and $30^{\circ}$ of knee angles than $0^{\circ}$ and $15^{\circ}$ of knee on the stable ground (p<0.05). On the balance ball, also the median frequency of the TA, PL, FDL and GC were significantly lower at $45^{\circ}$ and $30^{\circ}$ of knee angles than $0^{\circ}$ and $15^{\circ}$ of knee flexion (p<0.05). The iEMG of the TA, PL, FDL and GC were significantly higher on the balance ball at $0^{\circ}$, $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ of knee angles compared with stable ground. The median frequency of the TA, PL, FDL and GC were significantly lower on the balance ball at $0^{\circ}$, $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ of knee angles compared with stable ground. These results indicate that the ground conditions and angles of the knee joint involved to muscular activities and fatigue of ankles muscles, may performed at first on stable ground and then balance ball in order to $0^{\circ}$, $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ of knee flexion.

• Analytical Science and Technology
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• v.25 no.6
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• pp.375-381
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• 2012

In this study, we have developed a cryogenic concentration system for the analysis of non-methane hydrocarbons (NMHCs) in air sample. NMHCs with nmol/mol level of concentrations in the atmosphere were quantified by a comparative method with certified reference gas mixture. GC/FID with cryogenic concentration system operated in the range from $-67^{\circ}C$ to $180^{\circ}C$ was adopted. After cryogenic concentration, a fast desorption by heating could achieve a large amount of sample injection into the GC/FID. The linearity of the system was verified with the peak areas of NMHCs of the concentration amount of sample. The reproducibility is less than 10% and the limit of detection (LOD) is 0.1 nmol/mol. For the application of this system, we analyzed NMHCs in gas samples taken from air and soil in Daejeon, Seosan and Goheung.

• Korean journal of food and cookery science
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• v.22 no.3 s.93
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• pp.299-306
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• 2006

The numerous varieties of coffee beans contain a wide range prices and qualities. While the varieties of green coffee beans can generally be distinguished by their appearance, this visual criterion is impossible after the roasting process. Therefore, we need to develop a classification method or device. In this study, the potential of a new type of electronic nose, fast gas chromatography based on a surface acoustic wave sensor(SAW), was evaluated for the classification of origins and blended commercial brands in roasted coffee beans. Eight blended commercial brands and the origins of four similarly roasted ground coffee beans(with no significant difference of color) were rapidly(90 sec/sample) classified. The reproductive results were easily understandable over the aroma image pattern by $VaporPrint^{TM}$. In conclusion, GC-SAW electronic nose can be applied to the classification of origins and commercial brands in roasted ground coffee beans and to e evaluation of the similarities and differences of volatile pattern between samples.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.64-69
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• 2009

Musty and earth odors caused by geosmin and 2-MIB are the major complaints from the drinking water consumers. Therefore, early detection of geosmin and 2-MIB is the key to prevent off-flavor occurrence. In this study, a rapid method using stir bar sorptive extraction (SBSE) in combination with the GC/MS was investigated to analyze geosmin and 2-MIB in water. The SBSE method, a solventless extraction technique, was optimized and then applied to the analysis of geosmin and 2-MIB in water. The SBSE technique was found to be a simple and fast procedure that allows many samples to be extracted simultaneously using very small volume (10~20 mL). In addition, the SBSE method offered high recovery and good linear regression coefficient for the geosmin and 2-MIB. The good repeatability of this method can be deduced from the low RSD (7.2~7.6%) at 10 ng/L for geosmin and 2-MIB. The limit of detection was determined 1~2 ng/L and the limit of quantitation was 3~6 ng/L. Above all, the SBSE method proved to be a very practical technique for the analysis of geosmin and 2-MIB in water.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.401-416
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• 2011

The recent trend for pesticide residue analysis in food involves fast cleanup and use of mass spectrometry to achieve quantitative and qualitative analysis at the same time. Recently, the QuEChERS (quick, easy, cheap, effective, rugged and safe) multi-reside method has received much attention as a fast extraction and cleanup method of pesticide residue analysis. Therefore, multi-residue analysis of 236 pesticides was tested with the QuEChERS method by concurrent use of PTV-GC/TOFMS (gas chromatography/ time-of-flight mass spectrometry with programmable temperature vaporizer). PTV condition was optimized and when the method was applied to apples, pesticide recovery rates (spiked at 400 ng/g) ranged from 80% to 120%, and RSD values were under 10% for most compounds. The results showed that the QuEChERS sample preparation and PTV-GC/TOFMS analysis can be applied to multi-residue analysis of pesticides in fruits and vegetables.