• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1557-1561
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• 2006

The use of chemically modified silica-salen$(NEt_2)_2$ was studied for the separation and concentration of the metal ions from an aqueous solution by a solid phase extraction. After the salen(NEt2)2 was synthesized, it was chemically bonded to silica gel by a diazonium coupling reaction. The adsorption capacities and binding constants were obtained with respect to Cu(II), Mn(II), Pb(II) and Zn(II) by a graphical method. Some experimental conditions were optimized for the determination of the trace elements. After the silica-salen(NEt2)2 was pulverized in a sample solution of which the pH was adjusted, the solution was stirred to pre-concentrate the metal ions. The metal ions adsorbed were desorbed with nitric acid solution. And the concentrated analytes were determined by a flame AAS. The method proposed here was so rarely influenced by a sample matrix that the procedure was applied to 3 types of water samples. The reproducible results of less than 10% RSD were obtained at the concentration level of ca. 100 ng/mL and the recoveries of 95-109% were obtained in the spiked samples in which given amounts of analytes were added.

• Journal of Food Hygiene and Safety
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• v.5 no.4
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• pp.213-217
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• 1990

A simple and practical method for the determination of caffeine in coffee, black tea and green tea was studied. The analysis of caffeine was performed by reverse phase high perfomance liquid chromatography using a ${\mu}-Bondapak$ C18 column at isocratic condition with methanol-acetic acid-water (20: 1: 79) on UV detector at 280 nm. The extraction and clean-up of caffeine in sample is based on combing a simple pretreatment with the use of a Sep-Pak Alumina A cartridge. The average recoveries of caffeine from several samples were 95.2 -101.3%, the relative standard deviation for the whole procedure was 0.10 ~ 0.62%, and the detection limit of caffeine in sample solution was about $0.1\;\mu\textrm{g}\;per\;ml$.

• Food Science of Animal Resources
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• v.30 no.1
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• pp.36-41
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• 2010

The Hen's egg is widely used in many processed foods as an ingredient and is one of the most prevalent food allergens in children. To detect egg proteins in processed foods, we developed a competitive indirect enzyme-linked immunosorbent assay (ciELISA) using an anti-ovomucoid (OM) antibody, which was produced by immunization of rabbits with OM, the most heat-stable component of the egg proteins. The detection limit of this quantitative assay system was 30 ng/mL. Cross-reactivity of the anti-OM antibody toward OM, ovalbumin, skim milk, casein, whey protein isolate, and isolated soy protein was 100, 0.4, 0.2, 0.04, 0, and 0%, respectively. In the spike test of egg white powder in milk replacer, commercial sausage, and in-house sausage, the assay recoveries ($mean{\pm}SD$) were $129{\pm}13.7%$, $73.9{\pm}12.5%$, and $65.5{\pm}13.6%$, respectively. When egg white in a commercial crab meat analog and sausage was determined by ciELISA, the assay recovery was found to be 108% and 127%, respectively. The combined results of this study indicate that this novel ciELISA for OM detection could be applied for the quantification of hen's egg proteins in processed foods.

• Journal of the Korean Chemical Society
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• v.45 no.1
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• pp.40-44
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• 2001

Benomyl, one of the known endocrine disrupting chemicals, was analyzed to understand the its fate in water. Benomyl analysis process in water sample include the following sequential steps. Hydrolysis of benomyl into carbendazim, solvent extraction, concentration, and the concentration of final carbendazim solution was determined by LC/MS (TOF). Recoveries of the spiked samples were good with the range of 80.6 to 118.6% and the MDL was 1,600 times lower than that of LC/UVD method. The use of LC/MS (TOF) successfully eliminated the positive error incurred by interferencing materials in the matrix.

• Applied Biological Chemistry
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• v.41 no.8
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• pp.595-599
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• 1998

An analytical method was developed to determine tricyclazole residues in rice grain, straw, and soil using high-performance liquid chromatography (HPLC) with ultraviolet absorption detection. Tricyclazole was extracted with methanol from moist rice grain, straw, and soil samples. n-Hexane washing was employed to remove nonpolar co-extractives during liquid-liquid partition. Tricyclazole was then extracted with dichloromethane from alkaline aqueous phase, while acidic interferences remained in the phase. Dichloromethane extract was further purified by silica gel column chromatography prior to HPLC determination. Reverse-phase HPLC using an octadecylsilyl column was successfully applied to separate and quantitate the tricyclazole residue in sample extracts monitored at ${\lambda}_{max}$ 225nm. Recoveries from fortified samples averaged $95.5{\pm}3.0%\;(n=6),\;87.5{\pm}20.%\;(n=6),\;and\;84.3{\pm}2.8%$ (n=12) for rice grain, straw, and soil, respectively. Detection limit of the method was 0.02 mg/kg for rice grain and soil samples while 0.05 mg/kg for rice straw samples. The proposed method was reproducible and sensitive enough to evaluate the safety of tricyclazole residues in rice grain, straw, and soil.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.379-386
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• 1999

The adsorption and leaching of organophosphorus pesticides (phenthoate, diazinon, methidathion) were investigated in Namwon soli(black volcanic soil), Aewol soil(very dark brown volcanic soil) and Mureung soil(dark brown nonvolcanic soil) sampled in Cheju Island. The Freundlich constant, K value, was 52.4, 31.3 and 27.7 for phenthoate, diazinon and methidathion in Namwonsoil, respectively and decreased in the order of phenthoate, diazinon and methidathion among the pesticides. The K value of phenthoate was 52.4, 15.9 and 5.9 for Namwon, Aewol and Mureung soil, respectively and was the highest for Namwon soil with very high organic matter content and cation exchange capacity(CEC). The Freundlich constant, 1/n, showed a high correlation with organic matter content, i.e., its value was less than unity for organic matter rich soil(Namwon soil) and greater than unity for organic matter poor soil(Mureung soil). Total recoveries of pesticides in soil and leachate with leaching in soil column, were in the range of about 74~86%. The leaching of pesticides was less for phenthate with high K values, and more for methidathion with low K values among the pesticides. It was slower for Namwon soil with high K values, and more for methidathion with low K values among the pesticides. It was slower for Namwon soil with high K values, and faster for Mureung soil with low K values among the soils.

• Korean Journal of Environmental Agriculture
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• v.18 no.2
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• pp.154-163
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• 1999

A multiresidue method(MRM) for pesticides must be rapid and must test a wide variety of pesticides at relevant toxicological concentrations. In this study, three kinds of major analytical methods such as Korean Food Code Method, CDFA MRM, and Holstege's method are tested to compare the average recoveries, solvent consumption, and required time for the analysis of 18 organochlorines, 18 organophosphates, and 6 carbamates in spinach samples. Samples for pesticides analysis were extracted and cleaned up according to the respective methods and detected by gas chromatography with selective detectors, ECD and NPD, HPLC with postcolumn reaction system(PCRS). Average recovery of 42 pesticides by Korean Food Code method, CDFA method, and Holstege's method were 91.3%, 88.1%, 89.0%, respectively. Amount of solvent consumption and required time for the analysis of Korean Food Code method were from two and a half times to three times as much as those of another two methods. For the development and legal application of more rapid and effective MRMs, prolonged study is necessary.

• Journal of Food Hygiene and Safety
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• v.12 no.2
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• pp.117-124
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• 1997

A simple, rapid and simultaneous analytical method is described for the detection of Sulfonamide and Tetracycline residues, i.e., Sulfamerazine (SMR), Sulfamethazine (SMT), Sulfamonomethoxine (SMM), Sulfadimethoxine (SDM), Sulfaquinoxaline (SQN), Oxytetracycline (OXY), Tetracycline (TC), Chlortetracycline (CTC). Blank control and sulfonamide and tetracycline fortified fish muscle samples (0.5 f) were blended with octadecylsilyl (C18, 40 ${\mu}{\textrm}{m}$, 21% load, 60$\AA$) derivatized silica packing material (2 g). Blended fish samples were washed with hexane, then, benzene and dichloromethace were used for the elution of tetracycline and sulfonamide were analyzed by HPLC. Correlation coefficients of standard curves for individual sulfonamide and tetracycline isolated from fortified samples were linear (0.9993$\pm$0.0003~0.9997$\pm$0.0003, 0.9493$\pm$0.078~0.9753$\pm$0.036), respectively. The average percentage recoveries of sulfonamide and tetracycline ranged as 80.86~96.52% to 85.88~92.23%, and 30.01~37.12% to 65.89~73.40%, for the concentration range (0.1~1.0 ppm) examined, respectively. Limit of detection for sulfonamide was 0.0012 ppm for SMR in Paralichthys Olivacleus and 0.0020 ppm for SMR, 0.015 ppm for SMM in Cyprinus Carpio. The applicability of this procedure is demonstrated by separation and detection of incurred tetracycline and sulfonamide residues in fish muscle tissue.

• Journal of Food Hygiene and Safety
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• v.8 no.1
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• pp.17-23
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• 1993

In an attempt to quantitate and qualitate residual antibiotics and antibacterial agents n meat simultaneously, we studied a gas chromatogrphy-mass spectrometry (GC/MS) analysis. For a simultaneous analysis of macrolide antibiotics such as erythromycin and tylosin in meat, the homogenization with MeOH, defatting with n-hexane, extraction with CHCl3, elution with CHCl3 : MeOH=2:1 from Sep-Pak silica cartridge, acid gydrolysis, back extraction with CHCl3, and quantitation by selected ion monitoring(SIM) mode after trimethylsilyl derivatization were performed. The recoveries of erythromycin and tylosin (CV,%) at 10 ppm fortification level were 90.59(4.89) and 45.91(0.20) , and the detection limits of those were 0.02 and 2.0 $\mu\textrm{g}$/g beef, respectively. From these results, the developed analytical method using GC/MS-SIM mode allows excellent detection and quantitation of residual macrolide antibiotics in meats, using complementary method with bio-assay.

• 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.