• Journal of environmental and Sanitary engineering
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• v.23 no.4
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• pp.37-44
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• 2008

In this study we developed the analytical methods for the determination of three neurotoxin; anatoxin-a, saxitoxin and neosaxitoxin using HPLC/FLD system and this analytical methods were applied to real sample; algae culture and algae extracts. For the HPLC/FLD analysis of anatoxin-a samples were concentrated on WCX(Weak Cation Exchanger) SPE and then anatoxin-a in concentrate was derivatized with NBD-F solution. Supernatant was injected on HPLC system. For the HPLC/FLD analysis of saxitoxin and neosaxitoxin samples were separated on the column and then derivatizied by post column reactor for fluorescen detection. For post column reaction of saxitoxin we feed two kinds of reaction solution; Oxidizing Reagent of which composition was periodic acid(7mM) in 50mM potassium phosphate buffer, pH 9 and acidifying reagent of which Composition was 0.5M acetic acid. The LOD value for anatoxin-a, saxitoxin and neosaxitoxin in HPLC/FLD method was 24.3 ng. $35{\mu}g/L$, $27{\mu}g/L$ respectively. We determined the anatoxin-a content of lyophilized anabaena flos-aquae and $20{\mu}g/g$ d.w. of anatoxin-a was detected. We analyzed saxitoxin and neosaxitoxin in algae culture media and extracts of lypopyllized algal cell cultured and that of Deachung reservior. Saxitoxin and neosaxitoxin in real sample were below the limit of detection. Although there are various water treatment processes for removing neurotoxins were suggested no process give simultaneous and complete removal of neurotoxins. It was cocluded that nanofiltration which reject material by size can be a process for removal of neurotoxins.

• Analytical Science and Technology
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• v.20 no.2
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• pp.115-123
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• 2007

The heterocyclic amines (HAs) are a family of mutagenic/carcinogenic chemicals formed from the cooking of muscle meats such as beef, meat, fowl, and fish. A major draw back in the analysis of HAs from foods is their very low level of concentration (ng/g) and a number of matrix interferences in samples. Solid-phase extraction (SPE) is one of the procedures widely used for the extraction and purification of HAs in food samples. In this study, several SPE procedures of HAs determination were performed. Recoveries of the HAs were obtained from comparing a matrix such as a standard methanolic solution and pre-cooked meat extracts. Recovery values were ranging between 25.3 and 93.0 % at a concentration of 25.0 ng/g. HAs were determined with high sensitivity by micro-HPLC (${\mu}$-HPLC) analysis with electrospray ionization mass spectrometry (ESI-MS). Another developed method, which is freezing filtration method, shows better extraction recoveries and good precisions. The established method will be applicable to monitoring of heterocyclic amines from the cooked meat.

• Food Science of Animal Resources
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• v.33 no.3
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• pp.417-424
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• 2013

A rapid and simple analytical method for the determination of 9 isomaltooligosaccharides (IMO) species in yoghurts was developed using dispersive solid phase extraction (dSPE) clean-up technic and high performance liquid chromatography with evaporative light-scattering detector (HPLC-ELSD). In this study, 9 IMO were extracted from samples simply with chemical reagent using ISO22662 IDF198 method and additional dSPE clean-up. The optimum instrument conditions for the determination were used carbohydrate ES $5{\mu}$ column with gradient elution of water and acetonitrile and ELS detector. The linearity of this method was expressed as the correlation coefficient ($r^2$), the results of IMO 9 species were shown in 0.9999. LOD and LOQ were respectively 7.9-22.1 mg/kg, 25.9-72.8 mg/kg. The accuracy of intra- and inter-day measurements were in the range from $84.3{\pm}4.5$ to $104.9{\pm}6.5%$, and the preceision of the intra- and inter-day measurements were in the range from 0.8 to 7.7%. The recoveries were from $84.3{\pm}4.5$ to $104.9{\pm}6.5%$. The determination results of IMO 9 species for the 9 yoghurts circulated in the market were in the range from $0.317{\pm}0.007$ to $1.624{\pm}0.050$ g/100 g. The newly developed method is appropriate for the determination of IMO in yoghurts, is a rapid and simple method with excellent resolution in compared with previous method.

• Proceedings of the Korean Society of Toxicology Conference
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• 2006.11a
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• pp.65-74
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• 2006

Modem drug discovery requires rapid pharmacokinetic evaluation of chemically diverse compounds for early candidate selection. This demands the development of analytical methods that offer high-throughput of samples. Naturally, liquid chromatography / tandem mass spectrometry (LC-MS/MS) is choice of the analytical method because of its superior sensitivity and selectivity. As a result of the short analysis time(typically 3-5min) by LC-MS/MS, sample preparation has become the rate- determining step in the whole analytical cycle. Consequently tremendous efforts are being made to speed up and automate this step. In a typical automated 96-well SPE(solid-phase extraction) procedure, plasma samples are transferred to the 96-well SPE plate, internal standard and aqueous buffer solutions are added and then vacuum is applied using the robotic liquid handling system. It takes only 20-90 min to process 96 samples by automated SPE and the analyst is physically occupied for only approximately 10 min. Recently, the ultra-high flow rate liquid chromatography (turbulent-flow chromatography)has sparked a huge interest for rapid and direct quantitation of drugs in plasma. There is no sample preparation except for sample aliquotting, internal standard addition and centrifugation. This type of analysis is achieved by using a small diameter column with a large particle size(30-5O ${\mu}$m) and a high flow rate, typically between 3-5 ml/min. Silica-based monolithic HPLC columns contain a novel chromatographic support in which the traditional particulate packing has been replaced with a single, continuous network (monolith) of pcrous silica. The main advantage of such a network is decreased backpressure due to macropores (2 ${\mu}$m) throughout the network. This allows high flow rates, and hence fast analyses that are unattainable with traditional particulate columns. The reduction of particle diameter in HPLC results in increased column efficiency. use of small particles (<2 urn), however, requires p.essu.es beyond the traditional 6,000 psi of conventional pumping devices. Instrumental development in recent years has resulted in pumping devices capable of handling the requirements of columns packed with small particles. The staggered parallel HPLC system consists of four fully independent binary HPLC pumps, a modified auto sampler, and a series of switching and selector valves all controlled by a single computer program. The system improves sample throughput without sacrificing chromatographic separation or data quality. Sample throughput can be increased nearly four-fold without requiring significant changes in current analytical procedures. The process of Bioanalytical Method Validation is required by the FDA to assess and verify the performance of a chronlatographic method prior to its application in sample analysis. The validation should address the selectivity, linearity, accuracy, precision and stability of the method. This presentation will provide all overview of the work required to accomplish a full validation and show how a chromatographic method is suitable for toxirokinetic sample analysis. A liquid chromatography/tandem mass spectrometry (LC-MS/MS) method developed to quantitate drug levels in dog plasma will be used as an example of tile process.

• Journal of agriculture & life science
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• v.45 no.5
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• pp.73-80
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• 2011

Fifty substances of pesticide were selected for analysis through the historical investigation of pesticides detected from environmental-friendly agricultural soil, and the environmental-friendly agricultural soils in Gyeongnam area were collected and then were accepted Anve (accelerated solvent extraction) and SPve (solid-phase extraction) as multiresidue extraction and clean up methods suitable to the soils. The pesticide residues were analyzed by using GC/vCD/NPD, HPLC/UV/FL, GC/MSD, or HPLC/MSD. 50 kinds of pesticides for the soils were an average of 95.5% from retrieval ratio of the 72 to 118% range, and the average of 3.0% for CV (%). Among 40 samples of soil, 20 components were detected from pesticide residues of 21 samples, and average amounts detected for these components were 0.035 for endosulfan, 0.043 for ethoprophos, 0.020 for chlorpyrifos, 0.023 for chlorfenapyr, 0.047 for flufenoxuron, 0.070 for fenvalerate, 0.266 for cypermethrin, 0.016 for lufenuron, 0.022 for bifenthrin, 0.025 for fenobucarb/BPMC, 0.043 for difenoconazole, 0.059 for fenarimol, 0.020 for kresoxim-methyl, 0.026 for tetraconazole, 0.039 for isoprothiolane, 0.017 for iprobenfos, 0.014 for nolrimol, 0.156 for fluquinconazole, 0.047 for tebuconazole, and 0.045 mg/kg for oxadiazon. Therefore it is infered that the establishment of pesticide residues limit for environmental-friendly agricultural soil is needed as soon as possible.

• Journal of Life Science
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• v.16 no.3 s.76
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• pp.387-395
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• 2006

To isolate and purify anti-fungal active substances from immunized housefly (Musca domestica), low dose of Candida albicans was injected into the larvae of the housefly to induce the appearance of potent anti-fungal active substances in the hemolymph. This purification work was performed by the routine isolation and purification processes of protein, namely, solid phase extraction (SPE), SDS-PACE electrophoresis, HPLC purification. Three 4-16 kDa peptides which exhibited antifungal activity against Candida albican and other fungi were isolated from induced hemolymph. Consequently, further anti-fungal activity study showed that these three peptides were different either in molecular weight or in anti-fungal activity. All isolated substances were proved to be active and resistant to high-temperature. It was deduced that these peptides isolated from induced housefly were novel members of the insect defensin family and they were inducible.

• Analytical Science and Technology
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• v.24 no.4
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• pp.266-274
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• 2011

Using a Hitachi LaChrom Ultra 2000U, a reverse phase ultra high performance liquid chromatography (u-HPLC) method was developed for the rapid quantification of 14 PAHs in foods. The proposed method for PAH analysis is based on solid phase extraction (SPE) cartridges; the determination was carried out by u-HPLC with fluorimetric detection. The method was very sensitive; PAH concentration levels were in a low ${\mu}g$/kg range and could be detected and quantified. Six samples of food were analyzed. Among PAHs, PHE was found in most of samples, the concentration ranging from 2.5 to 19.9 ${\mu}g$/kg. The contents of benzo[c]fluorine (BCL), pyrene (PYR), benzo[a]anthracene (BaA), chrysene (CHR), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF) were low at the '${\mu}g$/kg' level or were less than LOD.

• Analytical Science and Technology
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• v.23 no.6
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• pp.551-559
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• 2010

This study was conducted to establish an analytical method for the determination of seven nitrosamines in chlorinated tap water by precolumn derivatization followed by high performance liquid chromatography coupled with fluorescence detection. The derivatization procedure was optimized for denitrosation and dansylation, and then two extraction methods, liquid-liquid extraction (LLE) with dichloromethane and solid phase extraction (SPE), were compared. The SPE method employing the optimized derivation procedure showed higher extraction recovery (54.4-88.7%) and reproducibility (1.9-19.4%) than the LLE method (51.4-87.7% and 4.2-33.3%, respectively). The method detection limits were between 0.5 and 4.4 ng/L. When chlorinated water samples were collected from two treatment plants and ten household taps, and analyzed for nitrosamines, Nnitrosodimethylamine (NDMA) was the major compound found between 26.1 and 112 ng/L.

• Korean Journal of Food Science and Technology
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• v.47 no.5
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• pp.556-560
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• 2015

This study was aimed at investigating the natural occurrence of caffeine, theobromine, and theophylline in tea leaves. Sample clean-up was based on a simple solid phase extraction (SPE) treatment, and simultaneous analysis was performed by high performance liquid chromatography (HPLC). This method showed good results in terms of linearity, recovery, precision, limit of detection (LOD), and limit of quantitation (LOQ). The caffeine, theobromine, and theophylline contents of tea leaves (n = 228) ranged from 5.4 to 58.2 mg/g, from not detected to 11.2 mg/g, and from not detected to 0.7 mg/g, respectively. The results obtained in this study can be used as fundamental data of caffeine, theobromine, and theophylline contents in tea leaves.

• The Korean Journal of Pesticide Science
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• v.16 no.4
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• pp.273-281
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• 2012

This study was conducted for the establishment of the analytical method of pesticide residues in rice straw for 9 pesticides; etofenprox, tricyclazole, diazinon, edifenphos, propiconazole, carbaryl, carbofuran, 3-hydroxy carbofuran and 3-keto carbofuran and for the monitoring of these pesticides in rice straw for livestock feed in Korea. These pesticides were classified into 4 groups according to analytical instrument condition. Group 1 (HPLC-UVD1) included tricyclazole and etofenprox while group 2 (HPLC-UVD2) included propiconazole and edifenphos. Group 3 (HPLC-FLD) included carbaryl, carbofuran, 3-hydroxy carbofuran and 3-keto carbofuran. Group 4 (GC-NPD) included Diazinon. The dried rice straw samples were extracted with acetone and purified by liquid-liquid partition and solid phase extraction (SPE): Combination of Florisil SPE and amino-propyl SPE was used for group 1 and group 2, amino-propyl SPE for group 3, and Florisil SPE was for group 4. Recovery was in the ranged 70~110% and the limits of quantitation (LOQ) were lower than the half of maximum residue limits. Therefore this method was proved to be efficient for monitoring of these pesticides residue in rice straw. A total of 18 rice straw samples from 6 provinces in Korea in 2010 were analyzed using established method and, only 3-keto carbofuran was detected in one sample at concentration of 0.04 mg/kg.