• 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 the Korean Society of Tobacco Science
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• v.28 no.2
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• pp.152-157
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• 2006

A new procedure has been developed for the quantitation of aromatic amines in mainstream cigarette smoke. Two solid-phase extraction (SPE) clean up steps, using a different retention mechanisms, are required to process the samples. The first step used a cation-exchange cartridge, followed by a second step that used a cartridge with a hydrophobic retention character. The aromatic amines eluted from the second SPE cartridge are derivatized with pentafluoropropionic anhydride. This new method have advantages over other reported techniques, being sensitive, robust, and easily automated. The detection limits were ranged from 0.12 ng/mL for 1-aminonaphthalene to 0.16 ng/mL for 3-aminobiphenyl and the recoveries were from 97 to 106%. Compared with other reports for analysis of 2R4F reference cigarette, this method shows a close analytical data and good repeatability.

• Ocean and Polar Research
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• v.26 no.2
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• pp.231-243
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• 2004

Sequential extraction was carried out on twenty two subsamples of three ferromanganese crusts from three seamounts (Lemkein, Lomilik, and Litakpooki) near the Marshall Islands in the western Pacific. The extraction was designed to fractionate Fe-Mn crust forming elements into low defined groups: (1) exchangeable and carbornate, (2) Mn-oxide, (3) Fe-oxyhyd.oxide, and (4) residual fraction. X-ray diffraction result shows that target material were well removed by each extraction step except for CFA in phosphatized crusts generation. According to chemical analysis of each leachate, most of elements in the Fe-Mn crusts are bound with two major phases. Mn, Ba, Co, Ni, Zn, (Fe, Sr, Cu, and V) are strongly bounded with Mn-oxide $({\delta}-MnO_2)$ phase, whereas Fe, Ti, Zr, Mo, Pb, Al, Cu,(V, P, and Zn) show chemical affinity with Fe-oxyhydroxide phase. This result indicates that significant amount of Al, Ti, and Zr can not be explained by detrital origin. Ca, Mg, K, and Sr mainly occur as exchangeable elements and/or carbonate phase. Outermost layer 1 and inner layer 2 which are both young crusts generations are similar in chemical speciations of elements. However, some of Fe-oxyhydroxide bounded elements (Pb, Y, Mo, Ba, Al, and V) in phosphatized innermost layer 3 are released during phosphatization and incorporated into phosphate (Pb, Y, Mo, and Ba) or Mn-oxide phase (Al and V). Our sequential extraction results reveal that chemical speciations of elements in the hydrogenetic crusts are more or less different from interelemental relationship calculated by statistical method based on bulk chemistry.

• Korean Journal of Food Science and Technology
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• v.42 no.3
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• pp.257-262
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• 2010

Patulin, a secondary metabolite of mold, is commonly found in rotten apples. Many countries regulate patulin at levels ranging from 30 to $50\;{\mu}g/L$. Most analytical methods for removing patulin from apple juice include liquid-liquid extraction (LLE), which is time and labor intensive. To replace the LLE method, a solid-phase extraction (SPE) method has been developed for apple juice and unfiltered apple juice. A portion of the test sample was applied to a macroporous copolymer cartridge and washed with 5 mL of 1% sodium bicarbonate, followed by 5 mL of 1% acetic acid. Patulin was eluted with 5 mL of 2% acetonitrile in anhydrous ethyl ether. The mobile phase was tetrahydrofuran in water (0.8:99.2) and was detected with a UV detector at 276 nm. Recoveries ranged from 95 to 101% in test samples, and the minimum detectable level was 30 ppb. Because this SPE method is fast, easy, reliable, and inexpensive, it could be applicable for companies or analytical agencies to analyze patulin concentrations in apple juice.

• 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.

• Analytical Science and Technology
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• v.14 no.5
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• pp.392-399
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• 2001

The analysis of n-butylbenzene and 1,2-dibromo-3-chloropropane (DBCP) as volatile organic compounds in biota samples was performed by gas chromatography/mass spectrometry-selected ion monitoring mode. The target compounds, n-butylbenzene and DBCP, in biota samples were extracted by headspace solid phase microextraction (SPME) with $100{\mu}m$ polydimethyl siloxane (PDMS) fiber and purge & trap method. The extraction recoveries of these compounds obtained by SPME was 85.8% for n-butylbenzene and 92.4% for DBCP, respectively. Each value of method detection limit were $0.15{\mu}g/kg$ and $0.05{\mu}g/kg$, respectively. While in the case of purge & trap method, the extraction recovery was 115.2% for n-butylbenzene, 80.9% for DBCP and method detection limit were $0.04{\mu}g/kg$ and $0.70{\mu}g/kg$, respectively. The extraction yields and detection limits of these compounds obtained by purge & trap were equivalent to those by SPME.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.3
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• pp.181-183
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• 2008

We developed simple and highly efficient synthesis method for [$^{11}C$]methionine using solid-phase extraction method. For synthesis, we used C18 cartridge. [$^{11}C$]methionine was synthesized on C18 cartridge according to the solid-phase [$^{11}C$]methylation of precursor L-homocysteine thiolactone hydrochloride. The radiochemical yields of [$^{11}C$]methionine was $48.9{\pm}7.93%$ decay corrected (results of 30 syntheses, mean$\pm$SD), with average production higher than 180 mCi. This procedure showed high yield and simple synthesis of [$^{11}C$]methionine.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.423.1-423.1
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• 2002

A simple. specific and sensitive method for the determination of cyclosporine A (CsA) in human serum has been developed by a high performance liquid chromatography/diode array detector (DAD) and applied to pharmacokinetic study of CsA. This method involves the use of solid phase extraction procedure following rapid protein precipitation with zinc sulphate from 1 $m\ell$ of human serum, using a disposable $C_{18}$ extraction cartridge. (omitted)

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.10
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• pp.1465-1469
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• 2001

A sensitive high-performance liquid chromatographic method was developed to determine the content of cholesterol in milk and dairy products. To optimize separation of cholesterol, mobile phases including acetonitrile:2-propanol (8:1, v/v), acetonitrile:methanol (3:1, v/v), and acetonitrile:methanoI:2-propanol (7:3: I, v/v/v) were compared. Acetonitrile/methanol/2-propanol was superior to the other mobile phase systems for separating cholesterol. Liquid-liquid extraction (LLE) of cholesterol was simplified using a non-polar solvent, hexane, to remove interfering compounds, and had an excellent recovery $(100{\pm}1.0%)$ of cholesterol. A solid phase extraction (SPE) method using Sep-pak $C_{18}$ was developed and compared with LLE. The SPE method was rapid and highly reproducible. Both extraction methods were useful when used in combination with saponification of esterified cholesterol to facilitate total cholesterol determination. The detection limit of cholesterol was $0.01{\mu}g$. The newly developed HPLC method was rapid, simple, and accurate, and has advantages over the many methods commonly used.

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1309-1313
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• 2004

A simple and reliable method has been developed to selectively separate and concentrate trace amounts of thallium ion from real samples for the subsequent measurement by flame atomic absorption spectrometry (FAAS). Thallium ions are absorbed quantitatively during passage of aqueous real samples through an octadecyl bonded silica membrane disk modified by 4-(4-Chloro-phenylazo)-2-[(4-hydroxy-phenylamino)-methyl]-phenol. The retained $Tl^+$ ions are then stripped from the disk quantitatively with a minimal amount of thiosulfate solution as eluent. The proposed method permitted large enrichment factors of about 130 and higher. The relative standard deviation for ten replicate extraction of thallium from 1 L samples containing 5 ${\mu}g$ thallium is 1.2%. The break through volume for 5 ${\mu}g$ thallium is 1000 mL. The limit of detection of the proposed method is 11.2 ng of $Tl^+$ per 1000 mL. The effects of various cationic interferences on the recovery of thallium in binary mixtures were studied. The method was applied to the recovery of $Tl^+$ ions from natural water and human hair samples.