• Korean Journal of Food Science and Technology
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• v.34 no.2
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• pp.141-150
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• 2002

Owing to a need for simple extraction and purification for analysis of water soluble vitamins in food samples by RP-HPLC with UV-detector, the methods of bromelain and protease hydrolysis and $C_{18}$ Sep-Pak solid phase extraction were employed. The recoveries of standard water soluble vitamins by the bromelain and protease hydrolysis and $C_{18}$ Sep-Pak solid phase extraction were significantly high compared to AOAC methods in most of vitamins. The contents of pyridoxal determined with protest in the pork was similar, but in the bromelain hydrolysis and AOAC method, was high compared to the results of reference. The niacinamide, thiamin and riboflavin determined with bromelain and protease hydrolysis showed similar values to the results of references. In the potato, pyridoxamine was detected in the AOAC method, which was not detected in the bromelain and protease hydrolysis methods. Pyridoxal contents in the protease hydrolysis and AOAC methods were very similar to the results of references. The recoveries of fortified standard vitamins in food samples were significantly high and accurate compared to those of AOAC methods. The extraction and purification with $C_{18}$ Sep-Pak solid extractor might be considered superior method for the determination of water soluble vitamins in food samples.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.12-17
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• 2002

Simultaneous determination of nine water-soluble vitamins contained in multi-nutrient tablets was carried out by reversed phase high-performance liquid chromatography (RP-HPLC) equipped with analytical $C_{18}$ column and UV (270 nm) detector. Those standard vitamins were successfully separated within 23 minutes by gradient elution with solvent A (0.5 M potassium phosphate monobasic) and solvent B (0.25 M potassium phosphate monobasic-methanol, 1:1). Calibration curves showed good linealities with correlation coefficients (> 0.92) in tested ranged respectively. The detection limits were considered to be 2.1 ng for ascorbic acids 60 ng for Vit B$_{6}$ 3 ng for p-aminobenzoic acid, 9 ng for niacinamide, 9 ng for thiamin, 5.0 ng for folic acid and 1.5 ng for riboflavin at 0.05 a.u.f.s. Solid phase extraction through Sep-Pak (C$_{18}$ ) cartridge was successfully applied for purification of water soluble vitamins in commercial multi-nutrient tablets.ts.

• Analytical Science and Technology
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• v.7 no.3
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• pp.421-425
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• 1994

A micro-high performance liquid chromatography(Micro-HPLC) techniquie with solid phase extraction was reported which detected carbendazim and carbaryl at picogram levels. They were separated on microbore packed $C_{18}$ column($1.0mm\;I.\;D{\times}150mm$, $d_f=5{\mu}m$) using a 50% methanol mobile phase and detected at UV 220nm(${\alpha}=2.94$, $R_s=4.71$), while they were not resolved on analtical HPLC system(${\alpha}=1.27$, $R_s=0.76$). The detection thresholds of carbendazim and carbaryl were 0.5ng and 0.1ng on Micro-HPLC, therefore Micro-HPLC system was 20~40 told more sensitive than anayltical HPLC system. Sep-Pak $C_{18}$ catridge was found to be efficient in enriching carbendazim and carbaryl from dilute aqueous solution with 97.0% and 97.8% recoveries of them. The Sep-Pak $C_{18}$ catridge followed by the Micro-HPLC had been applied to the quantitative analysis of carbendazim and carbaryl in spiked juices and a commercial drinking water.

• Korean Journal of Clinical Laboratory Science
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• v.55 no.4
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• pp.261-268
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• 2023

[¹⁸F]Fluorocholine is a radiopharmaceutical used non-invasively in positron emission tomography to diagnose parathyroid adenoma, prostate cancer, and hepatocellular carcinoma by evaluating the choline metabolism. In this study, a radiolabeling method for [¹⁸F]fluorocholine was optimized using a solid phase extraction (SPE) cartridge. [¹⁸F]Fluorocholine was labeled in two steps using an automated synthesizer. In the first step, dibromomethane was reacted with [¹⁸F]KF/K2.2.2/K₂CO₃ to obtain the intermediate [¹⁸F]fluorobromomethane. In the second step, [¹⁸F]fluorobromomethane was passed through a Sep-Pak^Ⓡ Silica SPE cartridge to remove the impurities and then reacted with N,N-dimethylaminoethanol (DMAE) in a Sep-Pak^Ⓡ C18 SPE cartridge to label [¹⁸F]fluorocholine. The reaction conditions of [¹⁸F]fluorocholine were optimized. The synthesis yield was confirmed according to the number of silica cartridges and DMAE concentration. No statistically significant difference in the synthesis yield of [¹⁸F]fluorocholine was observed when using four or three silica cartridges (P>0.05). The labeling yield was 11.5±0.5% (N=4) when DMAE was used as its original solution. On the other hand, when diluted to 10% with dimethyl sulfoxide, the radiochemical yield increased significantly to 30.1±5.2% (N=20). In conclusion, [¹⁸F]Fluorocholine for clinical use can be synthesized stably in high yield by applying an optimized synthesis method.

• Analytical Science and Technology
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• v.28 no.2
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• pp.125-131
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• 2015

A method was developed and fully validated for the determination of terbutaline, a β₂-receptor agonist, in human plasma. Plasma samples were prepared by solid-phase extraction with Sep-Pak silica, followed by high-performance liquid chromatography (HPLC). The terbutaline was pre-separated from the interfering components in plasma on a Luna C18 (2) column, and terbutaline and salbutamol as an internal standard were resolved and determined on a Luna Silica column. The two columns were connected by a switching valve equipped with silica pre-column. The pre-column was used to concentrate the terbutaline in the eluent from the C18 column before back-flushing onto the silica column with fluorescence detection at an excitation/emission wavelength of 276/306 nm. The method was shown to be specific by testing six different human plasma sources. Linearity was established for a concentration range of 0.4-20.0 ng/mL with a correlation coefficient of 0.9999. The lower limit of quantitation was 0.4 ng/mL with a precision of 10.1% as C.V.%.

• YAKHAK HOEJI
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• v.46 no.6
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• pp.392-397
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• 2002

A simple and sensitive high performance liquid chromatographic method to quantitate ursodeoxycholic acid in crude drug pharmaceuticals was investigated. Ursodeoxycholic acid react with 2-bromoacetyl-6-methoxynaphthalene (Br-AMN) in the presence of triethylamine to form highly fluorescent derivative. The derivatization procedure was performed at 7$0^{\circ}C$ and completed within 30 min. The optimal wavelength of the fluorescence detector are λ$_{ex}$=300 nm and λ$_{em}$ = 460 nm. The LOD of the ursodeoxycholic acid was 25 ng/mι based on the S/N =3, and the LOQ was 80 ng/mι based on S/N = 10. Crude drug pharmaceuticals pretreated by solid phase extraction (Sep-pak $C_{18}$ cartridge) which were shown very good separation and recovery values for the compound.d.

• Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.163-170
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• 2021

Peptides are naturally occurring biological molecules that are found in all living organisms. These biologically active peptides play a key role in various biological processes. The aim of this study is the extraction and the purification of bioactive materials that induce relaxation of an apical muscle from the pyloric caeca of Patiria pectinifera. The acidified pyloric caeca extract was partially separated by the solid phase extraction using a stepwise gradient on Sep-Pak C18 cartridge. Among the fractions, materials eluted with 60% methanol/0.1% trifluoroacetic acid was put a thorough of a series of high performance liquid chromatography (HPLC) steps to isolate a neuropeptide with relaxation activity. The purified compound was eluted at 28% acetonitrile in 0.1% trifluoroacetic acid with retention time of 25.8 min on the CAPCELL-PAK C18 reversed-phase column. To determine the molecular weight and the amino acid sequence of the purified peptide, LC-MS and Edman degradation method were used, respectively. The primary structure of the peptide was determined to be FGMGGAYDPLSAGFTD which corresponded to the amino acid sequence of a starfish myorelaxant peptide (SMP) isotype (SMPb) found in the cDNA sequence encoding SMPa and its isotypes. In this study, a muscle relaxant neuropeptide (SMPb) has been isolated from pyloric caeca of starfish P. pectinifera. This is the first report of SMPb isolation on the protein level from P. pectinifera.

• Analytical Science and Technology
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• v.16 no.2
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• pp.125-133
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• 2003

In order to determine the contents of trans-resveratrol in red wine, which was mainly consumed in Korea, both LC/MS-ESI and LC/MS-APCI methods were used after solid-phase (Sep-Pak $C_{18}$-cartridges) extraction. The contents of trans-resveratrol obtained by LC/MS-ESI were detected in the range of $0.06-4.31{\mu}g/mL$. The recoveries were ranged from 88.4 to 97.9%. The values of relative standard deviation were ranged from 0.6 to 4.6% and the detection limit was $0.001{\mu}g/mL$. The contents of trans-resveratrol obtained by LC/MS-APCI were detected in the range of $0.09-4.02{\mu}g/mL$ and the detection limit was $0.005{\mu}g/mL$.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1315-1322
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• 2006

The following study describes the gas chromatography-mass spectrometry (GC-MS) based screening and confirmation analysis of urinary androgenic steroids. Four commercially available solid-phase extraction (SPE) cartridges, Serdolit PAD-1, Sep-pak $C_{18}$, amino-propyl, and Oasis HLB, and three different extractive organic solvents, diethyl ether, methyl tert-butyl ether (MTBE), and n-pentane, were tested for sample preparation. Overall, Oasis HLB combined with MTBE extraction provided the highest recoveries in 39 of 46 total androgenic steroids examined and it showed a good extraction yield (>82.1%) for polar steroids, such as metabolites of fluoxymesterone, oxandrolone, and stanozolol, which gave a poor recovery in both n-pentane (9.2-64.3%) and diethyl ether (22.2-73.6%) extractions. All SPE sorbents tested showed potential, because they were efficient in extraction for most or selective steroids. When applied to positive urine samples based on the results obtained, the present method allowed selective and sensitive analysis for detection of urinary androgenic steroids. The experiments showed that the high-resolution MS method is clearly more efficient than the low-resolution MS technique for the detection of many urinary steroids. However, comprehensive sample clean-up procedures also might be needed especially in confirmation analysis to increase detectability.

• Analytical Science and Technology
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• v.11 no.5
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• pp.321-331
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• 1998

The separation and sample extraction methods of 19 polycyclic aromatic hydrocarbons (PAHs) in water samples were investigated by gas chromatography/mass spectrometry (GC/MS) and some extraction methods involved liquid-liquid extraction, disk extraction and solid-phase extraction methods. The separation of 19 PAHs was possible by partial variation of oven temperature of GC/MS in temperature range $80{\sim}310^{\circ}C$. Extraction procedures of PAHs in water samples were somewhat modified and compared as extraction recoveries and the simplicity of methods. Extraction recoveries of PAHs were 71.3~109.5% by liquid-liquid extraction method. By using disk extraction, good extraction recoveries (80.7~94.9%) were obtained in case of $C_{18}$ disk extraction method by filtration. And extraction recoveries of PAHs by $C_{18}$ solid-phase were in the range of 51.8~77.9%. Method detection limits (S/N=5) of 19 PAHs were in the range of 0.25~6.25 ppb by liquid-liquid extraction and solid-phase extraction and 0.05~1.25 ppb by disk extraction methods.