• Toxicological Research
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• v.35 no.2
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• pp.161-165
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• 2019

Cysteamine has been used in cosmetics as an antioxidant, a hair straightening agent, and a hair waving agent. However, recent studies indicate that cysteamine can act as an allergen to hairdressers. The objective of this study was to develop and validate a simple and effective reversed-phase high-performance liquid chromatography (RP-HPLC) method for the measurement of cysteamine and its dimer, cystamine. Sodium 1-heptanesulfonate (NaHpSO) was used as an ion-pairing agent to improve chromatographic performance. Separation was performed on a Gemini C18 column ($250mm{\times}4.6mm$, $5{\mu}m$ particle size) using a mobile phase composed of 85:15 (v/v) 4 mM NaHpSO in 0.1% phosphoric acid:acetonitrile. UV absorbance was monitored at 215 nm. The RP-HPLC method developed in this study was validated for specificity, linearity, limit of detection, limit of quantitation, precision, accuracy, and recovery. Cysteamine and cystamine were chromatographically resolved from other reducing agents such as thioglycolic acid and cysteine. Extraction using water and chloroform resulted in the recovery for cysteamine and cystamine ranging from 100.2-102.7% and 90.6-98.7%, respectively. This validated RP-HPLC method would be useful for quality control and monitoring of cysteamine and cystamine in cosmetics.

• Analytical Science and Technology
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• v.19 no.1
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• pp.31-38
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• 2006

Micellar electrokinetic capillary chromatography(MECC) and HPLC with ion-pairing mechanism were applied for the separation of the well known environmental wastes from dye industry. These compounds include H-acid, J-acid, ${\gamma}$-acid, orthanilic acid, sulfanilic acid and 2-naphthylamine-1,5-disulfonic acid, and are known to be the diazo components of the azo dye. MECC method was also applied to separate few acid dyes including Acid Orange 7, Acid Orange 5 and Acid Blue 92 and direct dye such as Direct Red 80. Informations about the diazo components of any azo dye could be obtained by comparison of electropherogram of the reduction solution of a given dye with those obtained from standard materials such as H-acid, J-acid, ${\gamma}$-acid, orthanilic acid, sulfanilic acid and 2-naphthylamine-1,5-disulfonic acid. It has been concluded that MECC and HPLC with ion-pairing mechanism could be successfully applied for the analysis of unknown dyes and their diazo components.

• Analytical Science and Technology
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• v.12 no.1
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• pp.28-33
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• 1999

Glutathione(GSH) in biological samples was determined by high performance liquid chromatographic(HPLC) method with fluorescence detector(FLD) after monobromobimane(MBB) or 4-fluoro-7-sulfobenzofurazan(SBD-F) derivatization. The detection limit of $0.03{\mu}g/mL$ was obtained after MBB derivatization, derivative of MBB was about 200 times more sensitive than that of SBD-F. N-acetylcysteine was used as internal standard and tetrabutylammonium ion as counter ion for better separation. The determination by ion-pairing chromatography after MBB derivatization was characterized by linearity in the range between $0.08{\sim}8.33{\mu}g/mL$ with a good correlation coefficient of 0.998. By precision test appeared relative standard deviation at less than 5% at three different concentrations. This method can be used for the analysis of GSH in plasma and tissue.

• Preventive Nutrition and Food Science
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• v.4 no.3
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• pp.171-174
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• 1999

For monitoring lipid oxidation development in cooked ground pork during refrigerationm, malonaldehydethiobarbituric acid(MA-TBA) contents were measured using high performance liquid chromatography(HPLC). As the oxidation proceeded during refergeration, TBA-reaction substances(TBARS) absorbances increased and the corresponding HPLC peak areas also increased proportationately. The correlation coefficient between the HPLC peak areas and MA-TBA absorbance were 0.9979. The treatemtn of cetrimide, an ion pairing agent, gave a complete resolution of the MA-TBA complex and the butanol extraction of the complex increased its recovery by 37.8%. Both cetrimide treatment and butanol extraction are essential steps for analyzing MA-TBA complex in ground pork wiht HPLC. A reliable and specific measurement of NA-TBA in ground pork was successfully performed using HPLC.

• Analytical Science and Technology
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• v.26 no.3
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• pp.182-189
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• 2013

The purpose of this research is to separate and quantitate selenium species in some food samples with HPLC-ICP-MS. Cation exchange chromatography showed efficient separation only for inorganic Se species while reversed phase ion pair chromatography showed good separation for both inorganic and organic Se species. $C_8$ column ($Symmetryshield^{TM}\;RP_8$, 3.5 ${\mu}m$, $4.6{\times}150$ mm) was used with optimum condition of 5% methanol mobile phase, 0.05% of nonafluorovaleric acid ion pairing reagent. Five standard Se species of Se(IV), Se(VI), SeCys(selenocystein), SeMet(selenomethionine) and Se-M-C(seleno methyl cystein) were separated successfully under the optimum condition (mobile phase; 5% methanol, ion-pairing reagent; 0.05% nonafluorovaleric acid, flow rate; 0.9 mL $min^{-1}$). To extract Se species, microwave assisted and enzyme-assisted extraction methods were studied. In enzyme-assisted extraction method, protease I for garlic, protease I plus trypsin for pork and mackerel, and protease XIV for tuna showed the best extraction efficiency. With the optimum condition for each sample, it was found that mostly inorganic Se, SeCys and SeMet are present in the sample studied ranging from few ${\mu}g$ $g^{-1}$ to few tens of ${\mu}g$ $g^{-1}$.

• Korean Journal of Veterinary Service
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• v.30 no.1
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• pp.1-12
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• 2007

A liquid chromatographic method has been developed for the analysis of aminoglycoside antibiotics (AMGs) using Heptafluorobutyric acid (HFBA) as a ion-pairing reagent. AMGs (amikacin, apramycin, dihydrostreptomycin, gentamicin, hygrosin B, kanamycin, neomycin, spectinomycin and tobramycin) were formed by reaction with HFBA as ion-pairing reagent. HFBA was attached to corresponding amino group of AMGs. These AMGs compounds were separated and detected by electrospray ionization mass spectrometry (ESI-MS). The experimental conditions for separation of AMGs were optimized and validated. A simple liquid chromatographic method for the determination of AMGs was demonstrated.

• Analytical Science and Technology
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• v.19 no.1
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• pp.50-57
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• 2006

Well known environmental wastes from dye industry were separated by the micellar electrokinetic capillary chromatography(MECC). These wastes include H-acid modifier and 2-naphthylamine-1,5-disulfonic acid, and are known to be the diazo components of the azo dye. The results of the separation were compared with the result obtained by the HPLC using ion-pairing mechnism. MECC method was also applied to separate a few direct dyes including Direct Blue 2, Direct Blue 6 and Direct Blue 15, and reactive dye such as Reactive Orange 4. Informations about the diazo components of any azo dye could be obtained by comparison of electropherogram of the reduction solution of given dye with those obtained from standard materials such as H-acid, J-acid, ${\gamma}$-acid, orthanilic acid, sulfanilic acid and 2-naphthylamine-1,5-disulfonic acid which are used as diazo components of the typical azo dyes. It has been concluded that MECC and HPLC with ion-pairing mechanism could be successfully applied for the analysis of unknown dyes and their diazo components.

• Preventive Nutrition and Food Science
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• v.4 no.3
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• pp.167-170
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• 1999

Various concentrations of malonaldehyde (MA) produced upon hydrolysis of 1, 1, 3,3-tetraethoxypropane (TEP) were reacted with 2-thiobarbituric acid (TBA)and th e contents of MA-TBA complex were measured both with spectrophotometer and high performance liquid chromatography (HPLC). As the concentrations of MA-TBA increased, their absorbances and the corresponding HPLC peak areas increased. The correlation coefficient between absorbances and HPLC peak areas of MA-TBA peaks from the other compounds and butanol extraction of the complex increased its recovery its recovery by 29.4% . Measurement of the content of MA-TBA complex for monitoring the development of lipid oxidation was proven to be successful with the use of high performance liquid chromatography.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1745-1750
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• 2013

A novel green aqueous mobile phase modified with room temperature ionic liquids (RTILs) was employed in the absence of volatile organic solvents or ion-pairing reagents to analyze thiamine, a very polar compound, by reverse phase high performance liquid chromatography (RP-HPLC). Due to its strongly hydrophilic nature, thiamine was eluted near the column dead time ($t_0$) using a mobile phase without adding RTILs or ion-pairing reagents, even if a 100% aqueous mobile phase, which has weak elution power under reverse phase conditions, was used. Thus, 1-ethyl-3-methyl-imidazolium hexafluorophosphate ([EMIM][$PF_6$]), which has the strongest chaotropic effect, was selected as a mobile phase additive to improve retention and avoid baseline disturbances at $t_0$. Various mobile phase parameters such as cation moiety, chaotropic anion moiety, pH and concentration of RTILs were optimized to determine thiamine at the proper retention time. Method validation was performed to assess linearity, intra- and inter-day accuracy and precision, recovery and repeatability; all results were found to be satisfactory. The developed method was also compared to the current official United States Pharmacopoeia (USP) and Korean Pharmacopoeia (KP) methods using an organic mobile phase containing an ionpairing reagent by means of evaluating various chromatographic parameters such as the capacity factor, theoretical plate number, peak asymmetry and tailing factor. The results indicated that the proposed method exhibited better efficiency of thiamine analysis than the official methods, and it was successfully applied to quantify thiamine in pharmaceutical preparations.

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.416-421
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• 1998

In the reversed-phase ion-pair high performance liquid chromatographic (RPIP-HPLC) elution behavior of noble metal-thiacrown ether complexes, the effects of the concentration of ion-pairing reagent and kind of ligands were studied. It was found that the less the number of atoms in the ring of the thiacrown ether molecule was, the larger the selectivity was, and the elution mechanism of the complexes was explained due to the formation of ion-pair when the concentration of sodium dodecyl sulfate (SDS) in mobile phase was lower than 10 mM and due to the formation of micelle when the SDS concentration was higher than 10 mM. As a conclusion, separations of the noble metal-thiacrown ether complexes in an optimum separation condition were accomplished successfully and the method was proved to be an useful one for the separation and determination of Ag (Ⅰ) ion in a black-white photographic fixing solution.