• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.142-148
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• 2018

To improve the performance of a launch vehicle, kerosene, a launch vehicle fuel, undergoes a densification process. Liquid nitrogen injection cooling is an effective densification method which has a simple system and is inexpensive. During the cooling process, however, nitrogen may dissolve in the kerosene, possibly resulting in changes to fuel properties. Therefore, it is essential to measure and eliminate the amount of dissolved nitrogen in the kerosene. In this study, the vacuum extraction principle is introduced to measure the content of dissolved nitrogen in the kerosene. In addition, the experimental results, which used a designed/manufactured nitrogen sampling device, are described. From the results, the validity of the nitrogen sampling device and the dissolved nitrogen measurement/elimination methods was demonstrated.

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.37-40
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• 2021

Nickel (Ni) is a kind of the rare earth resources. Since Ni-containing waste is drained after several plating operations in the factories, the effective recycling technique has been expected to be introduced. An actual magnetic separation technique using HTS bulk magnet generating the strong magnetic field has succeeded in collecting the paramagnetic slurry containing Ni-sulphate coarse crystals which were fabricated from the Ni-plating waste. The Ni compound in the collected slurry was identified as NiSO₄/6H₂O, showing slight differences in the particle size and magnetic susceptibility between the samples attracted and not-attract to the magnetic pole. This preferential extraction suggests us a novel recycling method of Ni resource because the compound is capable of recycling back to the plating processes as a raw material.

• Food Science of Animal Resources
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• v.41 no.4
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• pp.731-738
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• 2021

Herein, a novel analytical method using a high-performance liquid chromatography-fluorescence detector (HPLC/FLD) is developed for rapidly measuring an L-carnitine ester derivative in infant powdered milk. In this study, solid-phase extraction cartridges filled with derivatized methanol and distilled water were used to effectively separate L-carnitine. Protein precipitation pretreatment was carried out to remove the protein and recover the analyte extract with a high recovery (97.16%-106.56%), following which carnitine in the formula was derivatized to its ester form. Precolumn derivation with 1-aminoanthracene (1AA) was carried out in a phosphate buffer using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) as the catalyst. Method validation was performed following the AOAC guidelines. The calibration curves were linear in the L-carnitine concentration range of 0.1-2.5 mg/L. The lower limit of quantitation and limit of detection of L-carnitine were 0.076 and 0.024 mg/L, respectively. The intra- and interday precision and recovery results were within the allowable limits. The results showed that our method helped reduce the sample preparation time. It also afforded higher resolution and better reproducibility than those obtained by traditional methods. Our method is suitable for detecting the quantity of L-carnitine in infant powdered milk containing a large amount of protein or starch.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.281.1-281.1
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• 2002

Psoralen(7H-Furo［3.2-g］ ［1］benzopyran-7-one) and angelicin(2-Oxo-[2H]- furo[2.3-h]-1-benzopyran) are angular furocoumarin with diverse photobiological effects. They are major components of Psoralea corylifolia L.(破古紙). Psoralea corylifolia L. is used for a tonic and nursing one's energy. It can be also used for loss of virility. vitiligo. a skin disease, etc.. But a well known and often appreciated side effects f psoralens is the hyperpigmentation caused by this treatment. A women who used the herbal drug-mixed-medicine named'sobaeksu' to treat her vitiligo made a complaint against the orinetal medical doctor. She complained that her skin got burned to 2nd degree by the liquid. 'sobaeksu' through a medical celtficate. So we analyzed the components of that liquid with gas chromatography and gas chromatography/mass spectometry. It has 57.3% ethyl alcohol and two kinds of psoralens. Psoralens were psoralen and angelicin and each one of their contained quantity was 0.128mg/ml and 0.123mg/ml.

• Food Science of Animal Resources
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• v.41 no.5
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• pp.816-825
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• 2021

This study aims to validate a fast method of simultaneous analysis of 365 LCamenable and 142 GC-amenable pesticides in hen eggs by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS), respectively, operating in multiple reaction monitoring (MRM) acquisition modes. The sample preparation was based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction. Key method performance parameters investigated were specificity, linearity, limit of quantification (LOQ), accuracy, precision and measurement uncertainty. The method was validated at two spiking levels (10 and 50 ㎍/kg), and good recoveries (70%-120%) and relative standard deviations (RSDs) (≤20) were achieved for 92.9% of LC-amenable and 86.6% of GC-amenable pesticide residues. The LOQs were ≤10 ㎍/kg for 94.2% of LC-amenable and 92.3% of GC-amenable pesticides. The validated method was further applied to 100 egg samples from caged hens, and none of the pesticides was quantified.

• Mass Spectrometry Letters
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• v.13 no.4
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• pp.158-165
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• 2022

Many therapeutic class drugs such as beta-blocker, corticosteroids, NSAIDs, etc are prohibited substances in the horse racing industry. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology makes it possible to isolate drugs from interference, enables various drug analyses in complex biological samples due to its sensitive sensitivity, and has been successfully applied to doping control. In this paper, we describe a rapid and sensitive method based on solid-phase extraction (SPE) using solid phase cartridge and LC-MS/MS to screen for different class's 35 drug targets in equine plasma. Plasma samples were pretreated by SPE with the NEXUS cartridge consisted non-polar carbon resin and minimum buffer solvent. Chromatographic separation of the analytes was performed on ACQUITY HSS C18 column (2.1 × 150 mm, 1.8 ㎛). The elution gradient was conducted with 5 mM ammonium formate (pH 3.0) in distilled water and 0.1% formic acid in acetonitrile at a flow rate of 0.25 mL/min. The selected reaction monitoring (SRM) mode was used for drug screening with multiple transitions in the positive ionization mode. The specificity, limit of detection, recovery, and stability was evaluated for validation. The method was found to be sensitive and reproducible for drug screening. The method was applied to plasma sample analysis for the proficiency test from the Association of Racing Chemist.

• Journal of Surface Science and Engineering
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• v.34 no.6
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• pp.553-567
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• 2001

Electrodeposition technology is widely used in industry for various kinds of coatings. Modifications in this technology led to several processes to meet various requirements. Electrolysis in ionic liquids has many advantages such as low energy consumption of energy, low pollutant emission and low operating costs. Although ionic liquids have already been used in liquid/liquid extraction processes, only recently their use in electrodeposition was exploited. Electrochemical deposition of composites is an expanding area. Coupled with the progress in the synthesis of nanometric powder, this research will open a large number of innovative materials. Pulse current plating is another electrodeposition technique which yields improved coatings. Although electrodeposition is now regarded as an environmental non-friendly process, it is economically viable and has many inherent advantages. For certain applications, alternatives to electrodeposition have not yet been fully implemented. Hence, continued research in this technology is warranted. This article reviews some recent advances in electrodeposition technology. Aspects of electrodeposition such as electrolysis in ionic liquids, electrodeposition of composites, pulse current plating techniques, metal and alloy deposition, compound deposition and effects of additives are discussed in this review.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.67-72
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• 2023

A simple and accurate method was developed for the quantitative analysis of oleanonic acid (OA) from mastic gum. The analysis was carried out using reverse-phase high-performance liquid chromatography combined with a photodiode array detector (HPLC/PDA). Our optimized method was validated by measuring various parameters, using an INNO C18 column fitted with a gradient elution system. The results revealed limits of detection and quantification of 0.34 and 1.042 ㎍/mL, respectively. The OA calibration curve exhibited excellent linearity over the concentration range of 0.0625 to 2.0 mg/mL, with r² =0.9996. Accuracy tests revealed a high recovery rate of 99.44-103.66%, with precision values below 0.15%. These results suggest that the present analytical method can identify and quantify OA in mastic gum with high precision. The HPLC approach developed in this study might be applied to routine analyses and large-scale extraction procedures for OA content quantification.

• Analytical Science and Technology
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• v.37 no.5
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• pp.271-279
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• 2024

Bisphenols and phthalates are endocrine-disrupting chemicals that are commonly used in packaging and as plasticizers. However, they pose health risks through ingestion, inhalation, and dermal contact. Accurate analysis of these pollutants is challenging owing to their low concentration and their presence in complex oil matrices. Therefore, they require efficient extraction and detection methods. In this study, an analytical method for the simultaneous quantification of bisphenols and phthalates in corn oil is developed. The dynamic multiple reaction monitoring mode of liquid chromatography-tandem mass spectrometry is used according to the different polarities of bisphenols and phthalates. The method is validated by assessing system suitability, linearity, accuracy, precision, homogeneity, and stability. The determination coefficients are higher than 0.99, which is acceptable. The percentage recovery and coefficient of variation of the accuracy and precision confirm that this analytical method is capable of simultaneously quantifying bisphenols and phthalates in corn oil. The bisphenols and phthalates in the formulations and pretreatment samples are stable for 7 d at room temperature and 24 h in an auto-sampler. Therefore, this validated analytical method is effective for the simultaneous quantification of bisphenols and phthalates in oils.

• Mass Spectrometry Letters
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• v.15 no.3
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• pp.141-148
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• 2024

Rhododendron arboreum (Sm.) is one of the most frequently distributed an evergreen small tree species at 1500-3300m in Nepal. The flowers of Rhododendron are a promising source of bioactive constituents and could be used as functional food and edible colorants. The purpose of this study was to reveal the components of R. arboreum flowers by LC-MS/MS. Twelve compounds were identified by LC-ESI-MS/MS from the different crude fractions prepared by liquid-liquid extraction process. The MS/MS fragmentation patterns of each compound were determined and proposed. The isolated compounds belong to flavonoids, anthocyanins, triterpenoids and phosphatidylcholines. The major anthocyanin identified was cinnamtannin. The identified flavonoids are quercetin-3-O-glucoside, quercetin-3-O-pentoside, kaempferol-3-O-pentoside, quercetin and kaempferol. Ursolic acid represents triterpenoid derivative. 1-linoleoyl-sn-glycero-3-phosphoethanolamine, 1-linolenoyl-sn-glycero-3-phosphocholine, 1-linoleoyl-sn-glycero-3-phosphocholine, 1-Palmitoyl-sn-glycero-3-phosphocholine and 1-oleoyl-sn-glycero-3-phosphocholine belong to phosphatidylcholines. These phosphatidylcholines have been first time reported from the genus Rhododendron.