• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.570-577
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• 2000

A method was presented for determination of bisphenol F(BPF), bisphenol A(BPA), bisphenol F diglycidyl ether(BFDGE) and bisphenol A diglycidyl ether(BADGE) in 3 aqueous-based food simulants (water, 4% acetic acid, 20% ethanol) by reverse-phase high performance liquid chromatography(RP-HPLC)with fluorescence detection and gas chromatography with mass selective detection(GC/MSD). All the calibration lines in the range of $5{\sim}800\;{\mu}g/L$ had correlation coefficients greater than 0.9998 and detection limits of less than $1.2\;{\mu}g$ bisphenols/L. Precision at $200\;{\mu}g/L$ was under 3.1%. Recoveries of bisphenols simultaneously spiked to aqueous food simulants exceeded 95% for BPF and BPA but about 80% for BFDGE and BADGE. However, recoveris of BFDGE and BPADGE respectively spiked increased upto 95%. Detection limits in recovery test were less than $0.40\;{\mu}g$ bisphenols/L. In migration test bisphenols were determined by RP-HPLC coupled with confirmation by GC/MSD. Can coatings of epoxy phenol, modified epoxy, epoxy ester phenol and thermoset vinyl were exposed to the 3 aqueous food simulants. BPF, BFDGE and BADGE were not detected in all the can coatings but BPA was detected in 4% acetic acid and 20% ethanol in all the can coatings except modified epoxy.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.3
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• pp.167-174
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• 2010

The hair nourisher products are used for prevention of hair loss and classified as quasi-drug in Korea. As concerns about hair loss has been increased, the demand for hair nourisher products has been growing. It is difficult to analyze their main ingredients because they contain various ingredients including natural plant extracts, vitamins, preservatives and exfoliators. The purpose of this study was to develop and validate simultaneous analytical methods of active ingredients in hair nourisher products such as nicotinamide, tocopherol, salicylic acid, dexpanthenol and benzyl nicotinate by HPLC. The active ingredients were separated on a $C_{18}$ column by using acetonitrile/phosphate buffer as a mobile phase, and detected at UV 220, 270 and 300 nm. The calibration curve showed linearity in the range of $12.5{\sim}800\;{\mu}g/mL$ and the recoveries were 97.3 ~ 103.5 % (RSD 0.9 ~ 2.8 %) in liquid matrix and 101.9 ~ 115.9 % (RSD 0.7 ~ 7.7 %) in shampoo matrix. Validated method was applied to hair nourisher products obtained from distribution market. Fortunately, all samples met their criteria. This study might be expected to provide the method for determining active ingredients in hair nourisher products and lead to promote a rapid market entry.

• Clean Technology
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• v.17 no.3
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• pp.215-224
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• 2011

It is an important issue to develop quality assessing system for biofuel for the purpose of accelerating the mass production of biofuel. It is particularly challenging to conduct testing method in the mass production of bioethanol while meeting quality specifications such as ASTM (American Society for Testing & Materials) D4806-10. In order to address this challenge, this paper proposes on-line spectroscopic quality assesment system based on Near Infrared spectrum and Partial Least Squares method in Chemometrics. As a result of testing a number of preprocessing methods and Partial Least Squares, it was found out that Savitzky-Golay method showed the best performance in terms of spectrum correction, noise reduction, and model maintenance. The proposed system allows us to assess multiple quality components continuously using spectroscopic facilities with the cheap cost. Since the value of R2 is more than 0.99, it is possible to replace the laboratory analysis.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.889-892
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• 2005

Standardized method based on extraction, filtration, and gas chromatography (GC) was developed far propylene glycol analysis to set hygienic norm of safety measure for foods under governmental control. Various columns were tested fur propylene glycol analysis by GC with flame ionization detector. Known amount of propylene glycol was spiked into wheat flour dough and analyzed by developed method. Results showed 101.60% recovery rate for propylene glycol with HP-5 column. Reproducibility test of standards recorded 0.30 for standard variation and 0,42% for relative variation. Using analytical method established, contents of propylene glycol in more than hundred different foods were monitored. Propylene glycol was detected in most foods, indicating propylene glycol is not only commonly added during food preparation, but also is contained naturally in food.

• Bulletin of Food Technology
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• v.21 no.2
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• pp.49-54
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• 2008

농산물 중 잔류농약을 보다 쉽고 효율적으로 분석 할 수 있는 다성분 동시분석 방법에 따라서 UPLC-PDA을 이용하여 기기조건에 따른 검출한계 및 정량한계를 식품별 최저 MRL과 비교하여 유효성을 알아보고 회수율을 통하여 방법의 재현성을 조사한 결과 다음과 같다. 41종의 농약에 대한 검량선은 직선성이 우수하였으며 검출한계 $0.005{\sim}0.109mg/kg$으로 나타났으며 정량한계 는 $0.018{\sim}0.363ppm$으로 나타났다. Cycloprothrin 등의 경우처럼 검출기의 감응도가 최저 MRL 기준을 초과하는 농약에 대한 보완으로는 검출감도가보다 우수한 UV 검출기 등의 병행 활용이 필요하다. 회수율에 따른 재현성은 쌀의 경우 첨가 농도 0.4 mg/kg 일때 $62.09{\sim}99.58%$로 편차범위는 $1.03{\sim}13.92%$ 얻을 수 있었다.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.357-365
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• 2011

Exposure measurement of agricultural worker to pesticide is one of important part of health risk assessment of pesticide. Therefore exposure matrices, apparatus, instruments and methods must be validated in advance to field experiment. In this study, method validation with an organophosphorus insecticide fenthion was carried out for exposure monitoring of agricultural worker. LOD and LOQ were 0.01 and 0.05 ng, respectively. Calibration curve linearity ($R^2$ > 0.999) and reproducibility (C.V. < 3%) were also excellent. Recovery at LOQ, 10LOQ and 100LOQ levels from gloves, socks, mask, patch, solid sorbent, glass fiber filter was 76~113% (C.V. < 3%). Trapping efficiency was 95~105% while no breakthrough was observed. Method validation for the exposure monitoring was established successfully through several experiments. Such method validation can be usually performed in laboratory and not much different for each pesticide so that, this techniques will be applied widely in research for pesticide exposure monitoring by combination with body surface area and respiration rates.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.507-512
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• 2005

This research focuses on the development and application of a method for the detection of m-toluate in soils using a genetically engineered bioluminescent bacteria, Pseudomonas putida mt-2 KG1206. KG1206 produces light by direct (m-toluate and benzoate) and indirect (toluene analogs) inducers. For detection of m-toluate in soil system, 9.9 mL strain was amended with 0.1 mL soil ethanol extractant. A high correlation ($r^2>0.97$) was observed between bioluminescence and m-toluate concentration. The unknown concentrations of m-toluate in soil samples were pre-determined using a method developed based on bioluminescence activity of strain with extracted inducers. Values between by LC analysis and bioluminescence activity show moderate statistical results. These results demonstrate the feasibility of recombinant bioluminescent microorganism, engineered to generate a quantifiable bioluminescence signal in response to specific pollutants, may serve as combined sensing and reporting tools in environmental monitoring.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.3
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• pp.359-363
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• 2009

This study was performed to establish a rapid and simple analytical method for niacin (nicotinic acid and nicotinamide) using HPLC. A pretreatment method for the extraction and clean-up of niacin in infant formula sample and an instrumental condition for HPLC were optimized. Niacin was extracted by 5 mM hexanesulfonate with ultrasonication for 30 min. For the clean-up of the sample, the extract was applied to a HLB cartridge, and then niacin was eluted from the cartridge using 5 mL of 80% methanol after washing with 5 mL of n-hexane. The total recoveries were $83{\sim}104%$ and relative standard deviation were in the range of $1.5{\sim}3.5%$ during the extraction and clean-up process. Niacin was determined by gradient elution with sodium hexanesulfonate/methanol buffer as a mobile phase and a photodiode array detector (260 nm). It showed a high linearity between the content of niacin and the peak area ($r^2$=1.000) in the range of $0.02{\sim}10.0$ mg/L of nicotinic acid and nicotinamide. The detection limit was 0.02 mg/L (0.2 mg/kg in the sample). The method was successfully applied for the determination of niacin in infant formula. Total niacin contents were in the range of $53.5{\sim}140.3$ mg/kg.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.377-383
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• 2013

This study examined the radiopacity of eight contemporary luting cements by direct digital radiography. Five disc-shaped specimens ($5mm{\times}1mm$) were prepared for each material tested (BisCem, Clearfil SA Luting, Duolink, Maxcem Elite, Multilink Speed, Panavia F 2.0, RelyX Unicem Clicker, V-link). The specimens were radiographed using a Kodak CS 7600 image plate (Carestream Health, Inc., Rochester, NY, USA) and an aluminum step wedge with a range of thicknesses (1.5 to 16.5 mm in 1.5 mm increments) and a 1 mm tooth used as a reference. A dental X-ray machine Kodak 2200 Intraoral X-ray System (Carestream Health, Inc., Rochester, NY, USA), operating at 70 kVp, 4 mA, 0.156 s and a source-to-sample distance of 30 cm, was used. According to international standards, the radiopacity of the specimens was compared with that of an aluminum step wedge using NIH ImageJ software (available at http://rsb.info.nih.gov/ij/).The data was analyzed by ANOVA and a Tukey's post hoc test. Maxcem Elite (5.66) showed the highest radiopacity of all materials, followed in order by Multilink Speed (3.87) and V-link (2.83). The radiopacity of Clearfil SA Luting (1.35), BisCem (1.33), Panavia F 2.0 (1.29) and Duolink (1.10) were between enamel (1.79) and dentin (0.19). RelyX Unicem Clicker (0.71) showed the lowest radiopacity, which was higher than that of dentin. All materials showed a radiopacity above the minimum recommended by the International Organization for Standardization and the American National Standards/American Dental Association with the exception of RelyX Unicem Clicker.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.10
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• pp.1405-1411
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• 2006

The presence and content of residual hexane in the olive oils were studied. Total 41 olive oils of imported and domestic brands, which were labeled as extra virgin and refined (mixed), were collected from the market. For analysis, electronic nose and headspace SPME-GC/MS were used. Electronic nose equipped with 12 metal oxide sensors was used for the discrimination of odor pattern of olive oils against the different concentrations of hexane. From the results, it is assumed that the contents of residual hexane in the collected olive oils were below 5 ppm. For Qualitative and quantitative analysis of hexane, polydimethylsiloxane (PDMS) fiber was employed for SPME-GC/MS. In the results, the peak of residual hexane was detected in 8 samples from 41 olive oils. But the detected level was no more than 1 ppm that is under the regulation limit (5 ppm) by Korea Food Additive Code.