• Journal of the Korean Chemical Society
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• v.37 no.4
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• pp.453-461
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• 1993

Detection method was developed using a simply designed photochemical reactor made of teflon coil and low pressure mercury lamp. This method of UV photolysis of analytes followed by UV, fluorescence and electrochemical detection was found to be useful for four thiocarbamates. Analytes eluting from the column are irradiated with a high flux of 254 nm UV light, so that they change to either fluorescent active forms or highly electrochemically sensitive products. Appling this technique to the UV detection, thiocarbamates were converted into long wavelength absorbing products upon UV irradiation. In fluorescence detector four thiocarbamates are not detected at nonirradiated condition but fluorescence signals of MPTC, CPTC photolysates are appeared after irradiation with UV light. The electrochemical detection for the determination of thiocarbamates was enhanced up to 5∼20 fold signal after UV irradiation, compared to that of the nonirradiated. The detection limit of thiocarbamates on electrochemical detector was 13.3∼0.02 ng under pH 7.0, ionic strength $0.5{\times}10^{-2}$ M, phosphate buffer solution. Adducts produced by reaction of photolysates and OPA-MERC in the reaction coil were monitored at 425 nm with fluorescence detector, and one of the photolysates was primary amine.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.79-84
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• 1998

Tandem HPLC and atmospheric pressure chemical ionization(APcI) LC/MS method was used for the determination and confirmation of carbendazim residues in soybean sprout. Fluorescence(FL) detector was connected in tandem with the ultraviolet(UV) detector for dual detection of the carbendazim residue at the excitation and emission wavelength of 280 nm and 310 nm, respectively. The limit of detection for carbendazim was $0.1{\mu}g/kg$ sample. Recoveries of carbendazim from fortified soybean sprout at 0.5, 1.0 and 2.0 ppm were averaged 89.1%. Mass spectrometry using a APcI source confirmed the carbendazim residue in the soybean sprout sample. Fragmentation pattern on the APcI LC/MS spectrum of carbendazim was simpler than that from electron impact(EI) mass spectrum. Carbendazim produced 3 major ions including m/z 133, m/z 159 and m/z 191($M^{+}$). This method was sensitive enough to provide reliable and reproducible results for practical applications.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.3
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• pp.45-50
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• 2005

A UV camera is being used in various application regions such as industry, medical science, military, and environment monitoring. A ROIC(ReadOut IC) is developed and can read the responses from UV photodiode sensors which are made with III-V nitride semiconductors of GaN series haying high resolution and high efficiency. To design FPA(Focal Plane Array) UV $8{\times}8$ ROIC, the photodiode type sensor devices are modeled as the capacitor type ones. The ROIC reads out signals from the detector at)d outputs sequentially pixel signals after amplifying and noise filtering of them. The ROIC is fabricated using the $0.5{\mu}m$ 2Poly 3Metal N-well CMOS process. And then, it and photodiode array are hybrid bonded by gold stud bumping process using ACP(Anisotropic Conductive Paste). After the packaging, UV images appearing on PC verified the operations of the ROIC.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.5 s.347
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• pp.25-33
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• 2006

We have extracted the material parameters such as absorption coefficients of GaN, $Al_{0.2}Ga_{0.8}N$, and Schottky contact metal Ni of Schottky Diode UV-A and B detectors using a transfer matrix method (TMM). The ratios of the absorbed light to the total incident amount at the depletion regions of GaN and $Al_{0.2}Ga_{0.8}N$ have been calculated in order to obtain the spectral responsivity. Absorption coefficients of the materials have been obtained by fitting the simulated data with measured data. The depletion layer thickness has been obtanied by capacitance-voltage measurement. The results pave the way for the optimum design of UV Schottky detectors. Since the absorption coefficient of the Ni electrode is very high, its thickness is a major factor that determines the responsivity. It is possible to attain improved UV detectors using thinnest possible Ni electrodes and wide depletion regions of GaN and $Al_{0.2}Ga_{0.8}N$.

• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.406-412
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• 1989

Indirect photometric detection of aliphatic compounds such as alcohols, ketones and esters was investigated in high-performance liquid chromatography, These samples possessing nonchromophore or weak chromophore could be indirectly detected by a UV detector with addition of UV absorbing, p-chlorophenol or p-nitrophenol in mobile phase as detection reagent, and submicrogram detection limits were achieved. Some mixtures of samples were also able to be separated and quantitated with good resolution and comparatively high sensitivity under optimum conditions.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.453-454
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• 2006

• Analytical Science and Technology
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• v.26 no.1
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• pp.19-26
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• 2013

Gibberllic acid ($GA_3$) is one of gibberellins (GAs) that are a class of plant growth hormones that exert profound and diverse effects on plant growth and development. $GA_3$ is essentially non-UV absorbing and is difficult to assay by UV-detector. For effective extraction of gibberellic acid from fruits by using liquid-liquid extraction, optimized pH and extraction solvent were established. The selective and sensitive derivative of $GA_3$ for HPLC/UV-vis was derivatized using phenacyl bromide, and the experimental factors, including reaction time, reaction temperature and amount of derivatizing reagent and base were investigated for the effective synthesis. The derivatized $GA_3$ with phenacyl bromide was effectively analyzed by HPLC/UV-vis. The structure of derivatized $GA_3$ was confirmed by HPLC/ESI-MS. For apple, LOD and LOQ were 0.008 mg/kg and 0.027 mg/kg, respectively. For pear, LOD and LOQ were 0.003 mg/kg, 0.012 mg/kg, respectively. The established method can be applied to more effective analysis of $GA_3$ from plant and food.

• Journal of Food Hygiene and Safety
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• v.38 no.1
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• pp.26-30
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• 2023

In this study, we analyzed the microbial contamination level of ultraviolet sterilizer (UVS) chambers and suggested plans to improve hygiene management. In this study, UVS chambers targeted 98 UVS in some childcare centers in Jeollanam-do, Korea. Total aerobic bacteria and coliform bacteria were tested according to the Korean Food Code. Of the 98 UVS chambers, total aerobic bacteria were detected in 67 (68.4%) and coliform bacteria in 5 (5.1%). Six kinds of food-poisoning bacteria, including Salmonella spp., were not detected, but Bacillus cereus was detected in 1 (2.8%) out of 98 UVS chambers. According to the UV lamp replacement period, the detection rate of total aerobic bacteria was 3 (50%) out of 6 UVS within 3 months, 3 (60%) out of 5 UVS in 3 to 6 months, and 61 (70.1%) out of 87 UVS over 6 months. The detection rate of coliform bacteria according to the UV lamp replacement period was not detected within 6 months, however, they were detected in 5 (5.7%) out of 87 chambers after more than 6 months. The level of microbial contamination in the UVS chambers was higher as the lamp replacement period was longer. Considering these results, it was determined that the UVS chambers should be kept dry and clean, and the UV lamp should be replaced periodically. In addition, it is necessary to provide the staff catering for childcare centers with continuous education regarding the cleaning of UVS chambers and the replacement of UV lamps.

• The Korean Journal of Pesticide Science
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• v.9 no.4
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• pp.303-310
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• 2005

This study was performed to examine analytical method of a quinolone compound, oxolinic acid in paddy soil by HPLC coupled with UV detector. Two types of soil texture in different regions were used for this experiment. Oxolinic acid was extracted by a 4 M-KOH : MeOH(1 : 3, v/v) mixtures and acidified followed by liquid-liquid partitioning in dichloromethane. Dichlormethane layer was dehydrated, evaporated and analyzed by HPLC (262 nm). Retention time was 10.2 min. The standard calibration curve of oxolinic acid showed linearity ($r^2>0.999^{**}$, y=378.99x+135.08) in the range of $1{\sim}40$ ng. The mean recoveries, evaluated from fortified soil samples at two concentration levels of 0.2 mg/kg and 1.0 mg/kg, were $90.9{\pm}4.52%$(C.V. 4.97%) and $95.0{\pm}0.23%$(C.V. 0.24%) for soil 1 and $92.2{\pm}1.15%$(C.V. 1.25%) and $93.1{\pm}0.31%$ (C.V. 0.33%) for soil 2, respectively The detection limits of two types of soils were same as 0.05 ppm. Overall, the present analytical method of oxolinic acid by HPLC coupled with UV detector seems to be used reasonably.

• Analytical Science and Technology
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• v.13 no.3
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• pp.282-290
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• 2000

In this study, polymer additives were extracted and separated by Soxhlet extraction method and the dissolution-precipitation method from a polycarbonate (optical grade) which completely absorbed UV light below 390 nm. Analytical techniques such as UV-Vis spectroscopy, FT-IR, and HPLC were applied to analyze additives in polycarbonate. Separated materials from the polycarbonate may be a complex mixture containing additives such as UV stabilizer, antioxidants (primary and secondary), monomers, and oligomers. Several compounds such as bisphenol A, Irganox 1010, and Cyasorb UV-5411 were identified by chromatograms and UV spectra obtained from RP HPLC analysis using Bondapak $C_{18}$ column, methanol mobile phase, and a photodiode array (PDA) detector. Also, the content of UV-5411 in the polycarbonate was about 0.12 wt% by a quantitative analysis through UV spectroscopy.