• Analytical Science and Technology
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• v.10 no.6
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• pp.427-432
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• 1997

A selective method for the determination of iron(III) ion with a sodium dodecyl sulfate(SDS) modified glassy carbon electrode was proposed. It was based on the electrostatic attraction and complexation of the SDS modifier, $(DS^-)_n-Fe^{3+}$. The determination of iron(III) ion was performed by a differential pulse voltammetry(DPV), and the reduction peak potential of $(DS^-)_n-Fe^{3+}$ was +0.466(${\pm}0.002$)V vs. Ag/AgCl. For the determination of iron(III) ion, a linear calibration curve was obtained within the iron(III) ion concentration range of $0.50{\times}10^{-5}{\sim}10{\times}10^{-5}mol/L$, and the detection limit was $0.14{\times}10^{-5}mol/L$. $Cu^{2+}$, $Ni^{2+}$, $Co^{2+}$, $Pb^{2+}$, $Zn^{2+}$, and $Mn^{2+}$ showed little or no effect on the determination of iron(III) ion, respectively. But, ion such as each $CN^- $ and $SCN^-$ interfered seriously.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.14-21
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• 1982

Analytical methods for residues of six N-methylcarbamate insecticides were investigated to compare the minimum detectability, recovery from several crops and feasibility of multiple residue analysis. Those methods studied in this work included spectrophotometry by diazotization and gas chromatography by N-trifluoroacetylation(TFA), pentafluorobenzylether(PFB) and dinitrophenylether (DNP) derivatization. Maximum absorbed wavelength of the diazotized MIPC, XMC, BPMC, propoxur and carbofu ran was around 460 ㎚, while that of carbaryl recorded 510 ㎚. Recovery from brown rice and apple by diazotization method ranged from 80 to 120% and minimum detectable limits were 0.03 to 0.05 ppm in 50 g of the sample. Minimum detectability of PFB derivatives by gas chromatography was superior to TFA and DNP derivatives. DNP derivatives showed the longest retention time among the given derivatives. Recovery from crops by gas chromatographic met hod ranged 74 to 94%, 78 to 93%, and 85 to 99% in brown rice, rice straw and apple, respectively. Limit of detection was 0.01 ppm for TFA, 0.005 ppm for PFB and 0.02 ppm for DNP derivatives in 50 g of the crop samples.

• Journal of the Korean Chemical Society
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• v.48 no.3
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• pp.266-272
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• 2004

We developed a miniaturized solid-state carbonate ion-selective electrode (carbonate ISE) based on one-component room temperature vulcanizing type silicone rubber 730 (730 RTV) without adding plasticizer to the matrix. The optimized carbonate ion selective membrane is prepared with 85.8 wt% of 730 RTV, 11.1 wt% of trifluoroacetyl-p-decylbenzene (TFADB), and 3.1 wt% of tridodecyl-methylammonium chloride (TDMACl). This carbonate ISE exhibited excellent potentiometric properties (i.e., slope: 26.3 mV/dec; selectivity: $logKT^{pot}_{CO_{2},Cl^-}$= -4.00 and $logKT^{pot}_{TCO_{2},Sal^-}$=1.69); and detection limit for $TCO_2:\;4.0{\times}10^{-4}M$). In addition, the early potentiometric properties of the solid-state sensor with optimized membrane composition were not deteriorated for more than 60 days.

• Journal of Preventive Medicine and Public Health
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• v.35 no.4
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• pp.282-286
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• 2002

Objectives : The level of 4-hydroxyproline (4-Hyp) in human urine was measured using high performance liquid chromatography (HPLC) with a fluorescence detector. This method is useful for medical examinations and investigating the radicals induced by physical, chemical, mental stresses. This method is superior to many published several methods in terms of its low cost and ability to analyze many samples. Methods : The urine from workers in a tire manufacturing company (22 male pre- and post-shift workers) and 18 office-workers as controls were analyzed. Data concerning age, the cumulative drinking amount and the cumulative smoking amount was collected with a questionnaire. The optimum applied amount of dansyl-Cl, the optimum reaction temperature and time, the recoveries and the optimum pH of the eluent and buffer were determined.4-Hyp from human urine was derivatized with dansyl-Cl (dimethylamino-naphthalene-1-sulfonyl chloride) after removing the a-amino acid by a treatment with phthalic dicarboxaldehyde (OPA) and cleaned with Bond Elut C18 column. The 4-Hyp derivatives were separated on a reversed phase column by gradient elution with a phosphate buffer (5 mmol, pH 8.0) and acetonitrile, and detected by fluorescence measurements at 340 nm (excitation) and 538 nm (emission). Results : The detection limit for the urinary free 4-Hyp was $0.364{\mu}mol/l$. The recovery rate of 4-Hyp was 99.7%, and the effective pH of the phosphate buffer and borate buffer were 3.0 and 8.0, respectively. From statistical analysis, age, drinking and smoking did not affect the urinary free 4-Hyp in both the controls and workers. The range of urinary 4-Hyp in the controls, pre-shift, and post-shift workers were 0.33-16.44, N.D-49.06, and $0.32-56.27{\mu}mol/l$. From the pared-sample t-test, the urinary 4-Hyp levels in post-shift workers ($11.82{\pm}6.73\;nmmol/mg\;Cre$) were 2-fold higher than in pre-shift workers ($5.36{\pm}5.53\;nmol;/mg\;Cre$) and controls ($4.91{\pm}4.89\;nmol;/mg\;Cre$). Conclusions : This method was developed with high sensitivity, accuracy, and precision. The present method was effectively applied to analyze the urinary free 4-Hyp in both controls and workers.

• Food Science of Animal Resources
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• v.32 no.4
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• pp.483-490
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• 2012

Ready-to-eat chicken breasts were packaged in a multilayer, gas-tight tray with top film and various quality changes were investigated during the 24 wk of storage at $10^{\circ}C$. Over the storage period, total aerobes, mesophilic aerobic and anaerobic spore formers, and Clostridium spp. were not detected above 1.0 log CFU/g (detection limit). The residual oxygen ratio in the head space of tray and pH values tended to decrease with storage time, namely from initial values of 5.7% and 6.56 to 3.3% and 6.34 at week 24, respectively. Thiobarbituric acid reactive substances and volatile basic nitrogen values increased from 0.52 mg malonaldehyde (MA)/kg and 2.1 mg/100 g initially, to 3.70 mg MA/kg and 39.9 mg/100 g at week 24, respectively. In terms of the change in meat color during storage, the samples showed a slight increasing trend of CIE $a^*$, $b^*$, and ${\Delta}E$ values over the storage period until week 24 (p<0.05). The change in brine color showed a similar trend with meat of which Hunter $b^*$ and ${\Delta}E$ values increased slightly during storage during 24 wk (p<0.05). The values for the transmittance degree of brine in the samples tended to decrease. Moreover, values for the absorbance degree tended to increase with storage time until week 24. The sensory scores for color, texture, odour, and flavour were evaluated below 5.0 (marketability level) after 24 wk of storage. Based on this sensory evaluation, it could be concluded that retorted RTE chicken breast could remain marketable for at least 20 wk at $10^{\circ}C$.

• Journal of Radiation Industry
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• v.6 no.4
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• pp.299-304
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• 2012

The quality properties of freeze-dried apples, pears, strawberries and pineapples gamma-irradiated at 0, 1, 2, 3, 4, and 5 kGy were evaluated to develop germ-free products for immuno-compromised patients. The initial count of total aerobic bacteria in non-irradiated apples, pears, strawberries and pineapple was 2.5, 3.1, 2.6, and $3.2{\log}\;CFU{\cdot}g^{-1}$, respectively. Microorganisms were not observed in apples after 1 kGy, in pears and strawberries after 4 kGy, and in pineapples at 5 kGy within a detection limit of $10{\log}\;CFU{\cdot}g^{-1}$. In addition, the sterilization of each sample was confirmed at the same dose. The score for the overall acceptance of freeze-dried fruit irradiated at a sterilization dose was 5.5 for apples, 4.1 for pineapples, and 4.0 for the other fruits, whereas that of non-irradiated control sample was 5.6 for apples, 5.2 for pears, and 5.8 for strawberries and pineapples with a 7-point scale. As a result, gamma irradiation of 1 kGy for apples, 4 kGy for strawberries and pears, and 5 kGy for pineapples is sufficient to sterilize each freeze-dried fruit with acceptable sensory properties.

• Analytical Science and Technology
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• v.19 no.5
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• pp.383-388
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• 2006

Simple post-wash method by ion chromatography (IC) was established for the rapid and precise determination of fluoride ion in wastewater from mine in fluorite mineralized area. High sulfate in sample was retained in a pre-column and less strongly held fluoride ion was transferred to the principal separation system using modified conventional IC with switching technique. An analytical column with high capacity (AS 9 HC) was used as a pre-column to retain the amount of high sulfate. A guard column (AG 14) as a separation column was used to increase the response of fluoride and reduce the system pressure. According to the recovery of fluoride ion with one detector and the observation of sulfate peak with another conductivity detector, the optimum switching time of 10-port chromatographic injector was 4.3 min. The limit of detection (S/N = 3) of fluoride in synthetic solution containing $500mg\;L^{-1}$ sulfate was $2.4{\mu}g/L$, with $25{\mu}L$ sample volume.

• Korean Journal of Organic Agriculture
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• v.32 no.2
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• pp.233-245
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• 2024

In a field study, we investigated the consequences associated with the irrigation of red pepper with water contaminated by three types of veterinary antibiotics (amoxicillin, oxytetracycline, and chlortetracycline) on the soil residue, the absorption-translocation, and crop yields. As a result of evaluating the residue of veterinary antibiotics in pepper cultivation soil treated with veterinary antibiotics a total of 7 times from June 7 to August 26, 2023, the three antibiotics were not detected at the background level, but in the group treated with 10-fold and 50-fold of the background level was detected at a level of 2-10 ㎍/kg. For the leaf (stem) and fruit of red pepper, all three types of veterinary antibiotics were found to be below the detection limit at all treatments. However, trace levels were detected in red pepper roots. If veterinary antibiotics are unintentionally introduced into agricultural soil in the short term, the soil environment and crop safety will not be a problem. However, long-term introduction of veterinary antibiotics in agricultural soil may have negative effects by affecting soil microbial diversity and antibiotic resistance problems, so continuous monitoring and risk assessment are deemed necessary.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.8
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• pp.952-956
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• 2017

An high performance liquid chromatography (HPLC) analysis method was developed for standard determination of coixol as a functional cosmetic material in Coix lachryma-jobi var. ma-yuen roots extract. HPLC was performed on a $C_{18}$ Unison US column ($4.6{\times}250mm$, $5{\mu}m$ column) using a gradient elution of 0.1% (v/v) trifluoroacetic acid and acetonitrile at a flow rate of 1.0 mL/min at $30^{\circ}C$. The analyte was detected at 290 nm. The HPLC method was validated in accordance with the International Conference on Harmonization guideline of analytical procedures with respect to specificity, precision, accuracy, and linearity. The limit of detection and quantitation were 0.07 and 0.25 mg/mL, respectively. Calibration curves showed good linearity ($R^2$>0.9995), and the precision of analysis was satisfied (less than 0.29%). Recoveries of quantified compounds ranged from 98.36 to 100.30%. This result indicates that the established HPLC method is very useful for the determination of a marker compound in C. lachryma-jobi var. ma-yuen roots extracts.

• Journal of Food Hygiene and Safety
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• v.26 no.3
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• pp.214-221
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• 2011

Deoxynivalenol (DON) and zearalenone (ZEN) are mainly contaminated mycotoxins in feeds. The study was carried out to analyze and survey the contamination of DON and ZEN in one hundred thirteen samples of feeds. After cleaning all samples with immunoaffinity column, the mycotoxins were analysed by using high performance liquid chromatography/fluorescence with diode array detector (HPLC/FLD with DAD). The average recoveries of DON were 88.76 and 95.40% at the levels of 200 and 1,000 ${\mu}g/kg$ and 87.09 and 98.40% of ZEN were recovered at the levels of 100 and 500 ${\mu}g/kg$, respectively. The limit of detection (LOD) were 6.0 and 3.0 ${\mu}g/kg$ for DON and ZEN, respectively. The average concentrations of DON were 372.1, 324.0 and 990.9 ${\mu}g/kg$ in chicken, pig and cattle feed, respectively. Those of ZEN were 76.1, 43.7 and 196.2 ${\mu}g/kg$ for them, individually.