• Korean Journal of Environmental Agriculture
• /
• v.14 no.1
• /
• pp.45-54
• /
• 1995

esters of the acid analytes were synthesized using $H_2SO_4$ as the catalyst. Efficiency of derivatization and instrumental molecular-response were compared with herbicides methylated with $BF_3-methanol$(14% W/V), $H_2SO_4-methanol$(33% V/V), and diazomethane. The molecular integrity of TFE-2,4-D, TFE-dicamba, and TFE-mecoprop, in the mixture, was confirmed by the GC/MSD method. The TFE-Esterification efficiency was maximized by adjusting the volume of $H_2SO_4$ the reaction time, and temperature. Optimal efficiency for the herbicide mixture was obtained by adding 1 ml of $H_2SO_4$ and 1 ml of TFE to the dried sample and allowing the reaction to proceed at $22^{\circ}C$ for 8 hr or using 0.5 ml $H_2SO_4$ and 1 ml of TFE at $60^{\circ}C$. For 120 min increasing the temperature and decreasing the reaction time were required for maximum esterification efficiency. The sensitivity of the GC/ECD to the TFE esters was about $2{\sim}20$ times greater than that to the methyl ester derivatives. The herbicides were extracted and esterified to TFE derivatives simultaneously from soil leachates previously spiked with the analytes. Herbicide recovery, peak resolution, and detector sensitivity were excellent without using column cleanup procedures.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2002.04a
• /
• pp.49-51
• /
• 2002

To identify and evaluate the dichlorobenzidine(DCB)-DNA adducts in liver cell and bladder epithelial cells by $^{32}$ P-postlabeling and GC/MS-SIM, we orally exposed the dichlorobenzidine (20mg/kh body wt.,/day)to male sprague-dawley rats for 14 days. Two kinds of DCB-DNA adduct were found at the same site of thin layer chromatogram of $^{32}$ P-postlabeling method in liver cells and bladder epithelial cells. In liver cells, relative adduct labeling(RAL) $\times$ 10$^{12}$ of DCB-DNA adduct A1 were 34.1$\pm$3.71 and 69.9$\pm$5.02, that of adduct A2 were 74.1$\pm$10.1 and 105.1$\pm$10.1 on 10 and 14 days after treatment, respectively. And in bladder epithelia cells, RAL $\times$ 10$^{12}$ of DCB-DNA adduct A1 were 5.92$\pm$1.60 and 15.9$\pm$1.31, that of adduct A2 were 9,81$\pm$2.81 and 22.8$\pm$1.79 on 10 and 14 days after treatment, respectively. DCB metabolites formed DNA adducts were monoacetyl-dichlorobenzidine(acDCB) and diacety1-dichlorobenzidine(di-acDCB), which was identify by gas chromatography/mass spectrometry-scan ionization mode(GC/MS-SIM), along with hydrolysis, extraction and TFA(trifluoroacetyl anhyride) derivatization with DCB-DNA adducts isolated from live cells and bladder epithelial cells. The base peak of acDCB were 252 and 294 m/z, and that of di-acDCB were 252, 294 and 336 m/z. In conclusion, the exposed DCB formed two kinds of DCB-DNA adduct, the proximate materials of that were acDCB and di-acDCB in liver and bladder epithlial cells. And the above GC/MS-SIM method was found the DCB-DNA adducts could be monitoring by gas chromatography.

• The Korean Journal of Food And Nutrition
• /
• v.20 no.4
• /
• pp.440-449
• /
• 2007

The purpose of this study was to examine the effects of taurine supplementation on serum lipidperoxide(TBARS), a risk factor for cardiovascular disease. The subjects were 22 healthy middle-aged women(33 to 54 years). Serum lipids, thiobarbituric acid reactive substances(TBARS), and plasma taurine levels were measured before and after supplying 3 g of taurine per day for 4 weeks. Plasma taurine was analyzed by Dabsyl-Cl(4-dimethylamino azobenzen-4-sulfonyl-chloride) derivatization and reversed-phase HPLC. Serum TBARS was measured by the Yagi method. Daily dietary taurine intake was calculated by food frequency questionnaire method. The weight and height means of the 22 subjects were $57.9{\pm}5.2$ kg and $159.2{\pm}5.2$ cm, respectively. Their percent body fat and waist/hip ratio(WHR) were 26.8% and 0.84, respectively, which were slightly higher than the average for middle-aged Korean women. Serum TC, TG and LDL-C levels tended to decrease after taurine supplementation, but HDL-C was not changed. A positive correlation between plasma taurine and HDL-C was shown after taurine supplementation. The serum TBARS concentration was significantly decreased from $5.05{\pm}0.84nmol/d{\ell}$ to $4.17{\pm}0.64nmol/d{\ell}$ after taking taurine(p<0.01), and the plasma taurine concentration was significantly increased from $63.7{\pm}14.2{\mu}mol/{\ell}$ to $73.8{\pm}16.6{\mu}mol/{\ell}$ after taurine supplementation(p<0.05). The average dietary intake of taurine was $178.5{\pm}50.4$ mg/day, which is similar to the average daily taurine intake of Korean women. In conclusion, taurine is an effective nutrient that antagonizes TBARS levels. Therefore, this study suggests that a sufficient taurine intake may be an effective way to prevent cardiovascular disease such as atherosclerosis.

• The Korean Journal of Pesticide Science
• /
• v.14 no.1
• /
• pp.16-20
• /
• 2010

Thiosultap, a nereistoxin analog insecticide, registered in China has been used to control selected beetles and Lepidopteran pests on rice, vegetables and fruit trees. Although domestic use of thiosultap is not permitted, it is needed to monitor this insecticide from imported crops because that has been used on crops in many foreign countries, especially China. Thiosultap in hulled rice was determined as nereistoxin derived in basic condition by GC-FPD. This method accomplished ion-associated liquid-liquid partitioning for cleanup, and limit of quantification and linearity performed by the established method were 0.05 mg $kg^{-1}$ and 0.995$(r^2)$. The recoveries performed by control hulled rice fortified with thiosultap at 0.5 and 2.5 mg $kg^{-1}$ were $96.1{\pm}7.9\sim100.8{\pm}6.1%$.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.9 no.2
• /
• pp.167-176
• /
• 1999

A new analytical procedure for the measurement of monomeric isocyanates and total isocyanate group in workplaces has been investigated. The method described herd involves derivatization of the isocyanate sample upon collection with the reagent 9-anthracenylmethyl 1-piperazinecarboxylate (PAC). Laboratory investigations have demonstrated that excess PAC reagent can be satisfactorily removed from PAC-derivatized monomeric isocyanates-a requirement for the success f the analytical procedure. After removal of excess PAC reagent, the PAC derivatives of butyl isocyanate, phenyl isocyanate, HDI, MDI, and TDI were reacted with sodium thiomethoxide to convert them all to 9-anthracenylmethyl methyl sulfide (AMMS). Total isocyanate group was determined by HPLC analysis and quantification of the single AMMS peak. This circumvents many of the disadvantages associated with current HPLC methods. There were no longer problems associated with quantifying late-eluting peaks and analysis times were very short. A single detector was used for quantification because a standard of the analyte existed and the retention time could be determined. Because all species were converted to a single analyte, the problem of variability of response factors among different species was averted. Finally, there were no complex chromatograms to interpret. Monomers of other individual species were measured by analysis of the sample before the individual species were converted to AMMS. The favorable performance of PAC warrants its further study as a reagent for the determination of total isocyanate group in air.

• Analytical Science and Technology
• /
• v.8 no.3
• /
• pp.229-236
• /
• 1995

Multiple-step gradient method was used for the analysis of free amino acids in physiological fluids by high-performance liquid chromatography with diode array detector on the Amino Quant $C_{18}$ column under the condition of pH 7.2 of buffer solutions. Plasma samples of normal Korean people and abnormal Korean people who have schizophrenia were subjected to derivatization with o-phthalaldehyde in the presence of 3-mercaptopropionic acid. Quantitative analysis of amino acids in physiological fluids by internal standard method gave highly reproducible results within a relative standard deviation of less than 2~6%. And amino acids amounts of physiological fluids of Korean people gave some different results from those of foreigners. There was large differences in tyrosine amount between normal and abnormal man.

• Analytical Science and Technology
• /
• v.14 no.6
• /
• pp.499-503
• /
• 2001

A new simple, rapid and sensitive gas chromatographic technique for the determination of bisphenol-A in can materials, which is the major material of epoxy resin and polycarbonate polymer, is proposed. This method is characterised by derivatization of the bisphenol-A with a acylating reagent forming the acetate derivative to optimize the chromatographic property. The detection of bisphenol-A is performed based on GC/MS (gas chromatography/mass spectrometry). Several beverages were analyzed by the proposed method for the determination of bisphenol-A Bisphenol-A was assayed the range of $0.11{\sim}11.40{\mu}g/can$ from the can materials.

• Journal of Applied Biological Chemistry
• /
• v.59 no.2
• /
• pp.165-169
• /
• 2016

The quantitative analytical method for the bioactive substance, 3-cyano-4-methoxy-N-methyl-2-pyridone (ricinine) and an index compound, ricinoleic acid in castor plant (Ricinus communis) extract or oil was developed. For the determination of a pyridone alkaloid compound, ricinine, successive cartridge cleanup method combined with ultra-performance liquid chromatography was set up with $ENVI-Carb^{TM}$ (0.5 g) and $C_{18}$ SPE cartridges. Accuracy and precision were evaluated through fortification studies of one biopesticide (PE) at 10 and $100mg\;kg^{-1}$. Mean recoveries of ricinine were 98.7 and 96.0 % associated with less than 10 % RSD, respectively. For the determination of ricinoleic acid in castor extract and oil, saponification and methylation were optimized using gas chromatography-time of flight mass spectrometry. Recovery was more than 84.8 % associated with 6.2 % RSD after derivatization procedure. Both methodologies developed were applied to analyze real samples including three castor oil products and six commercially available biopesticides containing R. communis, collected at Korean market. The contents of ricinine and ricinoleic acid in most commercial biopesticides were less than the oil or extract contents indicated by label.

• Journal of Food Hygiene and Safety
• /
• v.31 no.2
• /
• pp.85-93
• /
• 2016

A rapid method using HPLC-MS/MS has been developed for quantitative determination of the metabolites of nitrofurans, namely 3-amino-2-oxazolidone (AOZ), 5-morpholinomethyl-3-amino-2-oxazolidinone (AMOZ), 1-ammino-hydantoin (AHD) and semicarbazide (SEM) in loach. The extraction procedure was founded on simultaneous acidic hydrolysis and derivatization using 2-nitrobenzaldehyde (2-NBA) for 1 hour at $50^{\circ}C$, followed by purification with liquid-liquid extraction. Recovery was evaluated by spiking standards into blank samples at three levels (0.5, 1.0 and $2.0{\mu}g/kg$), and the mean recovery was 75.1-108.1%. Precision values expressed as the relative standard deviation (%RSD) were ${\leq}8.7%$ and ${\leq}8.5%$ for intra-day and inter-day precision, respectively. Linearity was studied in the range of $0.2-20{\mu}g/Kg$ for NBAOZ, $0.8-20{\mu}g/Kg$ for NBAMOZ, $0.2-20{\mu}g/Kg$ for NBAHD, and $0.1-20{\mu}g/Kg$ for NBSEM, and the obtained coefficient correlations (r) were ${\geq}0.99$ for all compounds. Limits of detection (LODs) for the derivatized nitrofuran metabolites were established at $0.06{\mu}g/Kg$ for NBAOZ, $0.24{\mu}g/Kg$ for NBAMOZ, $0.06{\mu}g/Kg$ for NBAHD, and $0.03{\mu}g/Kg$ for NBSEM. Limits of quantification (LOQs) were established at $0.2{\mu}g/Kg$ for NBAOZ, $0.8{\mu}g/Kg$ for NBAMOZ, $0.2{\mu}g/Kg$ for NBAHD, and $0.1{\mu}g/Kg$ for NBSEM. This simplified rapid method for reducing the derivatization and hydrolysis times can be applied to the determination of nitro-furan residues in loach.

• Analytical Science and Technology
• /
• v.33 no.3
• /
• pp.115-124
• /
• 2020

Marker pens belong to school things that are controlled by the regulation system called safety confirmation under special act on the safety of products for children with the formaldehyde criteria of 20 mg/kg. With nine marker pens available commercially, formaldehyde in marker pen ink was analyzed by present test standard where marking on a fabric swatch with a pen and extracting the swatch in water and derivatization with Nash reagent followed by UV/Vis spectrophotometeric measurement (Nash-UV/Vis method), giving not detected results or a false positive result in case of a colored water extract. However, the contents of formaldehyde in ink of nine marker pens were determinded to range between 3.2 ~ 93.2 mg/kg with three results above the safety criteria of 20 mg/kg by HPLC/DAD measurements on DNPH derivatives of formaldehyde (DNPH-HPLC/DAD method) in ink dissolved directly in water using an ultrasonic bath. Therefore, the DNPH-HPLC/DAD method with the extraction of ultrasonic dissolving ink in water is proposed as a proper method for analyzing formaldehyde in ink. The proposed method has advantages of lower detection limit and accuracy with colored extracts as well as a simple and fast extraction. The accuracy and precision of this method was estimated to be 90.1 ~ 105.4 % and 0.6 ~ 3.3 %, respectively by spiking tests in the ranges of 20 mg/kg and 40 mg/kg using matrixes such as highlighter pen ink, board marker ink, chalk marker pen ink and painter marker ink.