• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.166-174
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• 2016

BACKGROUND: The current study developed a monitoring method of 6 veterinary antibiotics (amoxicillin, ampicillin, enrofloxacin, tetracycline, chlortetracycline, oxytetracycline) in agricultural soils using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive electrospray ionization mode.METHODS AND RESULTS: Sample preparation was carried out using acidic acetonitrile and citrate salts followed by purification with dispersive solid phase extraction (d-SPE). Separation on Eclipse Plus C₁₈ column was conducted in gradient of the mobile phase, 0.1% formic acid and 5 mM ammonium formate in methanol (A) and 0.1% formic acid and 5 mM ammonium formate in distilled water (B). The linearity of the matrix-matched calibrations expressed as the coefficient of determination was good with R²≥0.9900. The limit of quantifications (LOQs) ranged from 0.5 to 10 μg/kg for all analytes. Analysis of 51 agricultural soil samples taken in the Republic of Korea revealed concentrations less than 1.9 μg/kg for enrofloxacin, 75.5 μg/kg for chlortetracycline.CONCLUSION: The method was successfully applied to monitor 6 veterinary antibiotics from 51 field incurred agricultural soil samples in 17 provincial areas throughout the Republic of Korea. The developed method was simple, easy, and versatile and can be used for monitoring various veterinary antibiotics in soil.

• Analytical Science and Technology
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• v.34 no.6
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• pp.259-266
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• 2021

Cannabis (Marijuana) is one of the most widely used drugs in the world, and its distribution has been controlled in South Korea since 1976. Identification of 11-nor-Δ⁹-carboxy-tetrahydrocannabinol (THCCOOH) in urine can provide important proof of cannabis use, and it is considered scientific evidence in the forensic field. In this study, we describe a simultaneous quantitative method for identifying THCCOOH and THCCOOH-glucuronide in urine, using simple liquid-liquid extraction (LLE), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). THCCOOH-D₃ and THCCOOH-glucuronide-D₃ were used as internal standards. Validation results of the matrix effect, as well as recovery, linearity, precision, accuracy, process efficiency, and stability were all satisfactory. No carryover, endogenous or exogenous interferences were observed. The limit of detection (LOD) of THCCOOH and THCCOOH-glucuronide were 0.3 and 0.2 ng/mL, respectively. The developed method was applied to 28 authentic human urine samples that tested positive in immunoassay screening and gas chromatography/mass spectrometry (GC/MS) tests. The ranges of concentrations of THCCOOH and THCCOOH-glucuronide in the samples were less than LOQ~266.90 ng/mL and 6.43~2133.03 ng/mL, respectively. The concentrations of THCCOOH-glucuronide were higher than those of THCCOOH in all samples. This method can be effectively and successfully applied for the confirmation of cannabinoid use in human urine samples in the forensic field.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.4
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• pp.286-291
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• 2015

Equol has beneficial effects on human health. Fermented soy products contain equol, and many microbes participate in the equol production process. This study investigated fermented Korean soybean paste, doenjang. Thirty seven doenjang samples collected from different manufacturers were examined. Equol was detected in 3 samples (D2, D13, and D19) at the maximum content of 507 ng/100 g by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Fifteen microbial species were isolated and identified by 16S rRNA gene sequence analysis and by matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Bacillus spp, Paenibacillus spp, Tetragenococcus spp, Stapylococcus spp, and Clostridium species were the predominant bacteria in equol containing doenjang samples.

• Analytical Science and Technology
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• v.25 no.1
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• pp.25-32
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• 2012

Isotope dilution mass spectrometry (ID-MS) based on liquid chromatography tandem mass spectrometry (LC/MS/MS) was developed for the accurate determination of sorbic acid in tea-drink. An isotope analogue of sorbic acid, $^{13}C_2$-sorbic acid, was obtained by custom synthesis. MS was operated in the negative mode with selected reaction monitoring (SRM) mode of $[M-H]^-$ ${\rightarrow}$ $[M-CO_2H]^-$ channel at m/z 111 ${\rightarrow}$ 67 for sorbic acid and at m/z 113 ${\rightarrow}$ 68 for its isotope analogue. Chromatographic separation was accomplished with a C18 column and an isocratic mobile phase of 55% of 50 mM ammonium acetate (pH 4.5) and 45% of methanol. Homogeneous reference materials were prepared for validation of this method, including repeatability and reproducibility tests, by fortifying tea-drink with sorbic acid in our laboratory. Repeatability and reproducibility studies showed that the ID-LC/MS method is a reliable and reproducible method which provides less than 3.8% of relative standard deviation (RSD) for the analysis of sorbic acid.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.25-33
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• 2013

Clenbuterol and ractopamine, which are ${\beta}$-agonists, have been misused as a growth promoting agent in meat producing animals. Clenbuterol was banned for veterinary drug in Korea because of its problems regarding safety. Due to their adverse effects, such as cardiovascular and central nervous diseases on human health proper control and monitoring should be conducted. The existing analytical method of clenbuterol and ractopamine in the Food code was improved through our present study. The bovine muscle samples were subjected to enzymatic hydrolysis, extracted with ethyl acetate and defatted by hexane-methanol partitioning. A molecular imprinted polymer (MIP) solid phase extraction cartridge was used for clean-up and LC-MS/MS was operated in positive multiple reaction monitoring (MRM). Clenbuterol-$d_9$ and ractopamine-$d_3$ were used as an internal standard. The renewed method was validated according to the CODEX guideline. The limits of quantitation for clenbuterol and ractopamine were 0.2 and 0.5 ${\mu}g/kg$, respectively. The mean recoveries ranged in 104.2-113.5% for clenbuterol and in 107.6-118.1% for ractopamine. The improved method was able to save both time and expenses.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.05a
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• pp.18-18
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• 2010

Glucosinolates(GSLs) are major secondary products($\beta$-thioglucoside N-hydroxysulfates) containing sulfates that are found mainly in Cruciferae family such as cabbage, broccoli, radish, turnip, kale, mustard and rapeseed as the important crops in agronomic and economic aspects. Especially, isothiocyanates(ITCs) have been shown to inhibit carcinogenesis with regulation cancer cell development followed by regulating target enzymes, inducing cell cycle arrest and apoptosis against various human cancer cell lines. Total desulfo(DS)-GSLs of nine type in 210 Korean leaf mustard accessions were isolated and confirmed using electrospray ionization mass spectrometric(ESI-MS/MS) method and DS-GSLs powerful library maked from several reference data. The isolated individual DS-GSLs were identified by removed $\beta$-D-glucopyranose residue ($C_6H_{11}O_5$, MW 163) from MS/MS data. Among them sinigrin(41.7%), glucoiberverin(21.7%) and gluconasturtiin(12.6%) were major components, Especially, despite gluconapin was minor component, accession K046197-1 and K046197-2 showed higher content of 4.11 and 3.31 mg/g(DW), respectively. The total GSLs contents in 210 accessions were ranged from 5.3 to 23.2 mg/g(DW) with a mean value of 13.0 mg/g(DW). As a result of principal component analysis(PCA), the individual GSLs loading plots were composed of three groups and components belonged to each group showed correlationship in quantitative pattern.

• Mass Spectrometry Letters
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• v.10 no.1
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• pp.38-42
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• 2019

Damaurone D belongs to the genus Rosa and is a traditional medicinal product used for the treatment of depression, inflammation, and infectious diseases. The purpose of this study was to develop a simple liquid chromatography-tandem mass spectrometry method for the detection of damaurone D in rat plasma and to demonstrate its application in pharmacokinetic studies. Damaurone D and berberine (internal standard) were extracted with acetonitrile using a protein precipitation method. Mass transition was monitored in multiple reaction monitoring mode at m/z $323.2{\rightarrow}267.0$ for damaurone D and m/z $336.1{\rightarrow}320.0$ for berberine in positive ion mode. Analytical validation was conducted by evaluating the specificity, linearity, accuracy, precision, matrix effect, extraction recovery, and stability. The calibration curves were linear over 2-1000 ng/mL. The intra- and inter-day precision and accuracy of quality control samples were 4.79-13.33% and 86.23-102.75%, respectively. The matrix effect and extraction recovery were 96.11-98.47% and 96.11-102.25%, respectively. In the pharmacokinetic study after intravenous administration of damaurone D at a dose of 3 mg/kg in rats, the area under the curve and clearance of damaurone D in rat plasma were $16750.26{\pm}2676.10min{\cdot}ng/mL$ and $182.44{\pm}31.36mL/min/kg$, respectively.

• Analytical Science and Technology
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• v.28 no.1
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• pp.1-7
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• 2015

4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco specific nitrosamine found only in tobacco products. The ability to monitor biomarker concentrations is very important in understanding environmental tobacco smoke (ETS). In this study, an efficient and sensitive method for the analysis of NNK in dust was developed and validated using liquid chromatography tandem mass spectrometry. Dust was collected with filter paper soaked in methanol. The standard solution and dust sample were diluted with 100 mM ammonium acetate and extracted using dichloromethane. Our calibration curves ranged from 25 to $10^4pg/mL$. Excellent linearity was obtained with correlation coefficient values between 0.9996 and 1.0000. The limit of detection (LOD) was 5 pg/mL ($S/N{\geq}3$) and the retention time was 10 min. The limit of quantification (LOQ) was 25 pg/mL, and the acceptance criteria was the rate of 98-103% (80-120% at levels up to $3{\times}LOQ$). The coefficient of variations (CV) was 2.8%. Accuracies determined from dust samples spiked with four different levels of NNK racurves ranged that from 25 to 104 pg/mL. Excellent linearity was obtained between 92.1% and 114%. The precision of the method was acceptable (5% of CV). The recovery rates of the whole analytical procedure at low, medium, and high levels were 105.7-116.5% for NNK. The carry-over effects during LC-MS/MS analysis were not observed for NNK. This manuscript summarizes the scientific evidence on the use of markers to measure ETS.

• Journal of Applied Biological Chemistry
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• v.53 no.1
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• pp.25-30
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• 2010

This paper describes a simultaneous method for the determination of two aminoglycosides (neomycin and gentamicin) using solid phase extraction followed by liquid chromatograph-mass spectrometry. The extract was applied to an WCX and HLB solid phase extraction cartridge. The cartridges were washed with water and methanol, and analytes were eluted with TCA buffer-acetonitrile mixture. The aminoglycosides were separated by ion-pairing reversed phase mode prior to ESI-LC/MS. Under the conditions applied neomycin was almost separated from all the gentamicin compounds. No interfering peaks from endogenous compounds of matrix were noted at the elution position of the analytes. Recoveries of neomycin fortified at levels of 0.25, 0.5, 1.0 and 2.0 mg/kg seafood samples ranged from 92 to 115%. Recoveries of gentamycin fortified at levels of 0.05, 0.1, 0.2, 0.4 mg/kg seafood samples ranged from 99 to 116%. Method detection limits in four seafood sample matrices were between 0.002 and 0.033 mg/kg.

• Toxicological Research
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• v.31 no.3
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• pp.255-264
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• 2015

Heterocyclic amines (HCAs) and acrylamide are unintended hazardous substances generated by heating or processing of foods and are known as carcinogenic and mutagenic agents by the animal experiments. A simple method was established for a rapid and accurate determination of 12 types of HCAs (IQ, MeIQ, Glu-P-1, Glu-P-2, MeIQx, Trp-P-1, Trp-P-2, PhIP, $A{\alpha}C$, $MeA{\alpha}C$, Harman and Norharman) and acrylamide in three food matrices (non-fat liquid, non-fat solid and fat solid) by isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). In every sample, a mixture of internal standards including $IQ-d_3$, $MeIQx-d_3$, $PhIP-d_3$, $Trp-P-2-^{13}C_2-^{15}N$ and $MeA{\alpha}C-d_3$ was spiked for quantification of HCAs and $^{13}C_3$-acrylamide was also spiked for the analysis of acrylamide. HCAs and acrylamide in sample were extracted with acetonitrile and water, respectively, and then two solid-phase extraction cartridges, ChemElut: HLB for HCAs and Accucat: HLB for acrylamide, were used for efficiently removing interferences such as pigment, lipid, polar, nonpolar and ionic compounds. Established method was validated in terms of recovery, accuracy, precision, limit of detection, limit of quantitation, and linearity. This method showed good precision (RSD < 20%), accuracy (71.8~119.1%) and recovery (66.0~118.9%). The detection limits were < 3.1 ng/g for all analytes. The correlation coefficients for all the HCAs and acrylamide were > 0.995, showing excellent linearity. These methods for the detection of HCAs and acrylamide by LC-MS/MS were applied to real samples and were successfully used for quantitative monitoring in the total diet study and this can be applied to risk assessment in various food matrices.