• Analytical Science and Technology
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• v.22 no.3
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• pp.210-218
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• 2009

A gas chromatography-tandem mass spectrometry (GC-MS/MS) method was developed and validated for simultaneous determination of amphetamine derivatives and norketamine in human hair. Preparation of hair involves external decontamination, mechanical pulverization, incubation and extraction prior to instrumental analysis. The samples were derivatized using heptafluorobutyric anhydride, and analyzed by GC-MS/MS. The linear ranges were 0.05-20.0 ng/mg for the analytes except for 3,4-methylenedioxyamphetamine, with good coefficients of determination ($r^2$ >0.998). The intra-day and inter-day precisions were within 10.7% and 8.5%, respectively. The intra-day and inter-day accuracies were between -1.6 and 17.0% and -2.6 and 10.5%, respectively. The limits of detections for each analyte were lower than 0.007 ng/mg, while recoveries were 75.9-100.9%. When the method was applied to hair samples obtained from suspected drug abusers, the concentrations in hair samples were 0.97-19.30 ng/mg for methamphetamine and 0.14-2.56 ng/mg for amphetamine.

• Analytical Science and Technology
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• v.21 no.3
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• pp.191-200
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• 2008

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants in aquatic environmental samples. Therefore, it required rapidly and certainly analytical method for pharmaceuticals which are existed in environment. In this study, Liquid chromatography/tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI) was used to measure the concentrations of 7 pharmaceuticals (quinoxaline-2-carboxylic acid, acetylsalicylic acid, diclofenac-Na, naproxen, ibuprofen, mefenamic acid, talniflumate) from environmental water or aquatic samples simultaneously. Effective sample clean-up by solid-phase extraction (SPE) prior to LC-MS/MS analysis is necessary. For further purification, Mixed Cation eXchange (MCX) and Hydrophilic-Lipophilic Balance (HLB) solid-phase extraction (SPE) cartridges were used to eliminate the remaining interferences. LODs (Limits of Detection) and MDLs (Method Detection Limits) for the spiked sample in fresh water were in the range of 0.05~1.50 pg/mL and 0.17~4.90 pg/mL, respectively. The absolute recovery in the concentration of 1.0 ng/mL were between 81.9 and 116.3%. The acidic pharmaceuticals were detected in concentrations of 0.018~16.925 ng/mL in aquatic environmental samples.

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.24-33
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• 2021

For this study, we surveyed concentrations of 8 mycotoxins (aflatoxin B1, B2, G1, G2, ochratoxin A, fumonisin B1, B2 and zearalenone) in agricultural products used for food and medicine by liquid chromatography-tandem mass spectrometry and conducted a risk assessment. Samples were collected at the Yangnyeong Market in Seoul, Korea, between January and November 2019. Mycotoxins were extracted from these samples by adding 0.1% formic acid in 50% acetonitrile and cleaned up by using an ISOLUTE Myco cartridge. The method was validated by assessing its matrix effects, linearity, limit of detection (LOD), limit of quantification (LOQ), recovery and precision using four representative matrices. Matrix-matched standard calibration was used for quantification and the calibration curves of all analytes showed good linearity (r2>0.9999). LODs and LOQs were in the range of 0.02-0.11 ㎍/kg and 0.06-0.26 ㎍/kg, respectively. Sample recoveries were from 81.2 to 118.7% and relative standard deviations lower than 8.90%. The method developed in this study was applied to analyze a total of 187 samples, and aflatoxin B1 was detected at the range of 1.18-7.29 ㎍/kg (below the maximum allowable limit set by the Ministry of Food and Drug Safety, MFDS), whereas aflatoxin B2, G1 and G2 were not detected. Mycotoxins that are not regulated presently in Korea were also detected: fumonisin (0.84-14.25 ㎍/kg), ochratoxin A (0.76-17.42 ㎍/kg), and zearalenone (1.73-15.96 ㎍/kg). Risk assessment was evaluated by using estimated daily intake (EDI) and specific guideline values. These results indicate that the overall exposure level of Koreans to mycotoxins due to the intake of agricultural products used for food and medicine is unlikely to be a major risk factor for their health.

• Journal of Food Hygiene and Safety
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• v.31 no.6
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• pp.432-438
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• 2016

Ethoxyquin (EQ, 1,2-dihydro-6-ethoxy-2,2,4-trimethyl-quinoline) is quinoline-based antioxidant used in the animal feed and food industry to protect the raw materials and final products against oxidation. In recent years the use of synthetic antioxidants in fishmeal ingredients carry-over to farmed fish fillets has received increasing attention in food safety. This study was conducted to develop an analytical method to determine EQ in aquatic products. The analytes were confirmed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM). The sample was extracted with 1 N HCl (in case of flatfish extracted with 1 N HCl containing 10% acetonitrile). Then, solid phase extraction (SPE) was used for the cleanup. Standard calibration curves presented linearity with the correlation coefficient ($r^2$) > 0.99, analyzed at 0.005-0.2 mg/kg concentration. The developed method was validated according to the Codex Alimentarius Commission (CAC) guideline. The limits of quantitation for EQ were 0.01 mg/kg. Average recoveries ranged from 81.3% to 107%. The repeatability of measurements, expressed as the coefficient of variation (CV, %), was below 10%. The analytical method was characterized with high accuracy and acceptable sensitivity to meet CODEX guideline requirements and would be applicable to analyze the EQ residue in aquatic products.

• Clinical and Experimental Pediatrics
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• v.46 no.3
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• pp.295-301
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• 2003

Glutaric aciduria type 1(GA1) is an autosomal recessive disorder of the lysine, hydroxylysine and tryptophan metabolism caused by the deficiency of mitochondrial glutaryl-CoA dehydrogenase. This disease is characterized by macrocephaly at birth or shortly after birth and various neurologic symptoms. Between the first weeks and the 4-5th year of life, intercurrent illness such as viral infections, gastroenteritis, or even routine immunizations can trigger acute encephalopathy, causing injury to caudate nucleus and putamen. But intellectual functions are well preserved until late in the disease course. We report a one-month-old male infant with macrocephaly and hypotonia. In brain MRI, there was frontotemporal atrophy(widening of sylvian cistern). In metabolic investigation, there were high glutarylcarnitine level in tandem mass spectrometry and high glutarate in urine organic acid analysis, GA1 was confirmed by absent glutaryl-CoA dehydrogenase activity in fibroblast culture. He was managed with lysine free milk and carnitine and riboflavin. He developed well without a metabolic crisis. If there is macrocephaly in an infant with neuroradiologic sign of frontotemporal atrophy, GA1 should have a high priority in the differential diagnosis. Because current therapy can prevent brain degeneration in more than 90% of affected infants who are treated prospectively, recognition of this disorder before the brain has been injured is essential for treatment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.6
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• pp.828-834
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• 2016

The aim of this study was to evaluate the physicochemical properties and antioxidant and anti-proliferative activities of different plant parts of Elaeagnus umbellata Thunb. extracted with ethanol (EtOH). EtOH extract of stems presenting the highest content of polyphenols showed the strongest 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity ($EC_{50}=54.04{\mu}g/mL$). The total content of free amino acids decreased in the order of leaves (6,179.12 mg/100 g)> stems (1,211.69 mg/100 g)> fruits EtOH extract (378.88 mg/100 g), and asparagine (1,907.57 mg/100 g), ${\gamma}-aminobutyric$ acid (300.17 mg/100 g), and proline (233.48 mg/100 g) were the major free amino acid in leaves, stems, and fruits, respectively. Five phenolic compounds in each extract were measured by using liquid chromatography- tandem mass spectrometry, and gallic acid (98.95 mg/100 g) and (+)-catechin (1,575.99 mg/100 g) were present as major components in leaves and stems, respectively. EtOH extract of leaves showed the highest anti-proliferative activity against HepG2 cells as measured by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazoliumbromide and lactate dehydrogenase assay but had no effects on Chang liver cells.

• Korean Journal of Environmental Agriculture
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• v.39 no.3
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• pp.246-252
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• 2020

BACKGROUND: Pesticides are broadly used to control weeds and pests, and the residues remaining in crops are managed in accordance with the MRLs (maximum residue limits). Therefore, an analytical method is required to quantify the residues, and we conducted a series of analyses to select and validate the quick and simple analytical method for tolpyralate in five agricultural products using QuEChERS (quick, easy, cheap, effective, rugged and safe) method and LC-MS/MS (liquid chromatography-tandem mass spectrometry). METHODS AND RESULTS: The agricultural samples were extracted with acetonitrile followed by addition of anhydrous magnesium sulfate, sodium chloride, disodium hydrogencitrate sesquihydrate and trisodium citrate dihydrate. After shaking and centrifugation, purification was performed with d-SPE (dispersive-solid phase extraction) sorbents. To validate the optimized method, its selectivity, linearity, LOD (limit of detection), LOQ (limit of quantitation), accuracy, repeatability, and reproducibility from the inter-laboratory analyses were considered. LOQ of the analytical method was 0.01 mg/kg at five agricultural products and the linearity of matrix-matched calibration were good at seven concentration levels, from 0.0025 to 0.25 mg/L (R²≥0.9980). Mean recoveries at three spiking levels (n=5) were in the range of 85.2~112.4% with associated relative standard deviation values less than 6.2%, and the coefficient of variation between the two laboratories was also below 13%. All optimized results were validated according to the criteria ranges requested in the Codex Alimentarius Commission (CAC) and Ministry of Food and Drug Safety (MFDS) guidelines. CONCLUSION: In conclusion, we suggest that the selected and validated method could serve as a basic data for detecting tolpyralate residue in imported and domestic agricultural products.

• Korean Journal of Environmental Agriculture
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• v.39 no.2
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• pp.130-137
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• 2020

BACKGROUND: Mefentrifluconazole and triticonazole are the triazole fungicides. The maximum residue levels for agricultural products need to be set up. Therefore, development of the official analytical method for determination of mefentrifluconazole and triticonazole residues from agricultural crops was necessary due to safety management, and then a simultaneous analytical method was developed for the determination of mefentrifluconazole and triticonazole in agricultural crops. METHODS AND RESULTS: Samples were extracted using acetonitrile and purified using dispersive solid phase extraction, and then detected with liquid chromatograph-tandem mass spectrometry (LC-MS/MS). Matrix-matched calibration curves (0.0025-0.25 ㎍/mL) were linear into a sample extract with r²>0.99. For validation, the recovery test was carried out at three fortification levels (LOQ, 10 LOQ and 50 LOQ) from agricultural samples. The results for mefentrifluconazole and triticonazole ranged between 92.3 to 115.3% and 91.4 to 108.5%, respectively and RSD (relative standard deviation) values were also below 6.0%. Furthermore, inter-laboratory was conducted to validate the method. CONCLUSION: All values were corresponded with the criteria ranges requested by both the CODEX (CAC/GL 40-1993, 2003) and MFDS guidelines (2016). Therefore, the proposed method can be used as an official analytical method for determination of mefentrifluconazole and triticonazole (triazole fungicides) in the Republic of Korea.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.675-682
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• 2011

This study was conducted to monitor the concentrations of 24 anti-impotence drugs and their analogues in various foods and dietary supplements, with the aim of ensuring the safety of the foods and supplements. The measurements were done in 226 samples using high performance liquid chromatography/photodiode array detector (HPLC/PDA) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Five male sexual function enhancing products have been detected as follows: acethylvardenafil (21,476 mg/kg; 15 mg/capsule from one sample), sildenafil (52,778 mg/kg, 29 mg/capsule in one sample; 71,535 mg/kg, 48 mg/capsule in one sample), and tadalafil (9,772-55,545 mg/kg, 6-33 mg/capsule in four samples). A sustainable monitoring of anti-impotence drugs and their analogues in various foods and dietary supplement is recommended.

• Microbiology and Biotechnology Letters
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• v.38 no.1
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• pp.84-92
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• 2010

Antibacterial compound from Bacillus subtilis MJP1 was purified using C18 Sep-Pak cartridge, ion exchange chromatography, and gel filtration chromatography. The purified antibacterial compound showed antibacterial activity against Listeria monocytogenes, Bacillus subtilis, Staphylococcus aureus subsp. aureus, and Enterococcus faecalis. The purified antibacterial compound was found to be stable at $100^{\circ}C$ for 5 min and in the pH range of 3.0~9.0, but it was unstable at pH 10.0. It was inactivated by proteinase K and pronase E, and heat treatment at $121^{\circ}C$ for 15 min, but it was stable with lipase and $\alpha$-amylase treatment, which indicated its proteineous nature. Ultra performance liquid chromatography and electrospray ionization tandem mass spectrometry analysis were used to identify the purified antibacterial compound and confirmed the existence of two peptides (3356.54 Da, 3400.5244 Da).