• Clinical and Experimental Pediatrics
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• v.59 no.sup1
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• pp.41-44
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• 2016

We report here a case of maternal 3-methylcrotonyl-coenzyme A carboxylase (3-MCC) deficiency in a Korean woman. Her 2 infants had elevated 3-hydroxyisovalerylcarnitine (C5-OH) on a neonatal screening test by liquid chromatography-tandem mass spectrometry (LC-MS/MS), but normal results were found on urine organic acid analysis. The patient was subjected to serial testing and we confirmed a maternal 3-MCC deficiency by blood spot and breast milk spot test by LC-MS/MS, serum amino acid analysis, urine organic acid and molecular genetic analysis that found c.838G>T (p.Asp280Tyr) homozygous mutation within exon 9 of the MCCB gene. Especially, we confirmed marked higher levels of C5-OH on breast milk spot by LC-MS/MS, in the case of maternal 3-MCC deficiency vs. controls.

• Journal of Life Science
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• v.20 no.8
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• pp.1201-1206
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• 2010

We performed a comparative analysis using a Real-time PCR (Polymerase Chain Reaction) and LC/MS (Liquid-Chromatograph/Mass Spectrometer) method in order to detect microcystin in environmental sources. Among the three different primer sets tested for microcystin using three positive strains of Microcystis aeruginosa by Real-time PCR assay, only TOX2P/TOX2M primer pairs were able to detect Microcystis aeruginosa. According to the results of a survey carried out from June 2009 to September 2009, 11 out of 11 (100%) raw water samples were were found to have microcystin when the Real-Time PCR and LC/MS method was used, with total microcystin concentration ranging from 5.98~219.0 ${\mu}g/l$. A microcystin removal treatment process was used to ensure entire removal, by passing it through a BAC filtration step. It was concluded that real-time PCR assay can be used to estimate micrucystin detection more rapidly and easily than the LC/MS method.

• Journal of Pharmaceutical Investigation
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• v.37 no.3
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• pp.179-186
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• 2007

A simple, sensitive and selective liquid chromatographic/tandem mass spectrometric method (LC-MS/MS) was developed and validated for doxifluridine and 5-fluorouracil (5-FU) quantification in dog heparinized plasma. Sample preparation was based on liquid-liquid extraction using a mixture of isopropanol/ethyl acetate (1/9 v/v) to extract doxifluridine, 5-FU and 5-chlorouracil (5-CU, an internal standard) from plasma. Chromatography was performed on a C-18 analytical column and the retention times were 2.7, 1.5 and 1.7 min for doxifluridine, 5-FU and 5-CU, respectively with shorter analysis time within 5 min than previously reported methods. The ionization was optimized using ESI negative mode and selectivity was achieved by tandem mass spectrometric analysis by multiple reaction monitoring (MRM) using the transformations of m/z 244.8>107.6, 129.0>42.0 and 144.9>42.1 for doxifluridine, 5-FU and 5-CU, respectively. The achieved low limit of quantification was 20.0 ng/mL and the assay exhibited linear range of 20-2000 ng/mL ($R^2>0.99957$ for doxifluridine and $R^2>0.99857$ for 5-FU), using $100{\mu}L$ of plasma. Accuracy and precision of quality control samples for both doxifluridine and 5-FU met KFDA and FDA Guidance criteria of 15% for accuracy with coefficients of variation less than 15%. This method demonstrated adequate sensitivity, specificity, accuracy, precision and stability to support the simultaneous analysis of doxifluridine and 5-FU in dog plasma samples in pharmacokinetic and bioequivalence studies.

• Korean Journal of Clinical Pharmacy
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• v.16 no.1
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• pp.63-68
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• 2006

Gabapentin, 1-(aminomethyl-1-cyclohexyl)acetic acid, is anew antiepileptic drug related to ${\gamma}-aminobutyric$ acid(GABA) currently being introduced in therapy worldwide. The bioavailability and pharmacokinetics of gabapentin capsules were examined in 22 volunteers who received a single oral dose in the fasting state by randomized balanced $2{\times}2$ crossover design. After dosing, blood samples were collected for a period of 24 hours and analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). Time course of plasma gabapentin concentration was analyzed with non-compartmental and compartmental approaches. $WinNonlin^{(R)}$, the kinetic computer program, was used for compartmental analysis. One compartment model with first-order input, first-order output with no lag time and weighting by $1/(predieted\;y)^2$ was chosen as the most appropriate pharmacokinetic model for the volunteers. The major pharmacokinetic parameters $(AUC_{0-24hr},\;AUC_{inf},\;C_{max}\;and\;T_{max})$ and other parameters $(K_a,\;K_{el},\;V_d/F\;and\;Cl/F)$ of $Gapentin^{TM}$ (test drug) and $Neurontin^{TM}$ (reference drug) were estimated by non-compartmental analysis and compartmental analysis. The 90% confidence intervals of mean difference of logarithmic transformed $AUC_{0-24hr}\;and\;C_{max}$ were $log(0.9106){\sim}log(1.l254)\;and\;log(0.8521){\sim}log(1.0505)$, respectively. It shows that the bioavailability of the test drug is equivalent with that of the reference drug. There was no statistically significant difference between the two drugs in all pharmacokinetic parameters.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.419-424
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• 2014

Metabolite profiling of blueberry (cultivar "Spartan") was performed by extraction using different solvents, methanol and ethyl acetate, through metabolomic analysis using LC-MS/MS. Unsupervised classification method (PCA) and supervised prediction model (OPLS-DA) provided good categorization of metabolites according to the extraction solvents. Metabolites of the anthocyanin family, including delphinidin hexoside, delphinidin, 5-O-feruloylquinic acid, malvidin hexoside, malvidin-3-arabinoside, petunidin-3-arabinoside, and petunidin hexoside, were mainly detected in methanol fractions, whereas those of the flavonoid family, including chlorogenic acid, chlorogenic acid dimer, 6,8-di-C-arabinopyranosyl-luteolin, and luteolin were successfully prepared in the ethyl acetate fraction. Thus, metabolomic analysis of blueberry extracts allows for the simple profiling of whole and distinctive metabolites for future applications.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.12.1-12.7
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• 2011

Objectives: Perchlorate is an emerging contaminant that is found everywhere, including various foods. Perchlorate is known to disturb the production of thyroid hormones and leads to mental disorders in fetuses and infants, as well as metabolic problems in adults. In this study, we attempted to establish an LC-MS/MS method for measuring perchlorate in dairy products and used this developed method to investigate perchlorate levels in Korean milk and yogurt samples. Methods: The developed method of perchlorate analysis requires a shaker and 1% acetic acid/acetonitrile as the extracting solvent. Briefly, the samples were extracted and then centrifuged (4000 rpm, 1hour), and the supernatant was then passed through a $Envi^{TM}$ Carb SPE cartridge that had been prewashed sequentially with 6 mL of acetonitrile and 6 mL of 1% acetic acid in water. The final volume of the sample extract was adjusted to 40 mL with reagent water and the final sample was filtered through a 0.20-${\mu}m$ pore size PTFE (Polytetrafluoroethylene) syringe filter prior to LC-MS/MS. Results: The average levels of perchlorate in milk and yogurt samples were $5.63{\pm}3.49\;{\mu}g/L$ and $3.65{\pm}2.42\;{\mu}g/L$, respectively. The perchlorate levels observed in milk samples in this study were similar to those reported from China, Japan, and the United States. Conclusions: The exposure of Koreans to perchlorate through the consumption of dairy products was calculated based on the results of this study. For all age groups, the calculated exposure to perchlorate was below the reference of dose (0.7 ${\mu}g/kg$-day) proposed by the National Academy of Science, USA, but the perchlorate exposure of children was higher than that of adults. Therefore, further investigation of perchlorate in other food samples is needed to enable a more exact assessment of exposure of children to perchlorate.

• Mass Spectrometry Letters
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• v.12 no.1
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• pp.21-25
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• 2021

We aimed to develop and validate a sensitive analytical method of nannozinone A, active metabolite of Nannochelins A extracted from the Myxobacterium Nannocytis pusilla, in mouse plasma using a liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mouse plasma samples containing nannozinone A and 13C-caffeine (internal standard) were extracted using a liquid-liquid extraction (LLE) method with methyl tert-butyl ether. Standard calibration curves were linear in the concentration range of 1 - 1000 ng/mL (r2 > 0.998) with the inter- and intra-day accuracy and precision results less than 15%. LLE method gave results in the high and reproducible extraction recovery in the range of 78.00-81.08% with limited matrix effect in the range of 70.56-96.49%. The pharmacokinetics of nannozinone A after intravenous injection (5 mg/kg) and oral administration (30 mg/kg) of nannozinone A were investigated using the validated LC-MS/MS analysis of nannozinone A. The absolute oral bioavailability of nannozinone A was 8.82%. Plasma concentration of nannozinone A after the intravenous injection sharply decreased for 4 h but plasma concentration of orally administered nannozinone A showed fast distribution and slow elimination for 24 h. In conclusion, we successfully applied this newly developed sensitive LC-MS/MS analytical method of nannozinone A to the pharmacokinetic evaluation of this compound. This method can be useful for further studies on the pharmacokinetic optimization and evaluating the druggability of nannozinone A including its efficacy and toxicity.

• Korean Journal of Medicinal Crop Science
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• v.16 no.4
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• pp.231-237
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• 2008

This study was conducted to determine the amount of flavonoids in Salicomia herbacea L. grown by a liquid chromatography / mass spectrometry (LC/MS). The flavonoids-contained quercetin (124.43 ppm), rutin (2.57 ppm), quercetin-3-${\beta}$-glucoside (3992.49 ppm), quercetin-3',4'-glucoside (0.08 ppm) and isorhamnetin (27.81 ppm) were detected in the powder sample. In particular, quercetin-3-${\beta}$-glucoside accounted for more than 99% in hay and 96% in powder. These results suggest that S. herbacea, which is one of halophyte plants, has high functional substances as an antioxidant source.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3727-3734
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• 2012

An analytical method has been developed for the rapid determination of perfluorinated compounds (PFCs) in human serum samples. The extraction and purification of PFCs from human serum were performed by the modified method of previous report. Ten PFCs were rapidly separated within 3.3 min by C18-monolithic column liquid chromatography (LC) and detected by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) in negative ion mode. The runtime of PFCs on monolithic column LC was up to 4-fold faster than that on conventional column LC. The effect of triethylamine (TEA) to the mobile phase has investigated on the overall MS detection sensitivity of PFCs in ESI ionization. Quantification was performed by LC-MS/MS in multiple-ion reaction monitoring (MRM) mode, using $^{13}C$-labeled internal standards. Method validation was performed to determine recovery, linearity, precision, and limits of quantification, followed by, the analysis of a standard reference material (SRM 1957 from NIST). The overall recoveries ranged between 81.5 and 106.3% with RSDs of 3.4 to 16.2% for the entire procedure. The calibration range extended from 0.33 to 50 $ng\;mL^{-1}$, with a correlation coefficient ($R^2$) greater than 0.995 and the limits of quantification with 0.08 to 0.46 $ng\;mL^{-1}$. This approach can be used for rapid and sensitive quantitative analysis of 10 PFCs in human serum with high performance and accuracy.

• Analytical Science and Technology
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• v.37 no.1
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• pp.1-11
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• 2024

In agricultural households cultivating vegetables and fruits, the use of various pesticides to protect crops from diseases and pests or to control weeds is widely practiced enhancing quality and productivity. However, pesticides can pose a threat to consumer health by remaining on the food surface or migrating into the food interior. Households commonly peel off skins, wash with water, or use chemical methods to remove foreign substances including residual pesticides on the food surface. In this study, we measured the washing rate by comparing the pesticide concentrations before and after washing in the leafy vegetable perilla leaves and the fruits strawberries and apples, which were intentionally exposed to pesticides. We compared washing rates using tap water, a baking soda solution, and a commercially available food-specific cleaning solution. The target pesticides for analysis were azoxystrobin, bifenthrin, boscalid, difenoconazole, flubendiamide, and indoxacarb, and the residual pesticide analysis was performed using GC-MS/MS or LC-MS/MS. The removal rates of pesticides were highest with the food-specific cleaner, followed by baking soda and tap water in order.