• Korean Journal of Plant Tissue Culture
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• v.25 no.1
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• pp.27-31
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• 1998

Immature hybrid embryos of H. hybridum, 'Picottee', 'White Christmas', 'Eldorado', 'Origin', 'Red Lion', 'elstar', 'Crypsy' were cultured on the MS medium supplemented with various concentrations of 2,4-D, NAA, BA and TDZ. Among the treatments, NAA were more effective for the shoot regeneration and bulblet formation than other treatment. Addition of 0.5 ㎎/L NAA was effective for bulblet induction from explant Shoot regeneration was most effective on the medium with 1.0㎎/L NAA and 2.0 ㎎/L TDZ. The addition of 1.0-2.0㎎/L TDZ induced numerous shoots per explant but strongly inhibited root development when compared to 1.0-2.0㎎/L BA. When bulb scale segments of 'Star Van Holland' was incubated, bulblet formation was the most effective on MS medium with 0.5㎎/L NAA.

• Analytical Science and Technology
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• v.31 no.4
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• pp.161-170
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• 2018

The epidemic of disorders associated with synthetic stimulants, such as methamphetamine (MA) and amphetamine (AP), is a health, social, legal, and financial problem. Owing to the high potential of their abuse and addiction, reliable analytical methods are required to detect and identify MA, AP, and their metabolites in biological samples. Thus, a dilute-and-shoot liquid chromatography-tandem mass spectrophotometry (LC-MS/MS) was developed for simultaneous determination of MA, 4-hydroxymethamphetamine (4HMA), AP, and 4-hydroxyamphetamine (4HA) in urine. Urine sample ($100{\mu}L$) was mixed with $50{\mu}L$ of mobile phase consisting of 0.4 % formic acid and methanol and $50{\mu}L$ of working internal-standard solution. Aliquots of $8{\mu}L$ diluted urine was injected into the LC-MS/MS system. For all analytes, chromatographic separation was performed using a C18 reversed-phase column with gradient elution and a total run time of 5 min. The identification and quantification were performed by multiple reaction monitoring (MRM). Linear least-squares regression was conducted to generate a calibration curve, with $1/x^2$ as the weighting factor. The linear ranges were 2.0-200, 1.0-800, and 10-2500 ng/mL for 4HA and 4HMA, AP, and MA, respectively. The inter- and intraday precisions were within 6.6 %, whereas the inter- and intraday accuracies ranged from -14.9 to 11.3 %. The low limits of quantification were 2.0 ng/mL (4HA and 4HMA), 1.0 ng/mL (AP), and 10 ng/mL (MA). The proposed method exhibited satisfactory selectivity, dilution integrity, matrix effect, and stability, which are required for validation. Moreover, the purification efficiency of high-speed centrifugation was clearly higher than 6-15 % for QC samples (n=5), which was higher than that of the membrane-filtration method. The applicability of the proposed method was tested by forensic analysis of urine samples from drug abusers.

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.318-327
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• 2015

BACKGROUND: Trinexapac-ethyl is a plant growth regulator (PGR) that inhibits the biosynthesis of plant growth hormone (gibberellin). It is used for the prevention of lodging, increasing yields of cereals, and reducing mowing of turf. The experiment was conducted to establish a determination method for trinexapac-ethyl and its metabolites trinexapac in agricultural products using LC-MS/MS.METHODS AND RESULTS: Trinexapac-ethyl and trinexapac were extracted from agricultural products with methanol/ distilled water and the extract was partitioned with dichloromethane and then detected by LC-MS/MS. Limit of detection(LOD) was 0.003 mg/kg and limit of quantification(LOQ) was 0.01 mg/kg, respectively. Matrix matched calibration curves were linear over the calibration ranges (0.01-1.0 mg/L) for all the analytes into blank extract withr²> 0.997. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, 10LOQ, 50LOQ,n=5). Recoveries of trinexapacethyl and trinexapac were within the range of 73.6-106.9%, 72.7-99.2%, respectively. The relative standard deviations (RSDs) were less than 9.0%. All values were consistent with the criteria ranges requested in the CODEX guideline(CAC/GL 40, 2003).CONCLUSION: The proposed analytical method was accurate, effective and sensitive for trinexapac-ethyl and trinexapac determination and it can be used to as an official method in Korea.

• Journal of Plant Biotechnology
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• v.35 no.2
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• pp.155-161
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• 2008

This paper reported the establishment of mass production system of adventitious roots of Codonopsis lanceolata through shake flask and bioreactor culture. Induction of adventitious roots was started from the explants of leaf, stem and root on 1/2 strength Murashing and Skoog (MS) solid medium. Stem segments were the best explants for induction of adventitious roots compared to leaf and root segments. Among the different auxins tested (NAA, IBA and IAA), number of adventitious root per explant was highest on solid medium with 1.0 mg/L IBA, and produced $9.9{\pm}1.2$ roots per explant. However, growth of adventitious roots was fast in the presence of IBA at low concentration (0.1 mg/L). In shake flask culture, maximum production of adventitious roots (fresh weight) was obtained in half-strength MS medium compared to full-strength and one-third MS medium. When the adventitious roots produced in shake-flask culture were transferred to 5 L air-lift bioreactor, 16 times of fresh weight increase was gained after one month of culture. These results indicate that this protocol for the production of C. lanceolata adventitious roots can be applied to large scale culture for practical application.

• Korean Journal of Food Science and Technology
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• v.48 no.6
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• pp.531-535
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• 2016

Phlomis umbrosa and Dipsacus asperoides are distinct species, even though they have a similar appearance. Dipsacus asperoides is used as a Chinese medicinal plant for and has bone strengthening and fracture healing but Phlomis umbrosa has no effect on bone growth. Recently, these plants were used in children's food to improve their bone growth, without distinction in food. Intakes of Dipsacus asperoides in food may be dangerous, because it has never been used in food and its safety has never been tested in humans. We developed liquid chromatography with tandem mass spectrometry method to distinguish these plants in food. The method was validated for linearity, limits of detection, limits of quantification, accuracy and precision. In 5 of 17 samples, we identified Dipsacus asperoides, containing loganin $0.19-14.45{\mu}g/mL$, sweroside $0.13-4.61{\mu}g/mL$ and akebia saponin D $0.59-19.29{\mu}g/mL$. The developed method might be useful to identify Dipsacus asperoides in adulterated food.

• Journal of Food Hygiene and Safety
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• v.28 no.4
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• pp.376-380
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• 2013

Determination of PFOS in instant food packing materials by LC-MS/MS was developed. The procedure involves an extraction of the Food Packing Materials with 100% methanol soxcelet extraction method. The LC separation was performed by Hypersil Gold ($150mm{\times}2.1mm$ 5 um) with mobile phases of 2 mM amoniumacetate solution and acetonitrile. The Mass spectral acquisition was done in negative ESI/SRM using the TSQ Quantum Ultra. With this method, good linear relationship, sensitivity and reproducibility were obtained. The rate of recoveries of PFOS from paper material spiked with 1.0 ug/L were 99.84%, respectively. The limit of quantitation and limit of detection were below 0.03 ug/L and 0.009 ug/L. The method had been applied to determination of PFOS in instant food packing materials.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.5 s.347
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• pp.54-63
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• 2006

This work proposes a 14b 100MS/s 0.18um CMOS ADC with optimized resolution, conversion speed, die area, and power dissipation to obtain the performance required in the fourth-generation mobile communication systems. The 3-stage pipeline ADC, whose optimized architecture is analyzed and verified with behavioral model simulations, employs a wide-band low-noise SHA to achieve a 14b level ENOB at the Nyquist input frequency, 3-D fully symmetric layout techniques to minimize capacitor mismatch in two MDACs, and a back-end 6b flash ADC based on open-loop offset sampling and interpolation to obtain 6b accuracy and small chip area at 100MS/s. The prototype ADC implemented in a 0.18um CMOS process shows the measured DNL and INL of maximum 1.03LSB and 5.47LSB, respectively. The ADC demonstrates a maximum SNDR and SFDR of 59dB and 72dB, respectively, and a power consumption of 145mW at 100MS/s and 1.8V. The occupied active die area is $3.4mm^2$.

• Journal of Food Hygiene and Safety
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• v.36 no.3
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• pp.228-238
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• 2021

The aim of this research was to develop a rapid and easy multi-residue method for determining dimethipin, omethoate, dimethipin, chlorfenvinphos and azinphos-methyl in agricultural products (hulled rice, potato, soybean, mandarin and green pepper). Samples were prepared using QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) and analyzed using gas chromatography-tandem mass spectrometry (GC-MS/MS). Residual pesticides were extracted with 1% acetic acid in acetonitrile followed by addition of anhydrous magnesium sulfate (MgSO₄) and anhydrous sodium acetate. The extracts were cleaned up using MgSO₄, primary secondary amine (PSA) and octadecyl (C₁₈). The linearity of the calibration curves, which waas excellent by matrix-matched standards, ranged from 0.005 mg/kg to 0.3 mg/kg and yielded the coefficients of determination (R²) ≥ 0.9934 for all analytes. Average recoveries spiked at three levels (0.01, 0.1, 0.5 mg/kg) and were in the range of 74.2-119.3%, while standard deviation values were less than 14.6%, which is below the Codex guideline (CODEX CAC/GL 40).

• Journal of Plant Biotechnology
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• v.44 no.3
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• pp.330-334
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• 2017

To investigate optimal conditions for plant regeneration in Platycodon grandiflorum (Jacq. A. DC.).Both leaf and hypocotyl explants were cultured on Murashige& Skoog's (MS) medium supplemented with combinations of 0.1, 0.5, 1.0, or 2.0 mg/L cytokinins (BA and kinetin) and 1.0 mg/L 2,4-D for 6 weeks, respectively. According to the type of explant, the total shoot organogenesis (56.38%) in leaf explants was higher than in hypocotyls (28.20%). In comparison with kinetin and BA for the plant regeneration, the frequency (70.38%) of leaf explants was higher in combination with kinetin and 2,4-D than of BA with 2,4-D (42.38%), whereas the frequency (35.56%) of hypocotyls explants was higher in BA combination than kinetin combination (20.83%). Thehighest frequency (94.20%) was observed from the cultures of leaf explants on the MS medium supplemented with 1.0 mg/L kinetin and 1.0 mg/L 2,4-D. Upon transfer onto 1/2 MS basal medium containing 3% sucrose, shoots developed into plantlets with roots, and were well grown in soil in the greenhouse. These results lead us to speculate that the optimization of culture conditions was responsible for the mass propagation from in vitro cultures of Platycodon grandiflorum (Jacq. A. DC.).

• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.387-395
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.