• YAKHAK HOEJI
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• v.38 no.6
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• pp.749-755
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• 1994

An interspecific fusant strain, Streptomyces MS1 was obtained by protoplast fusion between S. peucetius subsp. caesius and S. platensis. We studied on the fermentation characteristics of the fusant strain. The fermentation products of the fusant MS1 was identical with S. peucetius, but its production of anthracycline was more stable than S. peucetius under various fermentation conditions in regard to acidogenesis of fermentation broth. The optimal medium composition for anthracycline production by fusant MS1 as follows: sucrose 2.0%, glucose 1.0%, soytone 0.7%, $CaCO_3$ 0.2%, $KH_2PO_4$ 0.013%, casamino acids 0.01%, $K_2SO_4$ 0.025%, $MaCl_2\;6H_2O$ 1.024%, 5M $CaCl_2\;5H_2O$ 0.4%, 1N NaOH 0.7%, 20% L-proline 1.5%. In this condition, the productivity of anthracycline was $80{\sim}100\;{\mu}g/ml$.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1097-1102
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• 2002

The mass spectrometry using an ion trap tandem mass spectrometer has been investigated to find optimum conditions for the analysis of benzo(a)pyrene (3,4-benzpyrene). The applicability to a real soil sample was also investigated to verify the usef ulness of the MS/MS (or collision induced dissociation, CID) analysis. The optimum CID condition was 1.5 and 0.45 for the RF excitation voltage and the q value, respectively. For comparison, CID and EI were applied to the analysis of a soil sample. CID analysis was more sensitive than EI analysis of the soil sample. The limit of detection (LOD) of benzo(a)pyrene was 3.18 ng mL-1 and 0.85 ng mL,-1 for EI and MS/MS analysis, respectively. The precision at the soil sample for EI and CID showed relative standard deviations of 6.1% and 4.1%, respectively, and the concentrations were 168 ㎍ kg-1 and 162 ㎍ kg-1 , respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.8
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• pp.1133-1137
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• 2001

An experiment was conducted to study the performance and carcass characteristics of Hanwoo steers fed whole crop corn silage ensiled with poultry manure (PM) for 18 months. The experiment was designed as a randomized block design with three phases. Steers were allotted in one of three dietary treatments, which were ammonia-treated rice straw (AS), whole crop corn silage (CS) and whole crop corn+30% PM silage (based on DM; MS). All diets were supplemented with concentrate. Total body weight gain and average daily gain (ADG) in MS group were increased (p<0.05) by 6% over AS group. The MS treatment enhanced (p<0.05) total and daily intakes of forage compared with the AS and CS treatments while there was compensatory effect on concentrate intake by AS group. Carcass characteristics were improved by feeding MS. MS increased (p<0.05) carcass weight and marbling score (7.5 and 22.5% of AS, respectively), and reduced (p<0.05) backfat thickness (13.2 of AS and 16.6% CS). Carcass grade and meat quality grade were also improved by MS compared with AS and CS. Under the conditions of this study, MS was an efficacious replacement for corn silage for steers.

• Analytical Science and Technology
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• v.15 no.6
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• pp.574-579
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• 2002

A sensitive and easy high performance liquid chromatograph (HPLC) / electrospray ionization (ESI)-mass spectrometric (MS) method has been developed for the quantitative and qualitative analyses of acarbose and its metabolites. After plasma samples were simply filtered with a syringe filter, the filtered plasma was analyzed by LC/MS. The standard calibration curve for acarbose was linear ($r^2=0.9963$) over the concentration range $0.1{\sim}10{\mu}g/m{\ell}$ in plasma. The metabolite component-I and II, which were metabolized by the ${\alpha}$-amylase and ${\beta}$-amylase, were found also by in vitro incubation. The developed method can be utilized to study acarbose and the other carbohydrates.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.764-770
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• 2014

This study assessed analysis of N-nitrosamines by separation, identification, and quantification using a gas chromatography (GC) mass spectrometer (MS) with electron impact (EI) mode. Samples were pretreated by a automated solid phase extraction (SPE) and a nitrogen concentration technique to detect low concentration ranges. The analysis results by EI-GC/MS (SIM) and EI-GC/MS/MS (MRM) on standard samples with no pretreatment exhibited similar results. On the other hand, the analysis of pretreated samples at low concentrations (i.e. ng/L levels) were not reliable with a EI-GC/MS due to the interferences from impurity peaks. The method detection limits of eight (8) N-nitrosamines by EI-GC/MS/MS analysis ranged from 0.76 to 2.09 ng/L, and the limits of quantification ranged from 2.41 to 6.65 ng/L. The precision and accuracy of the method were evaluated using spiked samples at concentrations of 10, 20 and 100 ng/L. The precision were 1.2~13.6%, and the accuracy were 80.4~121.8%. The $R^2$ of the calibration curves were greater than 0.999. The recovery rates for various environmental samples were evaluated with a surrogate material (NDPA-$d_{14}$) and ranged 86.2~122.3%. Thus, this method can be used to determine low (ng/L) levels of N-nitrosamines in water samples.

• Analytical Science and Technology
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• v.25 no.1
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• pp.19-24
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• 2012

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantitative determination of ertapenem in human plasma and urine. After addition of internal standard (ceftazidime), plasma and urine was diluted with methanol and analyzed by LC-MS/MS. Using MS/MS with multiple reaction monitoring (MRM) mode, ertapenem were selectively detected without severeinterference from human plasma and urine. The standard calibration curve for ertapenem was linear ($r^2$= 0.9996)over the concentration range 1~100 ${\mu}g/mL$ in human plasma. The intra- and inter-day precision over the concentration range of ertapenem was lower than 8.9% (correlation of variance, CV), and accuracy was between 97.2~106.2%. On the other hand, it was showed good relationship ($r^2$= 0.9992) and the precision (intra- and inter-day) over the concentration range of ertapenem was lower than CV 7.2%, and accuracy was between 97.9~111.6% for urine. This method has been successfully applied to the pharmacokinetic study of ertapenem in human plasma and urine.

• Analytical Science and Technology
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• v.21 no.6
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• pp.535-542
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• 2008

A liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) method was developed for the determination and confirmation of clenbuterol in bovine muscle and milk. Clenbuterol and clenbuterol-D9 using as an internal standard in samples were extracted with ethyl acetate after hydrolysis and evaporated to dryness. The extracts were dissolved in 20% methanol and cleaned using HLB solid-phase extraction cartridge. The analytes were detected by LC-ESI/MS/MS on a $C_{18}$ column. Mass spectral acquisition was done in selected reaction monitoring (SRM) in positive ion mode to provide a high degree of sensitivity. Using MS/MS with SRM mode, the transitions (precursor to product) monitored were m/z 277${\rightarrow}$203 for clenbuterol, and m/z 286${\rightarrow}$204 for internal standard. The limits of quantitation (LOQ) and mean recoveries of clenbuterol in bovine muscle were $0.2{\mu}g/kg$ and 84.3~91.1%, respectively. The LOQ and mean recoveries in milk were $0.05{\mu}g/kg$ and 87.7~98.3%, respectively.

• Mass Spectrometry Letters
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• v.2 no.2
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• pp.45-48
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• 2011

The authors describe a method for monitoring dicyclanil levels in lamb and chicken muscle tissues. The devised procedure involves dicyclanyl extraction by SPE and its detection HPLC-UV/Vis and LC/MS/MS. The method was found to have LOD and LOQ values of $0.02\;mg\;kg^{-1}$ and $0.05\sim0.06\;mg\;kg^{-1}$, respectively. The intraday precision and an accuracy of spiked samples were found to have 2.3~10.4 RSD% and 80.9~105.7%, respectively.

• Mass Spectrometry Letters
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• v.12 no.1
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• pp.1-10
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• 2021

A simple, specific, and economical LC-MS/MS method was investigated for the screening of 43 prescribed antihypertensive and related drugs in human urine. The urine samples were simply prepared by diluting and mixing with internal standard before directly introduced to the LC-MS/MS system, which is fast, straightforward, and cost-effective. Fractional factorial, Box-Behnken, and I-optimal design were applied to screen and optimize the mass spectrometric and chromatographic factors. The analysis was carried out on a triple quadrupole mass spectrometer system utilizing multiple reaction monitoring with positive and negative electrospray ionization method. Chromatographic separation was performed on a Thermo Scientific Accucore RP-MS column (50 × 3.0 mm ID., 2.6 ㎛) using two separate gradient elution programs established with the same mobile phases. Chromatographic separation was performed within 12 min. The optimal method was validated based on FDA guideline. The results indicated that the assay was specific, reproducible, and sensitive with the limit of detection from 0.1 to 50.0 ㎍/L. The method was linear for all analytes with coefficient of determination ranging from 0.9870 to 0.9981. The intra-assay precision was from 1.44 to 19.87% and the inter-assay precision was between 2.69 and 18.54% with the recovery rate ranges from 84.54 to 119.78% for all drugs measured. All analytes in urine samples were stable for 24 h at 25℃, and for 2 weeks at -60℃. The developed method improves on currently existing methods by including larger number of cardiovascular medications and better sensitivity of 12 analytes.

• Analytical Science and Technology
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• v.23 no.2
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• pp.119-127
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• 2010

An effective method for the simultaneous analysis of ${\beta}$-lactams from surface water was established. After solid-phase extraction with HLB (Hydrophilic Lipohilic Balance) cartridge at pH 2, seven ${\beta}$-lactams (amoxicillin, ampicillin, penicillin G, cefaclor, cefadroxil, cefatrizine and cephradine) were determined using LC/ESI-MS/MS. In this newly established method, correlation coefficients ($r^2$) of calibration curves for seven ${\beta}$-lactams in blank surface water appeared to be 0.9911~0.9995 in the concentration range of 0.01~1.0 ng/mL. The limits of detection (LODs) and the limits of quantificaiton (LOQs) in spiked surface water were shown to be 0.0003~0.0234 ng/mL and 0.0046~0.0778 ng/mL, respectively. The developed method is believed to serve as a rapid and reliable method for the qualitative and quantitative analysis of residual ${\beta}$-lactam antibiotics from aquatic environment.