LC-MS based simultaneous profiling of adrenal hormones of steroids, catecholamines, and metanephrines.

Metabolic changes in adrenocortical steroids and medullary catecholamines characterize adrenal tumors, but they are measured using different analytical protocols. To increase bioanalytical validity while maintaining sample homogeneity, LC-MS-based profiling of 29 cortical steroids and 6 medullary amines, including catecholamines and metanephrines, in a single run was developed. Alkyloxycarbonylation with isobutyl chloroformate was employed together with our comprehensive steroid assay, and all adrenal hormones were separated on a reversed-phase C18 column (50 × 2.

The genome insights of Streptomyces lannensis T1317-0309 reveals actinomycin D production.

The members of Streptomyces have been identified as a major source of antimicrobial agents with broad spectrum. This study is mainly focused on bioactivity-guided isolation and characterization of bioactive molecule from strain Streptomyces sp. T1317-0309 and its whole-genome sequence analysis for possible isolation of novel natural products.

Evaluation and analysis of volatile organic compounds and formaldehyde emission of building products in accordance with legal standards: A statistical experimental study.

Building materials have been developed mainly for thermal performance, strength, low energy consumption, and aesthetics. Consequently, large amounts of chemicals have been added to building products, resulting in the release of abundant pollutants that adversely affect human health. In particular, pollutants from the materials used to build modern dwellings can cause sick house syndrome, which leads to health resilience problems and diseases.

Effective Soil Extraction Method for Cultivating Previously Uncultured Soil Bacteria.

Here, a new medium, named intensive soil extract medium (ISEM), based on new soil extract (NSE) using 80% methanol, was used to efficiently isolate previously uncultured bacteria and new taxonomic candidates, which accounted for 49% and 55% of the total isolates examined ( = 258), respectively. The new isolates were affiliated with seven phyla (, , , , , , and ). The result of chemical analysis showed that NSE included more diverse components of low-molecular-weight organic substances than two conventional soil extracts made using distilled water.

Effective and sensitive determination of eleven disinfection byproducts in drinking water by DLLME and GC-MS.

The aim of this study was to optimize the dispersive liquid-liquid microextraction (DLLME) parameters for simultaneous analysis through DLLME-gas chromatography-mass spectrometry (GC-MS) of six iodo-trihalomethanes, four haloacetonitriles, and one halonitromethane, which are residual disinfection products found in drinking water. Eleven disinfection by-product (DBPs) remaining in aqueous samples were extracted and concentrated using a simple, rapid, and environmentally friendly DLLME method, and then analyzed simultaneously by GC-MS. The optimized DLLME parameters were a sample volume of 5 mL, 100 μL of dichloromethane as the extraction solvent, 1 mL of methanol as the dispersion solvent, an extraction time of 60 s, and 1.

Rapid Quantification of N-Methyl-2-pyrrolidone in Polymer Matrices by Thermal Desorption-GC/MS.

Analysis of a residual solvent in polymeric materials has become an important issue due to the increased regulations and standards for its use. N-Methyl-2-pyrrolidone (NMP) is a solvent widely used in many industries and restricted as one of the chemicals under EU REACH regulations due to its potential harmful effects. In this study, thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) is applied for the quantitative analysis of NMP with the use of a polymer-coated sample cup.

Description of Novosphingobiumflavum sp. nov., isolated from soil.

A novel yellow bacterial strain, designated UCM-28T, was isolated from forest soil in Gyeonggi-Do, South Korea. The isolated strain was Gram-stain-negative, aerobic, non-spore-forming, non-motile and rod-shaped, and grew at 10-37 °C, pH 5.5-9 and with 0-1 % NaCl.

Comparative study of thermal desorption and solvent extraction-gas chromatography-mass spectrometric analysis for the quantification of phthalates in polymers.

For the quantitative analysis of phthalates in polymers, a thermal desorption (TD)-GC-MS method was compared with solvent extraction (SE)-GC-MS methods which require the long pretreatment procedures using large amount of harmful organic solvents. Calibration curves of TD-GC-MS showed good linearity (r(2)>0.9997) and low method detection limit (<30mg/kg with 9.

Occurrence and ecological hazard assessment of selected veterinary medicines in livestock wastewater treatment plants.

The occurrence of some veterinary medicines in the livestock wastewater plants (WWTPs) was investigated. This investigation represented the occurrence of veterinary medicines to treat in the livestock WWTPs or be discharged into the water system in Korea since the sampling sites were widely distributed across the nation and samples were collected from the 11 livestock WWTPs. Nine antibiotics, two analgesics, and two disinfectants occurred in the livestock wastewater plants (WWTPs).

Simultaneous measurement of serotonin, dopamine and their metabolites in mouse brain extracts by high-performance liquid chromatography with mass spectrometry following derivatization with ethyl chloroformate.

In order to measure the levels of serotonin (5-hydroxyltryptamine, 5-HT), dopamine (DA), 3,4-hydroxyphenylacetic acid (DOPAC), 3-methoxytyramine (3-MT) and homovanillic acid (HVA) simultaneously, an effective derivatization method followed by high-performance liquid chromatography (HPLC) coupled to electrochemical ionization mass spectrometry was used. The derivatization reaction of biological samples with ethyl chloroformate occurred rapidly at room temperature in aqueous conditions, and the resulting derivatives were isocratically separated with good selectivity using a C18 reversed-phase column within 30 min. The study results showed that the new derivatization procedure offers an excellent means of simultaneous determination of 5-HT, DA and their metabolites in mouse brain homogenates, which are important in a number of physiological and behavioral functions.

Electronic effect on the kinetics of the diaza-cope rearrangement.

Hammett plot reveals that there is a significant electronic effect on the rate of resonance assisted hydrogen bond (RAHB) directed diaza-Cope rearrangement reaction with a rho value of 1.6. DFT computation shows that the rearrangement reaction becomes thermodynamically more favorable for the substrates with electron withdrawing substituents.

Gas chromatograph-mass spectrometric method for the determination of carvedilol and its metabolites in human urine.

A sensitive and efficient method was developed for the determination of carvedilol and its metabolites in human urine by gas chromatography-mass spectrometry (GC-MS). Urine samples were hydrolyzed with beta-glucuronidase/arylsulfatase (from Helix pomatia) and the target compounds were extracted with liquid-liquid extraction. The extracts were completely derivatized with MSTFA and MBTFA and analyzed by GC-MS using an Ultra-2 column.

Absorption, distribution, metabolism, and excretion of CKD-732, a novel antiangiogenic fumagillin derivative, in rats, mice, and dogs.

The pharmacokinetics of CKD-732 (6-O-4-[dimethyl-aminoethoxy)cinnamoyl]-fumagillol x hemioxalate) was investigated in male SD rats and beagle dogs after bolus intravenous administration. The parent compound and metabolites obtained from in vitro and in vivo samples were determined by LC/MS. The main metabolite was isolated and identified as an N-oxide form of CKD-732 by NMR and LC/MS/MS.

Analysis of benzene ethylamine derivatives in urine using the programmable dynamic liquid-phase microextraction (LPME) device.

An automated LPME device for a dynamic LPME method was manufactured and its extraction efficiency was tested using spiked urine samples. The developed home-made LPME device was a programmable automated syringe dispenser to overcome deteriorating precision and difficulties in manually manipulating the plunger repeatedly. To establish the optimum parameters for benzene ethylamines, the effects of sampling volume, solvent volume, pH, salt-effect, choice of solvents, plunger speed, and number of samplings were investigated.

The identification of in vitro metabolites of CKD-732 by liquid chromatography/tandem mass spectrometry.

The structural elucidation of fourteen metabolites of CKD-732, formed in vitro with rat liver microsomes, was performed using high-performance liquid chromatography/electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS). To identify proposed structures of the metabolites, the product ion mass spectra of the protonated molecules ([M + H]+), the retention times on reversed-phase HPLC, and UV-Vis spectra were utilized. Characteristic product ions for the identification of CKD-732 metabolites were observed at m/z 231, 236, and 252.

Mass spectrometric analysis of cyclofenil and its metabolites in human urine.

Using gas chromatography/electron impact-mass spectrometry (GC/EI-MS) and high performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry (HPLC/APCI-MS/MS), the structures of cyclofenil metabolites in human urine have been assigned. The hydroxyl metabolites liberated from the glucuronide conjugates after acid hydrolysis were characterized as the trimethylsilyl (O-TMS) derivatives using GC/MS. The conjugate glucuronide forms were detected without hydrolysis by HPLC/MS.