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Ju-Tsung Liu

Publications and source records attributed to Ju-Tsung Liu.

18 recordsLinked to original sources
PubMed2006

Stereoselective three-component synthesis of trans-endo-decahydroquinolin-4-one derivatives from aldehydes, aniline, and acetylcyclohexene.

The diastereoselective synthesis of trans-endo-decahydroquinolin-4-one (4) via a three-component reaction of aldehydes (1), anilines (2), and 1-acetylcyclohexene (3) in the presence of iodine in a one-pot reaction at room temperature is described. The short reaction time, easy workup, excellent yield, and mild reaction conditions make this novel annulation strategy both practical and attractive.

Aldehydes↗
PubMed2006

Screening of nerve agent degradation products by MALDI-TOFMS.

A novel method for the rapid screening of degradation products derived from nerve agents by matrix-assisted laser desorption ionization time-of-flight mass spectrometry is described. Five standard products were selected as model compounds, including isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PMPA), ethyl methylphosphonic acid (EMPA), isobutyl methylphosphonic acid (i-BuMPA), and cyclohexyl methylphosphonic acid (CHMPA), which are degradation products of Sarin (GB), Soman (GD), VX, Russian VX (RVX), and GF, respectively. For comparison, CHCA (alpha-cyano-4-hydroxycinnamic acid) and DCCA (7-(diethylamino)coumarin-3-carboxylic acid) were used as the MALDI-matrix when the third harmonic generation (355 nm) of a Nd:YAG laser and a hydrogen Raman laser (multifrequency laser) were used, respectively. The method permitted the five nerve agent degradation products to be screened rapidly and successfully, suggesting that it has the potential for use as a routine monitoring tool.

Central Nervous System↗
PubMed2005

Optimization of the separation and on-line sample concentration of phenethylamine designer drugs with capillary electrophoresis-fluorescence detection.

Five 2C-series of phenethylamine designer drugs, including 2,5-dimethoxy-4-ethylthio-phenethylamine (2C-T-2), 2,5-dimethoxy-4-(n)-propylthiophenethylamine (2C-T-7), 4-chloro-2,5-dimethoxyphenethylamine (2C-C), 4-bromo-2,5-dimethoxy-phenethylamine (2C-B), 2,5-dimethoxy-4-iodo-phenethylamine (2C-I), were synthesized and standard GC/MS and fluorescence spectra are reported for them. A mixture of the five drugs was separated and detected by means of capillary electrophoresis (CE) with native fluorescence and light emitting diode (LED)-induced fluorescence (LIF) detection, respectively, for comparison. In the former case, exciting at a wavelength of 300 nm from a Xe lamp was used. The detection limits were found to be only in the range of approximately 10(-4) M by the micellar electrokinetic chromatography (MEKC) mode but were improved to approximately 10(-7) M when the sweeping-MEKC mode was used. For a highly sensitive analysis, LED-induced fluorescence detection was examined by derivatizing the compounds with a fluorescent dye, fluorescein isothiocyanate isomer I (FITC). A blue-LED (approximately 2 mW) was used as the fluorescence excitation source. The detection limits were improved to approximately 10(-7) and approximately 10(-8) M, respectively, when the MEKC and stacking-MEKC modes were applied. A mimic urine sample was obtained by spiking urine from a volunteer with the five standards, and after liquid-liquid extraction, the sample was examined by means of the MEKC-LIF mode. The extraction procedures used for the urine sample and the CE conditions for the separation were optimized.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2005

Sample-stacking techniques in non-aqueous capillary electrophoresis.

In sample-stacking techniques, the detection limit cannot be improved by simply increasing the length of the sample solution, because the individual electrophoretic parameters must be optimized. In an attempt to increase the amount of sample injected, as well as to focus them onto a small zone, two novel methods are proposed. One of these employs an "ultra-high conductivity zone", which was inserted between the sample zone and background solution to build an unequal conductivity gradient. The other employs a "low temperature bath". A portion of the capillary (near the junction between the sample solution and the background solution) was immersed in a low temperature bath, which served as a "pseudo-high-conductivity zone" due to the fact that conductivity would increases when the temperature is decreased. As a result, a large volume of sample injection can be achieved. Using 3,4-methylenedioxymethamphetamine as a model compound, the detection limit was determined to be 1.6 x 10(-6) M (S/N = 3) by means of normal non-aqueous capillary electrophoresis (NACE). This could be improved to 3.0 x 10(-8) M, 4.8 x 10(-9) M and 5.0 x 10(-9) M, respectively, when the normal stacking, ultra-high conductivity zone NACE-stacking and the low-temperature zone NACE-stacking methods were applied.

Electrophoresis, Capillary↗
PubMed2005

Comparison of the use of aqueous and nonaqueous buffers in association with cyclodextrin for the chiral separation of 3,4-methylenedioxymethamphetamine and related compounds.

A comparison of the use of aqueous and nonaqueous buffers in association with beta-CD for the chiral separation of (R)- and (S)-3,4-methylenedioxymethamphetamine and related compounds is described. The (R)- and (S)-isomers of 3,4-methylenedioxymethamphetamine (MDMA) and its major metabolite 3,4-methylenedioxyamphetamine (MDA) were prepared. Under aqueous and nonaqueous buffer conditions and based on the CZE and MEKC modes, the order of migration of (R)-MDA, (S)-MDA, (R)-MDMA, and the (S)-MDMA enantioisomers were determined. Several electrophoretic parameters, including the concentration of beta-CD (aqueous, 25-60 mM; nonaqueous, 20-150 mM) used in the electrophoretic separation and the amount of organic solvents required for the separation, were optimized.

3,4-Methylenedioxyamphetamine↗
PubMed2004

The bioactivity of 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2) and its detection in rat urine by capillary electrophoresis combined with an on-line sample concentration technique.

The bioactivity of 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2) on nitric oxide (NO) production and the proliferation of spleen and thymus lymphocytes to mitogen stimulation in mice are reported for the first time. NO production by T and B lymphocytes in spleen and T cells in the thymus of mice decreased after the oral administration of 2C-T-2. This indicates that 2C-T-2 intake may perturb both neural and immune activity since a decrease in NO production is indicative of a weakened defense function. 2C-T-2 (the parent drug) in rat urine samples was detected by means of capillary electrophoresis/UV absorbance combined with an on-line sample concentration technique. When the CZE and MEKC modes were employed, the detection limit was found to be 4.5 and 5.0 microg/mL (at a 92.1% confidence level); whereas when on-line sample concentration methods, including stacking and sweeping-micellar electrokinetic chromatography were used, the detection limits were improved to 19.2 and 9.1 ng/mL, respectively. In an analysis of some actual samples from animal experiments, three male rats were administered 20 microg/g of body weight of 2C-T-2 by intra-peritoneal injection. The first- and second-day urine fractions were collected after the administration, for use in the analysis. As a result, 2.9 microg/mL and 0.25 microg/mL of 2C-T-2, respectively, were detected after ingestion of the doses.

Animals↗
PubMed2004

Stacking and low-temperature technique in nonaqueous capillary electrophoresis for the analysis of 3,4-methylenedioxymethamphetamine.

Low-temperature and ambient-temperature nonaqueous stacking techniques in capillary electrophoresis (CE) are described for the first time. A low-temperature bath was used to control the temperature from ambient to subzero degrees, by which a novel hyphenated method, low-temperature bath-nonaqueous capillary electrophoresis stacking (LTB-NACE stacking) is demonstrated. 3,4-Methylenedioxymethamphetamine (3,4-MDMA) was determined at a concentration of 4.7 x 10(-6) M (at a 92.1% confidence level) by normal nonaqueous capillary zone electrophoresis (NACZE) and this was improved to 2.6 x 10(-8) M and 5.0 x 10(-9) M, respectively, when the NACZE stacking and LTB-NACZE stacking techniques were applied. The content of 3,4-MDMA in an illicit drug and a suspect urine sample was readily detected. Upon application of the LTB to the separation of isomers the resolution (R) for the separation of 2,3-/3,4-MDMA was improved from 0.6 (LTB, 22 degrees C) to 1.6 (LTB, -55 degrees C) and for (+)3,4-MDMA/(-)3,4-MDMA, from 0.4 (LTB, 25 degrees C) to 1.0 (LTB, -10 degrees C).

3,4-Methylenedioxyamphetamine↗
PubMed2003

Identification of 2,5-dimethoxy-4-ethylthiophenethylamine and its metabolites in the urine of rats by gas chromatography-mass spectrometry.

A simple and specific method based on gas chromatography-selected ion monitoring-mass spectrometry (GC-SIM-MS) for the analysis of in vivo metabolism of 2,5-dimethoxy-4-ethylthiophenethylamine (2C-T-2) in rats is described. Three male rats were administered 20 mg/kg of 2C-T-2 by intra-peritoneal injection, and 24 h urine fractions were collected before and after the administration for analysis. After acidic hydrolysis of the urine samples, the metabolites were liquid-liquid extraction and analyzed by a quadruple mass spectrometer in the selected ion monitoring mode. The findings show that four metabolites of 2-(4-ethylthio-2,5-dimethoxyphenyl)-ethanol (Mw: 242), 4-ethylthio-2,5-dimethoxyphenyl acetic acid (Mw: 256), 1-acetoamino-2-(2-hydroxy-4-ethylthio-5-methoxyphenyl)-ethane (Mw: 269) and 1-acetoamino-2-(2-methoxy-4-ethylthio-5-hydroxyphenyl)-ethane (Mw: 269) are present and the metabolic pathway for 2C-T-2 in the rat is proposed.

Animals↗
PubMed2003

Optimization of a simple method for the chiral separation of methamphetamine and related compounds in clandestine tablets and urine samples by beta-cyclodextrine modified capillary electrophoresis: a complementary method to GC-MS.

The chiral separation of (+/-)-methamphetamine, (+/-)-methcathinone, (+/-)-ephedrine and (+/-)-pseudoephedrine by means of beta-cyclodextrine modified capillary electrophoresis is described. The distribution of enantiomers in clandestine tablets and urine samples were identified. Several electrophoretic parameters such as the concentration of beta-cyclodextrin, temperature, the applied voltage and the amount of organic solvent required for successful separation were optimized. The method, as described herein, represents a good complementary method to GC-MS for use in forensic and clinical analysis.

Central Nervous System Stimulants↗
PubMed2003

Triethylaluminum- or triethylborane-induced free radical reaction of alkyl iodides and alpha,beta-unsaturated compounds.

A series of alpha,beta-unsaturated compounds, 1a-c, 9, 13, and 17, were used as reactants in free radical conjugate addition reactions with different radicals generated from alkyl iodides such as 3, 4, or 5 in the presence of triethylborane-oxygen in air or via the use of triethylaluminum-benzoyl peroxide as a free radical initiator. When the reactions were carried out using triethylborane-air, the products, in most cases, were clean and were easily purified. However, higher yields of the 1,4-adducts and less side reactions occurred when less reactive substrates were used as Michael acceptors in reactions with triethylaluminum-benzoyl peroxide and alkyl iodide under similar conditions. A mechanism for this is proposed in Scheme 1.

Journal Article↗
PubMed2003

On-line identification of lysergic acid diethylamide (LSD) in tablets using a combination of a sweeping technique and micellar electrokinetic chromatography/77 K fluorescence spectroscopy.

This work describes a novel method for the accurate determination of lysergic acid diethylamide (LSD) in tablets. A technique involving sweeping-micellar electrokinetic chromatography (MEKC) was used for the initial on-line concentration and separation, after which a cryogenic molecular fluorescence experiment was performed at 77 K. Using this approach, not only the separation of LSD from the tablet extract was achieved, but on-line spectra were readily distinguishable and could be unambiguously assigned. The results are in agreement with analyses by gas chromatography-mass spectrometry (GC-MS). Thus, this method, which was found to be accurate, sensitive and rapid, has the potential for use as a reliable complementary method to GC-MS in such analyses.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2003

Determination of lysergic acid diethylamide (LSD) in mouse blood by capillary electrophoresis/ fluorescence spectroscopy with sweeping techniques in micellar electrokinetic chromatography.

The separation and on-line concentration of lysergic acid diethylamide (LSD) in mouse blood was achieved by means of capillary electrophoresis/fluorescence spectroscopy using sodium dodecyl sulfate (SDS) as the surfactant. Techniques involving on-line sample concentration, including sweeping micellar electrokinetic chromatography (sweeping-MEKC) and cation-selective exhaustive injection-sweep-micellar electrokinetic chromatography (CSEI-sweep-MEKC) were applied; the optimum on-line concentration and separation conditions were determined. In the analysis of an actual sample, LSD was found in a blood sample from a test mouse (0.1 mg LSD fed to a 20 g mouse; approximately 1/10 to the value of LD(50)). As a result, 120 and 30 ng/mL of LSD was detected at 20 and 60 min, respectively, after ingestion of the doses.

Animals↗
PubMed2003

Chiral separation of 3,4-methylenedioxymeth- amphetamine and related compounds in clandestine tablets and urine samples by capillary electrophoresis/fluorescence spectroscopy.

The R-(-)- and S-(+)-isomers of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolite 3,4-methylenedioxyamphetamine (MDA) were prepared, identified by gas chromatography/mass spectrometry (GC/MS) and then used as standards in a series of capillary electrophoresis (CE) experiments. Using these R-(-)- and S-(+)-isomers, the distribution of (RS)-MDA and (RS)-MDMA stereoisomers in clandestine tablets and suspect urine samples were identified. Several electrophoretic parameters, such as the concentration of beta-cyclodextrin used in the electrophoretic separation and the amount of organic solvents required for the separation, were optimized.

Designer Drugs↗
PubMed2002

Optimization of the separation of lysergic acid diethylamide in urine by a sweeping technique using micellar electrokinetic chromatography.

The separation and on-line concentrations of lysergic acid diethylamide (LSD), iso-lysergic acid diethylamide (iso-LSD) and lysergic acid N,N-methylpropylamide (LAMPA) in human urine were investigated by capillary electrophoresis-fluorescence spectroscopy using sodium dodecyl sulfate (SDS) as an anionic surfactant. A number of parameters such as buffer pH, SDS concentration, Brij-30 concentration and the content of organic solvent used in separation, were optimized. The techniques of sweeping-micellar electrokinetic chromatography (sweeping-MEKC) and cation-selective exhaustive injection-sweep-micellar electrokinetic chromatography (CSEI-sweep-MEKC) were used for determining on-line concentrations. The advantages and disadvantages of this procedure with respect to sensitivity, precision and simplicity are discussed and compared.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2002

Rapid analysis of 3,4-methylenedioxymethamphetamine: a comparison of nonaqueous capillary electrophoresis/fluorescence detection with GC/MS.

Because of the increasing use of 3,4-methylenedioxymethamphetamine (3,4-MDMA), a rapid and sensitive analytical technique is required for its detection and determination. Using nonaqueous capillary electrophoresis/fluorescence spectroscopy (NACE/FS) detection, it is possible to determine this drug at the level 0.5 ppm without any pre-treatment in less than 5 min. After liquid-liquid extraction, the sample can be condensed and a detection limit of 3,4-MDMA in urine of 50 ppb (S/N = 3) can be achieved. The precision of the method was evaluated by measuring the repeatability and intermediate precision of migration time and the corrected peak height by comparison with a 3,4-MDMA-D5 internal standard. With the conventional GC/MS method, it is necessary to derivatize the 3,4-MDMA before injection and the GC migration time also is in excess of 20 min. Therefore, NACE/FS represents a good complementary method to GC/MS for use in forensic analysis.

Electrophoresis, Capillary↗
PubMed1998

Free-Radical Reactions of Trialkylboranes with beta-Nitrostyrenes To Generate Alkenes.

beta-Nitrostyrenes 1 react with trialkylboranes under a nitrogen atmosphere to generate high yields of alkenes 2. The mechanism is proposed to be a free-radical reaction via NO(2)/alkyl substitution since the reaction is stimulated by the presence of a trace of oxygen in the nitrogen or tert-butyl peroxide or by photolysis and is retarded or inhibited by the addition of galvinoxyl to the solution.

Journal Article↗