Comparative <i>in Vitro</i>Studies of the Metabolism of Six 4-Substituted Methamphetamines and Their Inhibition of Cytochrome P450 2D6 by GC-MS with Trifluoroacetyl Derivatization

Use of new amphetamine-type stimulants (ATS) as designer drugs is a serious problem worldwide. ATS are used in tablet, capsule, and powder forms, and can be mixed with other drugs. There is little information available on how these new drugs are metabolized or their ability to inhibit the metabolism of co-administered drugs. This study aimed to investigate the metabolism of six 4-substituted analogs of methamphetamine (MA), and their potential inhibition of MA metabolism. The metabolism of MA and the 4-substituted MAs was examined in vitro using human metabolic enzymes. Metabolite analyses were performed using trifluoroacetyl derivatization and GC-MS. The experiments showed that cytochrome P450 2D6 (CYP2D6) was involved in the major metabolic pathway of MA, where it catalyzed N-demethylation of 4-fluoromethamphetamine (4-FMA), 4-chloromethamphetamine (4-CMA), 4-bromomethamphetamine (4-BMA), 4-iodomethamphetamine (4-IMA) and 4-nitromethamphetamine (4-NMA), and O-demethylation of 4-methoxymethamphetamine (4-MMA). The half maximal inhibitory concentration (IC50) values for CYP2D6 using MA as substrate were different for each of the 4-substituted MAs. The strongest inhibitors of amphetamine production from MA were, in order, 4-IMA, 4-BMA, 4-CMA, 4-MMA, 4-FMA, and 4-NMA. The same order was observed for the IC50 values for inhibition of p-hydroxymethamphetamine production from MA, except for the IC50 of 4-MMA. The IC50 values of 4-IMA were lower than the IC50 values of fluoxetine and higher than that of quinidine. The results of this study imply that the risk of illicit drug interactions fluctuates so widely that unintentional fatal drug poisonings could occur.

Analysis of Monosaccharide Composition of Pu-erh Tea Polysaccaride by Pre-column Derivatization HPLC

[Objective] This study aimed to establish a pre-column derivatization HPLC method for the identification and analysis of monosaccharide composition of Pu-erh tea polysaccharide. [Method] Pu-erh tea polysaccharide was extracted using the wa- ter extraction method, further isolated and purified by DEAE cellulose-52 columns. The obtained tea polysaccharide and four components TPS1, TPS2, TPS3 and TPS, were first derived by 1-phenyl-3-methyl-5-pyrazolone （PMP）, and then the PMP derivatives of monosaccharide were analyzed by high performance liquid chromatog- raphy （HPLC）. [Result] Pu-erh tea polysaccharide contained eight kinds of monosac- chaddes （mannose, rhamnose, glucuronic acid, galacturonic acid, grucose, galactose, arabinose, fucose）, without xylose; so it was the same with TPS1; each of TPS2, TPS3 and TPS4 contained seven monosaccharides, while no fucose. [Conclusion] This method is simplified and rapid, which can be used to determine the monosac- charide composition of Pu-erh tea polysaccharide and monosaccharide content.

Determination of Sparfloxacin in Human Urine by Reversed-Phase High Performance Liquid Chromatography With Nitrous Acid and Hydroiodic Pre-Column Derivatization

Sparfloxacin can be oxidized by nitrous acid, then react with hydroiodic acid to form a fluorescent derivative. Based on this, a reversed-phase high performance liquid chromatographic pre-column derivatization new method is described for the determination of sparfloxacin in human urine. The linear range is 0.05 mg/L to 4.0 mg/L, the recoveries are 91.5%similar to 95.7% and the RSD is 1.2%similar to4.2%. The results showed that this method is suitable for the determination of sparfloxacin in human urine.

Determination of 18 Kinds of Amino Acids in Fresh Tea Leaves by HPLC Coupled with Pre-column Derivatization

A rapid and accurate quantitative method of high performance liquid chromatography( HPLC) with fluorescence detector has been developed for the analysis of 18 kinds of amino acids in fresh tea leaves. The samples were minced and mixed,and extracted with ultra pure water at 90℃ for 20 min. The 6-aminoquinolyl N-hydroxy-succinimidyl carbamate( AQC) was used as pre-column derivatization reagent. Gradient HPLC separation was performed on a C_(18) column( Symmetry C_(18),3. 9 mm × 15 cm,4 μm). Good linearity between concentrations and peak areas was achieved in the concentration range of 5. 0-250 μmol/L for 18 kinds of amino acids. The method was validated by the analysis of five replicates. The 18 kinds of amino acid standards were spiked in fresh tea leaf samples and the average recovery rate was 86. 25%-109. 05% with relative standard deviations( n = 5) ranging from 6. 03% to 10. 56%. The limit of detection( LOD) for the analytes was0. 05-1. 27 μmol/L. The method was successfully applied to the analysis of the 18 kinds of amino acids in fresh tea leaves from east Dongting and west Dongting mountains in Suzhou. The results indicate that the method is simple,rapid,precise and reliable.

Enantioresolution of a Series of Chiral Benzyl Alcohols by HPLC on a Dinitrobenzoylphenylglycine Stationary Phase after Achiral Pre-Column Derivatization

High performance liquid chromatography method for the separation of a series of chiral benzyl alcohols on N-(3,5-dinitrobenzoyl)-D-phenylglycine stationary phase (Macherey Nagel, Chiral-2) after pre-column achiral derivatization was developed. Cheap and easy available aromatic acid chlorides were used as derivatization agents. Good to excellent separations of the enantiomers were achieved in all cases in relatively short analytical runs. It was shown that the enantiorecognition depends on the substituents both in the starting alcohol and in the acid chloride. The method presents an efficient alternative to the direct analyses on polysaccharide and cyclodextrine-derived stationary phases.

HPLC of Amino Acids and Oligopeptides by Pre-Column Fluorescence Derivatization with 9-Acridine Formyl Chloride

A highly sensitive HPLC method for the detection of amino acids and oligopeptides with 9-acridine formyl chloride by pre-column fluorescence derivatization has been developed. Glycine, glycylglycine, histidine, triglycine and glutathione were separated on a reversed-phase C-18 column with methanol-water-triethylamine eluent, derivatization and chromatographic conditions were optimized. The five derivatives were eluted in 28 min with a good reproducibility. Linear range of the calibration graph was 0.08-260 nmol/ml(-1). The relative standard deviations(n=6) are < 5%. Detection limits (signal-to-noise ratio=3) for the five derivatives are 20-40 fmol.

C_(18)固相萃取与GC-MS对生物基质样品中有机锡的测定

A simple and rapid method for determination of monobutyl,dibutyl,tributyl,monophenyl,di-phenyl and triphenyl in bio-matrix has been developed by C18SPE coupled with GC-MS using sodium tetraeth-ylboron as derivatization reagent.Hydrolyzation and extraction of sample were performed with 3 mol/L aceticacid containing0.005%tropolone.The extracts were analyzed by GC-MS under SIMmode and using1 mol/L TPrTas an internal standard.LOD of the method was down to 10 ng/g(dry sample),the recoveries were56%-113%for four samples spiked at50 ng/g with RSD of1.0%-11.9%,and 79%-113%for four sam-ples spiked at200 ng/g with RSD of 0.8%-6.5%,respectively.

GC-MS法测定头发中多胺的含量

A simple method for the determination of putrescine,spermidine and spermine in hair sample was developed by gas chromatography-mass spectrometry(GC-MS).After alkaline digestion,hair samples were extracted by solid phase extraction(SPE) with diatomaceous earth column,and then derivatized with heptafluorobutyryl chloride(HFB-Cl) in n-hexane.The analytes were determined by a mass spectrometer detector in selected ion monitoring(SIM) mode.A good reproducibility and accuracy were attained.The method was applied to the analysis of the hairs of 14 healthy men and 22 healthy women.Results showed that the most abundant polyamine was spermidine,followed by putrescine and spermine,and the levels of three hair polyamines in men were all found to be higher than in women,respectively.

An Application of Gas Chromatography-Mass Spectrometry (GC-MS) Fast Automated Scan/SIM Type (FASST) in Determining the Preservative Levels in Foods

The preservatives used in food products are strictly monitored and regulated. The present study aims to imply a sensitive and reliable analytical method to quantify two classes of preservatives (i.e. carboxylic acid and phenolic compounds) in food by means of gas chromatography-mass spectrometry (GC-MS), aimed at monitoring the products available within the local stores. Target analytes were derivatized via aqueous-phase isobutyl chloroformate-mediated reaction followed by dispersive liquid-liquid microextraction (DLLME) method. The quantity and quality determination of the studied samples were assured by performing FASST approach in a single run GC-MS analysis. The combination of standard addition method with sample dilution compensated the effect of sample matrix on the quantitative determination of the tested preservatives in the examined samples. The concentrations of sorbic acid (SA) were 210 μg/mL and 1000 μg/mL in soft drink and sauces samples, respectively. On the other hand, sodium benzoate (226 μg/mL) was only found in soft drink, whereas, no parabens were detected in any samples collected from the local stores.

Study of the Reaction Derivatization Glyphosate and Aminomethylphosphonic Acid (AMPA) with <i>N</i>,O-Bis(trimethylsilyl)trifluoroacetamide

This work aimed to study the derivatization unprecedented of glyphosate and AMPA solutions using N,O-bis (trimethylsilyl)trifluoroacetamide (BSTFA) combined with trimethylchlorosilane (TMCS), evaluating the composition of the reaction medium, use of ultrasound, volume of BSTFA:pyridine and pH of the reaction medium. From this study it was inferred that the reaction medium was composed of BSTFA:pyridine in ratio 60:100, respectively, without ultrasonic vibration and pH adjustment that provide optimal conditions for analysis by GC-MS. Furthermore, the methodology used was simple and fast, and that was the most practical method commonly used.

Reversed-phase high-performance liquid chromatographic analysis of seven pairs of chiral drug enantiomers in transport medium after chiral derivatization

A reversed-phase high-performance liquid chromatographic （RP-HPLC） method was established for the determination of the enantiomers of 7 aryloxy aminopropanol drugs （atenolol, sotalol, celiprolol, carvedilol, metoprolol, propranolol and propafenone） in transport medium. The method involved liquid-liquid extraction of chiral drugs from transport medium, and employed 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate （GITC, 1.0 mg/mL in acetonitrile） as a pre-column chiral derivatization reagent. After derivatization, the products were separated on an Agilent Zorbax C8 column （150 min×4.6 mm, 5 μm） at 25 ℃. The mobile phase consisted of a mixture of acetonitrile and 0.01 M phosphate buffer （pH 3.5）. The present methods were specific for the determination of enantiomers of each chiral drug. The absolute recoveries of the enantiomers and internal standards were 〉78%. The relative recoveries of the enantiomers were approximately 100%. The intra- and inter-day variations were 〈 15%. The method was reproducible and sufficiently sensitive to determine the enantiomers of seven aryloxy aminopropanol drugs in transport medium. The method could be used to study the transport of atenolol, sotalol, celiprolol, carvedilol, metoprolol, propranolol and propafenone.

Determination of 4-tert-octylphenol in surface water samples of Jinan in China by solid phase extraction coupled with GC-MS

Octylphenols, considered as xenoestrogens, mainly exist as 4-tert-octylphenol （OP） in aquatic environments. The high stability and accumulation of OP in aquatic systems have caused endocrine disruption. The OP in surface water in Jinan, China was analyzed by gas chromatography-mass spectrometry （GC-MS） coupled with solid phase extraction （SPE）. Water samples were extracted by SPE on a cartridge system containing C-18 as sorbent. To increase sensitivity and selectivity, OP was derivatized to 4-tert-octyl-phenoxy silane. With the use of phenanthrene-d10 as internal standard, the detection limit based on signal-to-noise ratio （S/N = 3） was 0.06 ng/mL. The average recovery was from 84.67% to 109.7%. The precision of the method given as the relative standard deviations （RSD） was within the range 6.24%-12.96%. In the target water samples, the concentrations of OP were as follows： 15.88-71.24 ng/L for Jinxiuchuan Reservoir, 3.850-26.68 ng/L for the city moat, 6.930-41.56 ng/L for Daming Lake, 66.03-474.2 ng/L for Xiaoqing River, 14.66-17.72 ng/L for the Yellow River, and 10.60-26.43 ng/L for Queshan Reservoir. The Xiaoqing River was seriously polluted due to the discharge of wastewater from Jinan. Jinxiuchuan Reservoir had a higher concentration of OP compared with the Yellow River and Queshan Reservoir, which is ascribed to the surrounding human activities. These data are reported for the first time, providing strong support for the control of OP pollution in Jinan.

Evaluation of Baishao(Radix Paeoniae Alba)and Chishao(Radix Paeoniae Rubra)from different origins based on characteristic spectra of amino acids

Objective To evaluate the difference between Baishao(Paeoniae Radix Alba,PRA)and Chishao(Paeoniae Radix Rubra,PRR)from different regions based on the characteristic spectra of amino acids(AAs).Methods Fingerprints of the 21 standard AAs were established using O-phthalaldehyde-9-fluorenylmethyl chloroformate(OPA-FMOC)pre-column derivation method.The AA components in PRA and PRR were characterized qualitatively and quantitatively,and different AAs were screened using pattern recognition technology.Results Twelve AAs were identified in both PRA and PRR.Meanwhile,aspartic acid,glutamic acid,arginine,alanine,and gamma-aminobutyric acid were screened as characteristic components,and their concentrations could effectively distinguish PRA from PRR.Conclusion The established characterization method,which is based on the characteristic spectra of AAs,is accurate,efficient,and sensitive and can effectively distinguish between PRA and PRR from different producing areas,thus providing a reference for the overall characterization and evaluation of Chinese medicinal materials.