Liquid Chromatographic and Mass Spectral Analysis of N,N-Disubstituted 3,4-Methylenedioxyamphetamines

Abstract

The tertiary amine N,N-disubstituted derivatives of 3,4-methylenedioxyamphetamine (MDA) were prepared and their liquic chromatographic and mass spectral properties compared to other analogues of 3,4-methylenedioxyamphetamine. The N-methyl-N-ethyl, N-methyl-N-i-propyl and N-methyl-N-n-propyl MDA derivatives were separated in a reversed-phase system consisting of a C₁₈ stationary phase and a mobile phase of pH 4 phosphate buffer-acetonitrile (55:45). The mass spectral fragmentation of these amines is similar to that observed for the secondary amine MDA derivatives and can be used for their specific structural identification.     

Liquid Chromatographic and Spectral Methods for the Differentiation of 3,4-Methylenedioxymethamphetamine (MDMA) from Regioisomeric Phenethylamines

Abstract

The analytical profiles are described for four amines, 3,4-methylenedioxymethamphetamine (MDMA) and three isomeric phen-ethylamines of MW = 193. These four amines all contain an identical 3,4-methylenedioxyphenyl moiety, thus the regioisomerism is within the carbon-carbon bond located alpha to the amine. Therefore these phenethylamines are regioisomeric within the imine fragment (m/z = 58) which is the base peak in the electron impact mass spectrum of MDMA. The ultraviolet absorption spectra for these compounds show the characteristic methylenedioxyphenyl group absorption bands in the 235 to 280 nm range. These amines may best be differentiated by chromatographic separation and are well resolved by liquid chromatographic techniques. The four regioisomeric amines were separated using an isocratic reversed-phase system consisting of a C₁₈ stationary phase and an acidic (pH) mobile phase. The elution order under these conditions appears to parallel the length of the carbon chain attached to the aromatic ring.     

Liquid Chromatographic Analysis of Some N-Alkyl-3,4-methylenedioxyamphetamines

Abstract

The liquid chromatographic separation of a series of low molecular weight N-alkyl derivatives of 3,4-methylenedioxyamphetamine (MDA) is reported. The N-methyl-, N-ethyl- and N,N-dimethyl-derivatives of MDA have appeared as street drugs in recent years. These compounds are becoming significant forensic problems due to their unique pharmacological properties and relative ease of chemical synthesis. These amines were synthesized via reductive amination of the corresponding ketone with alkylamines. The UV absorption spectra for these compounds produced almost equally intense absorbance at 234 and 285 nm. The compounds were separated by reversed-phase (C₁₈) HPLC procedures using a mobile phase of aqueous methanol at low pH.     

Liquid chromatographic and mass spectral analysis of 1-(3,4-methylenedioxyphenyl)-1-propanamines: regioisomers of the 3,4-methylenedioxyamphetamines

The title 1-(3,4-methylenedioxyphenyl)-1-propanamines represent positional isomers of the N-substituted 3,4-methylenedioxyamphetamines, clandestinely produced drugs frequently encountered by forensic laboratories. These propanamines are prepared by reductive amination of 3,4-methylenedioxypropiophenone with a series of N-alkylamines. Analytical methods are developed to distinguish these compounds from the MDA series. The ultraviolet spectra of the propanamines are very similar to those of the MDAs with absorption maxima at 284 and 236 nm. The propanamines are separated under reversed-phase liquid chromatographic conditions by using a C18 stationary phase and a mobile phase of acidic (pH 3) acetonitrile containing methanol and triethylamine. The relative retention properties of these compounds parallel those observed in the MDA series. The electron impact mass spectra of the propanamines are determined by GC-MS, and the fragmentation pattern clearly distinguishes these compounds from those of the MDA series having the same molecular weight.     

Syntheses and Mass Spectral Studies of (E)-1-Alkanesulfonylpropenes and (E)-1-Alkanesulfinylpropenes

(E)-1-Alkanesulfonylpropenes and (E)-1-Alkanesulfinylpropenes have been synthesized in good to excellent yields. Studies correlating molecular structure and fragmentation patterns upon electron impact have been carried out. Double hydrogen rearrangements with the elimination of alkenyl radicals are the most facile fragmentations for (E)-1-alkanesulfonylpropenes. Single hydrogen rearrangement with alkene elemination is however the most important fragmentation for (E)-1-alkanesulfinylpropenes. In this case the hydrogen atom only migrates to the sulfinyl oxygen. These differences in fragmentation patterns between the (E)-styryl-alkyl-sulfones/sulfoxides and the (E)-propenyl-alkyl-sulfones/sulfoxides are attributed to the fact that different ionization sites are involved.     

反相液相色谱法分离烷基苯磺酸钠同系物及其异构体

1　引　　言烷基苯磺酸钠表面活性剂广泛用于许多领域 ,传统的分析方法只能用于分类鉴别。现代分析技术包括气相色谱法(ＧＣ)、高效液相色谱法 (ＨＰＬＣ)和毛细管电泳 (ＣＥ)已广泛用于烷基苯磺酸钠的分离分析。由于烷基苯磺酸钠难以挥发 ,ＧＣ的应用受到限制 ,ＣＥ未实现烷基苯磺酸钠异构体的分离 ,ＨＰＬＣ具有可直接分析、分离模式多、检测方便等优点 ,广泛用于烷基苯磺酸钠的分析。ＨＰＬＣ已成功实现了烷基苯磺酸钠同系物分离 ,而对异构体的分离不完全 ,且报道不多。本文采用Ｃ18反相色谱柱、流动相中添加磷酸二氢钠电解质的液相色谱…     

Liquid chromatographic and mass spectral analysis of 1-(3,4-methylenedioxyphenyl)-3-butanamines, homologues of 3,4-methylenedioxyamphetamines

The 1-(3,4-methylenedioxyphenyl)-3-butanamines (HMDAs) are prepared via reductive amination of the corresponding ketone with a series of low molecular weight alkylamines. These amines are homologues of the N-substituted 3,4-methylenedioxyamphetamines (MDAs). Compounds of the HMDA series have UV absorption properties similar to the MDAs because both series contain the same 3,4-methylenedioxyphenyl chromophore. The HMDAs are separated via reversed-phase liquid chromatographic methods using a C18 stationary phase and an acidic aqueous acetonitrile mobile phase. The mass spectra of these potential designer drugs are very similar to the spectra of the MDA homologues having the same N-substituent.     

反相高效液相色谱法分离直链烷基苯磺酸钠同系物和异构体

建立了直链烷基苯磺酸钠的反相高效液相色谱分析方法。探讨了流动相中甲醇含量、电解质浓度及不同电解质对样品保留时间、选择性和分离度等的影响,得到最佳的色谱分离条件为：流动相为甲醇 30 mmol/L 磷酸二氢钠水溶液,采用折线梯度洗脱,检测波长为226 nm。结果表明,该法对烷基链为C8~C 16 的烷基苯磺酸钠的同系物能完全分离,对烷基苯磺酸钠的异构体有一定的分离能力。     

Structures of 1-（3,4-Dihydroxyphenyl）-2-（3,4-dimethoxyphenyl） ethanone and Its Hydrate Complex

The title compounds, C16H16O5 (I) and C16H16O5·H2O (II), were structurally characterized by single-crystal X-ray diffraction. Compound I crystallizes in monoclinic space group P21/c with a = 10.5574(10), b = 8.3576(9), c = 16.5528(16) , β = 91.762(3)°, Z = 4, R = 0.0524 and wR = 0.1084. The molecules are jointed into a chain by intermolecular O-H···O and C-H···O hydrogen bonds, which form layers parallel to (001). The chains run along the [110] and [110] directions alternatively layer by layer, and are assembled into a network by intermolecular O-H···O (carboxyl) hydrogen bonds. On the other hand, the hydrate complex (II) crystallizes in the triclinic space group P1 with a = 5.1451(2), b = 10.4583(4), c = 14.8267(5) , α = 70.900(2), β = 82.478(2), γ = 81.359(2)°, Z = 2, R = 0.0393 and wR = 0.0983. The molecules are linked into infinite two-dimensional ribbons by O-H···O (carbonyl) and solvent-bridged O-H···O hydrogen bonds.     

1-硝基蒽醌的高效液相色谱分析

用Ｖ（Ｎ,Ｎ－二甲基酰胺）：Ｖ（１,４－二氧六环）：Ｖ（二甲基亚砜）＝５：２：１混合溶剂溶解试样,利用Ｗａｔｅｒｓ Ｎｏｖａ－ｐａｋ Ｃ１８色谱柱,以１,４－二氧六环／甲醇／水＝１５／４５／４０（体积比）混合溶液为流动相,对１－硝基蒽醌样品进行了高效液相色谱法分离与分析研究。在所确定的色谱分离体系中,样品中各组分全部出峰且基本上达到基线分离,对定量方法进行了讨论,加标回收率除１,７－二硝基蒽醌外其     

High Performance Liquid Chromatographic Determination of (-)-N-Formylnorephedrine in Plasma

Abstract

An HPLC procedure for the detection and quantitative estimation of (-)-N-formylnorephedrine in rabbit plasma had been developed. The procedure involved the extraction of (-)-N-formylnorephedrine from plasma spiked with the internal standard (phenacetin), using ethyl acetate. The ethyl acetate extract is evaporated under nitrogen and the residue is reconstituted in water and injected onto the column. A u-Bondapak-C18 column 30 cm × 3.9 mm ID was used. The mobile phase is 20% acetonitrile in water; at a flow rate of 1.5 ml/min and uv detection at 256 nm. A linear relationship between concentration and peak height ratio (I/internal standard) was obtained (r = 1.00). The reported procedure allows the measurement of (-)-formylnorephedrine in concentrations as low as 150 ng/ml of plasma with total procedure time of about 10 min. The applicability of the procedure to pharmacokinetic studies is illustrated and metabolites are shown not to interfere with the assay procedure.     

Mass spectral fragmentation patterns of 2,5-bis(p-R2-phenyl)-(3,4)-R1-furans

The electron impact mass spectrometric fragmentation pathways for several 2,5-bis(p-R₂-phenyl)-(3,4)-R₁-furans, I, were investigated. Our investigation of the mass spectra of these compounds revealed interesting relationships between substitution pattern in the framework of I and the fragmentation patterns.     

Preparative High-Performance Liquid Chromatographic Separation of Natural Farnesol Isomers (1)

Abstract

Farnesol, 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol, is a naturally occurring sesquiterpenoid that is used in perfumery and synthesis. In synthesis, it is used as a starting material for other terpenoids and insect juvenile hormone derivatives. A preparative high-performance liquid chromatographic separation procedure was developed whereby 2.1 g of 2E,6E-farnesol could be readily isolated from 4.8 g of a 1:1 mixture of the 2E,6E- and 2Z,6E-isomers of farnesol. This rapid one-step procedure simplifies the separation of the mixed isomers on a preparative scale.     

Liquid Chromatographic Resolution of Enantiomeric Dipeptides on the Chiral Stationary Phase Derived from (S)-1-(6,7-Dimethyl-1-naphthyl)isobutylamine

Abstract

Liquid chromatographic resolution of fifteen enantiomeric dipeptide methyl esters as their N-3,5-dinitrobenzoyl derivatives was investigated on the chiral stationary phase (CSP) derived from (S)-1-(6,7-dimethyl-1-naphthyl)isobutylamine. The four stereoisomers present in each dipeptide derivative were observed to be separated quite well with the (R,R) isomer being eluted first. The separation factors for two enantiomeric pairs such as (R,R)/(S,S) and (R,S)/(S,R) and the elution orders are explained by two competing “opposite-sense” chiral recognition mechanisms.     

Liquid Chromatographic Analysis of Arabinosylcytosin and 1-β-D-Arabinofuranosyluracil in Treatment with Cyclophosphamide and Pirarubicin

A reversed-phase liquid chromatographic (RPLC) method has been developed for determination of arabinosylcytosin (Ara-C) and its metabolite 1-β-D-arabinofuranosyluracil (Ara-U) on a 250 mm × 4.6 mm i.d., 5 μm particle, Diamonsil C₁₈ column. The mobile phase was a mixture of 5% methanol and 95% 10 mmol L⁻¹ phosphate buffer adjusted to pH 5.5. The flow-rate was 1.0 mL min⁻¹ and the injection volume 20 μL. Eluting compounds were detected at 270 nm by use of an ultraviolet detector. Under these LC conditions cyclophosphamide (CTX) and pirarubicin (THP), two other medicines given with Ara-C in clinical treatment, do not interfere with measurement of Ara-C and Ara-U. Individual calibration plots of peak area against concentration generated from analysis of standard solutions were used to calculate the concentrations of Ara-C and Ara-U in sample solutions. The calibration plot was linear in the range 2.5–100 μg mL⁻¹, the average recovery of Ara-C and Ara-U was more than 98% (RSD < 2.5%), and between-day and within-day precision, expressed as relative standard deviation (RSD), were below 4.0%. LOQ for both Ara-C and Ara-U was 2 μg mL⁻¹. The method is rapid, simple, accurate and reproducible, and especially useful for application to patient samples.     

3－苄基－6－（1－氨基烃基）－1，2，4－三唑并[3,4-b]-1,3,4-噻二唑的合成与波谱表征

3－苄基－4－氨基－5－巯基－1，2，4－三唑与氨基酸在三氯氧磷存在下反应 ，合成3－苄基－6－（1－氨基烃基）－1，2，4－三唑并[3,4-b]－1，3，4－噻二 唑，其结构经元素分析、红外光谱、核磁共振氢谱、碳谱、质谱等确证。这是稠杂 环接氨基酸残基的首次报道。     

Mass spectra of stereoisomeric cis- and trans-2-alkyl-3-aryl(hetaryl)-4-(methoxycarbonyl)-3,4-dihydro-1h-isoquinol-1-ones and 1,2,3,4-tetrahydroisoquinolines

The molecular ions of the trans isomers of the investigated compounds are more stable than those of the cis isomers. Their principal fragmentation pathways involve retrodiene fragmentation of the molecular ions, which proceeds with greater probability in the case of the cis isomers, or loss of substituents from the 4 or 3 position. The latter process is characteristic only for tetrahydroisoquinoline derivatives, is not observed for 3,4-dihydro-1H-isoquinol-1-one derivatives, and proceeds more readily in the case of the trans isomers.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1395–1397, October, 1980.     

Liquid Chromatographic Analysis of Pentobarbital

Abstract

A method is described for a one step acetonitrile precipitation of serum or plasma and subsequent analysis of pentobarbital by reverse phase HPLC. The results of using two internal standards, N,N-Diethyl-m-toluamide and 5-(p-Methylphenyl)-5-phenylhydantoin are compared. Internal standard is added to serum (as little as 25 μL) and vortex-mixed with acetonitrile followed by centrifugation. An aliquote of the supernatant is analyzed on a C18 reverse phase column eluted with metanol/0.05 M (NH₄)₂HPO₄, pH 8/water (55/20/25, v/v/v). The effluent is monitored at 220 nm.