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 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.     

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.     

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.     

Liquid Chromatographic and Mass Spectral Analysis of 1-(3,4-Methylenedioxyphenyl)-1-ethanamines: Homologues of 3,4-Methylenedioxyamphetamines

Abstract

The deletion of a methylene unit from the arylamine side chain of the 3,4-methylenedioxyamphetamines (MDAs) produces the homologous 1-(3,4-methylenedioxyphenyl)-1-ethanamines. These ethanamines were prepared via reductive amination of the corresponding ketone with a series of N-alkylamines. Analytical methods were developed to distinguish these compounds from the MDA series. The ethanamines were separated under reversed-phase1 iquid chromatographic conditions using a c18 stationary phase and a mobile phase of aqueous acidic (pH3) acetonitrite containing triethylamine. The electron impact mass spectra of the ethanamines were determined by GC-MS and the fragmentation pattern clearly distinguishes these compounds from those of the MDA series having the same molecular weight.     

Cyclodextrin Bonded Phase for Liquid Chromatographic Separation and Analysis of Some Oral Contraceptives

Abstract

A specific and sensitive analytical HPLC procedure was described for quantitative determination of ethinylestradiol and norethisterone acetate (Anovlar 1) and ethinylestradiol and norgestrel (Primovlar) in tablet formulation. These steroids were extracted from the tablets with methanol. The steroids were then determined with high performance liquid Chromatograph-Cyclobond 1 column using mobile phase phosphate buffer pH 7.0: methanol (60:40), flow rate 0.5 ml min^?1 and the detection was effected spectrophotometrically at 280 nm, using variable wavelength UV detector.

There was > 99.3% recovery from synthetic mixtures and the coefficient of variation was < 2.0% for the formulations investigated. The method is highly quantitative and reproducible.     

某些酚类的高温液相色谱行为

建立了高温液相色谱系统,在高温条件下,采用甲醇-水作为流动相,在Polymerx RP-1聚合物(PSDVB)色谱柱上考察了6种酚类样品的色谱行为.实验条件:温度40～160 ℃,流速0.2～5.5 mL/min,流动相中甲醇浓度范围40%～80%.考察了温度、流速和流动相组成对酚类样品的保留、分辨、柱效和系统压力的影响,探讨了酚类样品在聚合物柱上的热力学行为.温度升高2.35℃大约相当于流动相中甲醇浓度增加1%,可以通过改变色谱柱温度调节样品保留和改变选择性.柱温升高,降低了流动相的粘度,允许在高温条件下使用较高的流速实现快速分离.在160℃、V(甲醇):V(水)=40:60,为流动相和3 mL/min流速条件下,可于2.5 min内实现6种酚类的完全分离.     

Liquid Chromatographic Separation of Some Common Benzodiazepines and their Metabolites

Abstract

A series of benzodiazepines commonly encountered in forensic samples were separated using isocratic reversed-phase liquid chromatography. These compounds display a wide range of capacity factors on a C₁₈ stationary phase in a pH 8 phosphate buffer and methanol mobile phase. Clorazepate must be analyzed under basic mobile phase conditions to prevent its decomposition to N-desmethyldiazepam. The separation of common parent benzodiazepines such as chlordiazepoxide, diazepam and flurazepam from their corresponding metabolites was achieved under a variety of reversed-phase conditions.     

邻苯二酚的高效液相色谱分析

本文提出了邻苯二酚成品质量的高效液相色谱分析方法。     

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     

高效液相色谱法测定柴油族组成

在银型磺酸键合硅胶柱上以含苯或环己烯的正己烷为流动相,实现了饱和烃、烯烃的基线分离,以改进的迁移丝式氢火焰离子化检测器（ＭＷ－ＦＩＤ）进行定量检测,同时考察了Ａｇ－ＳＣＸ柱的使用性能及改进的ＭＷ－ＦＩＤ的定量准确性。在此基础上建立了高效液相色谱体系分离柴油族组成（饱和烃、烯烃、芳烃及胶质）。     

Liquid Chromatographic Analysis of Various Formulations Containing Emtricitabine

A gradient liquid chromatographic (LC) method for control of emtricitabine (FTC) was validated for the analysis of FTC formulations (capsules and oral solution) and fixed-dose-combination tablets containing FTC [FTC combined with tenofovir disoproxil fumarate (TDF) and FTC combined with TDF and efavirenz (EFV)]. The method is based on the purity test recently prescribed in the International Pharmacopoeia and uses a Hypersil BDS C18 column (25 cm × 4.6 mm i.d.), 5 μm kept at a temperature of 35 °C. Other reversed-phase columns were also investigated. The mobile phases for gradient elution consist of acetonitrile, phosphate buffer and water. The flow rate is 1.0 mL min⁻¹ and UV detection is performed at 280 nm. The method is capable of separating the main components from one another, from the inactive ingredients and from the main degradation products. The method was validated with respect to accuracy, precision, sensitivity and linearity for each component and the solution media were optimized. Finally, commercial FTC capsules, FTC oral solution, FTC/TDF tablets and FTC/TDF/EFV tablets were examined.

     

Liquid Chromatographic Analysis of Bile Acid Methyl Esters

Abstract

Methods have been developed for the qualitative and quantitative analysis of hydroxy and keto derivatives of methyl cholanates utilizing a ¼″ by 1′ μPorasil column, various mixtures of hexane and ethyl acetate and a refractive index detector. The system has been calibrated for some of the methyl dihydroxycholanates using 3α;,7α-dihydroxy-12-oxocholanate as an internal standard and applied to the analysis of the mixtures of diols resulting from the reduction of methyl 3,12-dioxocholanate with NaBH₄ and with Raney nickel.     

高效液相色谱分析法测定色氨酸对映体

采用高效液相色谱法,以手性冠醚Crownpak CR( )为固定相、高氯酸溶液/甲醇混合溶液为流动相,成功地实现了色氨酸(Trp)对映体的色谱分离.考察了流动相中甲醇含量、流量和柱温等因素对分离效果的影响.研究表明,适当提高流动相中的甲醇含量、降低流动相流量、降低柱温可以有效地提高分离度.另一方面,提高流动相中的甲醇含量、提高流动相流量、升高柱温可以显著地缩短样品的保留时间.确定了一种最佳分析分离条件,即流动相为甲醇∶高氯酸溶液=15∶85(V/V),流动相流量0.8 mL/min,柱温20℃,波长220 nm,在此条件下进行色谱分离,样品的保留时间小于12 min,分离度达到2.06.该方法具有快速、高效、准确和精密度高等优点.     

Liquid Chromatographic Analysis of Styrene-Methacrylate and Styrene-Acrylate Copolymers

Abstract

Copolymers of styrene-methacrylate (methyl-, ethyl-, and n-butyl-) and styrene-acrylate (methyl-, ethyl-, and n-butyl-) were prepared by solution polymerization at a low degree of conversion. These copolymers were separated according to composition by liquid adsorption chromatography. Silica gel was the stationary phase and a mixture of chloroform and ethanol was the mobile phase. Ethanol content in the mobile phase affected the elution of the copolymers and methacrylate or acrylate rich copolymers required much ethanol to elute from a column. The retention of the copolymers was controlled by column temperature and the copolymers tended to retain in a column at higher column temperature. A linear gradient elution method way to increase ethanol in the mobile chase was effective to separate the copolymers in the order of increasing the methacrylate or acrylate content. Styrene rich copolymers eluted first from a column. Resolution between two adjacent peaks was improved with the increase in column temperature. In a mixture of copolymers of styrene-methacrylate or styrene-acrylate (methyl, ethyl, and n-butyl) having the same styrene content, the elution was in the order of n-butyl, ethyl, and methyl methacrylate or acrylate copolymers with styrene. In copolymrs having the same styrene content, a mixture of copolymrs having diffrent ester groups was separated and a mixtue of copolymrs having the same estr group (e.g., styrene-methyl mth-acrylate and styrene-methyl acrylate copolymers) was not separated.     

Liquid Chromatographic Analysis of Various Formulations Containing Emtricitabine

A gradient liquid chromatographic (LC) method for control of emtricitabine (FTC) was validated for the analysis of FTC formulations (capsules and oral solution) and fixed-dose-combination tablets containing FTC [FTC combined with tenofovir disoproxil fumarate (TDF) and FTC combined with TDF and efavirenz (EFV)]. The method is based on the purity test recently prescribed in the International Pharmacopoeia and uses a Hypersil BDS C18 column (25 cm × 4.6 mm i.d.), 5 μm kept at a temperature of 35 °C. Other reversed-phase columns were also investigated. The mobile phases for gradient elution consist of acetonitrile, phosphate buffer and water. The flow rate is 1.0 mL min^?1 and UV detection is performed at 280 nm. The method is capable of separating the main components from one another, from the inactive ingredients and from the main degradation products. The method was validated with respect to accuracy, precision, sensitivity and linearity for each component and the solution media were optimized. Finally, commercial FTC capsules, FTC oral solution, FTC/TDF tablets and FTC/TDF/EFV tablets were examined.     

Improved High Performance Liquid Chromatographic Method for the Determination of Some Corticosteroids

Abstract

A simple, selective and accurate high performance liquid chromatographic method for the determination of some pharmaceutically important corticosteroids has been developed. the suggested method uses a ultrasphere ODS column with acetonitrile-phosphate buffer (pH 8) as a mobile phase.

The mean percentage recovery ranged from 97.9 to 99.7, the proposed method was applied to the determination of the studied corticosteroids pro in some dosage forms. the statistical analysis of the results obtained were compared favourably with those given with the official method.     

Liquid Chromatographic Analysis of Pentazocine and Tripelennamine in Combination

Abstract

A reverse phase and normal phase liquid chromatographic procedure is described for the separation of pentazocine and tripelennamine. The isocratic methods use dual wavelength detection at 254, 280, and 313 nm.     

高效液相色谱法分析蜂蜜中的糖

本文研究了用四乙撑五胺（简称ＴＥＰＡ）作为胺基改善剂，在硅胶柱上定量分析蜂蜜含糖量的方法，并成功地分离了木糖、果糖、葡萄糖、蔗糖、麦芽糖和乳糖。对操作条件进行了探讨。采用示差折光检测器检测，含０．０１％ＴＥＰＡ的乙腈－水（７７＋２３）作流动相。六种糖的相对标准偏差均小于３．５％。     

Liquid Chromatographic Analysis of Antiepileptic Drugs: An Overview

Abstract

Extraction of antiepileptic drugs (AEDs) can be carried out by different procedures which include: (i) protein precipitation, (ii) liquid-liquid and (iii) liquid-solid extraction. The latter yields a cleaner sample and shows efficiency comparable to the other procedures; recovery ranges from 90 to 105% for most AEDs.

Types of column include: (i) conventional, (ii) microbore and (iii) high-speed. Compared with conventional and high-speed columns, microbore columns, which have a diameter of 1–2 mm, allow to achieve the highest sensibility (up to double values) and to reduce solvent consume (up to 70 %). High-speed columns, characterized by a length of 3–10 cm and by a reduced packing particle size (? 3μm), make the analysis time more rapid by at least 50%.

Reversed phase chromatography is the most versatile technique as compared to the normal phase and to the precision and accuracy. These parameters, in fact, resulted close to those of the fluorescence polarization immunoassay technique (FPIA), which was the most precise and accurate among the methods compared (79).