圆二色谱法分析 amphetamines

Amphetamines是一种受控物质，是一种有效的兴奋剂，可以诱导力量和能量的感觉，同时减少睡眠或进食的需要。大多数非法Amphetamines产品是外消旋的；因此，两种异构体将出现在生物液体中。相比之下，大多数药物代谢形成的分解产物表现出纯Amphetamines对映体。圆二色性是光吸收光谱的一种形式，它测量一种物质对左右圆偏振光和左圆偏振光的吸光度的差异（而不是各向同性光的常用吸光度）。由于不同的对映体吸收不同的光部分，它为对映体的检测提供了极好的手段。在此应用中，CD将用于研究安非他明和甲基苯丙胺的异构体。CD APPLICATION NOTE 01-04Circular Dichroism SpectrometryFor the Analysis of Amphetamines Amphetamines are controlled substances which are potent stimulants that induce feelings of strength and energy while decreasing the need to sleep or eat . The majority of illegal amphetamine products are racemic； consequently， both isomers will appear in the biological fluids unchanged. In comparison the break-down products formed by the metabolism of most pharmaceutical drugs show the 2appearanceof F pure amphetamine enantiomers. Circular dichroism is a form of light absorption1spectroscopy thatmeasures the difference in absorbance of right- and left-circularly polarized light (rather than the commonly used absorbance of isotropic l ight) by a substance.Sinceedifferentenantiomers absorbdifferent portions of the light， it provides and excellent means for enantiomer detection. Inthis application CD will be used to study the isomers of amphetamine and methamphetamine. Int r o d u c t io n Amphetamines are synthetic drugs that stimulate the central nervous system. They are structurally similar to ephedrine， a natural stimulant found in plants and to the hormone adrenaline. They are available legally by prescription and were once widely prescribed as a cure all for everything from asthma to epilepsy. Today，medical use of amphetamines is l imited to treating minimal brain dysfunction (MBD) in children and narcolepsy， a rare disorder in which an individual suddenly falls into an uncontrollable deep sleep. Amphetamines are a popular "street" drug.Legally produced amphetamines are sold illegally on the black market with variations in quality and quantity.Enterprising chemists have also developed a "look-alike" amphetamine manufactured to look l ike real amphetamines and mimic their effects.These are commonly referred to as "speed" or "uppers". These drugs contain varying amounts of lesspotent stimulants such as caffeine，，ephedr i ne 2and phenylpropanolamine-allllegal substances that are usually found in over-the-counter dietpills 2and decongestants. The majority of illegal amphetamine products are racemic； consequently， both isomers will appear in the biological fluids unchanged.. In comparison the break-down products formed by the metabolism of most pharmaceutical drugs show the appearance of pure amphetamine enantiomers. A large portion of abused amphetamines are produced surreptitiously by various S methods. This S produces productswith different qualities depending on the type of synthesis as well as on the chemicals used. The identification of by-products of the synthesis and the determination of the enantiomeric composition of the active substance as well as that of the i mpurities being present in the preparations， are important aims of the forensic and pharmacological analysis.. It is also useful for both comparative purposes and for the evaluation of the production methods. In this note we will show the applicability of CD to the determination of enantiomeric composition. Exp eri m e n t a l The individual isomers of amphetamine and methamphetamine ((1mg/mL in methanol) were purchased 1from Altech andused without further preparation. CD spectra were collected at room temperature using a Jasco J-810 spectropolarimeter in a l ow volume 1cm path length cell. The response time used was 1sec with a data pitch of 0.1nm and a scan speed of 100nm/min， giving complete analysis in less than 2 minutes. Figure 1. CD spectra of D-amphetamine (blue) and D-methamphetamine (red). Result s an d Di sc u ss i on Evaluation of the CD spectra of methamphetamine and amphetamine show very few differences. This is due to the fact that meth-amphetamine i s composed of an amphetamine molecule with an additional methyl group attached to i ts nitrogen (amine group).Figures 1-2 show the scans of the isomers of amphetamine and meth-amphetamine. Figure 2. CD spectra of L-amphetamine (blue) and L-methamphetamine (red). The most important use for CD is chiral detection and determination， and in the case methamphetamine is very useful for identification of the enantiomers.(Figure 3) Another important feature of the data is the HT[V] which is easily converted via software into absorbance units. Thus UV data is collected for everv sample at the same time. Since legal amphetamines are detected as pure enantiomers and street versions racemic， CD is a a quickmethod ffor determining prescription from illegal versions.(CD is also an effective method for determining which enantiomer is used in the drug as an aid to identification. Figure 3. CD spectra of L-methamphetamine (red) and D-methamphetamine (blue). C o n c lu s i ons CD spectrometry is a fast effective method for the determination of the chiral structures in amphetamines and many other compounds of interest. In addition CD is useful for protein secondary and tertiary structure，ligand binding， carbohydrate i nteraction and much，much， more. The simultaneous collection of both the CD and UV in one measurement wil l increase the speed and efficiency of all chiral determinations.