Amphetamine analysis

Why is methanol the preferred solvent for the preparation of samples for TLC in amphetamine analysis ... 

Mescaline Various amines, amphetamines Analysis stimulants in urine, precolumn derivatization Lichrosorb Si 100, or Wakogel LC 5H, 10pm 250x2 5 pm CHC1,-EtOAc-EtOH-n-hexane (25 10 1 50) 25... 

Klys M, Rojek S, KuUkowska J, Bozek E (2007) Usefulness of multiple opiate and amphetamine analysis of hair segments under methadone therapy using LC-AP Cl-MS-MS. Forensic Toxicol 25(2) 69-75... 

For most samples liquid-solid chromatography does not offer any special advantages over liquid-liquid chromatography (LLC). One exception is for the analysis of isomers, where LLC excels. Figure 12.32 shows a typical LSC separation of two amphetamines on a silica column using an 80 20 mixture of methylene chloride and methanol containing 1% NH4OH as a mobile phase. Nonpolar stationary phases, such as charcoal-based absorbents, also may be used. 

Example of the application of liquid-solid chromatography to the analysis of amphetamines. (Chromatogram courtesy of Alltech Associates, Inc. Deerfield, IL). 

Figure 11.14 Analysis of amphetamines by GC-NPD following HS-SPME exti action from human hair (a) Normal hair (b) normal hair after addition of amphetamine (1.5 ng) and methamphetamine (16.1 ng) (c) hair of an amphetamine abuser. Peak identification is as follows 1, a-phenethylamine (internal standard) 2, amphetamine 3, methamphetamine 4, N-propyl-/3-phenethyamine (internal standard). Reprinted from Journal of Chronatography, B 707,1. Koide et ai, Determination of amphetamine and methamphetamine in human hair by headspace solid-phase microextraction and gas cliromatography with niti ogen-phosphoms detection, pp. 99 -104, copyright 1998, with permission from Elsevier Science.

In a recent report, HS-SPME was used for the extraction of amphetamines from human hair (142). Human hair analysis is gaining interest in the analysis of drugs of abuse, since it offers attractive features easy and unlimited sampling, and as the... 

Sequences of aggressive behavior that are composed of characteristic acts and postures following each other rapidly are disrupted. These disorganizing effects parallel the analysis of amphetamine effects on other intricately patterned behaviors such as feeding, maternal care, play behavior, or reproductive interactions. For example, amphetamine suppresses play... 

Miezek, K.A., and Gold, L. Ethologieal analysis of amphetamine aetion on soeial behavior in squirrel monkeys (saimiri sciureus). In Miezek, K.A., ed. Ethopharmacology Primate Models of Neuropsychiatric Disorders. New York Liss, 1983. pp. 137-155. 

Engberg, G., and Svensson, T.H. Amphetamine-induced inhibition of central noradrenergic neurons A pharmacological analysis. Life Sci 24 2245-2254, 1979. 

Rats that have lost dopamine and/or serotonin terminals following treatment with amphetamine, methamphetamine, MDMA, MDA, / -chloroamphetamine, or fenfluramine show little in the way of overt ehanges in appearanee or behavior. Dr. Rieaurte (this volume) emphasized the need for more studies in primates, since MPTP-treated miee also show little in the way of observable functional changes, whereas MPTP-treated monkeys show marked neurologie deficits. It may be neeessary to do more detailed analysis of speeifie behaviors and other funetional outputs that are influeneed by dopamine and/or serotonin neurons, to detect functional deficits induced by some neurotoxic drugs. For instance, specific behaviors sueh as appetite-eontrolled behavior (Leibowitz and Shor-Posner 1986), murieidal behavior (Katz 1980), and sexual behavior (Tucker and File 1983) elieited by drugs... 

Drugs have been purified by SPE in the analysis of amphetamine (AM) by Kaleta et al. [98], by various consecutive washing steps with hexane in the analysis of methamphetamine (MA) by Jones-Lepp and Stevens [99], and by simple centrifugation after addition of water, to separate the aqueous extract from a bottom sediment layer and a top fat layer, in the analysis of AM, MA, cocaine (CO), and benzoylecgonine (BE) by Langford et al. [100], who found little improvement in reducing matrix effects when applying SPE cleanup. 

FIGURE 56-7 Repeated exposure to amphetamine or cocaine increases spine density and the number of branched spines in medium spiny neurons, the major cell type of the nucleus accumbens. Left camera lucida drawings of representative dendritic segments. Rats received 20 injections of saline (S), amphetamine (A) or cocaine (C) over 4 weeks and were then left undisturbed for about 1 month prior to analysis. Adapted from Robinson, T. E. and Kolb, B., Eur. ]. Neurosci. 11 1598-1604, 1999. 

Similar to the analysis above, phenol and the conjugate acid of amphetamine both have a pVa of 10 (Fig. 2.6), but phenol is un-ionized at pH 7.4 and amphetamine is mostly ionized. When the pVa of a base is reported, as in Figure 2.6, it is understood that it represents the pl< A of the protonated form and is calculated from the ratio of protonated to unprotonated as shown in the equation above. 

Some special approaches defined in the CE enantioseparation field can be found in References 37 and 38. In Reference 37, the authors tested four approaches to decrease the analysis time of a previously developed chiral separation method for amphetamine and its related compounds. The considered possibilities were (i) the short-end injection technique or (ii) increased electrical field combined with a capillary length reduction. 

Many stimulants, such as amphetamine, methamphetamine, and caffeine contain nitrogen atoms, which makes NPD analysis fairly straightforward (eg. Koide et al., 1998 Bach et al., 1999). Enantiomeric separation can be of particular importance for these drugs. A review by Liu and Liu (2002) provides extensive examples of methods for the determination of amphetamine and methamphetamine enantiomers and includes examples... 

Analysis using a CMPA is usually resolved on a nonchiral column. A transient diastereomeric complex is formed between the enantiomer and the chiral component in the mobile phase, similar to the complexes formed with chiral stationary phases. A review by Liu and Liu (2002) cites several papers where addition of CPMAs has been used in analyzing amphetamine-related compounds. Some CPMAs include amino acid enantiomers, metal ions, proteins, and cyclodextrins. Advantages of this method of analysis include the use of less expensive columns and more flexibility in the optimization of chiral separation (Misl anova and Hutta, 2003). 

Hernandez R, Falco P, Cabeza A. 1997. Liquid chromatographic analysis of amphetamine and related compounds in urine using solid-phase extraction and 3,5-dinitrobenzoyl chloride for derivatization. J Chromatogr Sci 35(4) 169-175. 

Bogusz MJ, Kruger KD, Maier RD. 2000. Analysis of under-ivatized amphetamines and related phenylethylamines with high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. J Anal Toxicol 24 77. 

Cristoni S, Bernardi LR, Gerthoux P, Gonella E, MocareUi P. 2004. Surface-activated chemical ionization ion trap mass spectrometry in the analysis of amphetamines in diluted urine samples. Rapid Commun Mass Spectrom 18 1847. 

When using PFT with a neutral selector, it is quite difficult to avoid any entrance of the chiral selector into the ionization source, particularly at a high pH, where EOF is important. The use of BGE at low pH and/or coated capillary to minimize EOF is therefore mandatory. However, the coaxial sheath gas, which generally assists the ionization process, leads to an aspirating phenomenon of the chiral selector in the MS direction. Javerfalk et al. were the first to apply PFT with a neutral methyl-/i-CD for the separation of racemic bupivacaine and ropivacaine with a polyacrylamide-coated capillary and an acidic pH buffer (pH 3). Cherkaoui et al. employed another neutral CD (HP-/1-CD) with a PVA-coated capillary for the analysis of amphetamines and their derivatives. To prevent a detrimental aspiration effect, analyses were carried out without nebulization pressure. Numerous other studies presented excellent results such as the enantioselective separation of adrenoreceptor antagonist drugs using tandem mass spectrometry (MS/MS) the separation of clenbuterol enantiomers after solid-phase extraction (SPE) of plasma samples or the use of CD dual system for the simultaneous chiral determination of amphetamine, methamphetamine, dimethamphetamine, and p-hydroxymethamphetamine in urine. 

FIGURE 4 Chiral CE ESI/MS analysis of five amphetamine derivatives and two pharmaceutical compounds. Total ion current (TIC) and extracted ion currents (XIC) of amphetamine (A), methamphetamine (MA), methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), and methylenedioxyethylamphetamine (MDEA), and tramadol (TMD) and methadone (MTD) in plasma after LLE with electrokinetic injection. 

Iwata, Y. T, Kanamori, T, Ohmae, Y., Tsujikawa, K., Inoue, H., and Kishi, T. (2003). Chiral analysis of amphetamine-type stimulants using reversed-polarity capillary electrophoresis/positive Ion electrospray Ionization tandem mass spectrometry. Electrophoresis 24, 1770—1776. 

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