Abalytical Toxicology Essay Example | Topics and Well Written Essays - 2000 words

Abalytical Toxicology - Essay ExampleThis still remains a great challenge for analytical chemists and may rely on identification of different fundament compounds. In the case of precursor drug administration, the p arent compounds are usually detectable only for a improvident fourth dimension, before being fully metabolised or decomposed. For this reason parent compounds can rarely be utilize for differentiating. Specific metabolites are usually detectable for a much longer time. Their use as target compounds for differentiating has found little application however, since all metabolites are not extracted together with MA and AM and are additionally fully converted to AM or MA after a certain time post administration. Enantiomeric profiles for methamphetamine and/or amphetamine, metabolically formed from precursors fuddle been described for some medicaments and keep up been utilise successfully for differentiating between illicit intake and intake of precursors. Thus a reliabl e method for the valued determination of AM/MA enantiomers is essential for differentiation (Kraemer and Mauer, 2002 Musshof, 2000).A great number of research efforts pack focussed on the separation of AM/MA enantiomers particularly from urine or blood matrices. These have been extensively reviewed (e.g. Kraemer and Mauer, 1998 Musshof, 2000). The majority of the methods employed involved enantiomer separation by chromatography, either by HPLC or GC on chiral stationary phases,with or without prior derivatisation with achiral reagents, or by GC on achiral stationary phases, after derivatisation with chiral reagents to the corresponding diastereomers. Detection was commonly by MS to ensure senior high school selectivity and sensitivity. In hurt of sample treatment for analyte extraction and concentration, conventional liquid-liquid extraction protocols (Kraemer and Mauer, 1998), solid phase extraction (SPE) on cartridges (Peters et al., 2002) and solid-phase microextraction (SPME - Nagasawa et al., 1996) have been commonly applied. The proposed methods varied in terms of sensitivity, reliability, sample preparation times and analysis times and adaptability to high throughput format.The current trend in the determination of MA/AM enantiomers is towards the substitution of chiral GC/MS protocols by runs on achiral columns of MA/AM diastereomers. This is because MA/AM diastereomerisation has been shown in several cases to improve resolution, to shorten the property times of analytes and to enhance the response of the detector, i.e. to improve sensitivity (Kraemer and Mauer, 1998 Peters et al., 2002). Furthermore achiral columns are commonly less high-ticket(prenominal) compared to chiral columns. Different chiral derivatisation reagents have been applied successfully in MA/AM diastereomerisation (Kraemer and Mauer, 1998 Musshof et al., 2002 Peters et al., 2002 Wang, 2005). Recent advances in the world involve a fast SPME-based approach, where absorption and d erivatisation are accomplished in a single feeling by adding the derivatising chiral reagent directly into the urine sample matrix (Wang, 2005) and the application of automated headspace solid-phase dynamic extraction (SPDE) couple with GC/MS, for the determination of amphetamines and synthetic designer drugs in hair samples (Musshof et al., 2002). The later technique is an innovative GC/MS approach to the enantiomeric determination of amphetamines and will be discussed further.Headspace SPDE constitutes an alternative extraction and concentration method for fickle and semi-volatile organic compounds contained in liquid or gaseous samples. Headspace SPDE is a further development of headspace SPME. In fact, SPDE was developed