Matrix biological

The analytical process can be divided into four major steps sample preparation, separation, detection, and data treatment. Eor the analysis of drugs and metabolites in biological matrices, sample preparation remains the most challenging task since the compounds of interest are often present at trace level in a complex matrix containing a large number of biomolecules (e.g. proteins) and other substances, such as salts. 

Microdialysis has also been used as a sampling method for measuring the concentration of drugs in human subcutaneous tissues for pharmacokinetic studies [50]. The microdialysates are simpler than other biological fluids and do not contain proteins, permitting their direct injection for analysis by liquid chromatography. 

As previously mentioned, besides conventional matrices such as urine and blood, alternative matrices have become of great interest in toxicology. Different reviews describe the analysis of dmgs of abuse in saliva, sweat, and hair [53-56]. For conventional matrices, LLE and SPE are usually the methods of choice. However, for hair analysis, a more drastic extraction step is necessary initially, followed by a purification step [57]. 

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The development of analytical strategies for the regulatory control of dmg residues in food-producing animals has also been reviewed (128). Because of the complexity of biological matrices such as eggs (qv), milk, meat, and dmg feeds, weU-designed off-line or on-line sample treatment procedures are essential. 

Trace enrichment and sample clean-up are probably the most important applications of LC-LC separation methods. The interest in these LC-LC techniques has increased rapidly in recent years, particularly in environmental analysis and clean-up and/or trace analysis in biological matrices which demands accurate determinations of compounds at very low concentration levels present in complex matrices (12-24). Both sample clean-up and trace enrichment are frequently employed in the same LC-LC scheme of course, if the concentration of the analytes of interest are Sufficient for detection then only the removal of interfering substances by sample clean-up is necessary for analysis. 

Multidimensional separations allow for the analysis of complex mixtures, such as those from biological matrices with thousands of components that would be difficult or impossible to separate by utilizing only one method. Electrodriven separations have been employed to separate biological molecules for many years, due to the charged nature of amino acids and nucleic acids. The addition of an electrodriven component to a multidimensional separation is therefore desirable, especially for the separation of biological mixtures. 

In biomedical analysis, LC-LC has been used most extensively and successfully in the heart-cut mode for the analysis of drugs and related compounds in matrices Such as plasma, serum or urine. Table 11.1 gives an overview of analytes in biological matrices which have been determined by heart-cut LC-LC systems. A typical example of such an approach is the work of Eklund et al. (16) who determined the free concentration of sameridine, an anaesthetic and analgesic drug, in blood plasma... 

In order to reduce or eliminate off-line sample preparation, multidimensional chromatographic techniques have been employed in these difficult analyses. LC-GC has been employed in numerous applications that involve the analysis of poisonous compounds or metabolites from biological matrices such as fats and tissues, while GC-GC has been employed for complex samples, such as arson propellants and for samples in which special selectivity, such as chiral recognition, is required. Other techniques include on-line sample preparation methods, such as supercritical fluid extraction (SFE)-GC and LC-GC-GC. In many of these applications, the chromatographic method is coupled to mass spectrometry or another spectrometiic detector for final confirmation of the analyte identity, as required by many courts of law. 

Funk et al. [231] have demonstrated that the sensitivity of the analysis can be extended down into the femtogram range for the detemunation of selemum in water and biological matrices (Fig. 53). 

Michael LC, Erickson MD, Parks SP, et al. 1980. Volatile environmental pollutants in biological matrices with a headspace purge technique. Anal Chem 52 1836-1841. 

Hansen KJ, LA Clemen, ME Ellefson, HO Johnson (2001) Compound-specific quantitative characterization of organic fluorochemicals in biological matrices. Environ Sci Technol 35 766-770. 

Biological matrices are very complex apart from the analytes, they usually contain proteins, salts, aeids, bases, and various organie eompounds. Therefore, effeetive sample preparation must inelude partieulate eleanup to provide the component of interest in a solution, free from interfering matrix elements, and in an appropriate concentration. 

The simple spectrophotometric thiobarbituric acid (TBA) test has been frequently used for many years as an indicator of the peroxidation of PUFAs present in biological matrices. This test involves the reaction of aldehydes in the sample with TBA at c. 100°C under acidic conditions (Equation 1.13) to produce a pink-coloured chromogen, which absorbs light strongly at a wavelength of 532 nm (Nair and Turner, 1984). 

Boreua P, Bargellini A, Caselgrandi E, Menditto A, Patriarca M, Taylor A, Vivoli G (1998) Selenium determination in biological matrices. Microchem J 58 325-336. 

Many pesticides are neurotoxicants poisoning the nervous system. A number of pesticides are acetyl cholinesterase inhibitors (Serat and Mengle 1973). Generally, pesticides determination has been performed by GC since the 1960 s (Morrison and Durham 1971 Fournier et al. 1978). There are no reference materials for pesticides in urine or serum, although as with PAHs there are a number biological matrices certified for the content of various pesticides available for environmental food and agriculture analysis and which may have some application in clinical chemistry. 

Of the radioassays that are commonly used to quantify americium, a-spectroscopy is used when isotopic analyses of americium must be conducted (e.g., 241Am and 243Am). 243Am is often added as a tracer to estimate the efficiency of the sample preparation method when quantifying 241Am in biological matrices. 

Pinkerton, T.C. (1991). High-performance liquid chromatography packing materials for the analysis of small molecules in biological matrices by direct injection. J. Chromatogr. 544, 13-23. 

N. H. Snow, Solid phase microextraction of drugs from biological matrices, J. Chromatogr. A, 885, 445 455 (2000). 

The palladium and magnesium nitrates modifier makes it possible to apply thermal pretreatment temperatures of at least 900-1000 °C for all investigated elements. For most elements this modifier supports substantially higher pyrolysis temperatures than did the matrix modifier recommended previously by Perkin-Elmer [688]. These higher pyrolysis temperatures allow for effective charring of biological matrices and removal of most inorganic concomitants prior to analyte element volatilisation. 

Rapid Purification Techniques for Drugs and Metabolites in Biological Matrices.3... 

E2.3.2 Elimination of Proteinaceous and Endogenous Contaminants from Biological Matrices to Minimize Ion Suppression during SPE ... 

RAPID PURIFICATION TECHNIQUES FOR DRUGS AND METABOLITES IN BIOLOGICAL MATRICES... 

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