Biological media

Another specific membrane has been studied by confocal Raman spectroscopy human skin. The Raman effect has been used to visualize water concentration profiles in human skin in vivo [58, 59] and transdermal drug delivery. Optical sections can be obtained without the needs for physically dissecting the tissue. 

Chalmers, P.R. Griffiths (Eds.), Handbook of Vibrational Spectroscopy, vol. 1 Theory and Instrumentation, John Wiley and Sons, Chichester, 2002. 

Dhamelincourt, Etude et realisation d une Microsonde Moleculaire a Effet Raman, PhD dissertation, Universite de Lille I, Lille, 1979. 

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Determination of benzene in air samples has been achieved by bubbling contaminated air through various solvents, followed by uv or in analysis of the solution (90). Methods for identifying benzene in soil, water, and biological media are further described in references 84 and 85. 

Sarkar, N. K., Graves, R. A., Park, J. R. and Usha, M. G. Corrosion of Gold Casting Alloys in Selected Biological Media , Journal of Dental Research, 66, 205 (Abstr. 792) (1987)... 

The main drawbacks of silicone mbber include poor interfacial adhesion between the two phases and leaching out of the hydrogel particles into the biological media. Eor this reason, it is required to synthesize properly engineered copolymers. 

GC/MS has been employed by Demeter et al. (1978) to quantitatively detect low-ppb levels of a- and P-endosulfan in human serum, urine, and liver. This technique could not separate a- and P-isomers, and limited sensitivity confined its use to toxicological analysis following exposures to high levels of endosulfan. More recently, Le Bel and Williams (1986) and Williams et al. (1988) employed GC/MS to confirm qualitatively the presence of a-endosulfan in adipose tissue previously analyzed quantitatively by GC/ECD. These studies indicate that GC/MS is not as sensitive as GC/ECD. Mariani et al. (1995) have used GC in conjunction with negative ion chemical ionization mass spectrometry to determine alpha- and beta-endosulfan in plasma and brain samples with limits of detection reported to be 5 ppb in each matrix. Details of commonly used analytical methods for several types of biological media are presented in Table 6-1. 

Several methods are available for the analysis of trichloroethylene in biological media. The method of choice depends on the nature of the sample matrix cost of analysis required precision, accuracy, and detection limit and turnaround time of the method. The main analytical method used to analyze for the presence of trichloroethylene and its metabolites, trichloroethanol and TCA, in biological samples is separation by gas chromatography (GC) combined with detection by mass spectrometry (MS) or electron capture detection (ECD). Trichloroethylene and/or its metabolites have been detected in exhaled air, blood, urine, breast milk, and tissues. Details on sample preparation, analytical method, and sensitivity and accuracy of selected methods are provided in Table 6-1. 

Almost all of the methods described in Chapter 23 can be used for in vivo analyses, both voltammetric and potentiometric ones. The former are used primarily in the analysis of organic substances, which, within certain ranges of potential, can be either oxidized or reduced. Another popular method is the amperometric determination of oxygen in different biological media with the Clark electrode (Section 23.3). 

Similarly, organophosphate esters are used in a wide variety of applications including hydraulic fluids, plasticizers, and antiwear additives to hydraulic fluids and engine oils. All of these uses have the potential to contaminate the environment, and all of the organophosphate ester components present in hydraulic fluids also are present in plasticizers and antiwear additives. Therefore, detection of a particular organophosphate ester in the environment or in biological media cannot identify the source of the contamination (i.e., hydraulic fluids, plasticizers, antiwear additives). 

Biomarkers of exposure for inorganic and organic forms of lead are usually the measurement of total lead levels in tissues or fluids. Total lead measurements of biological media includes all metabolites and endogenous lead sources as well as any original lead-containing exposure agent. Tetraalkyl lead compounds may also be measured in the breath. 

The poor dispersibility of CNTs in biological media can affect both the cytotoxicity [38] and the in vivo toxicity [39] of such nanomaterials. 

Steffansen, B., Model prodrugs for the intestinal oligopeptide transporter model drug release in aqueous solution and in various biological media, J. Controlled Release, 2001, 73, 21-30. 

In a study of the effect of electrolyte concentration on gas holdup, Bly and Worden (1990) found a strong effect. A salt solution resulted in twice the gas holdup that distilled water did under otherwise identical operating conditions, because the salt solution suppressed bubble coalescence. Investigation of this phenomenon is important in biofluidization, because biological media commonly have high electrolyte concentrations. 

It is also possible to synthesize metallic nanopartides with k- and i-carrageenan [59]. Both Ag and Au nanoparticles have considerable potential for biochemical analysis [60]. The advantage of Ag nanoparticles is that the range of dyes which remain effective in biological media is much more extensive. On the other hand, in some biological systems, such as cell suspensions, Ag can react positively with the cell and it is well know as a bactericide. Au, Ag and Cu nanoparticles have the ability to... 

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