Application in Clinical Analysis

During all sample preparation steps extreme care must be taken to avoid sample contamination (see Chap. 3). Soft tissues, e.g., liver, muscle, kidney, need only freeze drying and subsequent 

The particle size of powders may be established by the conventional operation of sieving or by a particle counter [1]. Homogeneity, an important item in SS-AAS, may be derived from the relative standard deviation (RSD) and the mass as follows [8]  

Although in SS-AAS the risk of contamination is considerably less than in indirect methods, care must be taken to avoid contamination and all used utensils must be thoroughly cleaned before use. 

In the case of determination of the dry weight concentration, the water content can be determined in the regular way by weighing and drying. Before analysis, the powder has to be moisture-equilibrated with the laboratory room. 

TABLE 1. Determination of Various Elements in Tissue with Solid Sampling Atomic Absorption 

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Zipp A., Homby W.B., Solid-phase chemistry its principles and applications in clinical analysis, Talanta 1984 31 863. 

Severinghaus electrodes have found wide application in clinical analysis. It is pertinent to mention here that the general principle of permeation of the gas through a hydrophobic membrane followed by its detection (with or without its solvolysis) has been used with different types of internal sensors, for example, optical, ampero-metric, conductimetric, or a mass sensor. The choice of the internal sensing element depends on the circumstances of the application in which the gas sensor would be used, such as the required time response, selectivity considerations, complexity of instrumentation, and so on. 

The immunoassay is today a relatively well-established technique, with numerous applications in clinical analysis, but also with a considerable growing interest in other fields, such as the food industry or environmental monitoring. Benefits such as high selectivity and sensitivity (for certain analytes not attainable by any alternative methods), speed and relatively low cost of analysis have also led to rapid commercialization of immunoassay kits and automated analysers [4]. 

The system developed in this work establish a general electrochemical detection methodology that can be applied to a variety of immunosystems and DNA detection systems, including lab-on-a-chip technology, with special interest for further applications in clinical analysis, food quality and safety as well as other industrial applications. 

Applications in Clinical Analysis An example of the application of a potentiometric enzyme-based biosensor in clinical analysis is an automated monitor designed specifically to analyze blood samples at the bedside of palicnls. The i-STAT Portable Clinical Analyzer, shown in I igure 23-14a. is a handheld device capable of determining a broad range of clinically important analytes such as polas-... 

Clinical Applications Perhaps the area in which ion-selective electrodes receive the widest use is in clinical analysis, where their selectivity for the analyte in a complex matrix provides a significant advantage over many other analytical methods. The most common analytes are electrolytes, such as Na+, K+, Ca +, H+, and Ch, and dissolved gases, such as CO2. For extracellular fluids, such as blood and urine, the analysis can be made in vitro with conventional electrodes, provided that sufficient sample is available. Some clinical analyzers place a series of ion-selective electrodes in a flow... 

Environmental Applications Although ion-selective electrodes find use in environmental analysis, their application is not as widespread as in clinical analysis. Standard methods have been developed for the analysis of CN , F , NH3, and in water and wastewater. Except for F , however, other analytical methods are considered superior. By incorporating the ion-selective electrode into a flow cell, the continuous monitoring of wastewater streams and other flow systems is possible. Such applications are limited, however, by the electrode s response to the analyte s activity, rather than its concentration. Considerable interest has been shown in the development of biosensors for the field screening and monitoring of environmental samples for a number of priority pollutants. 

Flow injection analysis has also found numerous applications in the analysis of clinical samples, using both enzymatic and nonenzymatic methods. A list of selected examples is given in Table 13.3. 

Analytical Applications. Chemiluminescence and bioluminescence are useful in analysis for several reasons. (/) Modem low noise phototubes when properly instmmented can detect light fluxes as weak as 100 photons/s (1.7 x 10 eins/s). Thus luminescent reactions in which intensity depends on the concentration of a reactant of analytical interest can be used to determine attomole—2eptomole amounts (10 to 10 mol). This is especially useful for biochemical, trace metal, and pollution control analyses (93,260—266) (see Trace and residue analysis). (2) Light measurement is easily automated for routine measurements as, for example, in clinical analysis. 

M. Forina, C. Armanino, S. Lanteri and R. Leardi, Methods of Varimax rotation in factor analysis with applications in clinical and food chemistry. J. Chemom., 3 (1988) 115-125. 

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. 

General books [213-217], chapters [218], and reviews were published in the 1980s reporting the suitability of CL and BL in chemical analysis [219-222], the specific analytical applications of BL [223], the CL detection systems in the gas phase [224], in chromatography [225, 226], the use of different chemiluminescent tags in immunoassay, and applications in clinical chemistry [227-232] as well as the applications of CL reactions in biomedical analysis [233]. 

Amperometric detection is a very sensitive technique. In principle, voltammetric detectors can be used for all compounds which have functional groups which are easily reduced or oxidized. Apart from a few cations (Fe , Co ), it is chiefly anions such as cyanide, sulfide and nitrite which can be determined in the ion analysis sector. The most important applications lie however in the analysis of sugars by anion chromatography and in clinical analysis using a form of amperometric detection know as Pulsed Amperometric Detection (PAD). 

Further progress of ECL probes immobilization methods should result in new robust, stable, reproducible ECL sensors. Especially, the use of electrochemilumi-nescent polymers may prove to be useful in this respect. There are also good prospects for ECL to be used as detection in miniaturized analytical systems particularly with a large increase in the applications of ECL immunoassay because high sensitivity, low detection limit, and good selectivity. One can believe that miniaturized biosensors based on ECL technology will induce a revolution in clinical analysis because of short analysis time, low consumption of reactants, and ease of automation. 

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