Glucose, determination in blood

S. Milardovic, I. Kruhak, D. Ivekovic, V. Rumenjak, M. Tkalcec, and B.S. Grabaric, Glucose determination in blood samples using flow injection analysis and an amperometric biosensor based on glucose oxidase immobilized on hexacyanoferrate modified nickel electrode. Anal. Chim. Acta 350, 91-96... 

Optical biosensor Colorimetric for oolor, photometric for light intensity Detection of disease-like cancer, direct glucose determination in blood using reagentless optical biosensor... 

Enzyme sensors in thick-film technology, according to the design in Fig. 7.36, are commercially available. Most common are glucose sensors of this type. The protecting layer allows one to use the sensors for glucose determination in blood samples without pretreatment. 

The glucose sensor is one of the best known everyday applications of the elec-troanalytical ideas we have met in this chapter. Such sensors provide a fast and reliable determination of the glucose concentration in blood. People with diabetes frequently require such assays, and pathology laboratories in hospitals and clinics also need these data, so analyses of this type need to be quick, cheap and above all, accurate and reliable. 

In vivo measurements during oral glucose tolerance tests on healthy volunteers were performed and results showed a delay time amounting to several minutes. Moreover, despite the (near) complete recovery theoretically achievable with the ultraslow flow rate, and which should allow an in vitro calibration [65], a one-point in vivo calibration was stiU necessary to improve the correlation between the glucose determined in dialysate and blood glucose values. 

Dzyadevich, S. V. (1999). Soldatkin application of enzyme field-effect transistors for determination of glucose concentrations in blood serum. Biosens Bioelectron 14, 283-287. 

With such methods, glucose is routinely determined in blood (normal level ca. 5 mol/L) and foodstuffs. In all these analyses, it is assumed that molecular oxygen is present in excess, but it is also possible to use the enzyme in an excess of glucose to estimate levels of dissolved oxygen in aqueous or mixed aqueous-organic solvents. This unexpected application exemplifies the broad range of enzymatic analyses. 

Target metabolomics Analysis restricted to specific metabolites (e.g., determining glucose levels in blood). 

Bertermann K., Elze P., Scheller F., Pfeiffer D. and Janchen M. (1982) The application of an enzyme electrode for blood glucose determination in the automated flow system. Anal. Utters, 15. 397-404. 

Perhaps the most common type of problem encountered in the analytical lab is a quantitative analysis. Examples of typical quantitative analyses include the elemental analysis of a newly synthesized compound, measuring the concentration of glucose in blood, or determining the difference between the bulk and surface concentrations of Cr in steel. Much of the analytical work in clinical, pharmaceutical, environmental, and industrial labs involves developing new methods for determining the concentration of targeted species in complex samples. Most of the examples in this text come from the area of quantitative analysis. 

There are also RMs which are prepared for a specific application and are used for validation of relevant methods. Cobbaert et al. (1999) made use of Ion Selective Electrode (ISE)-protein-based materials when evaluating a procedure which used an electrode with an enzyme-linked biosensor to determine glucose and lactate in blood. Chance et al. (1999) are involved with the diagnosis of inherited disorders in newborn children and they prepared a series of reference materials consisting of blood spotted onto filter paper and dried, from which amino-acids can be eluted and... 

In many practical problems, interactions between the variables appear so that the absolute global optimum can be found heavily. As an example, wavelength selection in NIR determination of blood glucose (see Sect. 6.2.6) is considered. The aim of the selection is to find such combinations of wavelengths with which calibration models are obtained their prediction quality is as near at the global optimum as possible (Danzer et al. [2001], p 174). The number of combinations C for the selection of k wavelengths from n channels of the spectrometer is given by... 

In connection with the NIR determination of blood glucose, GA has been used also to select spectra according to the quality of recordings (Fischbacher et al. [1994/96 1995]). 

Measurements in living things, e.g. patients, is occasionally done by sampling in a non-invasive way. Because no standard patients are available which can be selected for calibration, another principle of calibration must be applied, e.g., by a reference method that measures parallel to the actual measuring method. So, the calibration consists in a comparison of the measured results with that of the reference method which are considered to be true (that have been validated beforehand). An example of a reference calibration is represented by non-invasive blood glucose determination by means of NIR spectroscopy (Muller et al. [1997] Fischbacher et al. [1997] Danzer et al. [1998], see Sect. 6.2.6). 

The latter applies to NIR spectroscopy used for the non-invasive determination of blood glucose by means of a fibre-optical measuring-head (Jagemann et al. [1995] Muller et al. [1997] Danzer et al. [1998]). In addition to the weak overtone and combination bands resulting from glucose, strongly disturbing absorption of water, that is the main component... 

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