Concentration determination glucose

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. 

To verify the method a 1.00-mL aliquot of a standard solution of 40.0-ppm glucose was added to 1.00 ml of the combined reagents, requiring 34.6 s to produce the same extent of reaction. Determine the calculated concentration of glucose in the standard and the percent error for the analysis. 

Several biosensors are commercially available. One of the most useful is the glucose sensor. The standard sensor determines glucose concentration based on the glucose oxidase enzyme. The chemical reaction for oxidation of glucose is ... 

A control sample is a sample for which the concentrations of the test analyte is known and which is treated in an identical manner to the test samples. It should ideally be of a similar overall composition to the test samples in order to show similar physical and analytical features. For instance, if serum samples are being analysed for their glucose content, the control sample should also be serum with a known concentration of glucose. A control sample will be one of many aliquots of a larger sample, stored under suitable conditions and for which the between batch mean and standard deviation of many replicates have been determined. It may be prepared within the laboratory or purchased from an external supplier. Although values are often stated for commercially available control samples, it is essential that the mean and standard deviation are determined from replicate analyses within each particular laboratory. 

The current / from this second reaction is proportional to Cgiucose over limited concentration ranges generally, the concentration of glucose in the sample is determined from a calibration curve. 

Determination of the Michaelis constant for the cofactor NAD (A m.NAo) was carried out by measuring the initial rate of the reduction of NAD as a function of its concentration, at a constant concentration of glucose. All solutions were prepared in 0.1 M phosphate buffer pH 7.55. 

This cycle plays a major role in controlling the rates of both glucose uptake and release by the Uver. It is the changes in concentration of glucose in the Uver that determine the direction and rate of glucose metabolism (described above). 

The kit includes necessary enzymes (thermostable a-amylase and amyloglucosidase), some reagents (buffer concentrate and glucose oxidase/peroxidase [GOPOD] reagent) and standards (glucose solution and com starch) to carry out 100 starch determinations. The other reagents required for this procedure may be obtained from any chemical supplier. 

The sensor did not respond to volatile compounds such as acetic acid, ethyl alcohol, and amines (diethylamine, propylamine, and butylamine) or to nonvolatile nutrients such as glucose, amino acids, and metal ions (potassium and sodium ions). Therefore, the selectivity of this microbial sensor was satisfactory in the presence of these different substances. The current output of the sensor was almost constant for more than 21 days and 400 assays. The microbial sensor can be used to assay sodium nitrite for a long period. In the same experiments the concentration of sodium nitrite was determined by both the sensor proposed and the conventional method (dime-thyl-a-naphtylamine method). A good correlation was obtained between the sodium nitrite concentrations determined by the two methods (correlation coefficient 0.99). 

Lee etal. determined the concentration of glucose, acetate, formate, lactate, and phenylalanine simultaneously in two E. coli bioreactions using Raman spectroscopy.33 The bioreactor was modified to have a viewing port, and spectra were collected through the port window. This enabled researchers to sterilize the reactor and ensure that it would never be contaminated by contact with the instrument. 

Fig. 1. Relative concentrations of glucose, levulinic acid, acetic acid, formic acid, HMF, furfural, and phenolic compounds compared with the initial concentration (100%, upper dashed lines) in fractions obtained from dilute-acid hydrolysate of spruce allowed to pass through columns with six different anion-exchange resins. The sulfate concentration was also determined but was zero in the fractions shown. The right axis shows the pH (the initial pH, 1.9, is indicated by the lower dashed lines).

Figure 11-3 Coupled enzyme assay to determine glucose concentration. 

Based on the A340 of your plasma sample and the volume of plasma used in the assay, determine the concentration of glucose in your plasma sample. 

This method enables the concentrations of glucose and fructose to be determined separately or the sum of their concentrations to be determined in wines and musts. Phosphorylation of glucose and fructose. 

---