Calibration curves, glucose

FIGURE 17.5 Hie calibration curve of the electrocatalytic current on the concentration of glucose. Inset is the plot of Lineweaver-Burk equation. (From [253], with permission.)... 

Fig. 15.17 Response of glucose oxidase immobilized in sol gel using MCLW for detection of various concentrations of glucose and calibration curve. Reprinted from Ref. 52 with permission. 2008 Elsevier...

The blend of PVA with PEG- modified glucose oxidase could be used as glucose sensor characterized by the linearity of calibration curve in the range of concentration by 5 x 10"5 - 5 x 10"3 mol glucose L 1 [194],... 

As some other sugars are also present in blood sample, and besides the above reaction not being absolutely stoichiometric, it has become necessary in actual practice to establish an emperical calibration curve using known concentrations of glucose. The above reaction is allowed to proceed for exactly 8 minutes at 100°C. To the resulting solution phosphomolybdic acid is added, which is subsequently reduced by Cu20 to give rise to an intensely coloured molybdenum blue that is measured at 420 nm accurately. 

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. 

Conductivity was measured as described (10) using a conductivity meter (Radiometer, Copenhagen, Denmark) type CDM3 equipped with a CDC 304 immersion electrode with manual temperature compensator type CDA 100. The instrument was calibrated as specified by the manufacturer. The determination of the (NH4)2S04 concentration from the conductivity measurements was done at constant temperature (4°C) using a calibration curve, in the range of 0.016 mM to 120 mM AS in glucose or sucrose (total... 

A special case of the thin-film approximation considers that the substrate can diffuse within the film with negligible depletion. This corresponds to both Case V (unsaturated enzyme). Case I (saturated enzyme) and the border between them. A thin film is the only situation where we can fit experimental data to a theoretical calibration curve for the whole range of glucose concentrations with ... 

A challenge is to manufacture glucose monitors in such a reproducible manner that they do not require calibration. A user expects to add a drop of blood to the test strip and get a reliable reading without first constructing a calibration curve from known concentrations of glucose in blood. Each lot of test strips is highly reproducible and calibrated at the factory. 

Dilute the standard glucose solution to make 0.2, 0.4, 0.6, 0.8, and 1.0 g/ell solutions. Use these known glucose solutions as samples for step 3 and 4. Prepare a calibration curve which shows the absorbance versus glucose concentration. 

Read the value of glucose concentration corresponding to the absorbance from the calibration curve. 

Fig. 2.15 Theoretical (open points) and experimental (full points) calibration curve for glucose sensor for (a) 100% oxygen in 0.2 mM buffer, (b) 25% oxygen and 0.2 mM buffer, and (c) 100% oxygen and 1 mM buffer (adapted from Caras et al., 1985b, p. 1921)...

The calibration curves of the glucose sensor I are shown in Figure 6 and the linear range of the curves gradually decrease with decreasing of the oxygen tension from 21 to 5 %. 

Glucose sensors II and HI were prepared from the semipermeable membrane of PMSP, poly(1-trimethylsilyl-l-propyne), which has 4 times the oxygen permeability compared with that of FEP membrane. The response properties of sensor H, using a PMSP membrane with 25 Um diameter pinhole, were almost similer to that of the sensor I, so that their calibration curves were not presented in this paper. 

The calibration curves of the sensor IV, which was prepared with a PMSP membrane as an oxygen permeable membrane and an acetyl celulose(AC) membrane as a glucose semipermeable membrane, were shown in Figure 8. This AC membrane was cast by Manjikian s method and treated at a curing temperature of 85°C. The sensor ]V indicated a linear response up to 500 mg/dl of glucose concentration, even under 5 % of oxygen tension, and the output currents were hardly affected by oxygen tension. 

Figure 6. Calibration curves of glucose sensor I having glucose semipermeable FEPp membrane with 25 pm diameter pinhole.

Figure 7. Calibration curves of glucose sensor HI having glucose seraipermeable PMSPp( 1 ) membrane with 15ym diameter pinhole...

Figure 8. Calibration curves of glucose sensor ]y having a glucose semipermeable AC membrane. The AC membranes were cast using a solution of acetyl cellulose formamide aceton = 25 30 45 (wt %) and tempered at 85°C...

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