Specificity versus Function

The calibration method most often used in ion chromatography is direct comparison of the peak area in an unknown sample with that of a solution with a known content of the same substance. This method requires the injection of constant volumes under constant chromatographic conditions. Errors in the sample delivery, however, are almost excluded upon application of a sample loop valve. A prerequisite is the existence of reference compounds for all sample components to be analyzed. In practice, several different standard solutions in the investigated concentration range are prepared and chromatographed [8], When the resulting peak area is plotted versus the concentration of the standards, one obtains a substance-specific calibration function. 

According to this method, the activation energy is calculated at given values of conversion from a plot of ln(q) versus 1/T. This method provides estimation of E at every selected and constant value of conversion without knowledge of the specific reaction function. The OFW method assumes that E is constant, consequently some systematic error in the estimation of E should be expected, whenever E varies with a. 

D. D. Breimer. Specificity of doxorubicin versus rhodamine-123 in assessing P- glycoprotein functionality in the LLC-PK1, LLC-PK1 MDR1 and Caco-2 cell lines, Ear. J. Pharm. Sci. 2000, 11, 207-214... 

In order to test rate laws, a must be determined as a function of time using an appropriate experimental technique. If the reaction involves the loss of a volatile product as shown in Eq. (8.1), the extent of reaction can be followed by determining the mass loss either continuously or from sample weight at specific times. Other techniques are applicable to different types of reactions. After a has been determined at several reaction times, it is often instructive to make a graph of a versus time before the data are analyzed according to the rate laws. As will be shown later, one can often eliminate some rate laws from consideration because of the general shape of the a versus t curve. 

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