A non-linearity criterion applied to the calibration curve method involved with ion-selective electrodes.
Some rational functions of the Padé type, y=y(x; n,m), were applied to the calibration curve method (CCM), and compared with a parabolic function. The functions were tested on the results obtained from calibration of ion-selective electrodes: NH4-ISE, Ca-ISE, and F-ISE. A validity of the functions y=y(x; 2,1), y=y(x; 1,1), and y=y(x; 2,0) (parabolic) was compared. A uniform, integral criterion of nonlinearity of calibration curves is suggested. This uniformity is based on normalization of the approximating functions within the frames of a unit area.
Faculty of Engineering and Chemical Technology, Technical University of Cracow, 31-155 Cracow, Poland. Electronic address: michalot@o2.pl.
Tadeusz
T
Michałowski
Cerko Sp. z o.o. Sp.K., 81-451 Gdynia, Al. Zwycięstwa 96/98, Poland.
Bogusław
B
Pilarski
Department of Oncology, The University Hospital in Cracow, 31-501 Cracow, Poland.
Anna M
AM
Michałowska-Kaczmarczyk
Cerko Sp. z o.o. Sp.K., 81-451 Gdynia, Al. Zwycięstwa 96/98, Poland.
Agata
A
Kukwa
Curve fitting; ISE calibration; Potentiometric titration; Rational functions