Computerized curve-fitting to determine the equivalence point in spectrophotometric titrations

Abstract

value). The derived reactivity ratio for butene, i.e., the reciprocal of the slope, 0.51, is quite reasonable in comparison with the literature value of 0.50 (28) reported for a related catalyst system, Et3A1/TiC13. However, much more data would be required for a satisfactory measure of this parameter.These materials were then used in the heated cell infrared method of Tosi et al. (8). The absorbances were recorded together with those obtained for a number of blends of polybutene and polypropylene homopolymers. The blends and the standards generate two different lines (Equations 4 and 5 respectively) which, by t test, have significantly different slopes (t = 2.10; t0.06, 16 = 2.12). Thus, calibrated standards are necessary to carry out the method accurately. Presumably, this is the reason that blends were not used in earlier work on the infrared methods. y(absorbance ratio) = 1.015~ (molar ratio P/B) A nonllnear least-squares curve-fit Is used to determlne the equivalence polnt In spectrophotometrlc tltratlons. Tltratlon curves, wlth a maximum absorbance of 0.4 to 0.8, are cal-

Chemometrics

“…Other investigators have also reported the application of nonlinear regression analysis to potentiometric and spectrophotometric data (II,13,116,132). use computer graphics to examine Gran plots and error functions in order to determine the equivalence point of potentiometric titrations.…”

Using a Spreadsheet to Fit Experimental pH Titration Data to a Theoretical Expression: Estimation of Analyte Concentration and Ka

“…Although computer simulation of acid-base pH titrations has been discussed for over 30 years in this Journal (1)(2)(3)(4)(5)(6)(7)(8)(9)(10) and fitting experimental titration data to theoretical expressions has been discussed in the research literature (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22), it is interesting to note fitting experimental pH titration data has received relatively little pedagogical attention. In a 1993 article, focusing on the development of a single closed-form expression for the titration curve for a variety of titrations, de Levie (8a) indicates fitting experimental titration data to a derived theoretical expression is possible.…”

Versatile microcomputer-controlled titrator

“…In recent years, there has been considerable interest in using computers for titrations, particularly where Gran plots (9), Hofstee plots (10), or modification of these (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) could provide improved determination of the equivalence point in potentiometric, spectrometric, and amperometric experiments. More recently, microcomputers have greatly increased the possibilities of improved automated titrations at modest cost.…”