Feasibility and error in linear extrapolation titration procedures

Rosenthal, Donald; Jones, George L.; Megargle, Robert

doi:10.1016/s0003-2670(01)80081-7

Cited by 24 publications

(8 citation statements)

References 3 publications

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“…When the equilibrium constant is small, however, only a fraction of the titration curve is described by a linear equation. These results agree with previous reports (17,18).…”

Section: Resultssupporting

confidence: 94%

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

Goode¹

1977

Anal. Chem.

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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-

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“…When the equilibrium constant is small, however, only a fraction of the titration curve is described by a linear equation. These results agree with previous reports (17,18).…”

Section: Resultssupporting

confidence: 94%

“…A linear least-squares fit was applied to the segments of a spectrophotometric titration by Rosenthal et al (18). They examined the influence of the equilibrium constant and measurement error on the precision of the equivalence point.…”

Section: Location O F T H E Equivalence Point Bymentioning

confidence: 99%

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

Goode¹

1977

Anal. Chem.

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“…The endpoint of the titration is the point at which the analytical concentration of added metal, Cm, is equal to (a/b) Cl, where Cl is the analytical concentration of ligand. This point is determined by extrapolation of data points in the two regions to a point of intersection using guidelines suggested by Rosenthal et al (4).…”

Section: Theory and Proceduresmentioning

confidence: 99%

Stability constants of copper-organic chelates in aquatic samples

Shuman¹,

Woodward²

1977

Environ. Sci. Technol.

100

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A procedure similar to an amperometric titration of a ligand with copper was used to determine the conditional formation constants of copper-organic chelates in several fresh water samples at controlled pH. The titration curve was constructed using anodic stripping voltammetry to detect unreacted copper. An equation for this curve was developed and revealed that both the stoichiometry and the formation constant of the complex formed during the titration could be obtained. The ligand in the water samples responsible for copper binding was characteristic of a conjugate base of a weak acid, the acid being almost entirely ionized at neutral pH. Estimates of the conditional formation constants for these complexes ranged in value from 0.32 X 105 to 5.2 X 105 at pH 6.5.

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“…To date, the most thorough treatment of this subject in the analytical literature is the work of Rosenthal et al, 65 upon which much of the subsequent discussion is based. In the case of a chemically ideal titration any source of random error in the measured variable 0, which in the case of a thermometric titration is a voltage proportional to a temperature change, will propagate itself as an uncertainty in the location of the end point which will be termed f g Consider a perfect titration curve, which is described by the equations…”

Section: • 'J B Precision and Sensitivity Of Thermometric Titrationsmentioning

confidence: 99%

“…Implicit in Equation65 is the notion that sensitivity can be increased without bound by simply increasing aE R . Alternatively, a larger voltage can be developed by amplifying e 0 before presentation to the recorder.…”

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confidence: 99%