Comparison of potentiometric

Turner, D.R., Varney, M.S., Whitfield, M., Mantoura, R.F.C. and Riley, J.P (1987) Electrochemical studies of copper and lead complexation by fulvic acid. II. A critical comparison of potentiometric and polarographic measurements. Sci. Total Environ., 60, 17-34. 

Lugowska, M. and Rubel, S. (1982) A comparison of potentiometric, spectrophotometric and atomic absorption spectrometric methods for the determination of mercury in wastes. Anal. chim. Acta, 138, 397-402. 

Glomme, A., Marz, J., Dressman, J. B. Comparison of a miniaturized shake-flask solubility method with automated potentiometric acid/base titrations and calculated solubilities. /. Pharm. Set. 2005, 94, 1-15. 

Slater, B., McCormack, A., Avdeef A., Comer, J. E. pH-metric logP. 4. Comparison of partition coefficients determined by HPLC and potentiometric methods to literature values. J. Pharm. 

The synthesis of linear 4 —> 1-a-D-glucans from D-glucopyranosyl phosphate by the action of phosphorylases has been shown by comparison of results of methylation and end-group assay and viscosity determination,209 and by potentiometric, iodine titrations82 on the product. The chain length of the enzymic product (100 to 200 D-glucose units) is less than that of the natural component. Whether this is due to impure enzymes cannot yet... 

The values given in column 3 of Table IV were obtained from the data in column 2 ((2) and (6)]. A comparison of the results for 14 and 15 indicates that the introduction of methyl groups at sites 4 and 5 (see 12), leading to central chirality R at both carbon atoms, is the main cause of enantiomer selectivity. This is in agreement with the only slightly different enantiomer selectivity of 16 relative to 15. As expected, the effect of 17 is reversed by 18. Although valinomycin 1 is chiral, no enantiomer selectivity was detectable (see Table IV). The potentiometrically determined enantiomer selectivity AEMF is correlated to the transport selectivity [(2), (6), (10), and (11)]... 

Synthesis gas production. Alqahtany et al.92 have studied synthesis gas production from methane over an iron/iron oxide electrode-catalyst. Although the study was essentially devoted to fuel cell operation, for purposes of comparison some potentiometric work was performed at 950°C. It was found that under reaction conditions Fe, FeO or Fe304 could be the stable catalyst phase. Hysteresis in the rates of methane conversion were observed with much greater rates over a pre-reduced surface than over a pre-oxidised surface possibly due to the formation of an oxide. 

Comparison of the potentiometric titration curves of milk and CCP-free milk shows more reactive organic phosphate groups in the latter, suggesting that CCP is attached to the organic casein phosphate groups, thereby rendering them less active. 

This point may be located analytically by virtue of the fact that a semiconductor powder in a solution of adsorbing ions acts as a buffer for those ions everywhere but at the PZZP. Thus, potential drift or differential potentiometric titrations( 7,8 ) can be employed to determine the PZZP as illustrated in Figure 2 for CdS. Once the PZZP is determined in this fashion, a direct comparison of EA and is possible and has been done for a variety of semiconductors. (jO Figure 3 illustrates the vs. pH data for p-GaP and shows good agreement between the predicted at the PZZP from electronegativity calculations and the observed value.(9)... 

Potentiometric titration and measurement of conductivity are the classic methods for determining pKa experimentally. With a differential method that involves comparison of meter readings for two substances under carefully controlled conditions, it is possible to obtain accurate differences in pKa. 

The case study. A comparison of the TBN and TAN values obtained by potentiometric, conductometric, and calorimetric methods. The potentiometric ASTM D-2986 method was used as a standard technique and calorimetry and conductometry were used as supporting methods (Pawlak et al., 1989). The results... 

Depending on the circumstances at hand, several different types of mean comparisons can be made. In this section we review the method for comparison of two means with independent samples. Other applications, such as a comparison of means with matched samples, can be found in statistical texts. Suppose, for example, we have two methods for the determination of lead (Pb) in orchard leaves. The first method is based on the electrochemical method of potentiometric stripping analysis [1], and the second is based on the method of atomic absorption spectroscopy [2], We perform replicate analyses of homogeneous aliquots prepared by dissolving the orchard leaves into one homogeneous solution and obtain the data listed in Table 3.1. 

Mirrlees MS, Moulton SJ, Murphy CT et al. (1976) Direct measurement of octanol-water partition coefficients by high-pressure liquid chromatography. J Med Chem 19 615-619 Pagliara A, Khamis E, Thrinh A et al. (1995) Structural properties governing retention mechanisms on RP-HPLC stationary phases used for lipophilicity measurements. J Liquid Chromatography 18 1721-1745 Slater B, McCormack A, Avdeef A et al. (1994) pH-Metric log P. 4. Comparison of Partition Coefficients Determined by Shake-Flask, HPLC and Potentiometric Methods. J Phar-maceut Sci 83 1280-1283... 

The results of potentiometric titration, the number of edge sites, and intrinsic stability constants of the protonation and deprotonation reactions of calcium-, copper-, zinc-, manganese(II)-montmorillonites, and KSF montmorillonite are shown in Table 2.4. As a comparison, some similar data for other montmoril-lonites are also listed. 

In the non-steady state, changes of stoichiometry in the bulk or at the oxide surface can be detected by comparison of transient total and partial ionic currents [32], Because of the stability of the surface charge at oxide electrodes at a given pH, oxidation of oxide surface cations under applied potential would produce simultaneous injection of protons into the solution or uptake of hydroxide ions by the surface, resulting in ionic transient currents [10]. It has also been observed that, after the applied potential is removed from the oxide electrode, the surface composition equilibrates slowly with the electrolyte, and proton (or hydroxide ion) fluxes across the Helmholtz layer can be detected with the rotating ring disk electrode in the potentiometric-pH mode [47]. This pseudo-capacitive process would also result in a drift of the electrode potential, but its interpretation may be difficult if the relative relaxation of the potential distribution in the oxide space charge and across the Helmholtz double layer is not known [48]. 

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