Potentiometric titration method

Active matter (anionic surfactant) in AOS consists of alkene- and hydroxy-alkanemonosulfonates, as well as small amounts of disulfonates. Active matter (AM) content is usually expressed as milliequivalents per 100 grams, or as weight percent. Three methods are available for the determination of AM in AOS calculation by difference, the two-phase titration such as methylene blue-active substances (MBAS) and by potentiometric titration with cationic. The calculation method has a number of inherent error factors. The two-phase titration methods may not be completely quantitative and can yield values differing by several percent from those obtained from the total sulfur content. These methods employ trichloromethane, the effects from which the analyst must be protected. The best method for routine use is probably the potentiometric titration method but this requires the availability of more expensive equipment. 

Potentiometric titration methods have been used to study the tauto-merism of certain arylaminophosphazenes produced by the azide route... 

Conductometric titrations offer several advantages compared with potentiometric titration methods, such as better precision and better differentiation of the basic components in polymers, but they are more laborious. ASTM D 4928-96 is an established KF method for the determination of water in crude oils. 

Subsequently, Bos and Dahmen used in m-cresol65 (e = 12.29 at 25° C) a potentiometric titration method combined with conductometry. Essential precautions were the preparation of water-free m-cresol (<0.01% of water), the use of a genuine Bronsted base B, e.g., tetramethylguanidine (TMG), and the application of a glass electrode combined with an Ag-AgCl reference electrode filled with a saturated solution of Me4NCl in m-cresol. The ion product of the self-dissociation of m-cresol, Ks, was determined from the part beyond the equivalence point of the potentiometric titration curve of HBr with TMG comparison with titration curves calculated with various Ka values showed the best fit for Ks = 2 10 19... 

Stevenson F.J. Nature of divalent transition metal complexes of humic acids as revealed by a modified potentiometric titration method. Soil Sci 1977 123 10-17. 

The British Pharmacopoeia [2] describes a potentiometric titration method for the determination of penicillamine as the pure drug substance. The method is performed by dissolving 100 mg of the substance in 30 mL of anhydrous acetic acid. The mixture is titrated with 0.1 M perchloric acid, and the endpoint determined potentiometrically. Each milliliter of 0.1 M perchloric acid is equivalent to 14.92 mg of C6HnN02S. 

In addition, potentiometric titration methods exist in which an electrode other than an ion-selective electrode is used. A simple platinum wire surface can be used as the indicator electrode when an oxidation-reduction reaction occurs in the titration vessel. An example is the reaction of Ce(IV) with Fe(II) ... 

Selig reported a potentiometric titration method for the analysis of procaine and some other organic cations precipitated by tetraphenylborate [67]. The development of ion selective coated-wire electrodes, and their application in the titration of procaine and other pharmaceutically important substances, was reported [68]. 

The pKa value for 2,3,6,7,8,9-hexahydro-4//-pyrimido[l,2-a]pyrimidine has been determined to be 11.22 using potentiometric titration methods. This value is nearly identical for the pKa values reported for the corresponding imidazo[l,2-a]pyrimidine and imidazo-[ 1,2-a ][ 1,3]diazepine heterocycles (62CJC1160). 

A novel capillary electrophoresis method using solutions of non-crosslinked PDADMAC is reported to be effective in the separation of biomolecules [211]. Soil studies conducted with PDADMAC report the minimization of run-off and erosion of selected types of soils [212]. In similar studies, PDADMAC has found to be a good soil conditioner [213]. The use of PDADMAC for the simultaneous determination of inorganic ions and chelates in the kinetic differentiation-mode capillary electrophoresis is reported by Krokhin [214]. Protein multilayer assemblies have been reported with the alternate adsorption of oppositely charged polyions including PDADMAC. Temperature-sensitive flocculants have been prepared based on n-isopropylacrylamide and DADMAC copolymers [215]. A potentiometric titration method for the determination of anionic polyelectrolytes has been developed with the use of PDADMAC, a marker ion and a plastic membrane. The end-point is detected as a sharp potential change due to the rapid decrease in the concentration of the marker due to its association with PDADMAC [216]. 

ISO (2006a). Cheese and Processed Cheese Products—Determination of Chloride Content— Potentiometric Titration Method (Standard ISO 5943/IDF 88). International Organization... 

The conductometric titration method has several advantages over the potentiometric titration method. It is applicable in a straight forward manner, without back titration or other modifications, to the determination of TBN for a wide range of petroleum products including fresh and heavily used oils. The conductometric method is quick and easy to perform, with two intersecting lines at the equivalent point, also contamination of electrodes is eliminated. The... 

Issa et al. described a potentiometric titration method based on the use of ion-selective electrodes [19]. The electrode response was Nernestian over the range of 6.3 pM 0.1 M, when operated in the pH range of 2-7 and at a temperature range of 25—70°C. The response time was reported to be 20-30 s. The recovery was 97.37-103.35%, with relative standard deviation of 0.06-0.5%. 

The oxidation-reduction potential (E6) of adrenodoxin is 164 mV at pH 7.4 and 26° C by the potentiometric titration method with dithionite in a nitrogen atmosphere (29). However, Estabrook and his colleagues obtain a value of —196 mV in the determination of the potential anaerobically by titration with NADPH plus adrenodoxin reductase using dyes with electromotive activity. The difference in value between the two... 

Many simplified potentiometric titration methods have been described from time to time, and various forms of apparatus have been devised to facilitate the performance of these titrations for reference to these matters the more specialized literature should be consulted. ... 

Standard titration techniques, using indicators [4,5,13] with 2-butanol as the titrant, have greater error (3 standard deviations = 1-5% of value), but usually this is still acceptable. The real advantage of these indicator methods is that virtually no capital investment is required for the equipment. The equipment for the more accurate potentiometric titration method can cost upward of 15,000 dollars. This is why titrations using 2,2 -bipyridyl or 1,10-phenanthroline are more prevalent in the literature. 

Avdeef (1998) has reported an automated potentiometric titration method for the determination of solubilities of drug substances containing ionizable groups, where a graphical procedure is used for the estimation of solubility constants based on Bjerrum difference plots. One useful relation derived in this work was ... 

The same symbol is used for corrected (Equation 2.10) and uncorrected (Equation 2.12) Og, and the details of data handling are seldom reported in the experimental parts of scientific papers. A few publications report PZCs obtained by titration without clear explanations of whether they were obtained as CIPs or if titration was performed at only one ionic strength. Such results are indicated as Titration in the Method columns of the tables in Chapter 3. A few methods that give a PZC equivalent to that from the potentiometric titration method are described in Section 2.8.4. 

Pilot test the apparatus consist of a fixed-bed reactor containing 100 g of 1 mm catalyst particles. Hydrocarbon feed (carbureactor containing 125 ppm RSH) and air (6 bar) are passed trough the reactor with a space velocity of 1.2 h at 313 K. The residual mercaptan content was also determined using the same silver nitrate potentiometric titration method [23]. 

As the twentieth century progressed, there was increased emphasis and reliance on instrumental approaches to petroleum analysis. In particular, spectroscopic methods have risen to a level of importance that is perhaps the dream of those who first applied such methodology to petroleum analysis. Potentiometric titration methods also evolved, and the procedures have found favor in the identification of functional types in petroleum and its fractions. 

To determine the acid number by the potentiometric titration method (ASTM D-664, IP 177), the sample is dissolved in a mixture of toluene and isopropyl alcohol containing a small amount of water and titrated poten-tiometrically with alcoholic potassium hydroxide using a glass indicating electrode and a calomel reference electrode. The meter readings are plotted... 

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