Potentiometric titration with

Analytical and Test Methods. Potentiometric titration with sodium hydroxide [1310-73-2] is employed. Both equivalent points are... 

The potentiometric micro detection of all aminophenol isomers can be done by titration in two-phase chloroform-water medium (100), or by reaction with iodates or periodates, and the back-titration of excess unreacted compound using a silver amalgam and SCE electrode combination (101). Microamounts of 2-aminophenol can be detected by potentiometric titration with cupric ions using a copper-ion-selective electrode the 3- and... 

Titration of thioglycolate esters is also realized by iodine in alcohoHc solution. Titration of thioglycolic acid (acid number) in thioglycolate esters is effected by potentiometric titration with potassium hydroxide. 

The analysis of solutions of technical xanthates by Ag+ potentiometric titration, with the addition of ammonium hydroxide, has been successfully used at Dow (95). 

CrP" -selective and Ni " -selective electrodes have been used to detenuine the copper and nickel ions in aqueous solutions, both by direct potentiometry and by potentiometric titration with EDTA. They have also been used for detenuining the CiT and Ni " ions in indushial waters by direct potentiomehy. 

The general procedure for performing a potentiometric titration with non-aqueous solutions is in essence the same as that employed for aqueous solutions, but there are some important points of difference. 

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. 

The methods most commonly used to detect hydrogen sulfide in environmental samples include GC/FPD, gas chromatography with electrochemical detection (GC/ECD), iodometric methods, the methylene blue colorimetric or spectrophotometric method, the spot method using paper or tiles impregnated with lead acetate or mercuric chloride, ion chromatography with conductivity, and potentiometric titration with a sulfide ion-selective electrode. Details of commonly used analytical methods for several types of environmental samples are presented in Table 6-2. 

Potentiometric titration with a sulfide ion-selective electrode as an indicator has been used to measure hydrogen sulfide in the air at ppb levels (Ehman 1976). The method has been shown to have very good accuracy and precision. No interference could be found from nitrogen dioxide, sulfur dioxide, or ozone. 

Walash et al. [10] determined primaquine and other quinoline drugs in bulk and in pharmaceuticals by a titrimetric method. The method is based on reaction with l,3-dibromo-5,5-dimethylhydantoin or TV-bromosuccinimide as the titrant. Primaquine was determined either by usual titration or by potentiometric titration with the brominating agents. The recovery was approximately 100%. The method was simple, precise, and accurate. 

The secondary amine function of dobutamine hydrochloride may be determined by potentiometric titration with perchloric acid using glacial acetic acid as a nonaqueous solvent. Mercuric acetate is used to tie up the chloride ion. 

Valproic acid can be potentiometrically titrated with standardized 0.1 N tetra-n-butylammonium hydroxide in chlorobenzene using a modified glass-calomel electrode system, in which 1.0 M aqueous tetra-n-butylammonium chloride has been substituted for potassium chloride, and employing acetone as the sample solvent. 

The polyhedral boranes and carboranes discussed above may be regarded as boron clusters in which the single external orbital of each vertex atom helps to bind an external hydrogen or other monovalent atom or group. Post-transition main group elements are known to form clusters without external ligands bound to the vertex atoms. Such species are called bare metal clusters for convenience. Anionic bare metal clusters were first observed by Zintl and co-workers in the 1930s [2-5], The first evidence for anionic clusters of post-transition metals such as tin, lead, antimony, and bismuth was obtained by potentiometric titrations with alkali metals in liquid ammonia. Consequently, such anionic post-transition metal clusters are often called Zintl phases. 

If we follow the potentiometric titration with a voltmeter, what is the source of the emfl... 

A known volume of KBr solution is pipetted into a clean beaker and a freshly polished silver electrode is then immersed in this solution. After a potentiometric titration with AgNOj solution at 298 K, the electrode potential at the equivalence point (EAg+,Ag) is determined to be 0.441 V. What is for the pale yellow AgBr that is formed ... 

Direct potentiometric titration with alkali gave rather flat curves without distinct inflection points 26, 44). Villars 26) concluded that no chemical groups of distinct acidities were present. However, very often the potential becomes constant only several hours after the addition of alkali. Therefore, it was attempted in my laboratory 45-47) to differentiate the acid groups by neutralization with bases of different basicities. The samples were agitated for at least 16 hours with 0.06 N solutions of four bases NaHCOs, NajCO., NaOH, and Na ethoxide. The... 

The solution complexation behavior of manganese(II) and selected other transition and posttransition metal ions with 1-carboxymethyl-1,4,7-triazacyclononane has been investigated by potentiometric titration, with the stabilities of the 1 1 complexes found to follow the usual Irving-Williams stability order. " ... 

The chloride ion in the hydrochloride anion of chlorpromazine can be obtained with high precision using potentiometric titration with Ag(I) [65]. 05 M Ce(S04)2 was used for the determination of chlorpromazine in dilute H2SO4 solution to a colorless end-point [66]. 

Asahi et al. have determined procaine hydrochloride by potentiometric titration with perchloric acid in a mixture of acetic anhydride and anhydrous acetic acid [89]. Procaine was determined by titration in acetic anhydride. 

Potentiometric titration with KI3 dissolved in HMPT, according to equations 18 and 19, was proposed. The method is limited by the relatively low shelf stability of the titrant... 

The fluoride ion selective electrode is the most popular means of fluoride ion determination after sample destruction by any method but it does have limitations. It can be used either directly to measure the fluoride potential6 or as an end-point detector in a potentiometric titration with a lanthanum(l II) reagent as titrant.4,7 Problems can be experienced with potential drift in direct potentiometry, especially at low fluoride ion concentrations. Titration methods often yield sluggish end points unless water miscible solvents are used to decrease solubilities and increase potentia 1 breaks and sulfate and phosphate can interfere. End-point determination can be facilitated by using a computerized Gran plotting procedure.4... 

Other methods have been described which depend on reduction of the tellurium compound by means of titanous chloride, but these generally are not trustworthy owing to the formation of hydrogen telluride. Potentiometric titration with titanous chloride in the presence of hydrochloric acid has been recommended.1... 

Quadrivalent cerium salts may be volumetrically determined by arsenious acid in aqueous sulphuric acid solution using a manganese salt as catalyst, with potassium iodate present as a promoter.2 Excess of arsenious acid is used and back-titrated with permanganate. If nitric acid is present in place of sulphuric acid, an alkali chloride and a trace of iodine are used to promote the action of the manganese salt. Direct potentiometric titration with arsenious acid may also be employed. 

There are two types of fluoride ion-selective electrodes available [27] Orion model 96-09-00, a combination fluoride electrode, and model 94-09-00, which requires a reference electrode The author prefers to use Orton model 94-09-00 because it has a longer operational life and is less expensive When an electrode fails, the reference electrode is usually less expensive to replace The Fisher Accumet pH meter, model 825 MP, automatically computes and corrects the electrode slope It gives a direct reading for pH, electrode potential, and concentra tion in parts per million The fluoride ion-specific electrode can be used for direct measurement [28, 29] or for potentiometric titration with Th4+ or La3+ nitrate solutions, with the electrode as an end point indicator... 

The basicities of the few 1,3-thiazines studied are located between those of sodium bicarbonate and ammonia. Ethyl 2-methylamino-l,3-thiazine-5 carboxylate (72) has pKa 5.41 (65JOC2290). Russian authors have determined the basicities of some compounds by potentiometric titration with perchloric acid in ethanol. The 2-methyliminothiazine (119), pKa 7.84, is more basic than the isomeric aminothiazine (120), pKa 7.12 (71KGS946). 

Chen, Y. Wang, T. Helmy, R. Zhou, G.X. etal., Concentration determination of methyl magnesium chloride and other Grignard reagents by potentiometric titration with in-line characterization of reaction species by FTIR spectroscopy /. Pharm. Biomed. Anal. 2002, 29, 393 04. 

Preparation of 9-methyl-3-[(2-methyl-l-H-imidazol-l-yl)methyl]-l,2,3,9-tetrahydro-4H-carbazol-4-one hydrochloride dihydrate The process above described is followed, except that after cooling down the reaction mixture to room temperature after boiling, 20 ml of 37% aqueous hydrochloric acid are added thereto. Then, the precipitate is filtered off, washed with isopropanol and dried to obtain 2.40 g (65.6%) of the title salt, m.p. 178°-180°C. The active agent content of the product was found to be 100.3% based on potentiometric titration with sodium hydroxide solution. The theoretical water content is 9.85% (calculated for C18H19N30HCl2H20).The water content measured is 10.03%. 

Although mercury seldom is used as an indicator electrode in redox titrations (because it is so readily oxidized), it is used extensively for potentiometric titrations with complexing agents such as ethylenediaminetetraacetic acid... 

The number of reversible metal-metal ion electrodes is limited so that the accurate direct potentiometric measurement of the activity of a metal ion with an electrode of the same metal usually is not feasible, except perhaps with the Ag/Ag,(OH2)4 system. However, a number of metal ion-metal half-reactions are sufficiently reversible to give a satisfactory potentiometric titration with a precipitation ion or complexing agent. These couples include Cuu(OH2>6+/Cu, Pbn(OH2>4+/Pb, Cdu(OH2)l+/Cd, and Znn(OH2)i+/Zn. However, all these metals can be determined by EDTA titration and the mercury electrode that is described in the preceding section. 

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