Identification potentiometric

Principle. By means of potentiometric titration (in nonaqueous media) of a blend of sulfonic and sulfuric acids, it is possible to split the neutralization points corresponding to the first proton of sulfuric acid plus that of sulfonic acid, and to the second proton of sulfuric acid. The first derivate of the titration curve allows identification of the second points the corresponding difference in the volume of titrating agent is used as a starting point in the calculation method (Fig. 4). 

Uithoven K.A., Schmidt J.C., Ballman M.E., Rapid identification of biological warfare agents using an instrument employing a light addressable potentiometric sensor and a flow-through immunofiltration-enzyme assay system, Biosens. Bioelectron. 2000, 14 761-770. 

The main group duster chemistry discussed in this book can be considered to originate from two important, but apparently unrelated developments in inorganic chemistry in the 1930s. The first was the identification of the neutral boron hydrides by Stock [1]. The second was the observation by Zintl and co-workers [2-5] of anionic clusters formed from potentiometric titrations of post-transition metals (i.e., heavy main group elements) with sodium in liquid ammonia. 

W.-G. Hu, H.G. Thompson, A.Z. Alvi, L.P. Nagata, M.R. Suresh and R.E. Fulton, Development of immunofiltration assay by light addressable potentiometric sensor with genetically biotinylated recombinant antibody for rapid identification of Venezuelan equine encephalitis virus, J. Immunol. Methods, 289(1-2) (2004) 27-35. 

With respect to the type of sensors that can be used in an electronic tongue, practically all the main families of chemical sensors have been used to form the sensor array, viz. potentiometric, voltammetric, resistive, gravimetric and optical, if main sensor families have to be quoted [11], Table 30.1 sketches a survey of different approaches that can be recorded when the specialized literature is inspected. Even hybrid systems have been proposed, mainly those combining potentiometric and voltammetric sensors [3,12], The combination of electronic noses and electronic tongues to improve detection or identification capabilities, in a sensor fusion approach, has also been proposed [13,14],... 

After the operator has selected the desired method menu of the relevant samples and has started the instrument, all subsequent steps are fully automated. Since 1987 it is also possible to effect a direct identification of the sample so that there are no longer any problems in respect of a dialogue with a central EDP system. The samples are taken from the sample vessel by means of disposable single use pipette tips that are used for one sample only and exchanged via a computer-monitored pipetting unit. This method excludes the possibility of a carry-over between samples. In accordance with the preset conditions, the required slides are automatically moved to the sample dosage unit (see Fig. 23). Samples of 11 pi serum or plasma will be sufficient for kinetic measurements (enzymes), 10 pi of sample for all other tests. As soon as application of the sample has been completed, the slide is moved to the appropriate incubation chamber by means of the slide rotor (see Fig. 23). The chemical reactions take place in these chambers. This is followed by measurement either by reflectometer (end point or kinetic) or a potentiometric measurement unit. 

The feedstocks (straight-mn naphtha (SRN) and a blend of SRN and hydrocracked naphtha) and hydrotreated products were analysed by ASTM methods for density, carbon, hydrogen, hydrocarbon and boiling point distribution. Total sulfur was determined by ASTM D-4045 method, mercaptan sulfur by the potentiometric method (ASTM D-3227 and UOP-212), disulfides by the UOP-202 method, polysulfides by polarography [1], and elemental sulfur by the UOP-286 method. The Perkin-Elmer gas chromatograph (Model 8700), equipped with a flame photometric detector (GC/FPD) and a DB-1 fused silica capillary column (30 m x 0.53 mm), was used for identification of individual sulfur compounds [2-6]. The sensitivity of the GC/FPD technique was maximized by optimizing the gas flow rates and temperature programming as presented elsewhere [1]. 

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. 

Lewis GP, The importance of ionization in the activity of sympathomimetic amines, Br. J. Pharmacol, 9,488-493 (1954). NB Reported pK. values for a further 23 sympatfiomimetic amines. Where compounds contained phenolic group as well as the amine, both potentiometric and spectrophotometric methods were used. Methods were similar to Kappe and Armstrong, see Levarterenol (no. 729). Cited in Kanfer I, Haigh JM and Dowse R, Phenylpropanolamine hydrochloride, APDS, 12, 357-380 (1983). Warren RJ, Begosh PP and Zarembo JE, Identification of... 

Most of the evidence cited in the literature for the formation of polynuclear hydroxo lanthanide complexes is obtained from potentiometric measurements with computer fitting of rather smooth trends. Unfortunately, direct identification of the species formed has, thus far, been unobtainable due to the low solubility of the Ln(OH)3 compounds and to the simultaneous presence of a number of hydrolyzed species in solution. 

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