Photometric titrations applications

Molecular Fluorescence Spectroscopy Photometric Titrations Analytical Applications of Interferometry Vol. 9 Ultraviolet Photoelectron and Photoion Spectroscopy... 

Nearly all chemical sensors useful for liquid samples can be utiUzed to indicate titrations. Besides the preferred potentiometric, other electrochemical probes are also used, mainly amperometric and conductometric sensors. The so-called biamperometric titration works with simple wire pairs. Photometric and thermometric indication techniques are less common than electrochemical methods. Miniaturization does not play an important role for titration probes. Classical arrangements predominate to this day. Commercial titration instruments are only slowly starting to make use of the achievements of modern sensor technology. As an example, optodes have achieved a certain popularity in recent years for titration applications. 

Table 3.6 surveys applications of the photometric titration method together with a comparison with a potentiometric titration method. Generally the agreement is very satisfactory. 

Table 1.14 - Application of the Photometric Titration Method to Various Samples... 

Determination of organic compounds. The application of photometric titrimetry to organic compounds may be exemplified by the titration of phenols. This can be carried out by working at the /max value (in the ultraviolet) for the phenol being determined (see Section 17.50). It has been shown that by titrating with tetra-n-butylammonium hydroxide and using propan-2-ol as solvent, it is possible to differentiate between substituted phenols.24... 

Photometric and spectrophotometric measurements are useful for locating the equivalence points of titrations. This application of absorption measurements requires that one or more of the reactants or products absorb radiation or that an absorbing indicator be added to the analyte solution. 

A coulometric titration, like a more conventional volumetric procedure, requires some means of detecting the point of chemical equivalence. Most of the end-point detection methods applicable to volumetric analysis are equally saiisfactory here. Visual observations of color changes of indicators, as well as poicn-tionieiric, amperometric, and photometric measurements have all been used successfully. 

Fluorescent dye with numerous applications, e.g. as water-flow tracer and in cosmetics. Used as an adsorption indicator in the titration of Cl , Br , I , SCN and as a fluorescence acid-base indicator (pH range 4.0-4.5 - 6.0 colour change pink/green - green). Used for photometric detn. of I2. Exists in at least two forms, yellow amorph. and red cryst., possibly also in third, orange, modification. Structure assignments may not be certain. 

Mohammed, H. Y., F. F. Cantwell, Photometric ion-pair titrations in the presence of an immiscible solvent and their application to drug analysis. Anal. Chem., 1979,5/, 1006-1012. 

---