Argentometric analysis

Following are the four cardinal parameters that may be considered for a feasible argentometric analysis, namely ... 

Hi) Various cardinal parameters required for a feasible argentometric analysis. 

Argentometric titration involves the titrimetric determination of an analyte using silver nitrate solution as titrant. Its application in environmental analysis is limited to the determination of chloride and cyanide in aqueous samples. The principle of the method is described below. 

Ag+ preferentially reacts with the analyte to form a soluble salt or complex. During this addition, Ag+ reacts with the analyte only, and not the indicator. But when all the analyte is completely consumed by Ag+ and no more of it is left in the solution, addition of an excess drop of silver nitrate titrant produces an instant change in color because of its reaction with the silver-sensitive indicator. Some of the indicators used in the argentometric titrations are potassium chromate or dichlorofluorescein in chloride analysis and p -dime thy la m i nobe nzalrho da n i nc in cyanide analysis. Silver nitrate reacts with potassium chromate to form red silver chromate at the end point. This is an example of precipitation indicator, where the first excess of silver ion combines with the indicator chromate ion to form a bright red solid. This is also known as Mohr method. 

The use of argentometric, mercurimetric or iodometric amperometric titration is common [3,118], The reactions of thions and disulphide groups with mercuric salts have been described [118,119]. Amperometric titration of sulphydryl groups is often applied to the analysis of proteins or body fluids and tissues, respectively [3]. In particular the papers of Benesch, and Lardy and Benesch [121,122] and of others [123-126] are to be mentioned here. 

For F and Cl, the techniques used were mainly based on oxygen combustion, pyrohydrolysis or fusion with Na2C03 followed by ion selective electrode or ion chromatography. Neutron activation analysis with fast neutrons was also used by one laboratory for F, as well as visible light spectrometry the latter technique was also used for Cl as well as argentometric titration. A detailed description of the methods is given in the certification report [13],... 

Several methods can be used for the determination of chloride in water [2], The argentometric and mercuric nitrate methods are based on the titration of chlorine in the presence of an indicator. Experimental procedures are easy, but many substances may interfere with the results. There are also other methods such as potentiometry, capillary electrophoresis and other automated methods (ferricyanide method or flow injection analysis). 

Applications of precipitation titrations are listed in Table 6-1. The Volhard method is an argentometric titration, but the Fajans method has wider application. Because the Volhard titration is carried out in 1 M acid, it avoids some interference that affects other titrations. Silver salts of anions such as C03 (carbonate), C204 (oxalate), and AsO (arsenate) are soluble in acidic solution, so these anions do not interfere with the analysis. 

Zeisel s method is used to determinate methoxy and ethoxy groups. It is a method of both qualitative and quantitative organic analysis. It is mentioned under the heading General Methods of Analysis of the 10th edition of the french pharmacopeia. It ends with an argentometric titration. Its principle is based on the reaction of hydroiodic acid (Berthelot s universal reductor) with ether oxides, according to the reactions... 

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