Argentometric methods

Discuss the theoretical aspect of argentometric methods explicitely. 

Most applications of precipitation titrations are based on the use of a standard silver nitrate solution and are therefore sometimes called argentometric methods (Table 1). 

Argentometric methods were used, as mentioned above, in the determination of thiol compounds. The amperometric determination of mercaptansP > can be carried out as follows. 

Numerous determinations of the same kind as those given here have been recommended in previous pharmacopeias. Generally, they consist of titrating halide ions, once they are formed by mineralization, by an argentometric method. Usually, it is Charpentier-Volhard s method. We can also cite the examples of lindane (y-benzenehexachloride, DTT, iodoform, eosine, chlorotrianisene, etc.). The preliminary mineralization is carried out in alkaline medium, that is, with sodium or... 

Elemental composition Ca 36.11%, Cl 63.89%. An aqueous solution of the compound may be acidified and analyzed for calcium by AA or ICP methods (see Calcium). The solution may be analyzed for chloride ion by ion selective electrode, ion chromatography or by argentometric titration. 

End-point detection for precipitation titrations commonly relies on electrodes las in Figure 7-9) or indicators. This section discusses two indicator methods applied to the titration of Cl-with Ag+. Titrations with Ag4 are called argentometric titrations. 

Applications of precipitation titrations are listed in Table 7-1. Whereas the Volhard method is an argentometric titration, the Fajans method has wider applications. Because the Volhard titration is carried out in acidic solution (typically 0.2 M HN03), it avoids certain interferences that affect other titrations. Silver salts of CO -, C20 -, and AsO " are soluble in acidic solution, so these anions do not interfere. 

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. 

Precipitation titrimetry — A method for the - titration of species by a - precipitation reaction. Commonly, the - end point of precipitation reactions is monitored by chemical, potentiometric or amperometric methods. A chemical method involves an -> indicator that usually has a change in color at the -> endpoint, while the other methods can be implemented as a -> potentiometric titration or -> amperometric titration, respectively. An important precipitating reagent is silver nitrate, i.e., silver ions Ag+. Such titrations are called argentometric titrations [i], and silver - electrodes are useful as indicator electrodes. 

The consumption of cyanide is accurately determined by argentometric titration. The method was found to apply both to oxidized starch [439] as well as to cellulose [418], The method is accurate and recently the coefficient of variance and standard deviation for an oxidized cellulose containing 5.60 mmol per 100 g of ketone groups, were found to be 0.0046 and 0.0068, respectively. The corresponding values for the carboxyl groups by the methylene blue method of the same samples were 0.001 and 0.031 [440]. 

Argentometric titration method has been applied to the determination of sulfonamide mixtures. The sulfonamides are quantitatively precipitated by the addition of excess standard silver nitrate solution, the precipitated silver salts removed by filtration, and the excess silver nitrate titrated with standard ammonium thiocyanate using ferric alum as indicator (32). 

The analyst has little choice in the selection of a redox analytical method. In acid solution ceric ion is the most effective oxidant however, in acid solution there is possibility of analytical error because of the volatility ofhydrazoic acid. In alkaline solution, reduction of the azide ion by homogeneous or heterogeneous reduction methods results in variable stoichiometry and cannot be used. The argentometric determination of azide ion in neutral solution is satisfactory but has one serious drawback the manipulation of silver azide, a high cxplosix c. Two basic approaches have evolved for the assay of azide ion ... 

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). 

Abstract. Cyanides and hydrocyanic acid are one of the priority pollutants being most toxic. Therefore, it is very important to monitor cyanide concentration with specific and sensitive analytical methods. Some analytical methods for cyanide determination were presented in the last years spectrophotometer, potentiometer with silver cyanide electrode and titrimetric method. The paper presents original results concerning the spectrometric method and argentometric titration utilization for the measurement of cyanide concentration in some distilled alcoholic drinks from plums, grapes and apricots. The obtained cyanide concentrations vary between 0.0162 and 0.0970 mg/lOOmL, being under the imposed limits. 

The paper presents original results concerning the spectrometric method and argentometric titration utilization for the measurement of cyanide concentration in some distilled alchoolyc drinks from plums, grapes and apricots. 

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