Titrimetric determinations analytical reagents

Thermogravimetry is a valuable technique for the assessment of the purity of materials. Analytical reagents, especially those used in titrimetric analysis as primary standards, e.g. sodium carbonate, sodium tetraborate, and potassium hydrogenphthalate, have been examined. Many primary standards absorb appreciable amounts of water when exposed to moist atmospheres. TG data can show the extent of this absorption and hence the most suitable drying temperature for a given reagent may be determined. 

A standard solution (or a standard titrant) is a reagent of known concentration that is used to carry out a titrimetric analysis. A titration is performed by slowly adding a standard solution from a buret or other liquid-dispensing device to a solution of the analyte until the reaction between the two is judged complete. The volume or mass of reagent needed to complete the titration is determined from the difference between the initial and final readings. A volumetric titration process is depicted in Figure 13-1. 

Several analytical methods have been deployed for the determination of uranium in ores. Among the older methods that were used are radiometric methods that were already used over 50 years ago for ore sorting (Mal tsev 1960), titrimetric methods in which the nraninm content in the ore was determined with ferrous ion-phosphoric acid reduction (Hitchen and Zechanowitsch 1980), colorimetric methods where complexes of nraninm are formed with standard arsenazo 111 (Onishi and Sekine 1972), exotic siderophores (Renshaw et al. 2003) reagents and instrumental neutron activation analysis (INAA) based on measurement of Np in the ore (Chaudhry et al. 1978) in addition to nnmerons other approaches. Many modem techniques are now employed for destrnctive and nondestructive determination of uranium in ores. 

Analytical and Tast Methods. Numerous instrumental and chemical techniques are available for the determination of acrylonitrile. The method of choice is directed by the concentration and the medium involved. For direct assay of acrylonitrile, titrimetric procedures are frequently used. Dodecyl mercaptan reacts with acrylonitrile under base catalysis excess mercaptan is then hacktitrated with an acid bromate-iodide solution (63), or alternatively, for colored solutions, with silver nitrate (64). Hydrolysis of the nitrile with strong base generates ammonia, which can then be determined by Nessler s reagent (65). 

In gravimetric measurements, the mass of the analyte or some compound produced from the analyte was determined. In volumetric, also called titrimetric, procedures, the volume or mass of a standard reagent required to react completely with the analyte was measured. 

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