QUANTITATIVE ANALYSIS 



can be determined one after another by using voltages related (.. ilxir 

 respective decomposition potentials. 



The setup also can be used lor electrometrir titrations, if .1 

 reagent which reacts with the redox solute is added while the current 

 is measured at proper voltage, a drop in current will accompany the 

 disappearance of the redox solute, and the end jjoint will be indicated 

 when the current has fallen to a residual value, representing con- 

 ductance by factors other than the redox solute. 



For literature, theoretical discussion, description of the different 

 types of analysis to which the procedure has already been applied, 

 and the precautions that must be observed, the reader is referred to the 

 bibliography (35), in particular to KolthoflT (32,33) and Muller (34). 

 The various inorganic cations and anions are determinable; also re- 

 ducible organic compounds, such as aldehydes, ketones, and nitro 

 compounds. Eisenbrand and Picher (31) found that the sex hormones 

 with the 0=C — C=C — group are reducible at the mercury electrode 

 and can be determined polarographically: these hormones include 

 testosterone, progesterone, and desoxycorticosterone, but not andro- 

 sterone nor dehydroandrosterone. Application to solve a hitherto 

 difficult biochemical problem is illustrated by the work of Berggren 

 (30) and of Beecher et al. (29) in determining the oxygen tension of 

 arterial blood plasma and other body fluids. These authors also 

 describe their apparatus in detail. 



Spectrograph ic A nalys is 



Measurement of the intensity of light of characteristic wave 

 length emitted by incandescent elements has been long used in both 

 qualitative and quantitative analysis, and in special problems for 

 quantitative or semiquantitative estimation of minute amounts of 

 specific elements. Lundegardh (39) in 1929 applied the principle 

 in a manner which makes it applicable to micro determination of 

 mineral bases in biological fluids. The solution is sprayed from an 

 atomizer at a constant rate, and the stream of air with suspended fluid 

 is mixed with acetylene, which is burned, heating the mineral bases 

 in the suspension to such a temperature that they emit their charac- 

 teristic light bands, the intensity of which is measured by an electro- 

 photometer (37). The procedure is reviewed by Ells (38) and by 



