Masking and Sequestering Agents

In the mid 1930 s, the I.G. Farbenindustrie in Germany manufactured a compound with the trade name of Trilon 

After the War, Gerold Schwarzenbach, at the University of Zurich, investigated this compound and introduced it as a titrant in 1951. 

The pK s are 2.0, 2.76, 6.16, and 10.3. Two protons are readily lost. The acid is quite insoluble in water (0.2 g/L) so the disodium salt dihydrate usually is used to prepare a standard solution (NajHjY). 

Walter Biedermann and Schwarzenbach published the first titrimetric determination for the hardness of water using Erio-T as an indicator in January of 1948. In the next 10 years, over 1200 papers would be published on the uses of EDTA. 

Porcelain items only should be placed in a muffle furnace. No glass items should be placed in a muffle furnace. The glass will melt and cause a real mess. If such an accident happens, the furnace must be shut off, and cooled completely, and the glass carefully chipped out. You will likely never get it all out, so a ceramic plate must be placed on the bottom to keep other items from sticking. 

---

The use of masking and sequestering agents. Chapter 40, are probably the truest chemical separations there are. These reagents react with interfering materials in the solution and stay there, thus eliminating one or more subsequent steps. 

Chelating and sequestering agent builder in synthetic detergents. Aq. soln. of salts used as masking agent for many metals extraction separation of Cr(//7) (as complex with NTA) photometric detn. of Co. Prismatic cryst. (H2O). SI. sol. H2O. Mp 242° dec. Bpi3 167°. p/ i... 

What is the difference between a masking agent and a sequestering agent ... 

---