You need EDTA in your fab for
FASTER ANALYTICAL RESULTS, IMPROVED SYNTHESES and SEPARATIONS The word f f c h e l a t e " is derived frbrrï "the G r e e k " c h e l e " , d esigïià t i n g a claw such - as that o f thé crab. v .
You can benefit in many ways when you use Ethylenediamine Tetraacetic Acid, *Baker Analyzed' Reagent, and its disodium salt (dihydrate). E D T A has the ability to form stable and soluble complexes with most di- and trivalent metallic ions. This chelating property permits the use of E D T A for the selective precipitation and separation of some cations including those of the rare earths. In the purification of organic and inorganic chemicals, E D T A has been employed for its "masking action" on trace metals often present as contaminants. Further, E D T A can be used for the determination of many metallic ions employing various analytical techniques including spectrophotometry and titrimetry. For many applications the disodium salt (dihydrate) of E D T A is preferred because of its solubility, stability, and favorable pH. Many of the benefits of E D T A a r e described below in the specific applications. Also included are references to the broad line of associated chemicals and indicators which are being offered by Baker. DESCRIPTION Ethylenediamine Tetraacetic Acid (EDTA) and Disodium Ethylenediamine Tetraacetate, Dihydrate, are offered in the reagent grade as a crystalline powder and are controlled to an assay specification of greater than 99 per cent. Critical impurities—heavy metals and iron—are held at the low levels indicated by the actual lot analyses provided on the label. Both reagents are stable and may be used directly for the convenient preparation of solutions. APPLICATIONS • In Colorïmetry—EDTA serves in colorimetric analysis both as a masking agent permitting greater specificity and as a component of color systems.
• In Selective Separations—EDTA often functions as a complexing or masking agent in analytical and preparative separations to reduce interferences, secure greater specificity, or to permit more selective reactions and separations. The use of EDTA to gain added specificity in sulfide and potassium precipitations with thioacetamide and sodium tetraphenylboron, respectively, is of special interest. • In Polarography—EDTA serves as a masking agent and complexing agent in various polarographic procedures. • In Titrimetry—EDTA as its disodium salt serves as titrant in the EDTA titration by which over 40 elements may now be easily and rapidly determined either directly or indirectly. This titration employs many 'Baker Analyzed' reagents for buffering, pHadjustment, masking and demasking, preliminary separation, etc. Especially noteworthy are the metal indicators introduced or offered by J. T. Baker in the reagent grade with controlled sensitivity. These include Eriochrome Black Τ (CI 203), murexide, PAN, Pyrocatechol Violet, Zincon, and calcon (CI 202). Other 'Baker Analyzed' reagents finding use in end point indica tors for the EDTA titration include thiourea, ammonium and potassium thiocyanates, benzidine, dithizone, and potassium iodide. These metal indicators, of course, have other important applications especially as chromogenic agents for the detection and colorimetric analysis of various metals. Original articles and continuing reviews on EDTA are appearing in CHEMIST-ANALYST, the quarterly professional journal published by J. T. Baker. Product data sheets on EDTA and associated reagents and indicators are also available. Leaders in the field of analytical chemistry have described EDTA and sodium tetraphenylboron as the two most significant ad vances in laboratory reagents in the last decade. J. T. Baker has taken the initiative in informing the chemist about these advances through a strong publication program and in providing these rea gents produced to appropriate standards.
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Phillinsbura. New Jersev JULY
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1957
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