Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Eriochrome Black T (3-Hydroxy-4-[(1-hydroxy-2-naphthalenyl)azo]-7-nitro-1-naphthalenesulfonic Acid, Monosodium Salt; C.I. Mordant Black 11) Part 4, Monographs for Reagent Chemicals: General Descriptions, Specifications, and Tests eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
ABSTRACT This monograph for Eriochrome Black T provides, in addition to common physical constants, a general description including typical appearance and applications. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Clarity of Solution and Suitability as Complexometric Indicator.
C20H12N3NaO7S
Formula Wt 461.38
CAS No. 1787-61-7
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . brownish-black powder Applications . . . . . . . . . . . . . . . . . . . . . . . . indicator for complexometric titrations
SPECIFICATIONS Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Suitability as complexometric indicator . . . . . . Passes test UV absorption . . . . . . . . . . . . . . . . . . . . . . . . . λmax 503 nm
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4133 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Clarity of Solution Dissolve 0.1 g in 100 mL of water, warming if necessary. Not more than a faint trace of turbidity or insoluble matter should remain. Reserve the solution for the test for suitability.
Suitability as Complexometric Indicator Add 10 mL of pH 10 ammoniacal buffer solution to 100 mL of water. Add 0.5 mL of the solution reserved from the test for clarity of solution and 10.0 mL of magnesium ion I (Mg) standard solution. The color of the solution should be red-violet. Add 0.10 mL of 0.1 M EDTA volumetric solution. The color of the solution should change to blue.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4133 ACS Reagent Chemicals, Part 4
