Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Metalphthalein (Phthalein Purple; o-Cresolphthalein complexone) 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 Metalphthalein 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 a Mixed Indicator for Complexometry.
C32H32N2O12
Formula Wt 636.61
CAS No. 2411-89-4
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . light pink to tan crystalline solid Applications . . . . . . . . . . . . . . . . . . . . . . . . indicator
SPECIFICATIONS Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Suitability as a mixed indicator for complexometry Passes test
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4221 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Clarity of Solution Dissolve 0.18 g in 100 mL of water containing 0.5 mL of ammonium hydroxide. Not more than a trace of turbidity or insoluble matter should remain.
Suitability as a Mixed Indicator for Complexometry Using the test sample, prepare metalphthalein-screened indicator solution. Mix 50 mL of water and 50 mL of ethyl alcohol. Add 10.0 mL of 0.1 M EDTA volumetric solution, 10 mL of ammonium hydroxide, and 0.3 mL of the metalphthalein-screened indicator solution. Titrate with 0.1 M barium nitrate reagent solution. The color change is from gray-green to magenta. Add 0.05 mL of 0.1 M EDTA; the color should return to gray-green.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4221 ACS Reagent Chemicals, Part 4
