Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Neutral Red (Basic Red 5, C.I. 50040; 2-Amino-8-(dimethylamino)toluphenazine Hydrochloride) 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 Neutral Red provides, in addition to common physical constants, a general description including typical appearance, applications, and aqueous solubility. 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 Visual Transition Interval.
C15H17ClN4
Formula Wt 288.78
CAS No. 553-24-2
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . dark green solid Applications . . . . . . . . . . . . . . . . . . . . . . . . indicator for nitrogen determination; pH indicator Aqueous solubility . . . . . . . . . . . . . . . . . . . . soluble
SPECIFICATIONS Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Visual transition interval . . . . . . . . . . . . . . . . pH 6.8 (red) to pH 8.0 (yellow)
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4237 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Clarity of Solution Accurately weigh 0.1 g, and dissolve in 100 mL of water. The resulting solution should be clear, and no visible amount of insoluble residue remains. Reserve the solution for the visual transition interval test.
Visual Transition Interval Dissolve 1 g of potassium chloride in 100 mL of water. Adjust the pH of the solution to 6.0, using a pH meter, with 0.01 N hydrochloric acid or 0.1 N sodium hydroxide. Add 0.15 mL of the 0.1% solution reserved from the test for clarity of solution. Titrate the solution with 0.01 N sodium hydroxide to pH 6.8 (using a pH meter). The color of the solution should be red. Continue the titration to a pH of 8.0. The solution should be yellow.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4237 ACS Reagent Chemicals, Part 4
