Monograph pubs.acs.org/doi/book/10.1021/acsreagents
SPADNS (4,5-Dihydroxy-3-(4-sulfophenylazo)-2,7-naphthalene Disulfonic Acid, Trisodium Salt) 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 SPADNS 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 Sensitivity to Fluoride.
C16H9N2Na3O11S3
Formula Wt 570.40
CAS No. 23647-14-5
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . red to brown solid Applications . . . . . . . . . . . . . . . . . . . . . . . . fluoride indicator Aqueous solubility . . . . . . . . . . . . . . . . . . . . moderate (1–10%)
SPECIFICATIONS Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Sensitivity to fluoride . . . . . . . . . . . . . . . . . . Passes test
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4377 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Clarity of Solution Dissolve 0.30 g in 100 mL of water. The solution is complete.
Sensitivity to Fluoride To 50 mL of the fluoride working solution (described below), add 10 mL of the acid zirconyl–SPADNS reagent solution (described below). A distinct blue-violet color develops (A maximum at 570 nm).
For the Determination of Sensitivity to Fluoride
A c i d Z i r c o n y l - S PA D N S Re a g e n t S o l u t i o n . First, make SPADNS solution by dissolving 0.10 g of sample in 50 mL of water. Then make zirconyl acid reagent solution by dissolving 25 mg of zirconyl chloride octahydrate in 25 mL of water, add 70 mL of hydrochloric acid, and dilute to 100 mL with water. Finally, mix equal portions of SPADNS solution and zirconyl acid reagent solution. F l u o r i d e Wo r k i n g S o l u t i o n . Dilute 1 mL of the fluoride ion (F) standard solution to 10.0 mL with water. Dilute 1.0 mL of this solution to 50.0 mL.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4377 ACS Reagent Chemicals, Part 4
