Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sulfanilic Acid (4-Aminobenzenesulfonic Acid)
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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 Sulfanilic Acid provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), and aqueous solubility. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Residue after Ignition, Insoluble in Sodium Carbonate Solution, Chloride, Nitrite, and Sulfate.
NH2C6H4SO3H (anhydrous) Formula Wt 173.19 NH2C6H4SO3H • H2O Formula Wt 191.20 (monohydrate)
CAS No. 121-57-3
Note: This reagent is available in both the anhydrous and monohydrate forms. The identity should be indicated on the label.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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© 2017 American Chemical Society
white solid nitrite determination decomposes at 288 °C without melting 1 g in 100 mL at 20 °C
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4385 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98.0–102.0% of the form offered Maximum Allowable Residue after ignition. . . . . . . . . . . . . . . . . . 0.01% Insoluble in sodium carbonate solution . . . . . . . 0.02% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Nitrite (NO2) . . . . . . . . . . . . . . . . . . . . . . . 0.5 ppm Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.01%
TESTS Downloaded by CORNELL UNIV on May 29, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4385
Assay (By acid–base titrimetry). Weigh accurately about 0.7 g, and dissolve by warming gently in 50 mL of water. Cool, and titrate with 0.1 N sodium hydroxide, using 0.15 mL of phenolphthalein indicator solution. One milliliter of 0.1 N sodium hydroxide corresponds to 0.01732 g of NH2C6H4SO3H and to 0.01912 g of NH2C6H4SO3H · H2O.
Residue after Ignition Gently ignite 10.0 g in a tared, preconditioned crucible or dish until charred. Slowly raise the temperature until all carbon is removed, and finally heat at 800 ± 25 °C for 15 min.
Insoluble in Sodium Carbonate Solution Dissolve 5.0 g in 50 mL of a clear 5% sodium carbonate solution, and allow to stand in a covered beaker for 1 h. If an insoluble residue remains, filter through a tared, preconditioned porous porcelain or a platinum filtering crucible, wash with cold water, and dry at 105 °C.
Chloride Boil 5.0 g with 100 mL of water until dissolved. Cool, dilute with water to 100 mL, mix well, and filter through a chloridefree filter. Dilute 10 mL of the filtrate with water to 20 mL, and add 1 mL of nitric acid and 1 mL of silver nitrate reagent solution. Any turbidity should not exceed that produced by 0.01 mg of chloride ion (Cl) in an equal volume of solution containing the quantities of reagents used in the test. Save the remaining filtrate for the test for sulfate.
Nitrite Dissolve 0.70 g in 100 mL of water, warming if necessary but keeping the temperature below 30 °C. For the control, dissolve 0.20 g in about 75 mL of water, add 0.00025 mg of nitrite ion (NO2), and dilute with water to 100 mL. To each solution, add 5 mL of sulfanilic-1-naphthylamine solution (described below), and allow to stand for 10 min. Any pink color produced in the solution of the sample should not exceed that in the control.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4385 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Nitrite
S u l f a n i l i c - 1 - N a p h t h y l a m i n e S o l u t i o n . Dissolve 0.5 g of sulfanilic acid in 150 mL of 36% acetic acid. Dissolve 0.1 g of N-(1-naphthyl)ethylenediamine dihydrochloride in 150 mL of 36% acetic acid. Mix the two solutions. If a pink color develops on standing, it may be discharged with a little zinc dust.
Sulfate
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Cool about 30 mL of the solution reserved from the test for chloride to about 0 °C, and filter. To 10 mL of the filtrate, add 1 mL of dilute hydrochloric acid (1:19) and 1 mL of 12% barium chloride reagent solution. Any turbidity should not exceed that produced by 0.05 mg of sulfate ion (SO4) in an equal volume of solution containing the quantities of reagents used in the test. Compare 10 min after adding the barium chloride to the sample and standard solutions.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4385 ACS Reagent Chemicals, Part 4
