Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Aluminum Ammonium Sulfate Dodecahydrate (Ammonium Alum) 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 Aluminum Ammonium Sulfate Dodecahydrate 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, Insoluble Matter, Chloride, Heavy Metals, Calcium, Iron, Potassium, and Sodium.
AlNH4(SO4)2 · 12H2O
Formula Wt 453.31
CAS No. 7784-26-1
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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colorless solid buffer melting point, 93 °C 15 g in 100 mL at 20 °C
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98.0–102.0% AlNH4(SO4)2 · 12H2O Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.001% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.001% Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.01%
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4009 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By complexometry). Weigh accurately 0.8 g, and transfer to a 400 mL beaker. Moisten with 1 mL of glacial acetic acid, add 50 mL of water, 40.0 mL of 0.1 M EDTA volumetric solution, and 20 mL of ammonium acetate–acetic acid buffer solution. Warm on a steam bath until solution is complete, and boil gently for 5 min. Cool, add 50 mL of ethyl alcohol and 2 mL of dithizone indicator solution, and titrate with 0.1 M zinc chloride volumetric solution to a bright rose-pink color. Perform a blank titration of 40.0 mL of 0.1 M EDTA volumetric solution, using the same quantities of reagents as for the assay. One milliliter of 0.1 M EDTA consumed by the sample corresponds to 0.04533 g of AlNH4(SO4)2 · 12H2O.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10 g dissolved in 150 mL of water containing 5 mL of 25% sulfuric acid.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 1.0 g.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 2.0 g in 20 mL of water.
Calcium, Iron, Potassium, and Sodium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium, Iron, Potassium, and Sodium
S a m p l e S t o c k S o l u t i o n . Dissolve 10.0 g in 100 mL of water (1 mL = 0.1 g).
For the Determination of Calcium, Iron, Potassium, and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.20
0.05; 0.10
N/A
No
Fe
248.3
5.0
0.025; 0.05
A/A
Yes
K
766.5
0.10
0.25; 0.05
A/A
No
Na
589.0
0.20
0.01; 0.02
A/A
No
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4009 ACS Reagent Chemicals, Part 4
