Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Phosphomolybdic Acid (Molybdophosphoric Acid) 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 Phosphomolybdic 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: Insoluble Matter, Chloride, Sulfate, Ammonium, Calcium, Heavy Metals, and Iron.
CAS No. 51429-74-4
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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yellow solid test for alkaloids melting point, 79–90 °C very soluble
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Maximum Allowable 0.01% 0.02% 0.025% 0.01% 0.02% 0.005% 0.005%
SPECIFICATIONS Insoluble matter . . . Chloride (Cl) . . . . . Sulfate (SO4) . . . . . Ammonium (NH4) . . Calcium (Ca) . . . . . Heavy metals (as Pb) Iron (Fe) . . . . . . . .
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© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4266 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10 g dissolved in 250 mL of water.
Chloride Dissolve 1.0 g in 50 mL of water, add 1 mL of nitric acid, filter through a chloride-free filter, and divide into two equal portions. For the control, add 0.5 mL of silver nitrate reagent solution to one-half of the solution, let stand for 10 min, filter, and add 0.1 mg of chloride ion (Cl). For the sample, add 0.5 mL of silver nitrate reagent solution to the remaining half. Any turbidity in the solution of the sample should not exceed that in the control.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1].
Ammonium (By colorimetry, [Part 2: Colorimetry and Turbidimetry; Ammonium (Test for Ammonia and Amines)]). Dilute the distillate from a 1.0 g sample with water to 100 mL; 20 mL of the dilution shows not more than 0.02 mg of ammonium ion (NH4).
Calcium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium
S a m p l e S t o c k S o l u t i o n . Dissolve 1.0 g of sample in 50 mL of water in a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.01 g).
For the Determination of Calcium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.10
0.02; 0.04
N/A
No
*N/A is nitrous oxide/acetylene.
Heavy Metals Dissolve 3.0 g in 30 mL of water, filter, neutralize the filtrate to litmus paper with 10% sodium hydroxide reagent solution, and add 5 mL of 1 N sodium hydroxide in excess. Heat the solution to boiling to destroy any blue color. For the standard, boil a solution containing 5 mL of 1 N sodium hydroxide and 0.15 mg of lead in 30 mL of water. Cool the solutions to about 10 °C, and to each add 4.5 mL of 1 N hydrochloric acid and 10 mL of 10% (w/v) sodium sulfide solution. Any color in the solution of the sample should not exceed that in the standard.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4266 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Iron Dissolve 5.0 g in 30 mL of water, make alkaline with ammonium hydroxide, and add 0.25 to 0.30 mL of bromine water. Boil for a few minutes, filter, wash the precipitate several times, and discard the filtrate and washings. Pass 25 mL of dilute hydrochloric acid (1:1) through the filter to dissolve any precipitate, wash thoroughly, and dilute with water to 50 mL. Dilute 20 mL of this solution with water to 45 mL, and add 2 mL of ammonium thiocyanate reagent solution. Any red color should not exceed that produced by 0.1 mg of ferric ion (Fe3+) in an equal volume of solution containing 10 mL of dilute hydrochloric acid (1:1) and 2 mL of ammonium thiocyanate reagent solution.
© 2017 American Chemical Society
C
DOI:10.1021/acsreagents.4266 ACS Reagent Chemicals, Part 4
