Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Formaldehyde Solution 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
Downloaded by CORNELL UNIV on May 10, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4147
ABSTRACT This monograph for Formaldehyde Solution provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), aqueous solubility, and density. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Color (APHA), Residue after Ignition, Titrable Acid, Chloride, Sulfate, Heavy Metals, and Iron.
HCHO
Formula Wt 30.03
CAS No. 50-00-0
Note: This reagent contains 9–15% of methanol as a stabilizer.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . . Density . . . . . . . . . . . . . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
colorless solution reducing agent; to prevent polymerization boiling point, 96 °C miscible 1.08
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.5–38.0% HCHO Maximum Allowable Color (APHA) . . . . . . . . . . . . . . . . . . . . . . . 10 Residue after ignition. . . . . . . . . . . . . . . . . . 0.005% Titrable acid . . . . . . . . . . . . . . . . . . . . . . . 0.006 meq/g Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 5 ppm Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.002%
© 2017 American Chemical Society
A
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4147 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Heavy metals (by ICP–OES) . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm
TESTS Note: The assay procedure specified herein is intended to determine both formaldehyde and its paraformaldehyde polymerization product, which may form upon standing. A different procedure (see, for example, Reagent Chemicals, 5th ed.) should be used if only the formaldehyde content is desired.
Downloaded by CORNELL UNIV on May 10, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4147
Assay (By bisulfite addition and acid–base titrimetry). Transfer a glass-stoppered weighing vial containing 2.0 g of sample, accurately weighed, to 100 mL of 10% sodium sulfite solution in a 500 mL conical flask. Avoid getting any of the sample on the wall of the flask. Add 0.15 mL of thymolphthalein indicator solution, and then titrate to a colorless end point with 1 N sulfuric acid. Correct for a reagent blank and any significant quantity of acid (as HCOOH) in the sample. One milliliter of 1 N sulfuric acid corresponds to 0.03003 g of HCHO.
Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Evaporate 20.0 g (20 mL) to dryness in a tared, preconditioned dish on a hot plate (~100 °C), add 0.05 mL of sulfuric acid to the residue, and ignite gently to volatilize the excess sulfuric acid. Finally, ignite at 800 ± 25 °C for 15 min.
Titrable Acid To 10 mL in a flask containing 20 mL of water, add 0.15 mL of bromthymol blue indicator solution, and titrate with 0.1 N sodium hydroxide. Not more than 0.60 mL of 0.1 N sodium hydroxide should be required.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Dilute 2.0 mL with 20 mL of water.
Sulfate Method 1). Use 2.5 g (2.5 mL).
© 2017 American Chemical Society
B
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4147 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Heavy Metals ([Part 2: Trace and Ultratrace Elemental Analysis; Inductively Coupled Plasma−Optical Emission Spectroscopy (ICP–OES); Calculation of Heavy Metals (by ICP–OES) Results], by ICP–OES). Use 2.0 g sample.
Iron
Downloaded by CORNELL UNIV on May 10, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4147
[Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 2 (Hydroxylamine and 1,10-Phenanthroline)]. Dilute 2.0 mL with water to 15 mL. Adjust the pH to 5 with 2.5% ammonium hydroxide reagent solution after addition of the 1,10phenanthroline reagent solution.
© 2017 American Chemical Society
C
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4147 ACS Reagent Chemicals, Part 4
