Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Tetrabutylammonium Hydroxide, 1.0 M Aqueous Solution (TBAH) 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 Tetrabutylammonium Hydroxide, 1.0 M Aqueous Solution provides, in addition to common physical constants, a general description including typical appearance and applications. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Color (APHA), Carbonate, Tributylamine, Halide, Potassium and Sodium, Ultraviolet Spectrophotometry, and Polarographic Test.
(CH3CH2CH2CH2)4 • NOH
Formula Wt 259.48
CAS No. 2052-49-5
Suitable for general use or in ultraviolet spectrophotometry. Product labeling shall designate the uses for which suitability is represented on the basis of meeting the relevant specifications and tests. The ultraviolet spectrophotometry specifications include all of the specifications for general use.
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . colorless liquid Applications . . . . . . . . . . . . . . . . . . . . . . . . buffer; titrant; ion pair reagent
SPECIFICATIONS General Use Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 ± 0.02 M as (CH3CH2CH2CH2)4 · NOH Maximum Allowable Color (APHA) . . . . . . . . . . . . . . . . . . . . . . 30 Carbonate (CO3) . . . . . . . . . . . . . . . . . . . . 0.1% Tributylamine (Bu3N) . . . . . . . . . . . . . . . . . 0.2% Halide (as Cl) . . . . . . . . . . . . . . . . . . . . . . 0.08% Potassium (K) . . . . . . . . . . . . . . . . . . . . . . 2 ppm Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . 2 ppm
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4395 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Specific Use Ultraviolet Spectrophotometry Wavelength (nm) 280 . . . . . . . . . . . . . . . . . . . 254 . . . . . . . . . . . . . . . . . . . 245 . . . . . . . . . . . . . . . . . . . 240 . . . . . . . . . . . . . . . . . . . Polarographic test . . . . . . . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
Absorbance (AU) . 0.04 . 0.07 . 0.10 . 0.15 . Passes test
TESTS Assay (By acid–base titrimetry). Pipette 25.0 mL into a 250 mL conical flask. Add 100 mL of water and 0.15 mL of phenolphthalein indicator solution, and titrate with 1 N hydrochloric acid volumetric solution until the solution becomes completely colorless.
Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].
Carbonate and Tributylamine (By a two-step potentiometric titration, [Part 2: Titrimetric Methods; Potentiometric Titrations]).
Pa r t A . Pipette 25.0 mL of sample into a 400 mL beaker, and dilute with water to 200 mL. Standardize a pH meter with a glass electrode and reference electrode, usually a saturated calomel electrode (SCE) or a combination pH electrode. Use a magnetic stir plate and magnetic stir bar or equivalent agitation throughout the titration. Add dilute nitric acid (1:9) to the sample just short of the phenolphthalein end point (or pH 9.0). Titrate with 1 N hydrochloric acid volumetric solution potentiometrically to the first end point. Save the sample for the tributylamine determination in Part B. Pa r t B . Deoxygenate the sample from Part A with high-purity nitrogen gas for at least 5 min. Dropwise, add 1 N sodium hydroxide volumetric solution to a pH of 11–12. Titrate with standardized 0.1 N hydrochloric acid.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4395 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Halide (By potentiometric titration, [Part 2: Titrimetric Methods; Potentiometric Titrations]). Pipette 25.0 mL of sample into a 400 mL beaker, and dilute to 200 mL. Add 0.05 mL of phenolphthalein indicator solution to the solution, and agitate with a magnetic stirrer and stir bar. Add nitric acid dropwise until the sample is acidic. Titrate with 0.1 N silver nitrate volumetric solution using a silver electrode and a suitable millivolt meter.
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 Potassium and Sodium
S a m p l e S t o c k S o l u t i o n . Evaporate 50.0 g to dryness in a platinum crucible on a hot plate (~100 °C), and take up the residue in 10 mL of 5% nitric acid. Transfer to a 100 mL volumetric flask, and dilute to the mark with 5% nitric acid (1 mL = 0.50 g).
For the Determination of Potassium and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
K
766.5
10.0
0.02; 0.04
A/A
No
Na
589.0
10.0
0.01; 0.02
A/A
No
* A/A is air/acetylene.
Ultraviolet Spectrophotometry Use the procedure in [Part 2: Chromatography; Recommended Procedures; LC Suitability; Procedure for Absorbance] to determine absorbance.
Polarographic Test [Part 2: Direct Electrometric Methods; Polarographic Analysis]. Cathode . . . . . . . . . . . . . . . . . . . . . . . . . Dropping Hg electrode Anode. . . . . . . . . . . . . . . . . . . . . . . . . . . Pt wire Reference . . . . . . . . . . . . . . . . . . . . . . . . Saturated calomel electrode: make up with 1.0 M tetrabutylammonium chloride. Warm 1.0 M TBAH (25.95 g in 100 mL) to 30–35 °C. Deoxygenate with high-purity nitrogen gas until minimum background current is achieved (approximately 5 min). By using a drop time of 1 s, scan at 0.01 V/s from –1.2 to –2.6 V vs SCE with a sensitivity of 0.5 µA full scale with modulation amplitude of 50 mV. The material is acceptable if no impurity current greater than 0.05 µA is observed.
© 2017 American Chemical Society
C
DOI:10.1021/acsreagents.4395 ACS Reagent Chemicals, Part 4
