Diisopropanolamine

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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C₆H₁₅NO₂     133.19

2-Propanol, 1,1′-iminobis-;

1,1′-Iminodi-2-propanol CAS RN®: 110-97-4.

1 DEFINITION

Diisopropanolamine is a mixture of isopropanolamines, consisting largely of diisopropanolamine. It contains NLT 98.0% and NMT 102.0% of isopropanolamines, calculated as NH(C₃H₆OH)₂ on the anhydrous basis.

2 IDENTIFICATION

A. The IR absorption spectrum of a thin lm exhibits regions of absorption between 2.8 and 4.0 µm, between 6.7 and 7.1 µm, and between 8.5 and 9.4 µm; and several characteristic peaks, the most pronounced being at about 7.3, 7.5, 8.3, 9.6, 10.4, and 10.7 µm.

3 ASSAY

Procedure

Sample: 2 g

Blank: 50 mL of water

Titrimetric system

(See Titrimetry 〈541〉.)

Mode: Direct titration

Titrant: 0.5 N hydrochloric acid VS

Endpoint detection: Visual

Analysis: Transfer the Sample to a 250-mL conical ask. Add 50 mL of water and bromocresol green TS. Titrate with Titrant. Perform a blank determination, and make any necessary correction.

Calculate the percentage of isopropanolamines, expressed as NH(C₃H₆OH)₂, in the portion of Diisopropanolamine taken:

Result = {[(V_S− V_B ) × N × F]/W} × 100

V_S = Titrant volume consumed by the Sample (mL)

V_B = Titrant volume consumed by the Blank (mL)

N = actual normality of the Titrant (mEq/mL)

F = equivalency factor, 0.1332 g/mEq

W = Sample weight (g)

Acceptance criteria: 98.0%–102.0% on the anhydrous basis

4 IMPURITIES

Limit of Triisopropanolamine

Indicator solution: 1.5 mg/mL of methyl orange and 0.8 mg/mL of xylene cyanole FF

Sample: 20 g

Blank: 100 mL of methanol

Titrimetric system

(See Titrimetry 〈541〉.)

Mode: Direct titration

Titrant: 0.5 N alcoholic sulfuric acid VS

Endpoint detection: Visual

Analysis: To a glass-stoppered, 500-mL conical ask add 100 mL of methanol and 6–8 drops of Indicator solution, and neutralize with 0.1 N alcoholic sulfuric acid or 0.1 N alcoholic potassium hydroxide. The neutral solution is amber when viewed by transmitted light and is red brown when viewed by reflected light. Add the Sample, cautiously add 75 mL of acetic anhydride, and swirl to dissolve. Allow to stand at room temperature for 30 min. Cool to room temperature, if necessary. Titrate with Titrant. Perform a blank determination, and make any necessary correction.

Calculate the percentage of triisopropanolamine in the portion of Diisopropanolamine taken:

Result = {[(V_S − V_B ) × N × F]/W} × 100

V_S = Titrant volume consumed by the Sample (mL)

V_B = Titrant volume consumed by the Blank (mL)

N = actual normality of the Titrant (mEq/mL)

F = equivalency factor, 0.1914 g/mEq

W = Sample weight (g)

Acceptance criteria: NMT 1.0% by weight

5 SPECIFIC TESTS

Water Determination, Method I〈921〉

Solvent: A mixture of 5.0 mL of glacial acetic acid and 25 mL of methanol

Acceptance criteria: NMT 0.50%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers. No specific storage conditions are required.