Butyl Alcohol

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

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

DOWNLOAD PDF HERE
 

CH₃CH₂CH₂CH₂OH 74.12

1-Butanol;

1-Butyl alcohol;

n-Butanol;

n-Butyl alcohol CAS RN®: 71-36-3.

1 DEFINITION

Butyl Alcohol is n-butyl alcohol. It contains NLT 99.5% of n-butyl alcohol (C₄H₁₀O).

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197F (CN 1-May-2020)

B. The retention time of the major peak from the Sample solution corresponds to the 1-butanol peak from the System suitability solution, as obtained in the Assay.

3 ASSAY

3.1 Procedure

System suitability solution: USP 1-Butanol RS and USP 2-Methyl-1-Propanol RS (1:1)

Reference solution: 0.1% of Butyl Alcohol in water

Sample solution: Butyl Alcohol (neat)

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.53-mm × 30-m; coated with a 3.0-μm thickness of phase G43

Temperatures

Detector: 250°

Injection port: 140°

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 4.8–4.9 mL/min

Injection volume: 1 μL

Injection type: Split injection, split ratio is 30:1

[Note—A needle wash with the Sample solution is recommended to minimize the carry-over.]

3.2 System suitability

Sample: System suitability solution

[Note—The 2-methyl-1-propanol peak typically shows at about 11 min, and the 1-butanol peak at about 15 min. See Table 2.]

Table 2

System suitability requirements

Resolution: NLT 2.0 between 2-methyl-1-propanol and 1-butanol

Relative standard deviation: NMT 2.0%

3.3 Analysis

Samples: Reference solution and Sample solution

Calculate the percentage of butyl alcohol in the portion of sample taken:

Result = (r_U/r_T) × 100

r_U= peak response of butyl alcohol

r_T= sum of all the peaks except the peaks each of which with an area less than 0.1 times the area of the major peak from the

Reference solution

Acceptance criteria: NLT 99.5%

4 IMPURITIES

Limit of Butyraldehyde, 2-Butanol, Isobutyl Alcohol (2-Methyl-1-Propanol), and Butyl Ether

Reference solution: 0.1% of Butyl Alcohol in water

Standard solution: 0.2% of USP Butyraldehyde RS, 0.2% of butyl ether, 0.1% of USP 2-Methyl-1-Propanol RS, and 0.1% of USP 2-Butanol RS in

Butyl Alcohol

Sample solution and Chromatographic system: Proceed as directed in the Assay.

System suitability

Sample: Standard solution

[Note—See Table 3.]

Table 3

System suitability requirements

Resolution: NLT 1.5 between all adjacent peaks

Analysis

Samples: Reference solution, Standard solution, and Sample solution

If any peaks are present in the chromatogram from the Sample solution that have the same retention times as the peaks due to butyraldehyde, 2-butanol, isobutyl alcohol (2-methyl-1-propanol), and butyl ether, subtract the areas of any such peaks from the peak areas at these retention times in the chromatogram from the Standard solution.

Result (Δr) = r_S− r_U

r_S= peak response of each individual impurity (butyraldehyde, 2-butanol, isobutyl alcohol, or butyl ether) in the Standard solution

r_U = peak response of each individual impurity (butyraldehyde, 2-butanol, isobutyl alcohol, or butyl ether), if present, in the Sample solution

Acceptance criteria: See Table 4. Disregard any peak with an area less than 0.1 times the area of the major peak from the Reference solution, corresponding to 0.01%.

Table 4

5 SPECIFIC TESTS

5.1 Acidity

Sample: 74 mL (60 g)

Analysis: Titrate the Sample with 0.020 N alcoholic potassium hydroxide, using phenolphthalein TS as the indicator, until a pink color persists

for NLT 15 s.

Acceptance criteria: NMT 2.5 mL is consumed.

5.2 Water Determination, Method I〈921〉: NMT 0.1%

5.3 Limit of Nonvolatile Residue

Sample: 100 mL

Analysis: Evaporate the Sample in a tared porcelain dish on a steam bath, and dry at 105° for 30 min.

Acceptance criteria: The weight of the residue does not exceed 4 mg (0.004%).

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers, and prevent exposure to excessive heat.

USP Reference Standards 〈11〉

USP Butyraldehyde RS

USP 1-Butanol RS

USP 2-Butanol RS

USP 2-Methyl-1-Propanol RS