Alcohol

Alcohol

Final Authorized Version 1.0

C2H6O                           46.07

Ethanol;    

Ethyl alcohol [64-17-5].

 

DEFINITION

Alcohol contains NLT 92.3% and NMT 93.8% by weight, corresponding to NLT 94.9% and NMT 96.0% by volume, at 15.56°, of C2H5OH.

 

IDENTIFICATION

• A. Specific Gravity <841>: 0.812–0.816 at 15.56°, indicating 92.3%–93.8% by weight, or indicating 94.9%–96.0% by volume, of C2H5OH

• B. Spectrophotometric Identification Tests, Infrared Absorption <197F> or <197S>: Neat

 

IMPURITIES

• Limit of Nonvolatile Residue

Analysis: Evaporate 100 mL in a tared dish on a water bath, dry at 100°–105° for 1 h, and obtain the weight of the residue.

Acceptance criteria: NMT 2.5 mg

Volatile Impurities

Sample solution A: Alcohol (substance under test)

Sample solution B: 300 μL/L of 4-Methylpentan-2-ol in Sample solution A

Standard solution A: 200 μL/L of Methanol in Sample solution A

Standard solution B: 10 μL/L of Methanol and 10 μL/L of acetaldehyde in Sample solution A

Standard solution C: 30 μL/L of Acetal in Sample solution A

Standard solution D: 2 μL/L of Benzene in Sample solution A

Chromatographic system

(See Chromatography <621>, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.32-mm × 30-m fused silica capillary; bonded with a 1.8-μm layer of phase G43 (similar to DB-624) 

Split ratio: 20:1

Temperatures

Detector: 280°

Injector: 200°

Column: See Table 1.

Table 1

Initial
Temperature
(
°)

Temperature

Ramp
(° /min)

Final
Temperature
(°)

Hold Time at Final
Temperature
(min)

40

0

40

12

40

10

240

10

  

Flow rate: 35 cm/s

Carrier gas: Helium

Injection volume: 1.0 μL

System suitability

Sample: Standard solution B

Suitability requirements

Resolution: NLT 1.5 between the first major peak (acetaldehyde) and the second major peak (methanol)

Analysis

Samples: Sample solution A, Sample solution B, Standard solution A, Standard solution B, Standard solution C, and Standard solution D

 

Methanol calculation

 

Result = (rU/rS)

 

rU = peak area of methanol from Sample solution A

rS = peak area of methanol from Standard solution A

 

Acetaldehyde and acetal calculation

 

Result = {[AE/(AT AE)] × CS} + {[DE/(DT DE)] × CU}

 

AE = area of the acetaldehyde peak from Sample solution A

AT = area of the acetaldehyde peak from Standard solution B

CS = concentration of acetaldehyde added in Standard solution B, 10 μL/L

DE = area of the acetal peak from Sample solution A

DT = area of the acetal peak from Standard solution C

CU = concentration of acetal added in Standard solution C, 30 μL/L

 

Benzene calculation

 

Result = [BE/(BT BE)] × CS

 

 

BE = area of the benzene peak from Sample solution A

BT = area of the benzene peak from Standard solution D

CS = concentration of benzene added in Standard solution D, 2 μL/L

[Note—If necessary, the identity of benzene can be confirmed using another suitable chromatographic system (stationary phase with a different polarity).]

 

Other impurities calculation

 

Result = (rU/rM) × CM

 

rU = peak area of each impurity in Sample solution B

rM = peak area of 4-methylpentan-2-ol in Sample solution B

CM = concentration of 4-methylpentan-2-ol in Sample solution B

Acceptance criteria: See Table 2

Table 2

Name

Acceptance

Criteria

Methanol

NMT 0.5, corresponding to 200 μL/L

Acetaldehyde and Acetal

NMT 10 μL/L, expressed as acetaldehyde

Benzene

NMT 2 μL/L

Sum of all other impuritiesa

NMT 300 μL/L

aDisregard any peaks of less than 9 μL/L.

 

SPECIFIC TESTS

Ultraviolet Absorption

Analytical wavelength: 235–340 nm

Cell: 5 cm

Reference: Water

Acceptance criteria

Absorbance: NMT 0.40 at 240 nm; NMT 0.30, between 250 nm and 260 nm; NMT 0.10, between 270 nm and 340 nm

Curve: The absorption curve is smooth.

Clarity of Solution

[Note—The Sample solution is to be compared to Reference suspension A and to Blank in diffused daylight 5 min after preparation of Reference suspension A.]

Hydrazine solution: 10 mg/mL of hydrazine sulfate in water. [Note—Allow to stand for 4–6 h.]

Methenamine solution: Transfer 2.5 g of methenamine to a 100-mL glass-stoppered flask, add 25.0 mL of water, insert the glass stopper, and mix to dissolve.

Primary opalescent suspension: Transfer 25.0 mL of Hydrazine solution to the Methenamine solution in the 100-mL glass-stoppered flask. Mix, and allow to stand for 24 h. [Note—This suspension is stable for 2 months, provided it is stored in a glass container free from surface defects. The suspension must not adhere to the glass and must be well mixed before use.]

Opalescence standard: Transfer 15.0 mL of the Primary opalescent suspension to a 1000-mL volumetric flask, and dilute with water to volume. [Note—This suspension should not be used beyond 24 h after preparation.]

Reference suspension A: Opalescence standard and water (1:20)

Reference suspension B: Opalescence standard and water (1:10)

Sample solution A: Substance to be examined

Sample solution B: Dilute 1.0 mL of Sample solution A with water to 20 mL, and allow to stand for 5 min before testing.

Blank: Water

Analysis

Samples: Reference suspension A, Reference suspension BSample solution A, Sample solution B, and Blank

Transfer a sufficient portion of each of the Samples to individual test tubes of colorless, transparent, neutral glass with a flat base and an internal diameter of 15–25 mm to obtain a depth of 40 mm. Compare the Samples in diffused daylight, viewing vertically against a black background. (See Spectrophotometry and Light-Scattering <851>, Visual Comparison.) [Note—The diffusion of light must be such that Reference suspension A can readily be distinguished from Blank, and that Reference suspension B can readily be distinguished from Reference suspension A.]

Acceptance criteria: Sample solution A and Sample solution B show the same clarity as that of Blank or their opalescence is not more pronounced than that of Reference suspension A.

 • Acidity or Alkalinity

Phenolphthalein solution: Dissolve 0.1 g of phenolphthalein in 80 mL of alcohol, and dilute with water to 100 mL.

Sample solution: 20 mL of Alcohol

Analysis: To the Sample solution add 20 mL of freshly boiled and cooled water and 0.1 mL of Phenolphthalein solution. The solution is colorless. Add 1.0 mL of 0.01 N sodium hydroxide.

Acceptance criteria: The solution is pink (30 μL/L, expressed as acetic acid).

Color of Solution

Standard stock solution: Combine 3.0 mL of ferric chloride CS, 3.0 mL of cobaltous chloride CS, 2.4 mL of cupric sulfate CS, and 1.6 mL of dilute hydrochloric acid (10 g/L).

Standard solution: Transfer 1.0 mL of Standard stock solution to a 100-mL volumetric flask, and dilute with dilute hydrochloric acid (10 g/L) to volume. [Note—Prepare the Standard solution immediately before use.]

Sample solution: Substance to be examined

Analysis

Samples: Standard solutionSample solution, and water

Transfer a sufficient portion of each of the Samples to individual test tubes of colorless, transparent, neutral glass with a flat base and an internal diameter of 15–25 mm to obtain a depth of 40 mm. Compare the Samples in diffused daylight, viewing vertically against a white background. (See Spectrophotometry and Light-Scattering <851>, Visual Comparison.)

Acceptance criteria: The Sample solution has the appearance of water or is not more intensely colored than the Standard solution.

 

ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers, protected from light.

• USP Reference Standards  <11>

USP Alcohol RS

Other Versions

Proposed For Comment Version 0.2