Diethyltoluamide

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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C₁₂H₁₇NO          191.27

Benzamide, N,N-diethyl-3-methyl-;

N,N-Diethyl-m-toluamide CAS RN^®: 134-62-3; UNII: FB0C1XZV4Y.

1 DEFINITION

Diethyltoluamide contains NLT 95.0% and NMT 103.0% of the meta-isomer of diethyltoluamide (C₁₂H₁₇NO), calculated on the anhydrous basis.

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 of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

3.1 PROCEDURE

Solution A: 1 mL of phosphoric acid in 1000 mL of water

Mobile phase: Methanol and Solution A (45:55)

Diluent: Methanol and water (45:55)

ARS in Diluent. [NOTE-USP Diethyltoluamide Related Compound A RS is the p-isomer of diethyltoluamide.]

Standard solution: 0.2 mg/mL of USP Diethyltoluamide RS in Diluent

Sample solution: 0.2 mg/mL of Diethyltoluamide in Diluent

3.1.1 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 235 nm

Column: 4.6-mm × 15-cm; 3.5-µm packing L1

Flow rate: 1 mL/min

Injection volume: 10 µL

System suitability solution: 0.2 mg/mL of USP Diethyltoluamide RS (m-isomer) and 0.02 mg/mL of USP Diethyltoluamide Related Compound 

3.1.2 System suitability

Samples: System suitability solution and Standard solution

3.1.3 Suitability requirements

Resolution: NLT 1.5 between diethyltoluamide (m-isomer) and diethyltoluamide (p-isomer), System suitability solution

Tailing factor: NMT 2.0, Standard solution

Relative standard deviation: NMT 1.0%, Standard solution

3.1.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of diethyltoluamide (C₁₂H₁₇NO) in the portion of Diethyltoluamide taken:

                Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of the Standard solution (mg/mL)

C_U = concentration of the Sample solution (mg/mL)

Acceptance criteria: 95.0%-103.0% on the anhydrous basis

4 SPECIFIC TESTS

SPECIFIC GRAVITY (841): 0.996-1.002

REFRACTIVE INDEX (831): 1.520-1.524

ACIDITY

Sample solution: Dissolve 10.0 g in 50 mL of neutralized alcohol, and add phenolphthalein TS.

Analysis: Titrate the Sample solution with 0.010 N sodium hydroxide.

Acceptance criteria: NMT 4.0 mL of 0.010 N sodium hydroxide is required.

WATER DETERMINATION, Method 1 (921): NMT 0.5%

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers.

USP REFERENCE STANDARDS (11)

USP Diethyltoluamide RS

USP Diethyltoluamide Related Compound A RS

N,N-Diethyl-4-toluamide.

C₁₂H₁₇NO           191.27