Padimate O

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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C₁₇H₂₇NO₂ 277.40

Benzoic acid, 4-(dimethylamino)-, 2-ethylhexyl ester,

2-Ethylhexyl p-(dimethylamino)benzoate CAS RN^®: 21245-02-3; UNII: Z11006CMUZ.

1 DEFINITION

Padimate O contains NLT 97.0% and NMT 102.0% of padimate O (C₁₇H₂₇NO₂).

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

Mobile phase: Methanol, water, and glacial acetic acid (850:150:0.5)

Standard solution: 0.1 mg/mL of USP Padimate O RS in methanol

Sample solution: 0.1 mg/mL of Padimate O in methanol

3.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 308 nm

Column: 4.6-mm x 15-cm; 5-µm packing L1

Flow rate: 1.5 mL/min

Injection volume: 10 µL

3.3 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 0.73%

3.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of padimate O (C₁₇H₂₇NO₂) in the portion of Padimate O taken:

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

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Padimate O RS in the Standard solution (mg/mL)

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

Acceptance criteria: 97.0%-102.0%

4 IMPURITIES

ORGANIC IMPURITIES

Sample solution: 10 mg/mL of Padimate O in chloroform

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 3-mm x 1.8-m stainless steel packed with 10% liquid phase G9 on support S1A

Carrier gas: Helium

Column temperature: See Table 1.

Table 1

Injection volume: 2 µL

Analysis

Sample: Sample solution

Calculate the percentage of the total impurities in the portion of Padimate O taken:

[Σr_I/(Σr_I + r_U)] x 100

r_I = individual impurity peak response from the Sample solution

r_U = Padimate O peak response from the Sample solution

Acceptance criteria

Total impurities: NMT 2.0%

5 SPECIFIC TESTS

5.1 SPECIFIC GRAVITY (841)

0.990-1.000

5.2 REFRACTIVE INDEX (831)

1.5390-1.5430

5.3 FATS AND FIXED OILS, Acid Value (401)

NMT 1.0

5.4 FATS AND FIXED OILS, Saponification Value(401)

Analysis: Proceed as directed in the chapter, except to maintain reflux for 4 h.

Acceptance criteria: 195-215

6 ADDITIONAL REQUIREMENTS

6.1 PACKAGING AND STORAGE

Preserve in tight, light-resistant containers.

6.2 USP REFERENCE STANDARDS (11)

USP Padimate O RS