Tributyl Citrate

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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C₁₈H₃₂O₇ 360.44

1 DEFINITION

Tributyl Citrate contains NLT 99.0% of tributyl citrate (C₁₈H₃₂O₇), 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 System suitability solution, as obtained in the Assay.

3 ASSAY

Procedure

System suitability solution: 30 mg/mL each of USP Tributyl Citrate RS and USP Acetyltributyl Citrate RS in toluene

Sample solution: 30 mg/mL of Tributyl Citrate in toluene

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC, equipped with an on-column, temperature-programmable injector

Detector: Flame ionization

Column: 0.32-mm × 30-m, bonded with a 0.5-μm layer of phase G42

Temperatures

Injector: See Table 1.

Detector: 275°

Column: See Table 2.

Table 1

Carrier gas: Helium

Flow rate: 2.3 mL/min

Injection volume: 1 μL

System suitability

Sample: System suitability solution

[Note - The relative retention times for tributyl citrate and acetyltributyl citrate are 0.9 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 1.5 between tributyl citrate and acetyltributyl citrate

Relative standard deviation: NMT 2.0%, determined from both the tributyl citrate and acetyltributyl citrate peaks

Analysis

Sample: Sample solution

Calculate the percentage of tributyl citrate (C₁₈H₃₂O₇) in the portion of sample taken:

Result = (r_U/r_T) × 100

r_U = peak area of tributyl citrate from the Sample solution

r_T = sum of all peaks excluding the solvent peak

Acceptance criteria: NLT 99.0% on the anhydrous basis

4 SPECIFIC TESTS

Specific Gravity 〈841〉: 1.037–1.045

Refractive Index 〈831〉: 1.443–1.445

Acidity

Sample: 32.0 g

Analysis: Dissolve the Sample in 30 mL of isopropyl alcohol, previously neutralized to bromothymol blue. Add bromothymol blue TS, and titrate with 0.10 N sodium hydroxide to a faint blue endpoint.

Acceptance criteria: NMT 1.0 mL of 0.10 N sodium hydroxide is required.

Water Determination, Method I 〈921〉: NMT 0.2%

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

USP Reference Standards 〈11〉

USP Acetyltributyl Citrate RS

USP Tributyl Citrate RS