Identification - Organic Nitrogenous Bases

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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1 INTRODUCTION

The purpose of this test is the identification of tertiary amine compounds. This spectroscopic test has a limited degree of specificity and, therefore, the conformance with all additional identification tests listed in a particular monograph is necessary to ensure the identity of the specimen under examination.

2 ASSAY

2.1 PROCEDURE

Standard solution: in a separator dissolve 50 mg of the corresponding USP Reference Standard in 25 mL of 0.01 N hydrochloric acid.

Sample solution: Depending upon the nature of the sample, dissolve 50 mg of the bulk substance under test in 25 mL of 0.01 N hydrochloric acid, or shake a quantity of powdered tablets or the contents of capsules, equivalent to 50 mg of the substance, with 25 mL of 0.01 N hydrochloric acid for 10 min. Transfer the liquid to a separator, filtering if necessary, and washing the filter and the residue with several small portions of water.

Instrumental conditions

(See Mid-Infrared Spectroscopy (854).)

Mode: IR

Wavelength range: 7-15 µm (1430 cm^-1 to 650 cm^-1)

Cell: 1-mm

Blank: Carbon disulfide

Analysis

Samples: Standard solution and Sample solution

Treat each solution as follows: Add 2 mL of 1 N sodium hydroxide and 4 mL of carbon disulfide, and shake for 2 min. Centrifuge if necessary to clarify the lower phase, and pass it through a dry filter, collecting the filtrate in a small flask provided with a glass stopper. Determine the absorption spectra of the filtered Standard solution and Sample solution without delay.

Acceptance criteria: The spectrum of the Sample solution must show all of the significant absorption bands present in the spectrum of the Standard solution.