Creatinine

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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C₄H₇N₃O            113.12

1 DEFINITION

Creatinine contains NLT 98.5% and NMT 102.0% of C₄H₇N₃O, as Creatinine, calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K _{(CN 1-MAY-2020)}

3 ASSAY

PROCEDURE

Sample: 40 mg of Creatinine

Titrimetric system

(See Titrimetry (541).)

Mode: Direct titration

Titrant: 0.1 N perchloric acid VS

Endpoint detection: Potentiometric

Indicator electrode: Glass

Reference electrode: Silver-silver chloride

Reference electrode solution: Saturated lithium perchlorate and silver chloride in glacial acetic acid

Analysis: Dissolve the Sample in 10 mL of glacial acetic acid. Titrate the Sample with 0.1 N perchloric acid VS. Perform a blank determination, and make any necessary correction.

Calculate the percentage of creatinine (C₄H₇N₃O) in the Sample taken:

Result = [(V − B) × N × F × 100]/W

V = volume of the Titrant consumed by the Sample (mL)

B = volume of the Titrant consumed by the Blank (mL)

N = actual normality of the Titrant (mEq/mL)

F = equivalency factor, 113.12 mg/mEq

W = weight of the Sample (mg)

Acceptance criteria: 98.5%–102.0% on the dried basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.2%

5 SPECIFIC TESTS

 Loss on Drying 〈731〉: Dry a sample at 105° for 3 h: it loses NMT 3.0% of its weight.

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Creatinine RS