Ethyl Maltol

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

DOWNLOAD PDF HERE

1 DEFINITION

Change to read:

Ethyl Maltol contains NLT 97.5% and NMT 102.5% of 2-ethyl-3-hydroxy-4H-pyran-4-one, (NF 1-Dec-2020) calculated on the anhydrous basis.

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS 〈197〉 , Infrared Spectroscopy (NF 1-DEC-2020) : 197S, 1:50 solution in chloroform

Add the following:

B. Chromatographic Identity

Analysis: Examine the chromatograms obtained in the Assay.

Acceptance criteria: The retention time of the major peak of the Sample solution corresponds to that of the Standard solution. (NF 1-Dec-2020)

3 ASSAY

Change to read:

3.1 PROCEDURE

Diluent: Absolute alcohol

Internal standard solution: 0.5 mg/mL of USP Benzyl Alcohol RS (internal standard) in Diluent

System suitability solution: 1.0 mg/mL of USP Ethyl Maltol RS and 0.2 mg/mL of USP Maltol RS in Internal standard solution Standard solution: 1.0 mg/mL of USP Ethyl Maltol RS in Internal standard solution

Sample solution: 1.0 mg/mL of Ethyl Maltol in Internal standard solution

3.1.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.) Mode: GC

Detector: Flame ionization

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

Temperatures

Detector: 300°

Injection port: 280° Column: See Table 1.

Table 1

Carrier gas: Helium

Flow: 2 mL/min (constant flow mode) Injection volume: 1.0 µL

Injection type: Split ratio, 10:1

Liner: Ultra inert with glass wool, low pressure drop1

3.1.2 System suitability

Samples: System suitability solution and Standard solution

[NOTE—The approximate relative retention times of related substances are listed in Table 2.]

Suitability requirements

Resolution: NLT 1.5 between the maltol peak and the ethyl maltol peak, System suitability solution Tailing factor: NMT 2.0, determined from ethyl maltol peak, System suitability solution

Relative standard deviation: NMT 1% for the peak response ratio of ethyl maltol to the internal standard, Standard solution

3.1.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of ethyl maltol in the portion of sample taken:

Result = (R_u/R_s) × (C_s/C_u) × 100

R_u = peak response ratio of ethyl maltol to the internal standard (peak response of ethyl maltol/peak response of the internal standard) from the Sample solution

R_s = peak response ratio of ethyl maltol to the internal standard (peak response of ethyl maltol/peak response of the internal standard) from the Standard solution

C_s = concentration of USP Ethyl Maltol RS in the Standard solution (mg/mL)

C_u = concentration of Ethyl Maltol in the Sample solution (mg/mL)

Acceptance criteria: 97.5%–102.5% on the anhydrous basis (NF 1-Dec-2020)

4 IMPURITIES

Add the following:

4.1 Organic Impurities

Diluent and Chromatographic system: Proceed as directed in the Assay.

Protectant solution: 1.0 mg/mL of 4-hydroxy-6-methyl-2-pyrone (protectant) in Diluent

System suitability solution: 1.0 mg/mL of USP Ethyl Maltol RS and 0.2 mg/mL of USP Maltol RS in Protectant solution Standard solution: 0.02 mg/mL of USP Maltol RS and USP Ethyl Maltol RS in Protectant solution

Sample solution: 20.0 mg/mL of Ethyl Maltol in Protectant solution

4.1.1 System suitability

Samples: System suitability solution and Standard solution

[NOTE—The approximate relative retention times of related substances are listed in Table 2.]

Suitability requirements

Resolution: NLT 1.5 between the maltol peak and the ethyl maltol peak, System suitability solution Relative standard deviation: NMT 5.0%, determined from the ethyl maltol peak, Standard solution Signal-to-noise ratio: NLT 10, determined from the ethyl maltol peak, Standard solution

4.1.2 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of maltol impurity in the portion of sample taken:

Result = (r_u/r_s) × (C_s/C_u) × 100

r_u = peak area of maltol from the Sample solution

r_s = peak area of maltol from the Standard solution

C_s = concentration of USP Maltol RS in the Standard solution (mg/mL)

C_u = concentration of Ethyl Maltol in the Sample solution (mg/mL)

Calculate the percentage of each individual unspecified impurity in the portion of sample taken:

Result = (r_u/r_s) × (C_s/C_u) × 100

r_u = peak area of any individual unspecified impurity from the Sample solution

r_s = peak area of ethyl maltol from the Standard solution

C_s = concentration of USP Ethyl Maltol RS in the Standard solution (mg/mL)

C_u = concentration of Ethyl Maltol in the Sample solution (mg/mL)

Acceptance criteria: See Table 2.

Table 2.

4.2 RESIDUE ON IGNITION 〈281〉

NMT 0.2% at 800° for 15 min

5 SPECIFIC TESTS

WATER DETERMINATION 〈921〉 , Method I: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Change to read:

PACKAGING AND STORAGE: Preserve in tight containers ▲and avoid contact with metals.▲ (NF 1-Dec-2020)

Change to read:

USP REFERENCE STANDARDS 〈11〉

USP Benzyl Alcohol RS (NF 1-Dec-2020)

USP Ethyl Maltol RS

USP Maltol RS (NF 1-Dec-2020)