Amitraz

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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C₁₉H₂₃N₃ 293.41

Methanimidamide,N'-(2,4-dimethylphenyl)-N-[[(2,4-dimethylphenyl)imino]methyl]-N-methyl-;

N-Methyl-N'-2,4-xylyl-N-(N-2,4-xylylformimidoyl) formamidine;

N-Methylbis (2,4-xylyliminomethyl)amine CAS RN^®: 33089-61-1; UNII: 331AH5017S.

1 DEFINITION

Amitraz contains NLT 95.0% and NMT 101.5% of amitraz (C₁₉H₂₃N₃), calculated on the anhydrous basis.

2 IDENTIFICATION

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 1974, 197K, or 197M

B. The retention time of the amitraz peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

3.1 PROCEDURE

Internal standard solution: 0.7% v/v solution of squalane in methyl acetate

Standard solution: 5.0 mg/mL of USP Amitraz RS in Internal standard solution

Sample solution: 5.0 mg/mL of Amitraz in Internal standard solution

3.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.53-mm x 15-m fused silica; coated with a 1.5-µm layer of liquid phase G9

Temperatures

Detector: 300°

Inlet: 230°

Column: 220°

Carrier gas: Helium

Flow rate: 12 mL/min

Injection volume: 1 µL

3.3 System suitability

Sample: Standard solution

[NOTE-The elution order is amitraz followed by squalane.]

Suitability requirements

Resolution: NLT 3.0 between amitraz and squalane

Relative standard deviation: NMT 2.0% from the peak area ratio of amitraz to squalane

3.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of amitraz (C₁₉H₂₃N₃) in the portion of Amitraz taken:

Result = (R/R) × (C/C) × 100

R= peak response ratio of amitraz and squalane from the Sample solution

R = peak response ratio of amitraz and squalane from the Standard solution

Cs = concentration of USP Amitraz RS in the Standard solution (mg/mL)

C = concentration of Amitraz in the Sample solution (mg/mL)

Acceptance criteria: 95.0%-101.5% on the anhydrous basis

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281)

NMT 0.2%

4.2 ORGANIC IMPURITIES

Standard solution: 0.05 mg/mL of 2,4-dimethylaniline, 1.0 mg/mL of USP Amitraz Related Compound A RS, 0.5 mg/mL of USP Amitraz Related Compound B RS, and 1.0 mg/mL of USP Amitraz Related Compound C RS in methyl acetate

Sample solution: 50.0 mg/mL of Amitraz in methyl acetate

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.53-mm x 10-m fused silica; coated with a 5-um layer of liquid phase G27

Temperatures

Detector: 300°

Inlet: 230°

Column: See Table 1.

Table 1

Carrier gas: Helium

Flow rate: 12 mL/min

Injection volume: 1 µL

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 3.0 between amitraz related compound A and amitraz related compound B

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each of amitraz related compounds A, B, and C in the portion of Amitraz taken:

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

r_U = peak response of each individual impurity from the Sample solution

r_S = peak response of the corresponding related compound from the Standard solution

C_S = concentration of the corresponding related compound in the Standard solution (mg/mL)

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

Calculate the percentage of 2,4-dimethylaniline and any other individual impurity in the portion of Amitraz taken:

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

r_U = peak response of each individual impurity from the Sample solution

r_S = peak response of 2,4-dimethylaniline from the Standard solution

C_S = concentration of 2,4-dimethylaniline in the Standard solution (mg/mL)

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

Acceptance criteria: See Table 2. The reporting level for impurities is 0.05%.

Table 2

5 SPECIFIC TESTS

WATER DETERMINATION, Method I(921): NMT 0.1%

6 ADDITIONAL REQUIREMENTS

6.1 PACKAGING AND STORAGE

Preserve in well-closed containers.

6.2 LABELING

Label it to indicate that it is for veterinary use only.

6.3 USP REFERENCE STANDARDS (11)

USP Amitraz RS

USP Amitraz Related Compound A RS

2,4-Dimethylphenyl formamide;

N'-(2,4-Dimethylphenyl) formamide.

C₉H₁₁NO 11 149.19

USP Amitraz Related Compound B RS

2,4-Dimethylphenyl N-methyl-formamidine;

N'-(2,4-Dimethylphenyl)-N-methylformimidamide.

C₁₀H₁₄N₂ 162.23

USP Amitraz Related Compound C RS

Bisformamidine analog;

N,N'-Bis(2,4-dimethylphenyl) formimidamide.

C₁₇H₂₀N₂ 252.35 (USP 1-Dec-2024)