Pyrethrum Extract

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 DEFINITION 

Pyrethrum Extract is a mixture of three naturally occurring, closely related insecticidal esters of chrysanthemic acid (pyrethrins I: jasmolin I, cinerin I, and pyrethrin I) and three closely related esters of pyrethric acid (pyrethrins II: jasmolin II, cinerin II, and pyrethrin II). It contains NLT 90.0% and NMT 110.0% of the labeled amount of pyrethrins (sum of pyrethrins I and pyrethrins II). The ratio of pyrethrins I to pyrethrins II in the Extract is NLT 0.8 and NMT 2.8. It may contain pigments characteristic of chrysanthemum species, triglyceride oils, terpenoids, and Carotenoid. It may also contain suitable solvents and antioxidants. It contains no other added substances. 

2 IDENTIFICATION 

A. The retention times of the major peaks of the Sample solution correspond to those of the Standard solution, as obtained in the Assay. ASSAY 

Procedure 

Mobile phase: Hexanes and tetrahydrofuran (97.75:2.25) 

Standard solution: 0.5 mg/mL of USP Pyrethrum Extract RS in hexanes 

Sample solution: Nominally 0.5 mg/mL of pyrethrins from Extract in hexanes 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 240 nm 

Column: 4.6-mm × 25-cm; 5-µm packing L10 

Flow rate: 1.5 mL/min 

Injection volume: 10 µL 

System suitability 

Sample: Standard solution 

For relative retention times, see Table 1. 

Table 1 

Suitability requirements 

Resolution: NLT 2.0 between individual pyrethrin peaks 

Relative standard deviation: NMT 1.0% 

Analysis 1 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of pyrethrins (sum of pyrethrins I and pyrethrins II) in the portion of Extract taken: 

Result = {Σ[(r_U/r_S) × (C_S/C_U)]} × 100 

r_U = peak response of individual pyrethrin from the Sample solution 

r_S = peak response of individual pyrethrin from the Standard solution 

C_S = concentration of individual pyrethrin in the Standard solution (mg/mL) 

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

Acceptance criteria 1: 90.0%–110.0% 

Analysis 2 

Sample: Sample solution 

Calculate the ratio of pyrethrins I to pyrethrins II in the portion of Extract taken: 

Result = A/B 

A = sum of the quantities of pyrethrins I 

B = sum of the quantities of pyrethrins II 

Acceptance criteria 2: 0.8–2.8 

3 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve in tight, light-resistant containers. USP Reference Standards 〈11〉 

USP Pyrethrum Extract RS