Standard - pyrethrum extract
November 2009
1. Description: the material shall consist of the clear extracts or concentrates of substances occurring naturally in pyrethrum flowers (Chrysanthemum cinerariaefolium) and shall be free from visible extraneous matter.
2. Composition: Pyrethrum Extract is a mixture of three naturally occurring, closely related insecticidal ester of chrysanthemic acid (cinerin I, jasmolin I and pyrethrin I) and three closely related insecticidal ester of pyrethric acid (cinerin II, jasmolin II and pyrethrin II). The three chrysanthemic acid esters are commonly identified as “pyrethrins I”, and the three pyrethric acid esters are identified as “pyrethrins II”. Collectively, the six esters are called “pyrethrins”.
3. Common Name: Pyrethrins (pyrethrum)
4. Chemical Name (IUPAC):
Pyrethrin I: (Z)-(S)-2-methyl-4-oxo-3-(penta-2,4-dienyl)cyclopent-2-enyl (1R,3R)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate;
Pyrethrin II: (Z)-(S)-2-methyl-4-oxo-3-(penta-2,4-dienyl)cyclopent-2-enyl (E)-(1R,3R)-3-(2-methoxycarbonylprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate;
Cinerin I: (Z)-(S)-3-(but-2-enyl)-2-methyl-4-oxocyclopent-2-enyl (1R,3R)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate;
Cinerin II: (Z)-(S)-3-(but-2-enyl)-2-methyl-4-oxocyclopent-2-enyl (E)-(1R,3R)-3-(2-methoxycarbonylprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate;
Jasmolin I: (Z)-(S)-2-methyl-4-oxo-3-(pent-2-enyl)cyclopent-2-enyl (1R,3R)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate;
5. CAS Number:
Pyrethrins : 8003-34-7
Individual components
Pyrethrin I: 121-21-1
Pyrethrin II: 121-29-9
Cinerin I: 25402-06-6
Cinerin II: 121-20-0
Jasmolin I: 4466-14-2
Jasmolin II: 1172-63-0
6. Active constituent:
Because of the lack of absolute standards for each individual compound, the routine quantitation of pyrethrum extract may be reported as either “total Pyrethrins” or as “total Pyrethrins I” and “total Pyrethrins II”.
Commercially available pyrethrum extracts usually contain 20% or 50% total pyrethrins. The pyrethrins contents shall be declared and when determined by the method described below in section 7, the content shall not differ from that declared by more than + or - 5% of the declared content.
7. Analytical methods
- The analytical method used for the determination of the active constituent and toxicological significant impurities must be validated in accordance with the APVMA guidelines for the validation of analytical methods.
- The APVMA guidelines on validation of analytical methods state that “Analytical methods described in CIPAC handbooks and AOAC International Manual, and in recognized pharmacopoeias [BP, BP (Vet), Ph Eur and USP] for a particular active constituent or formulation are regarded as validated and do not require revalidation. However, the suitability of these methods must be verified under actual conditions of use i.e., the selectivity and accuracy of the method should be demonstrated for the published method when applied to the relevant sample matrix and laboratory conditions.
- When a CIPAC or AOAC method is used for the assay of an active constituent in a bulk active constituent, there is no matrix. The registrants need to check the specificity of the method to ensure there is no interference from impurities or degradation products. However, determination of accuracy of the method is not required as there is no matrix effect. However, when a CIPAC or AOAC method is used for the assay of an active constituent in a formulated product, determination of both specificity and accuracy is required as the matrix is relevant in formulated products (formulated products have different composition and quantities of excipients).
- Refer to Guidelines for the Validation of Analytical Methods for Active Constituent, Agricultural And Veterinary Chemical Products (PDF, 164kb).
- Unless the scope of the collaborative method (CIPAC and AOAC) also includes toxicological significant impurities in the active constituent, validation data for impurities are required.
8 Packaging
Pyrethrum extract is sensitive to bright light and should be stored in perfectly lacquered drums or dark coloured containers and stored in the dark.
*Note: the AOAC titrimetric method is not suitable for the analysis of pyrethrins in formulated agricultural and veterinary chemical products, as these products contain mixtures of pyrethrins, synergists and other non-active ingredients. Therefore, gas chromatography (GC) and high-performance liquid chromatography (HPLC) are more appropriate for the assay of pyrethrins in formulated products.