Pyrethrins detection

The detection of microgram quantities of pyrethrins, cinerins, keto alcohols, and chrysanthemum acids by paper chromatography and by application of these techniques to a study of possible metabolites enabled certain tentative conclusions that imply hydrolysis in insects of a large portion of the radioactive pyrethrins and synergists to corresponding keto alcohols and chrysanthemum acids. 

Determination of the contents of pyrethrin I and pyrethrin II was then made, for about 2 years (Fig. 2). Having detected pyrethrin I throughout the whole growing process of pyrethrum leaves, they reported that the pyrethrin I content, which had a close relationship with flowering, reached a peak of 0.27-0.40 wt% during flowering and was slightly lower than that in dried flowers. 

Pyrethrin II was also detected in young leaves 2 months after seeding, similarly to pyrethrin I, but the content remained at about 0.05 wt% without seasonal change for 2 years. The insecticidal potency of pyrethrins obtained from pyrethrum leaves was confirmed with Musca domestica. 

CD active compounds can be selectively detected when present in a complex matrix comprised of other, specifically achiral, compounds such as might normally be encountered in the extracts of either natural products or biological fluids. Pyrethrines, tryptophans, rotenoids, and amaryllidacae alkaloids have been used to evaluate the system [27]. Monitoring at selected wavelengths has enabled detection levels in the low microgram range to be realized. By using stopped-flow techniques, full CD spectra can be obtained. 

Debon and Segalen (1989) described how to detect pyrethrins and PBO at trace levels (down to 0.1 mg L ) in tap water using a solid-phase extraction cartridge to isolate and preconcentrate the compounds. Elution with small quantities of methanol provides a solution which can be analysed directly by RP-HPLC. 

In 1984 resistance to Dl>l, lindane, organopbosphorus compounds, carbaryI. bioresmethrin and pyrethrins was detected in O. surimmensis taken from the held Attia and Frecker, 1984). The resistance factor was low for pyrethrins (2,3) and bioresmethrin (3 8) but very high for fenitrothion (>160). The inclusion of PBO in the assays reduced the latter to 10 or less. 

A CEC separation of insecticidal pyrethrin esters was accomplished by Henry et al. [63]. Here it was shown that it is possible to identify pyrethrin esters (cinerin I, pyrethrin I, jasmolin I, cinerin II, pyrethrin II, and jasmolin II) in a commercially available pyrethrin dip and flea and tick mist (Figure 5.20). The column inner and outer diameters were 100 and 350 (im, respectively, and the total and effective lengths were 33 and 25 cm, respectively. The column was packed with 3 xm particle size Hypersil C18. The mobile phase was composed of 55 35 10, pH 9, ACN-25 mM Tris-tetrahydrofuran. Other parameters were an applied voltage of 30 kV, column temperature of 25°C, and UV detection at 254 mn. 

Six pyrethrins (jasmolin I and II, cinerin I and II, pyrethrin I and II) were extracted from the flower heads of chrysanthemums and separated on a C,g column (A = 230nm). A complex 32-min 58/42 - 100/0 acetonitrile/water gradient generated excellent resolution and peak shapes for all components [982]. Standards were prepared at lOOpg/mL and were easily detected. 

In the natural pyrethrin esters, the presence of two asymmetric cyclopropane carbons implies the possible existence of four stereoisomers (Deltamethrin Monograph 1982). However, in the natural pyrethrins, only the (IR, 3R) configuration exists. This fact limits the number of acids (isomers) that need to be considered in developing analytical methods for detecting pyrethrin residues in food products, or animal tissues and fluids (i.e., blood, urine, and feces). For the alcohol component, three alcohols exist pyrethrolone, cinerolone and jasmolone, and all three possess an asymmetric center that has an (S) configuration. 

Loper, B.L. Anderson, KA. Determination of pyrethrin and pyrethroid pesticides in urine and water matrices by liquid chromatography with diode array detection, J.AOAC Int, 2003, 86, 1236-1240. 

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