A capillary micellar electrokinetic chromatography method for the stereoselective quantitation of bioallethrin in biotic and abiotic samples

- A high resolution stereoselective CE methodology is proposed for bioallethrin.
- Application to the analysis of bioallethrin stereoisomers in a commercial formulation is shown.
- Toxicity parameters were obtained using bioallethrin real concentrations.
- Toxicity of bioallethrin was higher than that of esbiol in algae.
- Total inhibition of germination was observed for bioallethrin and esbiol.

A capillary micellar electrokinetic chromatography (MEKC) method was developed enabling the stereoselective separation of the insecticide bioallethrin. The use of sodium deoxycholate bile salt and acetyl-β-cyclodextrin (acetyl-β-CD) made possible the separation of bioallethrin stereoisomers with a high enantioresolution (7.4) in a short analysis time (6.5 min). The analytical characteristics of the developed method were evaluated in terms of linearity, accuracy, precision, and limits of detection (LOD) and quantitation (LOQ) showing a good performance for the quantitation of bioallethrin stereoisomers with LODs of 0.2 and 0.3 mg/L. The developed method was applied to the stereoselective analysis of a commercial bioallethrin pediculicide formulation and to evaluate the toxicity of bioallethrin stereoisomers on the growth of the unicellular freshwater green alga Pseudokirchneriella subcapitata and on the germination of the higher plant Sorghum bicolor (non-target organisms). The analysis of the commercial pediculicide showed a good agreement between the contents determined for the two stereoisomers and those labelled in the commercial samples. Different toxic responses and biodegradation profiles were found for each stereoisomer in ecotoxicity assays. The mixture of S/R stereoisomers of bioallethrin resulted more toxic than S-bioallethrin for green algae, with EC50 values of 1.10 ± 0.06 for the mixture and of 1.73 ± 0.05 mg/L for the pure S-biallethrin (esbiol). Germination of plants seeds was also affected.