| Abstract
| - A sensitive high-performance liquid chromatography−diode array detection (HPLC−DAD) assay isdescribed for the detection and quantification of the Beauveria metabolite oosporein from fungal culturebroth and two biocontrol agent formulations. In all cases, analyte recovery was achieved with a Britton−Robinson buffer system at pH 5.5 diluted with methanol 3:7 (v/v) (BR5.5-MeOH). The HPLC−DADassay, using a binary solvent gradient with acidic modifiers and detecting the metabolite at 287 nm,showed linearity over 3 orders of magnitude and a limit of detection (LOD) of 6.0 ± 2.3 μg ofoosporein/L of BR5.5-MeOH. The oosporein content of the representative fungal culture broth samplesand two Beauveria formulations (Melocont-Pilzgerste and Melocont-WP) was found to be 504.7 ±13.6 mg of oosporein/L of culture filtrate, 7.4 ± 0.6 mg of oosporein/kg of Melocont-Pilzgerste, and38.2 ± 1.3 mg of oosporein/kg of Melocont-WP with recovery rates of 93 ± 2, 99 ± 8, and 92 ± 3%,respectively. Keywords: HPLC−DAD; Beauveria brongniartii; oosporein; hydroxybenzoquinone derivative; analyteadsorption; biological pest control formulations; risk assessment
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