Analysis of fenvalerate in its formulations and environmental samples using spectrophotometry

Two rapid, simple, sensitive, and nonextractive spectrophotometric methods were described for the determination of fenvalerate (syntheitic pyrethroid) in its formulations, water and grain samples. The methods are based on the hydrolysis of fenvalerate with methanolic NaOH to form 3-phenoxybenzaldehyde. The resultant aldehyde group was condensed with 4-aminoantipyrine in the basic medium to form a red product having λ_max at 489 nm or condensed with4,4′-methylene-bis-m-nitroaniline to form a plae red product with an absorption maximum of 513 nm. Beer’s law was obeyed over the range 0.6–10 μg/mL (molar absorptivity 2.184 × 10⁴ L/mol cm) for 4-aminoantityrine and over the range of 1–12 μg/mL (molar absorptivity 4.162 × 10⁴ L/mol cm) for 4,4′-methylene-bis-m-nitroaniline. The formations of color derivatives with the reagents are instantaneous and stable for 40 and 32 h, respectively. The methods were rapid, simple, sensitive, and free from nontarget species. The proposed methods have been applied to the determination of fenvalerate in its formulations and environmental samples. The text was submitted by the authors in English.