K. SUNEETHAMMA, K. MANJULA, K. DEVAKI, M. PRADEEP AND P. LAVANYA KUMARI

Department of Entomology, S.V. Agricultural College, ANGRAU, Tirupati-517 502.

ABSTRACT

A modified quick, easy, cheap, efficient, rugged, and safe (QuEChERS) method coupled to Gas Chromatography with Electron Capture Detection was developed for the determination of profenophos residues in pigeonpea standing crop. Extraction and cleanup parameters were optimized; thus, the original QuEChERS method was modified to minimize solvent usage. After optimization, the method was validated by evaluating the analytical curves, linearity, Limits of Detection (LOD) and Limits of Quantification (LOQ) and accuracy (recovery). Retention time was 22.018 minutes and minimum detectable and quantifiable limits were 0.05 and 0.15 µg mL-1, respectively. Good linearity (R2=0.9935) of the calibration curves was obtained over the range from 0.1 to 1 µg mL-1. Good recovery in pigeonpea flower matrix was obtained with 90 to 98 per cent at 0.05 to 0.5 ppm with RSD value < 20% (0.93%). Results indicated that the developed method is rapid and easy to perform and making it applicable for analysis of profenophos in pigeonpea matrix. At 0 (2 hours) day after the insecticidal application an initial deposit of 0.72 mg kg-1 was recorded. The residues reached BDL on 7th day, exhibiting cent per cent dissipation with the half-life of 2.4 days.

KEYWORDS: Profenophos, pigeonpea, GC-ECD, linearity, recovery, LOD, LOQ, RSD.