Residue determination and dissipation of ioxynil octanoate in maize and soil

Abstract

A simple and efficient residue analysis method for direct determination of ioxynil octanoate in maize and soil was developed and validated with High Performance Liquid Chromatography-Ultra Violet (HPLC-UV). The samples were extracted with mixtures of acetonitrile and deionized water followed by Solid Phase Extraction (SPE) to remove co-extractives prior to analysis by HPLC-UV. The recoveries of ioxynil octanoate extracted from maize and soil samples ranged from 86 %–104 % and 84 %–96 %, respectively, with relative standard deviation (RSD) less than 7.84% and sensitivity of 0.01 mg kg⁻¹. The method was applied to determine the residue of ioxynil octanoate in maize and soil samples from experimental field. Data had shown that the dissipation rate in soil was described as pseudo-first-order kinetics and the half-life (t_1/2) was less than 1.78 days. No ioxynil octanoate residue (<0.01 mg kg⁻¹) was detected in maize at harvest time withholding period of 60 days after treatments of the pesticide. Direct confirmation of the analytes in field trial samples was realized by Liquid Chromatography-Mass Spectrometry (LC-MS).

Keywords:

• Ioxynil octanoate
• HPLC
• SPE
• determination

Notes

*Dissipation of ioxynil octanoate is calculated by formula: (Q₀–Q_t)/ Q₀*100%. Q₀ is the amount of residue of 0 day (2 h after spraying). Q_t is the amount of residue on the day of calculation.