Dissipation behavior of phorate and its toxic metabolites in the sandy clay loam soil of a tropical sugarcane ecosystem using a single-step sample preparation method and GC-MS

Abstract

The dissipation of phorate in the sandy clay loam soil of tropical sugarcane ecosystem was studied by employing a single-step sample preparation method and gas chromatography with mass spectrometry. The limit of quantification of the method was 0.01 μg/g. The recoveries of phorate, phorate sulfoxide, phorate sulfone, and phorate oxon were in the range 94.00-98.46% with relative standard deviations of 1.51-3.56% at three levels of fortification between 0.01 and 0.1 μg/g. The Half-life of phorate and the total residues, which include phorate, phorate sulfoxide and phorate sulfone, was 5.5 and 19.8 days, respectively at the recommended dose of insecticide. Phorate rapidly oxidized into its sulfoxide metabolite in the sandy clay loam soil. Phorate sulfoxide alone accounted for more than 20% of the total residues within 2 h post-application and it was more than 50% on the fifth day after treatment irrespective of the doses applied. Phorate sulfoxide and phorate sulfone reached below the detectable level on 105 and 135 days after treatment, respectively as against 45 days after treatment for phorate residues at the recommended dose. Thus, the reasonably prolonged efficacy of phorate against soil pests may be attributed to longer persistence of its more toxic sulfoxide and sulfone metabolites.

Controllable synthesis of flower-like hierarchical porous TiO2 at room temperature and its affinity application

“…Moreover, the analysis sensitivity was excellent, with the limit of detection (LOD, S/N = 3) and the limit of quantification (LOQ, S/N = 10) of phorate, chlorpyrifos and PS36:3 as low as 0.05 mg kg À1 (LOD of phorate), 0.15 mg kg À1 (LOQ of phorate), 0.01 mg kg À1 (LOD of chlorpyrifos), 0.03 mg kg À1 (LOQ of chlorpyrifos), 3.00 mg kg À1 (LOD of PS36:2), 10.00 mg kg À1 (LOQ of PS36 : 2), respectively (Table S4, ESI †). As shown in Table S5 (ESI †), the analysis performance using FHP-TiO 2 was superior to those of previously reported phorate (LOD 3-4.83 mg kg À1 ), 26,29 and chlorpyrifos (LOD 5-8.29 mg kg À1 ). 26,30 This can be attributed to two factors: firstly, the unique hierarchical porous flower-like structure of FHP-TiO 2 and the affinity mechanism of MOAC; secondly, the efficiency of solid phase microextraction (SPME) compared to liquid-liquid extraction (LLE).…”

Screening for Lactobacillus plantarum Strains That Possess Organophosphorus Pesticide-Degrading Activity and Metabolomic Analysis of Phorate Degradation

“…The National Pesticide Information Center of United States listed chlorpyrifos, phorate, dimethoate, malathion, acephate, naled, dicrotophos, phosmet, diazinon, and azinphos-methyl as the most used OPPs (NPIC 1 ). Residues of some OPPs are repeatedly reported in the terrestrial and aquatic food chains ( Regueiro et al, 2015 ), e.g., dimethoate residues in soil ( Liu et al, 2016 ), olives ( Paíga et al, 2016 ), and apples ( Szpyrka et al, 2015 ); phorate residues in green tea ( Steiniger et al, 2010 ), livestock products ( Rahman et al, 2016 ), and soil ( Stoleru et al, 2015 ; Ramasubramanian and Paramasivam, 2016 ); and omethoate residues in various vegetables ( Stoleru et al, 2015 ). Therefore, our work focused on identifying lactobacilli that could degrade these three OPPs, i.e., dimethoate, phorate, and omethoate.…”