Evaluation of photocatalytic degradation of imidacloprid in industrial water by GC-MS and LC-MS

Abstract

Abstract. The insecticide Imidacloprid was oxidized in water at 50 mg/L under photocatalytic TiO 2 in presence of formulating agents. Analysis of oxidized solutions was performed with both GC-Ion Trap-MS using either EI and CI as ionization modes and LC-Atmospheric Pressure Chemical Ionization (APCI)-MS in order to confirm and evaluate the decay of Imidacloprid and the presence of degradation products (DPs). LC-APCI-MS techniques allowed the monitoring of Imidacloprid and 6-chloronicotinic acid along the degradation process. GC-MS techniques allowed the detection of five DPs, three of which were unequivocally identified. Other complementary techniques such as Total Organic Carbon (TOC) and Ion Chromatography (IC) allowed the evaluation of the mineralization degree achieved. A tentative degradation pathway of Imidacloprid under photocatalysis is proposed. After 450 minutes of irradiation, none of the DPs or Imidacloprid were detected. Nearly total mineralization was achieved after 700 minutes of irradiation.

Monitoring of Photocatalytic Degradation of Selected Neonicotinoid Insecticides by Cathodic Voltammetry with a Bismuth Film Electrode

“…For the MS evaluations the positive molecular ion mode (M þ H) þ was applied. In accordance with earlier literature data [2,7,10,27] in the case of imidacloprid several degradation products (m/z) with typical 1Cl isotope clusters were observed, of which some are probably oxy-or hydroxyl derivatives -with oxidizable function groups [27] -(e.g., 185, 225, and 272) of the parent compound (256) and the presence of the 6-CNA (158) can also be supposed. Acetamiprid (223) has two significant degradation products with isotope cluster signals (257 and 209).…”

“…Important causes of pesticide water pollution are effluents from agricultural industries and from formulating or manufacturing pesticide plants which may generate water pollution at concentrations of up to 500 mg/dm 3 [2]. Apart from the frequently used biodegradation processes for wastewater treatment, aiming at total mineralization of organic pollutants, the advanced oxidation processes (AOPs) such as photo-Fenton (Fe/H 2 O 2 /UV) and semiconductor photocatalysis (e.g., TiO 2 /UV) are of special importance.…”

“…In relevance of this we have also studied the voltammetric response of 6-chloronicotinic acid (6-chloropyridine-3-carboxilic acid, 6-CNA, Fig. 1C), which is the last stable product in the degradation chain before total mineralization [2]. The electroanalytical method developed was validated by HPLC/DAD and FTIR procedures.…”

Atmospheric cold plasma dissipation efficiency of agrochemicals on blueberries

“…In this study, the degradation of boscalid is likely due to attack of hydroxyl radicals at −H in the three rings (benzene and pyridine rings) leading to four mono and di hydroxylated products and other carboxylic acids (Lagunas-Allué, Martínez-Soria, Sanz-Asensio, Salvador, Ferronato, & Chovelon, 2010). Furthermore, the suggested degradation of imidacloprid is due to the reaction of hydroxyl radicals to form 6-chloronicotinic aldehyde and 6-chloronicotinic acid (Agüera, Almansa, Malato, Maldonado, & Fernández-Alba, 1998;Malato, et al, 2001). …”

Comparison of different iron-based catalysts for photocatalytic removal of imidacloprid

“…Imidacloprid ((EZ)-1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine) is the most frequently used insecticide from the group of neonicotinoids. There are numerous literature reports on the oxidation and hydrolysis studies of this insecticide and its formulated products [2,3,9,10,12,[16][17][18][19][20][21][22][23]. Our recent studies showed that the O 2 /TiO 2 , UVA light system (400-320 nm) can be successfully applied for the photocatalytic removal of pyridine-based neonicotinoids such as imidacloprid [9] and acetamiprid [9,10].…”