Department of Chemistry and Physics, Research Centre for Agricultural and Food Biotechnology (BITAL), University of Almería, Agrifood Campus of International Excellence, ceiA3, E-04120 Almería, Spain.
Department of Chemistry and Physics, Research Centre for Agricultural and Food Biotechnology (BITAL), University of Almería, Agrifood Campus of International Excellence, ceiA3, E-04120 Almería, Spain..
Sci Total Environ. 2017 Dec 31;607-608:204-213. doi: 10.1016/j.scitotenv.2017.06.261. Epub 2017 Jul 27.
A comprehensive degradation study of quizalofop-p, quizalofop-p-ethyl, quizalofop-p-tefuryl and propaquizafop in soil samples have been firstly performed using ultra high performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS). Thus, metabolites or degradation products, such as CHHQ (dihydroxychloroquinoxalin), CHQ (6-chloroquinoxalin-2-ol), PPA ((R)-2-(4-hydroxyphenoxy)propionic acid) and 2,3-dihydroxyquinoxaline were also monitored. An extraction procedure based on QuEChERS procedure was used. Acidified water (0.1M hydrochloric acid) and acidified acetonitrile (1% acetic acid, (v/v)) were used as extraction solvents, and magnesium sulfate and sodium chloride were used as salts. Dispersive solid phase extraction with C as sorbent, was needed as a clean-up step. Several commercial products (Panarex®, Master-D® and Dixon®) were used to evaluate the degradation of the target compounds into their metabolites. The concentration of the main active substances (quizalofop-p-tefuryl, quizalofop-p-ethyl and propaquizafop) decreased during the degradation studies, whereas the concentration of quizalofop-p increased. Dissipation rates of half-live of quizalofop-p were also evaluated, and it was observed that this compound is easily degraded, obtaining values lower than 1day. Taking into account that quizalofop-p is the R enantiomer of quizalofop, a chiral separation was performed by liquid chromatography coupled to tandem mass spectrometry, concluding that in samples containing quizalofop-p-tefuryl, there was a 15% contribution from the S enantiomer and a 85% contribution from the R enantiomer. Metabolites such as PPA, CHHQ and CHQ were detected in soil samples after 15days of application commercial product at concentrations between the limits of detection (LOD) and the limits of quantification (LOQ). CHQ and CHHQ were detected at concentrations higher than the LOQ in samples after 50 and 80days of application, with their concentration increasing during this time up to 500%.
首次使用超高效液相色谱-轨道阱质谱（UHPLC-Orbitrap-MS）对土壤样品中的精喹禾灵、精喹禾灵乙酯、精喹禾灵砜和高效氟吡甲禾灵进行了全面的降解研究。因此，还监测了代谢物或降解产物，如 CHHQ（二羟基氯喹喔啉）、CHQ（6-氯喹喔啉-2-醇）、PPA（（R）-2-（4-羟基苯氧基）丙酸）和 2,3-二羟基喹喔啉。采用 QuEChERS 方法作为提取程序。酸化水（0.1M 盐酸）和酸化乙腈（1%乙酸，（v/v））用作提取溶剂，硫酸镁和氯化钠用作盐。需要用 C 作为吸附剂的分散固相萃取作为净化步骤。使用几种商业产品（Panarex®、Master-D®和 Dixon®）来评估目标化合物降解为其代谢物的情况。在降解研究过程中，主要活性物质（精喹禾灵砜、精喹禾灵乙酯和高效氟吡甲禾灵）的浓度降低，而精喹禾灵-p 的浓度增加。还评估了精喹禾灵-p 的半衰期消散率，结果表明该化合物易于降解，获得的半衰期值低于 1 天。考虑到精喹禾灵-p 是精喹禾灵的 R 对映体，通过液相色谱-串联质谱对其进行了手性分离，结论是在含有精喹禾灵砜的样品中，S 对映体的贡献为 15%，R 对映体的贡献为 85%。在应用商业产品 15 天后，在土壤样品中检测到 PPA、CHHQ 和 CHQ 等代谢物，其浓度在检测限（LOD）和定量限（LOQ）之间。在应用后 50 和 80 天的样品中检测到 CHQ 和 CHHQ 的浓度高于 LOQ，在此期间其浓度增加到 500%。
