Packed in-tube solid phase microextraction with graphene oxide supported on aminopropyl silica: Determination of target triazines in water samples

On-line in-tube solid phase microextraction (in-tube SPME) coupled to high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS) was successfully applied to the determination of selected triazines in water samples. The method based on the employment of a packed column containing graphene oxide (GO) supported on aminopropyl silica (Si) showed that the extraction phase has a high potential for triazines extraction aiming to its physical-chemical properties including ultrahigh specific surface area, good mechanical and thermal stability and high fracture strength. Injection volume and loading time were both investigated and optimized. The method validation using Si-GO to extract and concentrate the analytes showed satisfactory results, good sensitivity, good linearity (0.2–4.0 µg L^?1) and low detection limits (1.1–2.9 ng L^?1). The high extraction efficiency was determined with enrichment factors ranging from 1.2–2.9 for the lowest level, 1.3–4.9 intermediate level and 1.2–3.0 highest level (n = 3). Although the analytes were not detected in the real samples evaluated, the method has demonstrated to be efficient through its application in the analysis of spiked triazines in ground and mineral water samples.     

Effect of sewage amendment on the dissipation of terbuthylazine,its degradation compound desethyl-terbuthylazine,and S-metolachlor in a field study

This study evaluates the effect of sewage amendment (SA) on the dissipation of terbuthylazine, its degradation compound desethyl-terbuthylazine, and S-metolachlor in the soil. The experiment was conducted at Padua Experimental Farm (Italy). Herbicides dissipation was evaluated in soils differently fertilized for three years: with inorganic fertilizer, with sewage sludge, and with a combination of them. Terbuthylazine and S-metolachlor were applied on sorghum as a formulated product at a dose of 2.8?L ha^?1, and their dissipation was followed for 2.5 months. The concentrations of herbicides and one metabolite in soil were analyzed by liquid chromatography-mass spectrometry. The dissipation of terbuthylazine and S-metolachlor followed a pseudo first order kinetics; they dissipated faster in soil amended only with inorganic fertilizer than in soils amended with sewage or sewage?+?inorganic fertilizer. The reduction in mineralization of the herbicides after sewage addition can be attributed to the reduced herbicide availability to microorganisms. The degradation of terbuthylazine led to the formation of desethyl-terbuthylazine. SA slowed down the formation and the degradation of desethyl-terbuthylazine, leading to a higher amount measured at the end of the incubation. These findings have practical implications for the assessment of the environmental fate of terbuthylazine and S-metolachlor in agricultural areas.     

Relative influence of the dissolved humic material on the solid-phase extraction efficiency of pesticides from environmental water

The effect of organic matter on the solid-phase extraction (SPE) efficiency for pesticides belonging to different chemical groups (urea-derivatives, carbamates and triazines) and having different polarities, was simultaneously studied for the first time in pure and simulated water samples. SPE was carried out in precolumns packed with C18 silica or styrene-divinylbenzene copolymer PLRP-S phases on-line coupled to high performance liquid chromatography (HPLC) analysis. Retention factors in water (k'_W) were estimated for 25 compounds and used for the calculation of the theoretical breakthrough volume (Vb_T) in pure water. Experimental breakthrough volumes (Vb_E) were first determined using purified and deionized water as the matrix for selected compounds having Vb_T < 500 mL; then, the same water with an added humic acid sodium salt (HA) at 0.4–5.6 mg/L of dissolved organic carbon (DOC) content, was used as the matrix for compounds having VbE < 500 mL in pure water. Several polar pesticides showed negative linear or logarithmic Vb_E curves depending on HA content; their recoveries were also determined in environmental samples having low dissolved organic carbon values, between 0.5–6.4 mg/L. A similar behavior was observed for these compounds in simulated and natural water samples, where DOC concentration and the percolated volume (Vp) mainly determine the solute recoveries values. However, the variation of recoveries as a function of DOC content could be negative or null depending on the two examined conditions (Vp lower or larger than Vb_E in pure water). Results demonstrated that breakthrough volume must always be considered to correctly interpret the participation of dissolved humic material on the SPE efficiency of organic micropollutants in water.     

Pesticides in the aquatic environment ‐ experiences from Austrian monitoring programmes

The present paper deals with the impact of pesticides on water quality in Austria. Results of different monitoring programmes and surveys concerning the contamination of groundwater and running waters are provided; various aspects of sediment analyses and bioindication are also discussed. The evaluation of the data reveals a rather serious situation particularly in the eastern parts of the country intensively used by agricultural activities. The substances most often detected are triazines and lindane. Legal measures and key figures on the Austrian agriculture are also presented.     

环境水体中三嗪类除草剂的SPME-GCMS联用仪测定

文章研究了固相微萃取-气相色谱/质谱联用技术测定环境水体中的11种三嗪类除草剂的方法.选择了以聚二甲基硅氧烷(PDMS)/二乙烯苯(DVB)和聚丙烯(PA)作为涂层材料的两种不同固相微萃取纤维对11种除草剂的萃取能力进行比较,PDMS/DVB萃取效果较好.为了提高萃取效果,分别从pH、解吸温度、萃取时间、盐效应等方面优...     

Effects of soil composition on solid phase microextraction determination of triazine and organophosphorus pesticides

The influence of organic matter and clay contents on headspace solid phase microextraction (HS-SPME) determination of triazine and organophosphorus pesticides in different soils was studied. The results of the study showed that content of soil organic matter dominantly participated in sorption of triazines (simazine, atrazine and prometryn) to soil, while sorption of organophosphorus pesticides (phorate and tebupirimfos) could not be explained only by contents of dominant soil sorption components (soil organic matter and clay). Sorption of all pesticides studied to different soil types was similar at their lower concentrations while the influence of soil composition was expressed at higher concentration levels. Except for phorate, the obtained sorption trends were different from those obtained by direct SPME mode (DM-SPME) and exhaustive liquid-solid extraction (LSE) method. These results indicated that most likely co-extractants from the analyzed medium complicated evaporation and diffusion of the pesticides to the PDMS fiber during HS-SPME sampling.     

Analytical methods for the determination of alachlor,metolachlor, simazine and atrazine mobility in soils

Abstract

A method for the determination of the mobility of the herbicides, alachlor, metolachlor, simazine and atrazine in soil is described . The method is based on the use of soil thin‐layer chromatography (TLC) and does not require the use of radiolabelled compounds. Soil on the TLC plate after development was separated into various bands, the material in each band was extracted with solvents and analyzed by gas chromatography.