Determination of the polar pesticide degradation product N,N-dimethylsulfamide in aqueous matrices by UPLC–MS/MS

What is the spatial-temporal behavior of a low, medium and high adsorptive compound in two contrasting natural sediments in OECD 218/219 test systems?

Artificial sediment used in studies according to OECD 218/219 (Sediment Water Chironomid Toxicity Test Using Spiked Sediment/Water) does not necessarily mirror the characteristics of natural sediments. To investigate the influence of sediment characteristics on the spatial-temporal behaviors of bixafen (KfOM = 2244 mL/g), fluopyram (KfOM = 162 mL/g) and N,N-dimethylsulfamide (KfOM ≈ 0 mL/g), experiments according to OECD 218/219 with two contrasting natural sediments were conducted. The silt loam sediment provided a high content of organic matter (OM) (13.1%), while the OM (0.45%) of the sandy sediment was low. Diffusion into (OECD 219) or out (OECD 218) of the sediment was dependent on the extent of adsorption, which is linked to the model compounds ́ adsorption affinities and the sediments ́ OM. Consequently, N,N-dimethylsulfamide showed unhindered mobility in each experimental set up, while the high adsorption affinities of fluopyram and bixafen limited the diffusion in the respective sediments. Therefore, in experiments with the silt loam sediment, both compounds revealed a limited mobility and either accumulated in the top 5 mm of the sediment (OECD 219) or remained homogenously distributed over the sediment depth (OECD 218). A greater mobility was observed within the sandy sediment.The influence of OM as found in a study using artificial sediment could be confirmed. Moreover, the applicability of a TOXSWA model was reassured to predict the measured concentrations at different sediment depths. TOXSWA is used in the regulatory exposure assessment to simulate the behavior of pesticides in surface waters. Calibration of three driving input parameters by inverse modelling (diffusion-, adsorption coefficient and OM) revealed no potential for improvement. The core sampling technique used and the model may contribute to a more realistic determination of concentration to which the Chironomid larvae are exposed to. This applies to water sediment test systems where the test organisms do not evenly inhabit the sediment.

What is the actual exposure of organic compounds on Chironomus riparius? - A novel methodology enabling the depth-related analysis in sediment microcosms

A novel active sampling method enabled determination of sediment depth profiles revealing the spatial distribution of model compounds N,N-dimethylsulfamide, fluopyram and bixafen (low, medium, high adsorption affinity) in sediment microcosms according to OECD Test 218/219 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment/Spiked Water). After the overlying water was removed, plastic tubes were inserted into the sediment and the microcosms were frozen. For depth-related analysis, each "sediment core" was mounted in a cutting device and sawed into three 5-mm-slices, respectively (top, middle, bottom). Each slice was centrifuged for sediment and pore water separation. By various sampling dates within 28 days, we could follow the behavior of model compounds depending on sorption affinities and display specific distribution patterns within the sediment. N,N-dimethylsulfamide showing no sediment adsorption, migrated unhindered in (OECD 219) and out (OECD 218) of the sediment via pore water, resulting in homogenous distributions in both test designs. Fluopyram with moderate adsorption affinity revealed a concentration gradient with declining amounts from top to bottom layer (OECD 219) and higher amounts in the middle and bottom layer as compared to the top layer (OECD 218). Bixafen providing a strong adsorption affinity accumulated in the top layer in OECD 219, while no concentration gradients became visible in OECD 218. For establishing a Toxic Substances in Surface Waters (TOXSWA) model, we compared our measurements with simulated results revealing good agreements. The presented methodology is a useful tool to determine more realistic sediment and pore water concentrations, which the Chironomid larvae are exposed to.

Photoelectrocatalytic Degradation of Paraquat by Pt Loaded TiO₂ Nanotubes on Ti Anodes

Nanotube structured TiO₂ on Ti surface were prepared in ethylene glycol (Ti/TiO₂NTEG) medium by anodic oxidation method with different times and then the plates were calcinated at different temperatures. Non-nanotube structured Ti/TiO₂, prepared by thermal oxidation method, and nanotube structured TiO₂ on Ti plate in hydrogen fluoride solution were also prepared for comparison. Pt loaded Ti/TiO₂NTEG photoanodes were also prepared by cyclic voltammetry method with different cycles and the optimum loaded Pt amount was determined. Photoanodes were characterized by using X-ray Diffraction (XRD), Scanning Electron Microscopy-Energy-Dispersive X-ray Analysis (SEM-EDX), and photocurrent methods. XRD analyses proved that almost all TiO₂ is in anatase phase. SEM analyses show that nanotubes and Pt nanoparticles on nanotube surface are dispersed quite homogeneously. The longest nanotubes were obtained in the ethylene glycol medium and the nanotube length increased by increasing applied anodic oxidation time. In addition, a linear correlation between nanotube length and XRD peak intensity was found. Moreover, SEM-EDX and XRD analyses evidence that Pt nanoparticles on nanotube surface are metallic and in cubic structure. Photoelectrocatalytic degradation of paraquat was performed using the prepared photoanodes. Moreover, electrocatalytic and photocatalytic degradations of paraquat were also investigated for comparison, however lower activities were observed. These results evidence that the photoanodes show a significant synergy for photoelectrocatalytic activity.

Determination of glyphosate in surface water with high organic matter content

In this paper, we investigate the sample preparation and analysis process in order to achieve adequate results for surface water collected from rivers that flow through swamps and are consequently rich in organic matter. We show that matrix effects in glyphosate determination can be reduced by optimizing sample volume, liquid chromatography (LC) mobile phase buffer concentration and pH as well as gradient speed. Also, aspects of derivatization procedure (borate buffer concentration, fluorenylmethyloxycarbonyl chloride concentration) and their influence on accuracy are considered in detail. We encountered a cross-talk effect in the mass spectra, interfering with quantization during analysis, which was removed by optimizing MS parameters. As a result it was demonstrated that isotope-labelled internal standard with just one 13C atom is sufficient for the analysis.All these aspects were found to strongly impact the accuracy of the glyphosate determination but have received little or no attention in earlier works. We propose a reliable solid phase extraction and LC/ESI/MS/MS method for determination of glyphosate in organic-rich waters and demonstrate that LoD can be decreased by about two times using an ESI nebulizer with a modified design.

Broad spectrum screening of 463 organic contaminants in rivers in Macedonia

Target screening of 463 organic contaminants in surface water using ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) with direct injection was performed in spring of 2015 in northern Macedonia, at six sampling sites in four rivers belonging to Vardar basin: Kriva, Zletovska, Bregalnica and Vardar. The aim of the study was to differentiate between various types of organic contamination characteristic for different types of anthropogenic activities, such as mining, agriculture, and urbanization. Depending on the studied river, 9-16% of analyzed compounds were detected. The highest total levels of organic contaminants were recorded in agriculturally impacted Bregalnica River (1839-1962ngL^-1) and Vardar River downstream from the city of Skopje (1945ngL^-1), whereas the lowest level was found in the mining impacted Zletovska River (989ngL^-1). The principal organic contaminants of the Bregalnica River were herbicides (45-55% of all detected compounds; 838-1094ngL^-1), with the highest concentrations of bentazone (407-530ngL^-1) and molinate (84-549ngL^-1), common herbicides in rice cultivation. The main organic contaminants in the other rivers were drugs (70-80% of all detected compounds), with antibiotics as a predominant drug class. The highest drug concentrations were measured in the Vardar River, downstream from Skopje (1544ngL^-1). Screening of surface water by UHPLC-QTOF-MS was proven as a practical tool for fast collection of comprehensive preliminary information on organic contamination of natural waters, which can present a significant contribution in the monitoring and preservation of good ecological status of freshwater ecosystems.

Characterization of Pharmaceuticals and Personal Care products in hospital effluent and waste water influent/effluent by direct-injection LC-MS-MS

Two USEPA Regional Laboratories developed direct-injection LC/MS/MS methods to measure Pharmaceuticals and Personal Care Products (PPCPs) in water matrices. Combined, the laboratories were prepared to analyze 185 PPCPs (with 74 overlapping) belonging to more than 20 therapeutical categories with reporting limits at low part-per-trillion. In partnership with Suffolk County in NY, the laboratories conducted PPCP analysis on 72 samples belonging to 4 Water Systems (WS). Samples were collected at different stages of the WS (hospital effluents, WWTP influents/effluents) to assess PPCP relevance in hospital discharges, impact on WWTP performance and potential ecological risk posed by analytes not eliminated during treatment. Major findings include: a) acceptable accuracy between the two laboratories for most overlapping PPCPs with better agreement for higher concentrations; b) the measurement of PPCPs throughout all investigated WS with total PPCP concentrations ranging between 324 and 965 μg L(-1) for hospital effluent, 259 and 573 μg L(-1) for WWTP influent and 19 and 118 μg L(-1) for WWTP effluent; c) the variable contribution of hospital effluents to the PPCP loads into the WWTP influents (contribution ranging between 1% (WS-2) and 59% (WS-3); d) the PPCP load reduction after treatment for all WS reaching more than 95% for WS using activated sludge processes (WS-2 and WS-4), with inflow above 6500 m(3) d(-1), and having a lower percentage of hospital effluent in the WWTP influent; e) the relevance of four therapeutical categories for the PPCP load in WWTP effluents (analgesics, antidiabetics, antiepileptics and psychoanaleptics); and f) the risk quotients calculated using screening-level Predicted Non Effect Concentration indicate that WWTP effluents contain 33 PPCPs with potential medium to high ecological risk. To our knowledge no other monitoring investigation published in the scientific literature uses direct-injection methods to cover as many PPCPs and therapeutical categories in different types of WS.

Pan-European survey on the occurrence of selected polar organic persistent pollutants in ground water

This study provides the first pan-European reconnaissance of the occurrence of polar organic persistent pollutants in European ground water. In total, 164 individual ground-water samples from 23 European Countries were collected and analysed (among others) for 59 selected organic compounds, comprising pharmaceuticals, antibiotics, pesticides (and their transformation products), perfluorinated acids (PFAs), benzotriazoles, hormones, alkylphenolics (endocrine disrupters), Caffeine, Diethyltoluamide (DEET), and Triclosan. The most relevant compounds in terms of frequency of detection and maximum concentrations detected were DEET (84%; 454 ng/L), Caffeine (83%; 189 ng/L), PFOA (66%; 39 ng/L), Atrazine (56%; 253 ng/L), Desethylatrazine (55%; 487 ng/L), 1H-Benzotriazole (53%; 1032 ng/L), Methylbenzotriazole (52%; 516 ng/L), Desethylterbutylazine (49%; 266 ng/L), PFOS (48%, 135 ng/L), Simazine (43%; 127 ng/L), Carbamazepine (42%; 390 ng/L), nonylphenoxy acetic acid (NPE(1)C) (42%; 11 microg/L), Bisphenol A (40%; 2.3 microg/L), PFHxS (35%; 19 ng/L), Terbutylazine (34%; 716 ng/L), Bentazone (32%; 11 microg/L), Propazine (32%; 25 ng/L), PFHpA (30%; 21 ng/L), 2,4-Dinitrophenol (29%; 122 ng/L), Diuron (29%; 279 ng/L), and Sulfamethoxazole (24%; 38 ng/L). The chemicals which were detected most frequently above the European ground water quality standard for pesticides of 0.1 microg/L were Chloridazon-desphenyl (26 samples), NPE(1)C (20), Bisphenol A (12), Benzotriazole (8), N,N'-Dimethylsulfamid (DMS) (8), Desethylatrazine (6), Nonylphenol (6), Chloridazon-methyldesphenyl (6), Methylbenzotriazole (5), Carbamazepine (4), and Bentazone (4). However, only 1.7% of all single analytical measurements (in total 8000) were above this threshold value of 0.1 microg/L; 7.3% were > than 10 ng/L.