Target, suspect and non-target screening analysis from wastewater treatment plant effluents to drinking water using collision cross section values as additional identification criterion.

The anthropogenic entry of organic micropollutants into the aquatic environment leads to a potential risk for drinking water resources and the drinking water itself. Therefore, sensitive screening analysis methods are needed to monitor the raw and drinking water quality continuously. Non-target screening analysis has been shown to allow for a more comprehensive investigation of drinking water processes compared to target analysis alone. However, non-target screening is challenging due to the many features that can be detected. Thus, data processing techniques to reduce the high number of features are necessary, and prioritization techniques are important to find the features of interest for identification, as identification of unknown substances is challenging as well. In this study, a drinking water production process, where drinking water is supplied by a water reservoir, was investigated. Since the water reservoir provides surface water, which is anthropogenically influenced by wastewater treatment plant (WWTP) effluents, substances originating from WWTP effluents and reaching the drinking water were investigated, because this indicates that they cannot be removed by the drinking water production process. For this purpose, ultra-performance liquid chromatography coupled with an ion-mobility high-resolution mass spectrometer (UPLC-IM-HRMS) was used in a combined approach including target, suspect and non-target screening analysis to identify known and unknown substances. Additionally, the role of ion-mobility-derived collision cross sections (CCS) in identification is discussed. To that end, six samples (two WWTP effluent samples, a surface water sample that received the effluents, a raw water sample from a downstream water reservoir, a process sample and the drinking water) were analyzed. Positive findings for a total of 60 substances in at least one sample were obtained through quantitative screening. Sixty-five percent (15 out of 23) of the identified substances in the drinking water sample were pharmaceuticals and transformation products of pharmaceuticals. Using suspect screening, further 33 substances were tentatively identified in one or more samples, where for 19 of these substances, CCS values could be compared with CCS values from the literature, which supported the tentative identification. Eight substances were identified by reference standards. In the non-target screening, a total of ten features detected in all six samples were prioritized, whereby metoprolol acid/atenolol acid (a transformation product of the two ß-blockers metoprolol and atenolol) and 1,3-benzothiazol-2-sulfonic acid (a transformation product of the vulcanization accelerator 2-mercaptobenzothiazole) were identified with reference standards. Overall, this study demonstrates the added value of a comprehensive water monitoring approach based on UPLC-IM-HRMS analysis.

Quantitative screening and prioritization based on UPLC-IM-Q-TOF-MS as an alternative water sample monitoring strategy.

Suspect and non-target screening based on the use of high-resolution mass spectrometry (HRMS) has become more common in water analysis over the past years. However, this only yields lists of features or suspects without quantitative information. To expand the use of HRMS data to a quantitative screening, we have developed and validated a simple and fast method for more than 140 micropollutants using ultra high-performance liquid chromatography coupled to traveling wave ion mobility quadrupole time-of-flight mass spectrometry (UPLC-IM-Q-TOF-MS). Positive findings from suspect and non-target screening can be prioritized and identified by reference standards. The quantitative screening is then performed by additional measurement of calibration standards. This is carried out by means of direct injection and external calibration, without consideration of matrix effects. For all substances, limits of quantification (LOQs) of less or equal than 100 ng/L are achieved. The calibration is carried out in a range of 100 to 1000 ng/L and the results are reported as concentration ranges, in which the concentration of the analyte in the sample is to be expected. All substances were evaluated using quadratic regressions. For the verification of the accuracy, different water matrices (drinking water, groundwater, and surface water) were spiked with five concentration levels (50 ng/L, 300 ng/L, 500 ng/L, 800 ng/L, and 2000 ng/L) and indicate that for the drinking water and groundwater sample, 97% correct assignments were found, whereas for the surface water sample, 88% correct assignments were achieved. A comparative study of water samples of various matrices was accomplished using the quantitative screening analysis method and validated target methods by means of three UPLC tandem mass spectrometry (MS/MS) methods and two gas chromatography (GC) coupled to MS and MS/MS methods. A total of 510 data could be compared, which showed a good match of both approaches in more than 80% of the results. As an alternative strategy for the monitoring of water samples by UPLC-IM-Q-TOF-MS, this method provides quantitative information about target components, besides tentatively or identified substances from suspect or non-target screening. Depending on the resulting concentration range and reporting requirements, validated target methods can be further used for the previously detected targets. Graphical abstract.

Comparison of CCS Values Determined by Traveling Wave Ion Mobility Mass Spectrometry and Drift Tube Ion Mobility Mass Spectrometry.

Collision cross section (CCS, Ω) values determined by ion mobility mass spectrometry (IM-MS) provide the study of ion shape in the gas phase and use of these as further identification criteria in analytical approaches. Databases of CCS values for a variety of molecules determined by different instrument types are available. In this study, the comparability of CCS values determined by a drift tube ion mobility mass spectrometer (DTIM-MS) and a traveling wave ion mobility mass spectrometer (TWIM-MS) was investigated to test if a common database could be used across IM techniques. A total of 124 substances were measured with both systems and CCS values of [M + H]+ and [M + Na]+ adducts were compared. Deviations <1% were found for most substances, but some compounds show deviations up to 6.2%, which indicate that CCS databases cannot be used without care independently from the instrument type. Additionally, it was found that for several molecules [2M + Na]+ ions were formed during electrospray ionization, whereas a part of them disintegrates to [M + Na]+ ions after passing through the drift tube and before reaching the TOF region, resulting in two signals in their drift spectrum for the [M + Na]+ adduct. Finally, the impact of different LC-IM-MS settings (solvent composition, solvent flow rate, desolvation temperature, and desolvation gas flow rate) were investigated to test whether they have an influence on the CCS values or not. The results showed that these conditions have no significant impact. Only for karbutilate changes in the drift spectrum could be observed with different solvent types and flow rates using the DTIM-MS system, which could be caused by the protonation at different sites in the molecule.

Stability of organochlorine pesticides during storage in water and loaded SPE disks containing sediment.

With regard to the Water Framework Directive (WFD) and the required investigation of the whole water sample including suspended particulate matter (SPM), a storage stability study was conducted to determine the suitable storage time and conditions of 21 organochlorine pesticides (OCPs) spiked in water samples and pre-concentrated on solid-phase extraction disks (SPE disks). Furthermore, this work demonstrates the behaviour of three different certified sediment reference materials (CRMs) contaminated with OCPs in water samples as well as loaded on SPE disks under different temperature conditions and storage time periods. Extracts collected on SPE disks were stored for 3, 14 and 30 days at both 4 °C and -18 °C in darkness covered in (a) freezer bags and (b) aluminum foil. With few exceptions the results of these tests demonstrate stability of OCPs up to 30 days at -18 °C. The recoveries for most substances range between 84% and 133%. Furthermore, the stability of OCPs in water samples additionally spiked with CRM up to 500 mg and stored at a temperature of 4 °C in darkness up to 56 days was investigated. The addition of sodium azide enhanced the stability of some substances during storage, especially the endosulfans (I, II) but most substances were stable regardless of sodium azide addition over the entire storage period. An important conclusion of this study is that the storage of loaded SPE disks is an appropriate alternative to storing water samples.

Fate of five pharmaceuticals under different infiltration conditions for managed aquifer recharge.

Infiltration of treated wastewater (TWW) to recharge depleted aquifers, often referred to as managed aquifer recharge, is a solution to replenish groundwater resources in regions facing water scarcity. We present a mass balance approach to infer the amounts of five pharmaceuticals (carbamazepine, diclofenac, fenoprofen, gemfibrozil, and naproxen) degraded in column experiments based on concentrations of pharmaceuticals in the aqueous and solid (sorbed) phases. Column experiments were conducted under three different conditions: continuous infiltration, wetting and drying cycles, and wetting and drying cycles with elevated concentrations of antibiotics (which may reduce microbially aided degradation of other compounds). A mass balance comparing pharmaceutical mass in the water phase over the 16-month duration of the experiments to mass sorbed to the soil was used to infer the mass of pharmaceuticals degraded. Results show sorption as the main attenuation mechanism for carbamazepine. About half of the mass of diclofenac was degraded with wetting and drying cycles, but no significant degradation was found for continuous infiltration, while 32% of infiltrated mass sorbed. Fenoprofen was degraded in the shallow and aerobic part of the soil, but degradation appeared to cease beyond 27 cm depth. Gemfibrozil attenuated through a combination of degradation and sorption, with slight increases in attenuation with depth from both mechanisms. Naproxen degraded progressively with depth, resulting in attenuation of >90% of the mass. In the column with elevated concentrations of antibiotics, the antibiotics attenuated to about 50% or less of inflow concentrations by 27 cm depth and within this zone, less degradation of the other compounds was observed.

Influence of the drying step within disk-based solid-phase extraction both on the recovery and the limit of quantification of organochlorine pesticides in surface waters including suspended particulate matter.

In this study, 21 organochlorine pesticides (OCPs) were determined based on sample preparation using solid-phase extraction disks (SPE disks) coupled with programmable temperature vaporizer (PTV)-large-volume injection gas-chromatography mass spectrometry (LVI-GC-MS). The work includes a comprehensive testing scheme on the suitability of the method for routine analysis of surface and drinking water including suspended particulate matter (SPM) with regard to requirements derived from the European Water Framework Directive (WFD, Directive 2000/60/EC). SPM is an important reservoir for OCPs, which contributes to the transport of these compounds in the aquatic environment. To achieve the detection limits required by the WFD, a high pre-concentration factor during sample preparation is necessary, which was achieved by disk SPE in this study. The performance of disk SPE is strongly influenced by the drying step, which could be significantly improved by effective elimination of the residual water by combination of a high vacuum pump and a low humidity atmosphere. Detection limits of the WFD in the ng/L range were achieved by large volume injection of 100µL sample extract. The recoveries ranged from 82% to 117% with an RSD smaller than 13%. The applicability of this method to natural samples was tested for instrumental qualification and system suitability evaluation. Successful participation in an interlaboratory comparison proved the suitability of the method for routine analysis.

Fully automated standard addition method for the quantification of 29 polar pesticide metabolites in different water bodies using LC-MS/MS.

A reliable quantification by LC-ESI-MS/MS as the most suitable analytical method for polar substances in the aquatic environment is usually hampered by matrix effects from co-eluting compounds, which are unavoidably present in environmental samples. The standard addition method (SAM) is the most appropriate method to compensate matrix effects. However, when performed manually, this method is too labour- and time-intensive for routine analysis. In the present work, a fully automated SAM using a multi-purpose sample manager "Open Architecture UPLC®-MS/MS" (ultra-performance liquid chromatography tandem mass spectrometry) was developed for the sensitive and reliable determination of 29 polar pesticide metabolites in environmental samples. A four-point SAM was conducted parallel to direct-injection UPLC-ESI-MS/MS determination that was followed by a work flow to calculate the analyte concentrations including monitoring of required quality criteria. Several parameters regarding the SAM, chromatography and mass spectrometry conditions were optimised in order to obtain a fast as well as reliable analytical method. The matrix effects were examined by comparison of the SAM with an external calibration method. The accuracy of the SAM was investigated by recovery tests in samples of different catchment areas. The method detection limit was estimated to be between 1 and 10 ng/L for all metabolites by direct injection of a 10-µL sample. The relative standard deviation values were between 2 and 10% at the end of calibration range (30 ng/L). About 200 samples from different water bodies were examined with this method in the Rhine and Ruhr region of North Rhine-Westphalia (Germany). Approximately 94% of the analysed samples contained measurable amounts of metabolites. For most metabolites, low concentrations ≤0.10 µg/L were determined. Only for three metabolites were the concentrations in ground water significantly higher (up to 20 µg/L). In none of the examined drinking water samples were the health-related indication values (between 1 and 3 µg/L) for non-relevant metabolites exceeded.

Determination of organic priority pollutants in the low nanogram-per-litre range in water by solid-phase extraction disk combined with large-volume injection/gas chromatography-mass spectrometry.

Polybrominated diphenyl ethers, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides in the low nanogram-per-litre range in water were enriched by solid-phase extraction (SPE) disks and their concentration determined by large-volume injection/gas chromatography-mass spectrometry (LVI/GC-MS). One advantage of using SPE disks in comparison with SPE cartridges is that suspended particulate matter (SPM) does not have to be separated prior to the enrichment step, which saves time and effort. To increase the sensitivity of the method, the SPE disk procedure was combined with LVI/GC-MS, which has not been reported so far for water analysis. The method was calibrated in ranges from 0.25 to 2.5 ng/L and from 2.5 to 25 ng/L. The average recovery was 76% at an analyte concentration of 2.5 ng/L. The limits of quantification, defined at a signal-to-noise ratio of 6:1, reach from 0.1 to 24.0 ng/L and are up to 400 times lower than previously reported in water analysis. By the developed SPE/LVI/GC-MS method, it is possible to investigate the whole water sample without prior separation of the SPM within 2 h including GC-MS analysis.

Multi-component trace analysis of organic xenobiotics in surface water containing suspended particular matter by solid phase extraction/gas chromatography-mass spectrometry.

Suspended particulate matter (SPM) often disturbs the analysis of surface water by conventional methods, such as liquid-liquid extraction (LLE) or solid phase extraction (SPE), caused by insufficient extraction or by plugging. Water and SPM are therefore often separately analysed, which is associated with high expenditure of time, work and costs. Hence, SPM is partly ignored, if the fraction of sorptively bound analytes is small compared to the total analyte concentration. However, the European Water Framework Directive (WFD, Directive 2000/60/EC) requires explicitly an investigation of the whole water sample including SPM, because many priority and priority hazardous substances can sorb substantially to SPM. Therefore, an SPE disk based method was developed for the determination of 54 priority and priority hazardous pollutants including polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), polybrominated diphenyl ethers (PBDE), organic chlorinated pesticides (OCP) and other pesticides in surface water containing SPM. The developed SPE disk method allows analysis of 1L surface water containing up to 1000 mg SPM without prior separation of SPM in about 2h including gas chromatography-mass (GC-MS) spectrometry analysis. The limits of quantification vary in a range of 0.8 to 38 ng/L.

Reduction of matrix effects and improvement of sensitivity during determination of two chloridazon degradation products in aqueous matrices by using UPLC-ESI-MS/MS.

The development and validation of a sensitive and reliable detection method for the determination of two polar degradation products, desphenyl-chloridazon (DPC) and methyl-desphenyl-chloridazon (MDPC) in surface water, ground water and drinking water is presented. The method is based on direct large volume injection ultra-performance liquid chromatography electrospray tandem mass spectrometry. This simple but powerful analytical method for polar substances in the aquatic environment is usually hampered by varying matrix effects, depending on the nature of different water bodies. For the two examined degradation products, the matrix effects are particularly strong compared with other polar degradation products of pesticides. Therefore, matrix effects were studied thoroughly with the aim of minimising them and improving sensitivity during determination by postcolumn addition of ammonia solution as a modifier. An internal standard was used in order to compensate for remaining matrix effects. The calibration curve shows very good coefficients of correlation (0.9994 for DPC and 0.9999 for MDPC). Intraday precision values were lower than 5 % for DPC, 3 % for MDPC and the limits of detection were 10 ng/L for both substances. The method was successfully used in a national round robin test with a deviation between 3 and 8 % from target values. Finally, about 1,000 samples from different water bodies have been examined with this method in the Rhine and Ruhr region of North-Rhine-Westphalia (Germany) and in the European Union. Approximately 76 % of analysed samples contained measurable amounts of DPC at concentrations up to 8 µg/L while 53 % of the samples showed MDPC concentrations up to 2.3 µg/L.

Occurrence of residual water within disk-based solid-phase extraction and its effect on GC-MS measurement of organic extracts of environmental samples.

Solid-phase extraction (SPE) is a widespread and powerful sample preparation technique in many analytical areas. Many of the used methods reduce residual water during sample preparation by drying the phase material. Despite the importance of this step, hardly any study deals specifically with the drying process, and if so, only few aspects are mentioned. The present study is the first systematic investigation of the drying process using SPE disks, including the influence of process parameters on the amount of residual water and its consequences for subsequent elution and gas chromatography-mass spectrometry (GC-MS) analysis. The following points were investigated in detail: (1) the change of pressure and volume flow during the drying process, (2) the remaining amount of water at different drying times for different SPE materials, (3) the influence of suspended particulate matter on the drying process and (4) the effects of the residual water on the elution step by using different organic solvents. The study shows that the volume of residual water in the SPE disk is affected by the fixation of the sorbent, the phase material, the amount of sorbent, the pumping settings and the duration of the drying process. Furthermore, systematic investigations demonstrate the influence of residual water on the GC-MS analysis and show analytical interferences only for a few of the investigated analytes. All results suggest that more problems in SPE GC-MS methods are caused by residual water than previously assumed.

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.

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

This study presents a fast, sensitive, and robust method for the determination of the polar pesticide degradation product N,N-dimethylsulfamide (DMS) in water based on ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). To provide a robust analysis method, the use of an internal standard for both natural waters and model water was examined in order to compensate for matrix effects. The relative standard deviation was found to be +/-15% (n = 10) and the limit of detection was 10 ng/L by direct injection in the UPLC-MS/MS system. The only sample preparation step required is the addition of the internal standard. The chromatographic analysis of one sample takes 4 min and thus is applicable for economic routine laboratory work. More than 600 samples of drinking water, surface water, and groundwater have been examined successfully with this method in the Rhine and Ruhr region of North Rhine Westphalia (Germany). Approximately 65% of analyzed samples contained measurable amounts of DMS at concentrations up to 63 microg/L.

Total concentration analysis of polycylic aromatic hydrocarbons in aqueous samples with high suspended particulate matter content.

The European water framework directive (WFD) requires priority pollutants to be measured in the whole water sample and not only in the dissolved phase. However, it does not give clear definitions on how to achieve this. To overcome this limitation, a new methodology of sample preparation procedure for the analysis of polycyclic aromatic hydrocarbons on the basis of extraction disks is introduced here. The automatable procedure includes a "one-step" extraction of the analytes both dissolved in the liquid phase of the sample and sorbed to suspended particulate matter. The latter is extracted concurrently with the solid-phase extraction (SPE) material within the elution step of the procedure. Separation, identification, and quantification of the analytes is performed by GC-MS. Results from surface water samples spiked with certified sediment up to 1000 mg/l are presented in this work and compared with results derived from liquid-liquid extraction (LLE). Most measured values are within or at least near certified uncertainty limits of the sediment. The SPE disk method shows much higher recoveries and better precision (relative standard deviations between 2% and 11%) than the standard LLE method. For all substances under investigation, the limits of quantification achieved range between 0.001 and 0.005 microg/l.