Determination of pharmaceuticals in biosolids using accelerated solvent extraction and liquid chromatography/tandem mass spectrometry

An analytical method was developed to quantitatively determine pharmaceuticals in biosolid (treated sewage sludge) from wastewater treatment plants (WWTPs). The collected biosolid samples were initially freeze dried, and grounded to obtain relatively homogenized powders. Pharmaceuticals were extracted using accelerated solvent extraction (ASE) under the optimized conditions. The optimal operation parameters, including extraction solvent, temperature, pressure, extraction time and cycles, were identified to be acetonitrile/water mixture (v/v 7:3) as extraction solvent with 3 extraction cycles (15 min for each cycle) at 100 °C and 100 bars. The extracts were cleaned up using solid-phase extraction followed by determination by liquid chromatography coupled with tandem mass spectrometry. For the 15 target pharmaceuticals commonly found in the environment, the overall method recoveries ranged from 49% to 68% for tetracyclines, 64% to 95% for sulfonamides, and 77% to 88% for other pharmaceuticals (i.e. acetaminophen, caffeine, carbamazepine, erythromycin, lincomycin and tylosin). The developed method was successfully validated and applied to the biosolid samples collected from WWTPs located in six cities in Michigan. Among the 15 target pharmaceuticals, 14 pharmaceuticals were detected in the collected biosolid samples. The average concentrations ranged from 2.6 μg/kg for lincomycin to 743.6 μg/kg for oxytetracycline. These results indicated that pharmaceuticals could survive wastewater treatment processes, and accumulate in sewage sludge and biosolids. Subsequent land application of the contaminated biosolids could lead to the dissemination of pharmaceuticals in soil and water environment, which poses potential threats to at-risk populations in the receiving ecosystems.     

Stereoisomer quantification of the beta-blocker drugs atenolol, metoprolol, and propranolol in wastewaters by chiral high-performance liquid chromatography-tandem mass spectrometry

A chiral liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method was developed and validated for measuring individual enantiomers of three beta-blocker drugs (atenolol, metoprolol, and propranolol) in wastewater treatment plant (WWTP) influents and effluents. Mean recoveries of the pharmaceuticals ranged from 67 to 106%, and the limits of detection of the analytes were 2-17 ng/L in wastewater effluents. The method was demonstrated by measuring, for the first time, the stereoisomer composition of target analytes in raw and treated wastewaters of two Canadian WWTPs. In these trials, racemic amounts of the three drugs were observed in influent of one wastewater treatment plant, but nonracemic amounts were observed in another. Effluents of the two plants contained nonracemic amounts of the drugs. These results indicate that biologically-mediated stereoselective processes that differ among WWTPs had occurred to eliminate individual enantiomers of the target analytes.     

Determination of pharmaceutical compounds in sewage sludge using a standard addition method approach

An analytical method for the simultaneous determination of eight pharmaceutical compounds in biosolids from urban wastewater treatment plants (WWTPs) was developed and validated. The compounds evaluated were non-steroidal anti-inflammatory drugs (naproxen, diclofenac, and ibuprofen), lipid regulators (clofibric acid), and antibiotics (sulfathiazole, sulfapyridine, sulfamethazine, and sulfamethoxazole). Ultrasound assisted extraction with a water–methanol solvent mixture (1:1, v:v) was performed and the compounds were then determined by liquid chromatography coupled with tandem mass spectrometry. The design of the method was based on the application of the standard addition calibration methodology to reduce matrix interferences. Validation procedures were conducted with rabbit excrements as blank samples. Recoveries of the target analytes ranged from 76 to 131% in spiked samples at 50, 200 or 1000 ng g^?1 dry weight (dw). The relative standard deviations were in the range of 5–15% and the method detection limits ranged from 2 to 12 ng g^?1dw. The method was applied to monitor pharmaceutical concentrations in biosolids from different WWTPs over an eight-month period (May to December 2011). Diclofenac, sulfapyridine and ibuprofen were detected in most of the samples whereas sulfamethazine and ibuprofen were the pharmaceuticals found in the highest concentrations (>200 ng g^?1 dw on average).     

Pharmaceuticals and personal care products in biosolids/sewage sludge: the interface between analytical chemistry and regulation

Modern sanitary practices result in large volumes of human waste, as well as domestic and industrial sewage, being collected and treated at common collection points, wastewater treatment plants (WWTPs). In recognition of the growing use of sewage sludge as fertilizers and soil amendments, and the scarcity of current data regarding the chemical constituents in sewage sludge, the US National Research Council (NRC) in 2002 produced a report on sewage sludge. Among the NRC’s recommendations was the need for investigating the occurrence of pharmaceuticals and personal care products (PPCPs) in sewage sludge. PPCPs are a diverse array of non-regulated contaminants that had not been studied in previous sewage sludge surveys but which are likely to be present. The focus of this paper will be to review the current analytical methodologies available for investigating whether pharmaceuticals are present in WWTP-produced sewage sludge, to summarize current regulatory practices regarding sewage sludge, and to report on the presence of pharmaceuticals in sewage sludge.     

Quantitative analysis of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants.

Polycyclic aromatic hydrocarbons (PAHs) are an important group of organic contaminants present in sewage sludge. Due to their persistence and toxic potential, information about their presence in sewage sludge is needed in order to assess applicability on agricultural land. A method for the gas chromatographic-mass spectrometric (GC-MS) determination was developed and applied to the trace determination of PAHs present in sewage sludge samples from six wastewater treatment plants (WWTPs) differing in the type of treatment and the origin of wastewater. PAHs were extracted from freeze-dried samples by a dichloromethane-methanol (2:1) mixture in a sonication bath. The sludge extracts were cleaned-up by an alumina column. The method showed recovery values varying from 60 to 98%. Four surrogate standards ([2H8]naphthalene, [2H10]anthracene, [2H12]benzo[a]anthracene, and [2H12]benzo[ghi]perylene) were used for quantitation by GC-MS. A reference sludge sample was analysed in order to validate the method. The sum of the 16 US Environmental Protection Agency PAHs analysed in the sewage sludge samples varied from 1.13 to 5.52 mg/kg. No significant difference between the different WWTPs was found.     

Direct rapid analysis of multiple PPCPs in municipal wastewater using ultrahigh performance liquid chromatography–tandem mass spectrometry without SPE pre-concentration

Ultrahigh performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) was utilized to develop a rapid, sensitive and reliable method without solid phase extraction (SPE) pre-concentration for trace analysis of 11 pharmaceuticals and personal care products (PPCPs) in in?uent and ef?uent from municipal wastewater treatment plants (WWTPs). This method not only shortened the analysis time but also reduced analysis cost significantly by omitting SPE process and avoiding the consumption of SPE cartridge. Detection parameters for UHPLC–MS/MS analysis were optimized, including sample pH, eluent, mobile phase (solvent and additive), column temperature, and ?ow rate. Under the optimal conditions, all analytes were well separated and detected within 8.0 min by UHPLC–MS/MS. The method quantification limits (MQLs) for the 11 PPCPs ranged from 0.040 to 88 ng L⁻¹ and from 0.030 to 90 ng L⁻¹ for influent and effluent, respectively. The matrix effect was systematically investigated and quantified for different types of samples. The analysis of in?uent and ef?uent samples of two WWTPs in Hong Kong revealed the presence of 11 PPCPs, including acyclovir, benzophenone-3, benzylparaben, carbamazepine, ethylparaben, fluconazole, fluoxetine, methylparaben, metronidazole, propylparaben, and ranitidine. Their concentrations ranged from 9.1 to 1810 ng L⁻¹ in influent and from 6.5 to 823 ng L⁻¹ in effluent samples collected from Hong Kong WWTPs.     

Simultaneous determination of pharmaceutically active compounds in wastewater samples by solid phase extraction and high-performance liquid chromatography with diode array and fluorescence detectors

In the present work, an analytical method for the simultaneous determination of five anti-inflammatory drugs (acetaminophen, diclofenac, ibuprofen, ketoprofen and naproxen), an antiepileptic drug (carbamazepine) and a nervous stimulant (caffeine) is proposed for the routine analysis of these pharmaceuticals in wastewater influents and effluents from WWTPs. The method involves pre-concentration and clean-up by solid phase extraction (SPE) using Oasis HLB extraction cartridges. Final analysis of the selected pharmaceutical compounds was carried out by high-performance liquid chromatography (HPLC) with diode array detector (DAD). Confirmation of the presence of the fluorescence compounds (ibuprofen and naproxen) was performed by on-line fluorescence detection. Recoveries were ranged from 71 to 103% with relative standard deviation below 15.1%. Limits of quantification were in the range 6.2–319.8 and 3.0–160.0 ng ml⁻¹ for influent and effluent wastewater samples, respectively. The described method was applied to the determination of the drugs in wastewater samples from four treatment plants in Seville.     

Occurrence,fate and removal efficiencies of pharmaceuticals in wastewater treatment plants (WWTPs) discharging in the coastal environment of Algiers

In the last few decades, the presence of pharmaceutical products in the environment is known under the name of emerging contaminants. These substances can enter the aquatic environment via different sources, as parent compounds, metabolites or a combination of both. In this work, we have investigated the presence of four pharmaceutical active compounds belonging to the group of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), in wastewater, surface water and drinking water of Algiers, which have a direct impact on the Mediterranean Sea. The target analytes (ibuprofen (IBU), naproxen (NAP), ketoprofen (KET), and diclofenac (DIC)), were extracted from the water samples by using Solid Phase Extraction Oasis^® HLB Cartridges; the identification and quantification were realized by Gas Chromatography–Mass Spectrometry (GC–MS). To obtain the best resolution and precision, N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA) was used as the derivatization reagent and ibuprofen-d₃ was used as the internal standard. The obtained recoveries were good, ranging from 82% for ketoprofen to 120% for naproxen with relatively small standard deviations (≤20%). The target compounds were detected in wastewater, influent/effluent with concentrations ranging from 155.5 to 6554 ng/L, implicating removal efficiencies of wastewater treatment plants (WWTPs), between 30.3 and 95%. The surface water was also contaminated with pharmaceuticals from 72.9 ng/L for diclofenac to 228.3 ng/L for naproxen. In addition, the occurrence of ibuprofen and ketoprofen in drinking water, at concentrations of 142.1 and 110.9 ng/L, respectively, attracts concerns about possible impacts on human health.     

Cleanup strategies and advantages in the determination of several therapeutic classes of pharmaceuticals in wastewater samples by SPE–LC–MS/MS

This work describes the development and validation of an offline solid-phase extraction with simultaneous cleanup capability, followed by liquid chromatography–(electrospray ionisation)–ion trap mass spectrometry, enabling the concurrent determination of 23 pharmaceuticals of diverse chemical nature, among the most consumed in Portugal, in wastewater samples. Several cleanup strategies, exploiting the physical and chemical properties of the analytes vs. interferences, alongside with the use of internal standards, were assayed in order to minimise the influence of matrix components in the ionisation efficiency of target analytes. After testing all combinations of adsorbents (normal-phase, ion exchange and mixed composition) and elution solvents, the best results were achieved with the mixed-anion exchange Oasis MAX cartridges. They provided recovery rates generally higher than 60%. The precision of the method ranged from 2% to 18% and 4% to 19% (except for diclofenac (22%) and simvastatin (26%)) for intra- and inter-day analysis, respectively. Method detection limits varied between 1 and 20 ng L⁻¹, while method quantification limits were <85 ng L⁻¹ (both excluding ibuprofen). This analytical method was applied to gather preliminary results on influents and effluents of two wastewater treatment plants (WWTPs) located in the urban region of Porto (Portugal). Typically, paracetamol, hydrochlorothiazide, furosemide, naproxen, ibuprofen, diclofenac and bezafibrate were detected in concentrations ranging from 1 to 20 μg L⁻¹, while gemfibrozil, simvastatin, ketoprofen, azithromycin, bisoprolol, lorazepam and paroxetine were quantified in levels below 1 μg L⁻¹. These WWTPs were given particular attention since they discharge their effluents into the Douro river, where water is extracted for the production of drinking water. Some sampling spots in this river were also analysed.     

Determination of pharmaceuticals in sewage sludge by pressurized liquid extraction (PLE) coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS)

In this study, we aimed at optimizing a sensitive and reliable method for a simultaneous determination of 31 pharmaceuticals belonging to predominant therapeutic classes identified in different types of sewage sludge proceeding from conventional and advanced wastewater treatment. Freeze-dried sewage sludge was extracted by pressurized liquid extraction technique using accelerated solvent extractor Dionex 300. In order to minimize interferences with matrix components and to preconcentrate target analytes, solid phase extraction was introduced in the method as a clean-up step. The entire method was validated for linearity, precision, accuracy, and method detection limits (MDLs). The method turned out to be specific, sensitive, and reliable for the analysis of sludge of different composition, type, and retention time in the process. The developed sample preparation protocol and previously published method for LC-MS/MS analysis (Gros et al., Talanta 70:678–690, 2006) were successfully applied to monitor the target pharmaceuticals in different types of sewage sludge, i.e., primary sludge, secondary sludge, treated sludge, and sludge proceeding from pilot-scale membrane bioreactors (MBRs) operating in parallel to the conventional activated sludge treatment. Among the investigated pharmaceuticals, 20 were detected in the sludge proceeding from full-scale installations, whereas the MBR sludge concentrations were below MDLs for several compounds. The highest concentrations were recorded for treated and primary sludge. For example, the mean concentration of ibuprofen in the digested sludge was 299.3?±?70.9 ng g^?1 dw, whereas in the primary sludge, it was enriched up to 741.1 ng g^?1 dw. Other pharmaceuticals detected at relatively high concentrations were diclofenac, erythromycin, glibenclamide, ketoprofen, ofloxacin, azithromycin (up to 380.7, 164.2, 190.7, 336.3, 454.7, 299.6 ng g^?1 dw in the primary sludge, respectively), gemfibrozil, loratidine, and fluoxetine (up to 189.1, 189.7 and 174.1 ng g^?1 dw in the treated sludge, respectively).     

Determination of phenolic xenoestrogens in environmental samples by liquid chromatography with mass spectrometric detection

A method is proposed for the determination of several phenolic xenoestrogens in aqueous and solid environmental samples. The method uses solid-phase extraction (preceded by ultrasonic solvent extraction for solid samples), reversed-phase liquid chromatographic separation, and mass spectrometric detection using both atmospheric pressure chemical ionization and electrospray ionization. This method was developed to support several studies undertaken to obtain aquatic and sedimentary data for rivers and seashores in Spain that are likely to be contaminated by endocrine-disrupting compounds (EDCs) as a consequence of wastewater discharge. Nonylphenol polyethoxylates (NPEOs), nonylphenoxy carboxylates (NPECs), nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA) were determined in various samples of surface water and sediment, collected at different locations upstream and downstream from outfalls of municipal wastewater treatment plants (WWTPs). Seawater and marine sediments were collected in different harbor areas in Spain. Additionally, WWTP influent and effluents were analyzed to monitor the occurrence and transformation of phenolic EDCs during physicochemical and biological treatment. Rather high concentrations of the compounds investigated were found in some samples. Concentrations of NP were < or = 590 microg/kg in sediments and < or = 15 microg/L in water samples. NPEOs and NPECs were found in water samples in concentrations < or = 41 and < or = 35 microg/L, respectively. In solid samples (river sediment), concentrations of NPEO were < or = 818 microg/kg and those of NP1EC were 95 microg/kg.     

Analysis of 70 Environmental Protection Agency priority pharmaceuticals in water by EPA Method 1694

The U.S. Environmental Protection Agency (EPA) Method 1694 for the determination of pharmaceuticals in water recently brought a new challenge for treatment utilities, where pharmaceuticals have been reported in the drinking water of 41-million Americans. This proposed methodology, designed to address this important issue, consists of solid-phase extraction (SPE) followed by liquid chromatography–mass spectrometry (LC/MS–MS) using triple quadrupole. Under the guidelines of Method 1694, a multi-residue method was developed, validated, and applied to wastewater, surface water and drinking water samples for the analysis of 70 pharmaceuticals. Four distinct chromatographic gradients and LC conditions were used according to the polarity and extraction of the different pharmaceuticals. Positive and negative ion electrospray were used with two MRM transitions (a quantifier and a qualifier ion for each compound), which adds extra confirmation not included in the original Method 1694. Finally, we verify, for the first time, EPA Method 1694 on water samples collected in several locations in Colorado, where positive identifications for several pharmaceuticals were found. This study is a valuable indicator of the potential of LC/MS–MS for routine quantitative multi-residue analysis of pharmaceuticals in drinking water and wastewater samples and will make monitoring studies much easier to develop for water utilities across the US, who are currently seeking guidance on analytical methods for pharmaceuticals in their water supplies.     

Evaluation of pharmaceutical activities of G-protein coupled receptor targeted pharmaceuticals in Chinese wastewater effluent

The occurrence of biologically active pharmaceuticals in aquatic environments raised the potential risks to aquatic species. Among these marketed biological active pharmaceuticals, it has been estimated that 40% of them target G-protein-coupled receptors (GPCRs). We have illustrated pharmaceutical activities of GPCR targeted pharmaceuticals in English and Japanese wastewater by the in vitro transforming growth factor-α (TGFα) shedding assay. However, as the most important producer and consumer of pharmaceuticals, the occurrence of GPCR targeted pharmaceuticals in China had remained unclear. In this study, we investigated the pharmaceutical activities of GPCR targeted pharmaceuticals in secondary effluents of Chinese wastewater treatment plants. We discovered antagonistic activities against angiotensin (AT1) receptor at up to 7.2 × 102 ng-valsartan-equivalent quantity/L in Chinese wastewater for the first time as well as agonistic activities against dopamine (D2) receptor. Furthermore, in parallel with the assay, we determined concentrations of GPCR targeted pharmaceuticals in target wastewater by liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS). Through the comparison of predicted antagonistic activities calculated by concentrations and potency values from the assay, we found that the measured antagonistic activities against AT1 receptor from the assay were higher than the predicted AT1 activities from valsartan, irbesartan, and losartan, indicating the potential existence of other unknown AT1 antagonists in wastewater.     

Determination of various estradiol mimicking-compounds in sewage sludge by the combination of microwave-assisted extraction and LC-MS/MS

In this work, we present the development and application of a microwave assisted extraction followed by liquid chromatography-tandem mass spectrometry methodology (MAE-LC-MS/MS) for the determination of various estradiol-mimicking compounds in sewage sludge samples. For the purification of the MAE extracts, we have employed a solid phase extraction (SPE) clean-up procedure, previously optimised. The entire method provides recoveries between 71.7% and 103.1%, with relative standard deviation lower than 11.1% and limits of detection ranging from 0.6 to 3.5 ng g⁻¹. The developed method was applied to samples from three wastewater treatment plants (WWTPs) located in Las Palmas of Gran Canaria (Spain), two of which had a conventional activated sludge treatment (AST), whereas the third treatment plant had an advanced membrane bioreactor treatment (MBR). All of the analytes in the study, including (nonylphenol (NP), octylphenol (OP), and some of their ethoxylated chains AP_nEOs (n ≤ 7), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE) and bisphenol-A (BPA)), were found in almost all samples in concentrations ranging from 0.9 to 710.2 ng g⁻¹.     

Toxicity assays applied to wastewater treatment

The utility and validity of toxicity tests for monitoring of wastewater treatment have been assessed. The evaluated acute toxicity tests have been Vibrio fischeri, Selenastrum capricornotum and Daphnia magna tests. The validation studies indicated that the acute toxicity tests can be considered as high sensitivity analytical tools to detect common environmental concentrations of the pollutants at concentration levels as low as ng l⁻¹. The toxicity tests showed to have discriminatory ability to distinguish between different degrees of toxicity, and the toxic specificity of the compounds on target organisms. Synergistic, additive or antagonistic effects were evaluated indicating the capacity of the toxicity test to assess the combined effects of chemicals in wastewaters. The reproducibility of these tests, calculated as relative standard deviation, is acceptable in the range of 5-22.3%. The application of multivariate date analysis proved that toxicity and chemical measures are complementary analytical tools for monitoring of wastewaters quality. The toxicity tests are useful analytical tools for screening of chemical analysis and as an early warning system to monitor the treatment of WWTPs. The use of single toxicity test or battery of tests is the best approach to evaluate the risk because they are reliable indices of the toxic impact of effluents in the aquatic environment. The toxicity tests were applied in the quality control of different European WWTPs.     

Determination of non-ionic and anionic surfactants in environmental water matrices

Solid-phase extraction (SPE) combined with liquid chromatography electrospray mass spectrometry (LC-(ESI)MS) was used to determine 16 non-ionic and anionic surfactants in different environmental water samples at ng L⁻¹ levels. The proposed method is sensitive and simple and has good linear range and detection limits (less than 50 ng L⁻¹) for most compound classes.The effect of ion suppression was studied in aqueous matrices from several treatment plants—including urban and industrial wastewater treatment plants (WWTPs), drinking-water treatment plants (DWTPs) and seawater desalination plants (SWDPs)—and it was considered when quantifying our samples. In addition, conventional treatments and tertiary treatments that use advanced membrane technologies, such as ultrafiltration (UF) and reverse osmosis (RO) were evaluated in order to determine their efficiency in eliminating these compounds.The concentrations of non-ionic surfactants in the raw waters studied ranged from 0.2 to 100 μg L⁻¹. In effluents, the concentrations ranged from 0.1 to 5 μg L⁻¹, which reflects consistent elimination. Anionic surfactants were present in all waters studied at higher levels. Levels up to 3900 μg L⁻¹ of linear alkylbenzene sulfonates (LASs) and 32,000 μg L⁻¹ of alkyl ethoxysulfates (AESs) were detected in urban WWTP influents, while levels up to 25 μg L⁻¹ of LASs and 114 μg L⁻¹ of AESs were found in drinking-water and desalination treatment plants.The results indicate that conventional processes alone are not sufficient to completely remove the studied surfactants from waste streams. Tertiary treatments that use advanced membrane technologies such as UF and RO can further reduce the amount of target compounds in the effluent water.     

Decomposition of persistent pharmaceuticals in wastewater by ionizing radiation

Pharmaceuticals in wastewater were treated by the combined method of activated sludge and ionizing radiation in laboratory scale. Oseltamivir, aspirin, and ibuprofen at 5 μmol dm^?3 in wastewater were decomposed by the activated sludge at reaction time for 4 h. Carbamazepine, ketoprofen, mefenamic acid, clofibric acid, and diclofenac were not biodegraded completely, but were eliminated by γ-ray irradiation at 2 kGy. The rate constants of the reactions of these pharmaceuticals with hydroxyl radicals were estimated by the competition reaction method to be 4.0–10×10⁹ mol^?1 dm³ s^?1. Decompositions of the pharmaceuticals in wastewater by ionizing radiation were simulated by use of the rate constants and the amount of total organic carbon as parameters. Simulation curves of concentrations of these pharmaceuticals as a function of dose described the experimental data, and the required dose for the elimination of them in wastewater by ionizing radiation can be estimated by this simulation.     

Recent advances in persulfate-based advanced oxidation processes for organic wastewater treatment

In recent years, with the emergence of new pollutants, the effective treatment of wastewater has become very important. Persulfate-based advanced oxidation processes have been successfully applied to the treatment of wastewater, such as wastewater containing antibiotics, pharmaceuticals and personal care products, dyes, endocrine-disrupting chemicals, chlorinated organic pollutants, and phenolics, for the degradation of refractory organic contaminants. This paper summarizes the production of sulfate radicals, which can be generated by the activation of persulfate via conventional and emerging approaches. The existing problems of persulfate-based advanced oxidation processes were analyzed in detail, including residual sulfates, coexisting factors (coexisting inorganic anions and natural organic matter), and energy consumption. This paper proposes corresponding possible solutions to the problems mentioned above, and this paper could provide a reference for the application of persulfate-based advanced oxidation processes in actual wastewater treatment.     

Assessment of the pollutant elimination efficiency by gas chromatography/mass spectrometry, liquid chromatography-mass spectrometry and -tandem mass spectrometry. Comparison of conventional and membrane-assisted biological wastewater treatment processes

The elimination efficiency of advanced conventional biological wastewater treatment was compared to membrane-assisted biological wastewater treatment. The sum parameter analyses dissolved organic carbon (DOC) and chemical oxygen demand (COD) or substance-specific analyses such as gas chromatography combined with mass spectrometry, flow injection analysis (FIA-MS) and liquid chromatography (LC-MS) in combination with mass or tandem mass spectrometry (MS-MS) were applied to assess elimination of hardly eliminable compounds in both types of wastewater treatment plants (WWTP). Reduction of DOC and COD in wastewater treatment processes confirmed a favourable elimination efficiency. Substance-specific methods which were applied in addition permitted a qualitative and semi-quantitative assessment of elimination with a visual pattern recognition approach. In order to identify pollutants either the NIST library of electron impact mass spectra for unpolar compounds or the laboratory-made collision-induced dissociation spectra library for polar pollutants was used. To assess elimination efficiency FIA-MS in the selected ion monitoring mode (SIM) besides high selective substance-specific mass spectrometric techniques such as parent ion scans and neutral loss scans were used for quantification. Results proved that membrane-assisted treatment was more effective than advanced biological treatment. In both types of WWTPs predominantly unpolar pollutants were eliminated, while all effluents were dominated by polar compounds of anthropogenic and biogenic origin. These unpolar and polar compounds which had been identified as hardly eliminable are reported about. Quantitative results obtained by FIA-MS, LC-MS and MS-MS for the elimination of alkyl polyglycol ethers, nonylphenol ethoxylates and linear alkylbenzenesulfonic acids from wastewater are presented.