Simultaneous determination of acidic,neutral and basic pharmaceuticals in urban wastewater by ultra high-pressure liquid chromatography-tandem mass spectrometry

In this work, an ultra high-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method has been developed for the simultaneous quantification and confirmation of the 20 most consumed pharmaceuticals in Spain in urban wastewater and surface water samples. The scope of the method included acidic, neutral and basic compounds belonging to different therapeutic classes and allows their simultaneous determination in just a single injection, giving realistic information of the most widely consumed pharmaceuticals in only one analysis. An enrichment step based on solid-phase extraction using Oasis HLB cartridges was carried out, followed by UHPLC-MS/MS measurement with a fast-acquisition triple quadrupole mass analyzer. It allowed working with short dwell times and made possible to acquire three simultaneous SRM transitions per compound to assure a reliable identification. Several isotope-labelled internal standards were used as surrogates to correct SPE losses, as well as matrix effects that notably affect quantification of analytes. The method was validated in surface water and effluent and influent urban wastewater at different concentrations from 0.005 μg/L (surface water) to 1.25 μg/L (influent wastewater). The optimized method was applied to the analysis of 84 urban wastewater samples (influent and effluent), with the result that 17 out of 20 compounds monitored were detected in the samples. Analgesics and anti-inflamatories, cholesterol lowering statin drugs and lipid regulators were the major groups found, with diclofenac, ketoprofen, naproxen, 4-aminoantipyrine, bezafibrate, gemfibrozil and venlafaxine being the most frequently detected. The highest concentration level reached was 277 μg/L for salicylic acid in influent wastewater.     

Multi‐residue analysis of 44 pharmaceutical compounds in environmental water samples by solid‐phase extraction coupled to liquid chromatography‐tandem mass spectrometry

A solid‐phase extraction combined with a liquid chromatography‐tandem mass spectrometry analysis has been developed and validated for the simultaneous determination of 44 pharmaceuticals belonging to different therapeutic classes (i.e., antibiotics, anti‐inflammatories, cardiovascular agents, hormones, neuroleptics, and anxiolytics) in water samples. The sample preparation was optimized by studying target compounds retrieval after the following processes: i) water filtration, ii) solid phase extraction using Waters Oasis HLB cartridges at various pH, and iii) several evaporation techniques. The method was then validated by the analysis of spiked estuarine waters and wastewaters before and after treatment. Analytical performances were evaluated in terms of linearity, accuracy, precision, detection, and quantification limits. Recoveries of the pharmaceuticals were acceptable, instrumental detection limits varied between 0.001 and 25 pg injected and method quantification limits ranged from 0.01 to 30.3 ng/L. The precision of the method, calculated as relative standard deviation, ranged from 0.3 to 49.4%. This procedure has been successfully applied to the determination of the target analytes in estuarine waters and wastewaters. Eight of these 44 pharmaceuticals were detected in estuarine water, while 26 of them were detected in wastewater effluent. As expected, the highest values of occurrence and concentration were found in wastewater influent.     

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.     

Multi-class determination of around 50 pharmaceuticals, including 26 antibiotics, in environmental and wastewater samples by ultra-high performance liquid chromatography-tandem mass spectrometry

A multi-class method for the simultaneous quantification and confirmation of 47 pharmaceuticals in environmental and wastewater samples has been developed. The target list of analytes included analgesic and anti-inflammatories, cholesterol lowering statin drugs and lipid regulators, antidepressants, anti-ulcer agents, psychiatric drugs, ansiolitics, cardiovasculars and a high number (26) of antibiotics from different chemical groups. A common pre-concentration step based on solid-phase extraction with Oasis HLB cartridges was applied, followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) measurement. All compounds were satisfactorily determined in just one single injection, with a chromatographic run time of only 10 min. The process efficiency (combination of the matrix effect and the extraction process recovery) for the 47 selected compounds was evaluated in nine effluent wastewater (EWW) samples, and the use of different isotope-labelled internal standards (ILIS) was investigated to correct unsatisfactory values. Up to 12 ILIS were evaluated in EWW and surface water (SW). As expected, the ILIS provided satisfactory correction for their own analytes. However, the use of these ILIS for the rest of pharmaceuticals was problematic in some cases. Despite this fact, the correction with analogues ILIS was found useful for most of analytes in EWW, while was not strictly required in the SW tested. The method was successfully validated in SW and EWW at low concentration levels, as expected for pharmaceuticals in these matrices (0.025, 0.1 and 0.5 μg/L in SW; 0.1 and 0.5 μg/L in EWW). With only a few exceptions, the instrumental limits of detection varied between 0.1 and 8 pg. The limits of quantification were estimated from sample chromatograms at the lowest spiked levels tested and normally were below 20 ng/L for SW and below 50 ng/L for EWW. The developed method was applied to the analysis of around forty water samples (river waters and effluent wastewaters) from the Spanish Mediterranean region. Almost all the pharmaceuticals selected in this work were detected, mainly in effluent wastewater. In both matrices, analgesics and anti-inflammatories, lipid regulators and quinolone antibiotics were the most detected groups.     

Simultaneous LC-HRMS determination of 28 benzodiazepines and metabolites in hair

A liquid chromatography–high resolution mass spectrometry (LC-HRMS) method for the simultaneous identification and quantification of 28 benzodiazepines, including 6 metabolites, in 50 mg of hair has been validated. Positive ion electrospray ionization and HRMS determination in full-scan mode were realized on an Orbitrap mass spectrometer at a nominal resolving power of 60,000. In-source collisional experiments were conducted to obtain additional information for a more reliable identification of the investigated drugs. HRMS in full-scan mode allowed the exact determination of molecular masses of all analytes eluting in the HPLC run, so that both the immediate and retrospective screening of results for drugs and their metabolites were available. Sample preparation consisted of an overnight incubation in phosphate buffer pH 8.4 and a subsequent liquid/liquid extraction with methylene chloride/diethyl ether (90:10). Gradient elution was performed on a Luna C18 analytical column and four deuterated analogues were used as internal standards (IS). Validation was performed using both spiked hair samples and hair samples from subjects treated with benzodiazepines. Selectivity was evaluated by analysis of 20 certified blank hair samples. Extraction efficiency and matrix effects were evaluated by analysis of true positive samples. The lowest limits of quantification (LLOQs) ranged from 1 to 10 pg/mg. Linearity was investigated in the range from LLOQ to 1,000 pg/mg, for each compound (R ² 0.998–0.999). Mean relative errors, calculated at three concentration levels, ranged from 1 to 20% (absolute value). Precision, at concentrations higher than the LLOQs, was always less than 15% expressed as percentage relative standard deviation. After validation, the procedure was applied to real samples collected for clinical and forensic toxicology purposes from subjects who were assumed to have taken benzodiazepines.     

On-line desalting and determination of morphine, morphine-3-glucuronide and morphine-6-glucuronide in microdialysis and plasma samples using column switching and liquid chromatography/tandem mass spectrometry

A sensitive and reproducible method for the determination of morphine and the metabolites morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) was developed. The method was validated for perfusion fluid used in microdialysis as well as for sheep and human plasma. A C18 guard column was used to desalt the samples before analytical separation on a ZIC HILIC (hydrophilic interaction chromatography) column and detection with tandem mass spectrometry (MS/MS). The mobile phases were 0.05% trifluoroacetic acid (TFA) for desalting and acetonitrile/5 mM ammonium acetate (70:30) for separation. Microdialysis samples (5 microL) were directly injected onto the system. The lower limits of quantification (LLOQ) for morphine, M3G and M6G were 0.50, 0.22 and 0.55 ng/mL, respectively, and the method was linear from LLOQ to 200 ng/mL. For plasma, a volume of 100 microL was precipitated with acetonitrile containing internal standards (deuterated morphine and metabolites). The supernatant was evaporated and reconstituted in 0.05% TFA before the desalting process. The LLOQs for sheep plasma were 2.0 and 3.1 ng/mL and the ranges were 2.0-2000 and 3.1-3100 ng/mL for morphine and M3G, respectively. For human plasma, the LLOQs were 0.78, 1.49 and 0.53 ng/mL and the ranges were 0.78-500, 1.49-1000 and 0.53-500 ng/mL for morphine, M3G and M6G, respectively.     

Validation of a liquid chromatography coupled with tandem mass spectrometry method for the determination of drugs in wastewater using a three‐phase solvent system

Pharmaceuticals constitute one of the most important emerging classes of environmental pollutants. A three‐phase solvent system of water, water containing 0.1% of formic acid and acetonitrile was successfully used to separate, by liquid chromatography with mass spectrometry (LC‐MS), polarity‐matched pharmaceuticals, that is, carbamazepine, clarithromycin, and erythromycin, as well as amoxicillin and metformin. Despite of polarity similarities, these pharmaceuticals were completely resolved in the analytical run time of 15 min. The optimized three‐phase solvent system based‐method was validated for the simultaneous analysis of six matched‐polarity pharmaceuticals in wastewater samples. Good linearity (coefficient of determination more than 0.993) and precision (relative standard deviation less than 15.66%) were achieved. Recovery of analytes from the wastewater was between 0.70 and 1.18. Limits of detections ranged from 0.0001 to 0.5114 µg/L. No significant matrix effect, evaluated by post extraction addition, was observed in the electrospray ionization (ESI) source. Then, this methodology has been successfully applied to environmental study of pharmaceutical residues occurring in influent and effluent wastewater samples, from the main wastewater treatment plant in Potenza (Basilicata, Southern Italy).     

Trace-level determination of pharmaceutical residues by LC-MS/MS in natural and treated waters. A pilot-survey study

A pilot-survey study was performed by collecting samples (influent and effluent wastewaters, rivers and tap waters) from different locations in Europe (Spain, Belgium, Germany and Slovenia). A solid-phase extraction (SPE) followed by liquid chromatography–tandem mass spectrometry method was applied for the determination of pharmaceuticals (ibuprofen, naproxen, ketoprofen, diclofenac and clofibric acid). Method detection limits and method quantification limits were at the parts-per-trillion level (7.5–75 ng/L). The recovery rates of the SPE from deionized water and effluent wastewater samples spiked at 100- and 1,000-ng/L levels ranged from 87 to 95%. Identification criteria in compliance with the EU regulation for confirmatory methods of organic residues were applied. A detailed study of signal suppression evaluation for analysis of pharmaceutical residues in effluent wastewaters is presented.     

High speed hydrophilic interaction liquid chromatographic method for simultaneous determination of selected pharmaceuticals in wastewater using a cyano-bonded silica column

In this work, a fast analytical method based on hydrophilic interaction liquid chromatographic-Ultraviolet detection (HILIC-UV) using a short narrow bore cyano-bonded silica column packed with fully porous sub-2?µm particles has been developed for simultaneous determination of eight pharmaceuticals in wastewater. The method involved pre-concentration and clean-up by solid phase extraction using Oasis HLB extraction cartridges. The analytes were separated using a mobile phase consisted of acetonitrile and 5?mM ammonium acetate buffer (95:5?v/v) with a flow rate of 0.6?mL/min. The chromatographic separation was optimized in order to achieve short analysis time and good resolution for all analytes in a single run. Each analyte was detected at its maximum wavelength for higher sensitivity. All analytes could be separated in 5.7?min with resolution ≥2.7. The optimized method was validated based on linearity, precision, detection and quantification limits, selectivity and accuracy. The detection limits of the studied pharmaceuticals ranged from 0.6 to 3?µg/L, while limits of quantification were in the range from 2 to 10?µg/L with UV detection. The developed method is fast, reliable, cost-effective and could be used for the analysis of the studied analytes in other matrices such as food, pharmaceutical preparations and biological fluids.     

A multiresidue analytical method using solid-phase extraction and high-pressure liquid chromatography tandem mass spectrometry to measure pharmaceuticals of different therapeutic classes in urban wastewaters

An analytical method with two extraction steps has been developed and validated for the simultaneous determination of 30 pharmaceuticals belonging to various therapeutic categories in urban wastewater. The aim was to boost the little available information on drugs' fates in sewage treatment plants (STPs) and in the receiving surface water. Aqueous samples were divided into two aliquots, each extracted by a different solid-phase extraction (SPE) method and analysed by reversed-phase liquid chromatography tandem mass spectrometry (HPLC-MS-MS). Recoveries of the pharmaceuticals were mostly greater than 70% and the overall variability of the method was below 8%. The instrumental quantification limit (IQL) varied between 30 and 400 pg injected, and the limits of quantification (LOQ) were in the low ng/L range. Nineteen pharmaceuticals were detected in concentrations between 0.5 and 2000 ng/L in effluents collected from several STPs in Italy. Atenolol, ciprofloxacin, furosemide, hydrochlorothiazide, ofloxacin, ranitidine and sulphamethoxazole were the most abundant compounds. The present analytical method was useful to check for pharmaceuticals in various Italian STPs and to identify the most abundant compounds.     

Analysis of hormone antagonists in clinical and municipal wastewater by isotopic dilution liquid chromatography tandem mass spectrometry

A comprehensive method was developed for the simultaneous trace analysis of ten hormone antagonist pharmaceuticals (raloxifene, exemestane, letrozole, anastrozole, mifepristone, finastride, tamoxifen, N-desmethyltamoxifen, clomiphene, and toremifene) in municipal sewage and hospital wastewater samples. The target compounds were firstly extracted using an Oasis HLB cartridge, followed by purification by an aminopropyl cartridge, and were then analyzed by liquid chromatography electrospray ionization tandem mass spectrometry in positive ion mode. The recoveries for the analytes based on internal standard calibration in different test matrices ranged from 67.6 to 118.6% (with the exception of mifepristone in clinical wastewater samples), with relative standard deviations less than 20%. The method quantification limits of the ten pharmaceuticals were in the range 0.10–2.0 ng/L. Excluding exemestane and N-desmethyltamoxifen, eight drugs were detected at 0.20–195.0 ng/L in hospital wastewater and municipal wastewater samples from Beijing.     

Application of graphene for the analysis of pharmaceuticals and personal care products in wastewater

A novel and reliable analytical method based on a graphene adsorbent for solid-phase extraction (SPE) derivatized with N-tert-butyldimethylsilyl-N- methyltrifluoroacetamide and analyzed by gas chromatography–mass spectrometry was developed for determination of nine pharmaceuticals and personal care products (PPCPs) in wastewater samples. Different ratios of graphene/silica gel were tested, with 20 % graphene/silica gel giving the best performance as an SPE adsorbent. The mean recoveries of the target analytes obtained by 20 % graphene/silica gel SPE ranged from 58.1 to 87.6 %. The limit of quantification ranged from 30 to 259 ng/L and from 13 to 115 ng/L for the influent and effluent, respectively. By comparing the accuracy and precision of 20 % graphene/silica gel and Oasis HLB SPE cartridges, we demonstrated that the method can be satisfactorily used for the analysis of PPCPs in wastewater samples. We applied the method to wastewater samples from a sewage treatment plant near Riverside, California, to track the concentration change of PPCPs in the treatment processes.     

High temperature-high efficiency liquid chromatography using sub-2 μm coupled columns for the analysis of selected non-steroidal anti-inflammatory drugs and veterinary antibiotics in environmental samples

A high efficiency HPLC method was developed by coupling three sub-2 μm columns in series and operating them at high temperature for the separation of selected non-steroidal anti-inflammatory drugs and veterinary antibiotics in environmental samples. The separation was performed at 80 °C to reduce the solvent viscosity, thus reducing the column backpressure. The chromatographic performance of high temperature-extended column length HPLC method was used to determine the most widely used non-steroidal anti-inflammatory drugs and veterinary antibiotics such as sulphonamides in wastewater samples. The method could simultaneously determine 24 pharmaceuticals in short analysis time with high efficiency. The method involved pre-concentration and clean-up by solid phase extraction (SPE) using Oasis HLB extraction cartridges. It was validated based on linearity, precision, detection and quantification limits, selectivity and accuracy. Good recoveries were obtained for all analytes ranging from 72.7% to 98.2% with standard deviations not higher than 6%, except for acetaminophen and acetyl salicylic acid, for which low recovery was obtained. The detection limits of the studied pharmaceuticals ranged from 2 to 16 μg L⁻¹, while limits of quantification were in the range from 7 to 54 μg L⁻¹ with UV detection.     

Multi-residue method for trace level determination of pharmaceuticals in solid samples using pressurized liquid extraction followed by liquid chromatography/quadrupole-linear ion trap mass spectrometry

A simple and sensitive method for simultaneous analysis of 43 pharmaceutical compounds in sewage sludge and sediment samples was developed and validated. The target compounds were extracted using pressurized liquid extraction (PLE) and then purified and pre-concentrated by solid phase extraction (SPE) using a hydrophilic-lipophilic balanced polymer. PLE extraction was performed on temperature of 100 °C, with methanol/water mixture (1/2, v/v) as extraction solvent. The quantitative analysis was performed by liquid chromatography tandem mass spectrometry using a hybrid triple quadrupole-linear ion trap mass spectrometer (LC-QqLIT-MS). Data acquisition was carried out in selected reaction monitoring (SRM) mode, monitoring two SRM transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the Information Dependent Acquisition (IDA) function. The method was validated through the estimation of the linearity, sensitivity, repeatability, reproducibility and matrix effects. The internal standard approach was used for quantification because it efficiently corrected matrix effects. Despite the strong matrix interferences, the recoveries were generally higher of 50% in both matrixes and the detection and quantification limits were very low. Beside the very good sensitivity provided by LC-QqLIT-MS, an important characteristic of the method is that all the target compounds can be simultaneously extracted, treated and analysed. Hence, it can be used for routine analysis of pharmaceuticals providing large amount of data. The method was applied for the analysis of pharmaceuticals in river sediment and wastewater sludge from three treatment plants with different treatment properties (i.e. capacity, secondary treatment, quality of influent waters). The analysis showed a widespread occurrence of pharmaceuticals in the sludge matrices.     

Analysis of 21 progestagens in various matrices by ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with diverse sample pretreatment

In this study, a highly sensitive and robust method using an ultra-high-performance liquid chromatography-tandem mass spectrometry combined with solid-phase extraction and ultrasonic extraction for pretreatment and silica gel purification steps has been developed for determination of 21 natural and synthetic progestagens in river surface water and sediments, and influents, effluents, and sludge from municipal wastewater treatment plants, and flush water and feces from swine farms. For the various matrices considered, the optimized method showed satisfactory performance with recoveries of 70–129 % (except AD, 5α-DHP, DPT, HPC), the limits of quantification below 2.30 ng/L for liquid samples and 2.59 ng/g for solid samples (except AD), and good linearity and reproducibility. This developed method was successfully applied in the analysis of progestagens in environmental samples from Liuxi Reservoir, Xintang municipal wastewater treatment plant, and Shunfeng swine farm in South China. Six analytes were detected at trace levels in surface water, effluent, and sediment samples. Seven analytes (0.7 (HPA)–35.1 ng/L (DGT)) were found in the influent samples and three analytes (5.6 (DGT)–11.8 ng/g (5α-DHP)) in the dewatered sludge samples. Moreover, 13 analytes were detected in swine farm, with high concentrations ranging from 23.8 ng/L (ET) to 5,024 ng/L (P) in flush water, and from 20.0 ng/g (MPA) to 1952 ng/g (P) in feces.     

Liquid chromatography/tandem mass spectrometry method for the simultaneous determination of olanzapine, risperidone, 9-hydroxyrisperidone, clozapine, haloperidol and ziprasidone in rat plasma

A simple, sensitive and rapid liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method was developed and validated for simultaneous quantification of olanzapine, clozapine, ziprasidone, haloperidol, risperidone, and its active metabolite 9-hydroxyrisperidone, in rat plasma using midazolam as internal standard (IS). The analytes were extracted from rat plasma using a single step liquid-liquid extraction technique. The compounds were separated on a Waters Atlantis dC-18 (30 mm x 2.1 mm i.d., 3 microm) column using a mobile phase of acetonitrile/5 mM ammonium formate (pH 6.1 adjusted with formic acid) with gradient elution. All of the analytes were detected in positive ion mode using multiple reaction monitoring (MRM). The method was validated and the specificity, linearity, lower limit of quantitation (LLOQ), precision, accuracy, recoveries and stability were determined. LLOQ was 0.1 ng/mL and correlation coefficient (R(2)) values for the linear range of 0.1-100 ng/mL were 0.997 or greater for all the analytes. The intra-day and inter-day precision and accuracy were better than 8.05%. The relative and absolute recovery was above 77% and matrix effects were low for all the analytes except for ziprasidone. This validated method has been successfully used to quantify the plasma concentration of the analytes after chronic treatment with antipsychotic drugs.     

Simultaneous determination of triazines and their main transformation products in surface and urban wastewater by ultra-high-pressure liquid chromatography–tandem mass spectrometry

This work describes the optimization, validation and application of an ultra-high-pressure liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) method for the quantification and confirmation of 11 compounds (atrazine, simazine, terbuthylazine, terbumeton, terbutryn and their main transformation products) in surface and wastewater samples. Several of these analytes are included in the list of priority substances in the framework on European Water Policy. The application of this method to water samples reveals that the most relevant transformation products (TPs) should be incorporated into current analytical methods to obtain a more realistic knowledge of water quality regarding pesticide contamination. TPs are generally more polar and mobile than parents and can be transported to the aquatic environment more easily than their precursors. This can explain their concentrations found in water, which in many cases are much higher than intact triazines. To efficiently combine UHPLC with MS/MS, a fast-acquisition triple quadrupole mass analyser was used. Working in selected reaction monitoring mode, up to three simultaneous transitions per compound were acquired, allowing a reliable quantification and confirmation at nanogram per litre levels. The method developed includes a pre-concentration step based on solid-phase extraction (OASIS HLB cartridges). Satisfactory recoveries (70–120%) and relative standard deviations (<20%) were obtained for all compounds in different water sample types spiked at two concentrations (0.025 and 0.1 μg/L in surface water; 0.25 and 1.0 μg/L in effluent wastewater; 0.5 and 2.0 μg/L in influent wastewater). The optimized method was found to have excellent sensitivity with instrumental detection limits as low as 0.03 pg. In addition, the influence of the matrix constituents on the ionization efficiency and the extraction recovery was studied in different types of Italian and Spanish surface and urban wastewater. Signal suppressions were observed for all compounds, especially for influent wastewater. The use of isotope-labelled internal standards was found to be the best approach to assure an accurate quantification in all matrix samples.     

Use of solid phase extraction and liquid chromatography-tandem mass spectrometry for simultaneous determination of various pharmaceuticals in surface water

This article presents the development, validation and application of a new multi-residue method for simultaneous determination of 36 pharmaceuticals (histamine receptor antagonists, psychoactive stimulant, antiepileptics, antihypertensive, non-steroidal anti-inflammatory, analgesic and antipyretic, lipid regulator, antibiotics, antibacterial, skin care ingredient and metabolites of nicotine and lipid regulators) in surface water using solid phase extraction (Strata-X at pH 5) and liquid chromatography-tandem mass spectrometry (LC–MS/MS). Recoveries were greater than 70% with less than 20% SD for the majority of analytes. The instrumental quantification limit was between 2 and 181 pg, and method quantification limit varied from 0.5 to 98 ng L^?1 in spiked stream water. The pH and sorbent dependence of matrix effects is discussed. The optimised method was used to determine the occurrence of target analytes in surface water from the coastal Lake Erie in Oregon, northwest Ohio. Seventeen analytes were detected with concentrations up to hundreds of nanogram per litre in stream and lake water samples.     

Comparison of four extraction methods for the analysis of pharmaceuticals in wastewater

As one category of the most urgent emerging pollutants, pharmaceuticals have provoked much public and scientific attention due to widespread contamination in aquatic environment. In this study, two active methods by Oasis HLB and MCX and two passive methods by XAD-16 and XAD-16/7 were evaluated for determining the concentrations of 10 pharmaceuticals (carbamazepine, clofibric acid, diclofenac, gemfibrozil, ibuprofen, ketoprofen, naproxen, paracetomol, terbutaline and triclosan) in reclaimed wastewater. Recoveries of the target pharmaceuticals extracted by MCX were higher than HLB except for diclofenac and ketoprofen. For the passive methods, the addition of polar resin XAD-7 improved the recovery compared with the addition of XAD-16 only. The mean recoveries of the target analytes by XAD-16/7 ranged from 22 to 75.8%. The limit of quantification (LOQ) ranged between 25 and 280 ng/L. In addition, by comparing the accuracy and precision of XAD-16/7 method and MCX method, we further demonstrated that the XAD-16/7 method can be satisfactorily used for the analysis of pharmaceuticals in wastewater samples. We applied the method to some wastewater samples from sewage treatment plant (STP) nearby Riverside, CA to track the concentration change of pharmaceuticals in the treatment processes. The result shown that pharmaceuticals were effective reduced in STP mostly by activated sludge.