Occurrence and distribution of selected pharmaceutical compounds on sewage-impacted section of River Acheloos,Western Greece

The occurrence of eight pharmaceutical compounds (PhCs), two metabolites and caffeine was investigated in River Acheloos, located in Western Greece, during a twelve-month monitoring period (March 2007–February 2008). Solid-phase extraction (SPE) was used for the extraction and pre-concentration of the target pollutants and gas chromatography mass spectrometry (GC–MS) for the detection and quantification. Recoveries were determined between 74.0–100.4% for distilled water and 72.6–95.1% for the river water, whereas the relative standard deviation was less than 9.4% for distilled water and 8% for the river water, respectively. The limits of detection ranged between 1–40 ng L^?1. Two pharmaceuticals (paracetamol and carbamazepine), caffeine and the metabolite (salicylic acid), have been detected in all the analysed samples. Maximum concentration levels determined in river samples reached 305 ng L^?1 recorded for paracetamol. The concentrations of target compounds were significantly higher in the samples collected at the sampling station situated after the wastewater treatment plant (WWTP) of Agrinio City compared to the samples collected in upper and lower parts of the river. Seasonal variations were attributed mainly to river flow variations and removal percentages by WWTP. Risk quotient method for median environmental concentrations revealed minimal to median risk with the exception of triclosan, ibuprofen and diclofenac, which presented high risk when maximum environmental concentrations were used.     

HPLC-MS/MS multiclass determination of steroid hormones in environmental waters after preconcentration on the carbonaceous sorbent HA-C@silica

In this study, a sensitive and multiclass method has been developed for analysis of three families of steroid hormones, i.e. progestins, oestrogens, androgens, by SPE-HPLC-ESI-MS/MS. The extraction efficiency of thermally condensed humic acids onto silica sorbent (HA-C@silica), here for the first time studied for multiclass enrichment of these sex hormones, was tested in different environmental waters (tap and river water, urban wastewater treatment plant effluent) spiked at the nanograms per litre levels (5–1000 ng L⁻¹). Quantitative adsorption was achieved using 200 mg sorbent for preconcentration of 250–1000 mL sample, at the native pH (pH = 6.5–7.7). Elution was performed by two sequential fractions (methanol followed by acetonitrile), obtaining in all the matrices investigated satisfactory recoveries (71% to 124% for river waters and 71–113% for urban wastewater treatment plant effluent) and RSDs below 15% (n = 3). The high enrichment factors (up to 4000) coupled with high-performance liquid chromatography tandem mass spectrometry quantification (MRM mode) provided low limits of detection and quantification (a few ng L⁻¹), that are suitable for environmental monitoring. Most of the analytes were detected in river water and in wastewater effluent samples (in the ng L⁻¹ concentration range), attesting their environmental diffusion. The proposed method was extended to a fourth class, Glucocorticoids, achieving good results in river samples, by the same SPE cartridge and chromatographic run.     

Chemometrics assisted spectrophotometric determination of pyridine in water and wastewater

The paper reports a direct method for the determination of pyridine in water and wastewater samples based on ultraviolet spectrophotometric measurements using multi-way modeling techniques. Parallel factor analysis (PARAFAC) and multi-way partial least squares (N-PLS) regression methods were employed for the decomposition of spectra and quantification of pyridine. The study was carried out in the pH range of 1.0-12.0 and concentration range of 0.67-51.7 μg mL⁻¹ of pyridine. Both the three-way PARAFAC and tri-PLS1 models successfully predicted the concentration of pyridine in synthetic (spiked) river water and field wastewater samples. The mean recovery obtained from PARAFAC regression model were 97.39% for the spiked and 99.84% for the field wastewater samples, respectively. The sensitivity and precision of the method for pyridine determination were 0.58% and 5.95%, respectively. The N-PLS regression model yielded mean recoveries of 99.29% and 100.18% for the spiked and field wastewater samples, respectively. The prediction accuracy of the methods was evaluated through the root mean square error of prediction (RMSEP). For PARAFAC, it was 0.65 and 0.82 μg mL⁻¹ for spiked river water and field wastewater samples, respectively, while for N-PLS, it was 0.25 and 0.37 μg mL⁻¹, respectively. Both the PARAFAC and N-PLS methods, thus, yielded satisfactory results for the prediction of pyridine concentration in water and wastewater samples.     

Development of an analytical method for eight fluoroquinolones using solid-phase extraction and liquid chromatography with fluorescence detection

In this study, a practicable and effective analytical method based on solid-phase-extraction and reversed-phase liquid chromatography with fluorescence detection (SPE-LC-FLD) was developed and partially validated for routine analysis of eight FQs in wastewater at the trace level. Different SPE materials, pH conditions and eluents were modified to find an economic and effective SPE conditions. In our work, it is the first time that well-known commercially available SPE sorbent are compared to ‘generic’ cheap SPE sorbent. Aqueous samples (pH 2–3) were extracted using Anpel? MEP cartridges where they were subsequently eluted by 6?mL of 2% formic acid in MeOH. The aqueous extracts were analysed by gradient elution LC-FLD, whose initial mobile phase was composed of ACN and 10?mmol?L^?1 tetrabutyl ammonium bromide (4/96, v/v, pH 3). The LODs and LOQs of the wastewater were as low as 0.32–2.12?ng?L^?1 and 1.07–7.07?ng?L^?1, respectively. The precisions of the overall method (RSD, n?=?3) using wastewater were below 10%. The method was used to quantify FQs in influents and effluents of several typical sewage treatment plants (STPs) in Shanghai. The extraction recoveries of 100?mL influent, 500?mL effluent and 500?mL of river water samples were between 88.6 and 102.6%, 79.2 and 109.2%, 80.0 and 105.5% and 87.4 and 99.4%, respectively. FQs of interest except sarafloxacin were identified in the influents, effluents and river waters with concentrations varying from 0.012–1.163?µg?L^?1, 0.003–0.291?µg?L^?1, and 0.002–0.040?µg?L^?1, respectively. The method can serve as a tool to obtain detailed information on occurrence, behaviour and fate of FQs in the aquatic environment. Occurrence of FQs detected in summer is higher than in spring at STPs, and those detected in the suburban area are less than those in the urban area. Complete removal of FQs is not achieved from the STPs, indicating domestic wastewater and STP discharge is the source of FQs in the surface water.     

Vortex-assisted liquid-liquid microextraction of octylphenol, nonylphenol and bisphenol-A

A new and fast equilibrium-based solvent microextraction technique termed vortex-assisted liquid-liquid microextraction (VALLME) has been developed and used for the trace analysis of octylphenol, nonylphenol and bisphenol-A in water and wastewater samples. According to VALLME, dispersion of microvolumes of a low density extractant organic solvent into the aqueous sample is achieved by using for the first time vortex mixing, a mild emulsification procedure. The fine droplets formed could extract target analytes towards equilibrium faster because of the shorter diffusion distance and larger specific surface area. Upon centrifugation the floating extractant acceptor phase restored its initial single microdrop shape and was used for high-performance liquid chromatographic analysis. Different experimental parameters were controlled and the optimum conditions found were: 50 μl of octanol as the extractant phase; 20 ml aqueous donor samples; a 2 min vortex extraction time with the vortex agitator set at a 2500 rpm rotational speed; centrifugation for 2 min at 3500 rpm; no ionic strength or pH adjustment. The calculated calibration curves gave high levels of linearity yielding correlation coefficients (r²) greater than 0.9935. The repeatability and reproducibility of the proposed method were found to be good and the limits of the detection were calculated in the low μg l⁻¹ level ranging between 0.01 and 0.07 μg l⁻¹. Matrix effects were determined by applying the proposed method to spiked tap, river water and treated municipal wastewater samples. The proposed method was finally applied to the determination of target pollutants in real wastewater effluent samples using the standard addition method.     

Parts per trillion level determination of endocrine-disrupting chlorinated compounds in river water and wastewater effluent by stir-bar-sorptive extraction followed by gas chromatography–triple quadrupole mass spectrometry

A new analytical method using stir-bar-sorptive extraction (SBSE) followed by liquid desorption (LD) and gas chromatography with triple-quadrupole mass spectrometric detection (GC-QqQ-MS-MS) has been used for quantitative determination of 25 chlorinated endocrine-disrupting compounds (EDCs) in river water and wastewater. The experimental conditions affecting the SBSE-LD performance were studied and are discussed in detail. Results from systematic assay revealed that a 100-mL water sample, stir bars coated with 47?μL PDMS, an extraction time of 14?h (at 900?rpm), 5?% MeOH as modifier and 10?% NaCl resulted in the best analytical recovery of all the target compounds studied. Use of 1:1 ACN-MeOH as back-extraction solvent and two successive sonication steps, each for 5?min, resulted in the best performance for monitoring EDCs in water matrices. The method detection limits for most of the target compounds were very good- ≤?2?ng?L(-1) and ≤10?ng?L(-1) for river water and wastewater effluents respectively. Experimental recovery for all the compounds was >70?%, with the exception of simazine for which recovery from the matrix was 65?%. Signal enhancement observed for a few of the compounds in wastewater effluents was managed by use of matrix-matched standards and different injection liners. The method was successfully used for analysis of river water samples from Henares River (Spain) and wastewater effluent samples from wastewater-treatment plants (WWTP). Eleven of the 25 compounds studied were detected in both river water and wastewater effluents. Terbutylazine and methoxychlor were detected in almost all the river water and effluent samples; amounts varied between 37-58.5?ng?L(-1) and 15.2-46.8?ng?L(-1), respectively. This method was shown enable reliable, effective, and sensitive monitoring of chlorinated EDCs at nanogram levels in surface water and wastewater effluent.     

Application of polydimethylsiloxane rod extraction to the determination of sixteen halogenated flame retardants in water samples

An extraction and preconcentration procedure for the determination in water samples of several halogenated flame retardants (FRs), nine brominated diphenyls ethers (BDEs) and seven non-BDE FRs, was developed and validated. The optimised procedure is based on polydimethylsiloxane (PDMS) rods as sorptive extraction material, followed by liquid desorption and gas chromatography coupled to negative chemical ionisation–mass spectrometry (GC–NCI–MS) determination, rendering an efficient and inexpensive method. The final optimised protocol consists of overnight extraction of 100 mL of sample solutions containing 40% MeOH and 4% NaCl, followed by a 15-min sonication-assisted desorption with 300 μL of ethyl acetate, solvent evaporation and GC–NCI–MS analysis. Under these conditions, extraction efficiencies in the 9 to 70% range were obtained, leading to enrichment factors between 108 and 840, detection limits in the range from 0.4 to 10 ng L⁻¹and RSD values in the 2–23% range. After method validation, different real water samples, including river, ria, sea, landfill leachate, influent and effluent wastewater from an urban sewage treatment plant (STP) and effluent wastewater from a textile industry, were analysed. BDE-47, BDE-99, BDE-100 and BDE-197 were detected in wastewater and landfill leachate samples at concentration levels up to 2887 ng L⁻¹. Among the non-BDE FRs, bis (2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (DEHTBP) was detected in surface water samples (sea, river and ria) between 1.3 and 2.2 ng L⁻¹ and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) in the landfill leachate (64 ng L⁻¹).     

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.     

Sodium polyacrylate as a binding agent in diffusive gradients in thin-films technique for the measurement of Cu and Cd in waters

An aqueous solution containing sodium polyacrylate (PA, 0.0030 M) was used in diffusive gradients in thin-films technique (DGT) to measure DGT-labile Cu²⁺ and Cd²⁺ concentrations. The DGT devices (PA DGT) were validated in four types of solutions, including synthetic river waters containing metal ions with or without complexing EDTA, natural river water (Hun River, Shenyang, China) spiked with Cu²⁺ and Cd²⁺, and an industrial wastewater (Shenyang, China). Results showed that only free metal ions were measured by PA DGT, recovery = 98.79% for Cu²⁺ and recovery = 97.80% for Cd²⁺ in solutions containing only free metal ions, recovery = 51.02% for Cu²⁺ and recovery = 51.92% for Cd²⁺ in solution with metal/EDTA molar ratio of 2:1 and recovery = 0 in solutions with metal/EDTA molar ratio of 1:1 and 1:2. These indicated that the complexes of Cu-EDTA and Cd-EDTA were DGT-inert or not DGT-labile. The DGT performance in spiked river water (recovery = 8.47% for Cu²⁺ and recovery = 27.48% for Cd²⁺) and in industrial wastewater (recovery = 14.16% for Cd²⁺) were also investigated. Conditional stability constants (log K) of PA-Cu and PA-Cd complexes were determined as 6.98 and 5.61, respectively, indicating strong interaction between PA and the metals.     

Quantification of human pharmaceuticals in water samples by high performance liquid chromatography-tandem mass spectrometry

An improved analytical method for determination of human pharmaceuticals in natural and wastewaters with ng L⁻¹ sensitivity is presented. The method is applicable to pharmaceuticals from a wide range of therapeutic classes including antibiotics, analgesics, anti-inflammatories and anti-cancer compounds. Pharmaceuticals were extracted from waters using solid-phase extraction, and after concentration, analysed by high performance liquid chromatography with tandem mass spectrometric detection (HPLC-MS/MS). Identification of each compound was secured using retention time and by the selected reaction monitoring of two transitions, one of which was additionally used for quantification. Limits of detection ranged from 0.03 to 0.96 ng L⁻¹ and were up to two orders of magnitude lower than those of previously published methods. The method was validated using spiked samples prepared from tap, river and sea water as well as wastewater effluents, collected from the North of Scotland. Analysis of wastewater effluents revealed the presence of mefenamic acid, ibuprofen, erythromycin, diclofenac and trimethoprim. None of the selected pharmaceuticals were detected in river, tap or sea water samples.     

Determination of bisphenols A and F and their diglycidyl ethers in wastewater and river water by coacervative extraction and liquid chromatography-fluorimetry

A simple, rapid and sensitive analytical method was developed for the simultaneous determination of bisphenol A (BPA), bisphenol F (BPF) and their corresponding diglycidyl ethers (BADGE and BFDGE) in wastewater and river water, in order to have a useful tool for evaluating their fate and distribution in aquatic environments. It was based on their extraction with coacervates made up of decanoic acid reverse micelles and subsequent determination by liquid chromatography-fluorimetry. The procedure involved the extraction of 10.8 mL of water sample for 5 min, its centrifugation for 10 min to accelerate phase separation and then the chromatographic analysis of the target compounds. Clean-up or solvent evaporation steps were not necessary to get the required sensitivity and selectivity. Extraction efficiencies and concentration factors mainly depended on the amount of decanoic acid and tetrahydrofuran making up the coacervate. A general equation for the prediction of the volume of the coacervate as a function of its components has been proposed and fitted by nonlinear regression. This equation permits to know a priori the maximum concentration factors that can be achieved under given experimental conditions. Extractions were independent of salt addition (up to 1 M), the temperature (up to 60 °C) and the pH (below 4) rendering the method robust. Recoveries in samples ranged between about 80 and 92% and the actual concentrations factors were between 87 and 102, which resulted in practical detection limits around 30-35 ng L⁻¹. The method was successfully applied to the determination of the target pollutants in raw and treated sewage from four mechanical-biological treatment plants and three rivers. Bisphenols and their diglycidyl ethers were present in wastewater influents at concentrations in the range 0.96 to 1.6 μg L⁻¹. The biological treatment at the wastewater treatment plants (WWTP_s) studied reduced the concentration of BPA and BPF in a percentage above 75%, while diglycidyl ethers were not detected in most of the effluents investigated. Only BPA was detected in surface waters.     

Beta-Cyclodextrin-Decorated Magnetic Activated Carbon as a Sorbent for Extraction and Enrichment of Steroid Hormones (Estrone, β-Estradiol,Hydrocortisone and Progesterone) for Liquid Chromatographic Analysis

A β-cyclodextrin-decorated magnetic activated carbon adsorbent was prepared and characterized using various analytical techniques (X-ray diffraction (XRD), scanning electron microscopy–electron diffraction spectroscopy (SEM-EDS) and transmission electron microscopy (TEM)), and the adsorbent was used in the development of a magnetic solid-phase microextraction (MSPE) method for the preconcentration of estrone, β-estradiol, hydrocortisone and progesterone in wastewater and river water samples. This method was optimized using the central composite design in order to determine the experimental parameters affecting the extraction procedure. The quantification of hormones was achieved using high-performance liquid chromatography equipped with a photodiode array detector (HPLC-DAD). Under optimum conditions, the linearity ranged from 0.04 to 300 µg L⁻¹ with a correlation of determinations of 0.9969–0.9991. The limits of detection and quantification were between 0.01–0.03 and 0.033–0.1 µg L⁻¹, with intraday and interday precisions at 1.1–3.4 and 3.2–4.2. The equilibrium data were best described by the Langmuir isotherm model, and high adsorption capacities (217–294 mg g⁻¹) were obtained. The developed procedure demonstrated high potential as an effective technique for use in wastewater samples without significant interferences, and the adsorbent could be reused up to eight times.     

Simultaneous sonication-assisted extraction, and determination by gas chromatography-mass spectrometry, of di-(2-ethylhexyl)phthalate, nonylphenol, nonylphenol ethoxylates and polychlorinated biphenyls in sludge from wastewater treatment plants

Di-(2-ethyl-hexyl)phthalate (DEHP), nonylphenol, nonylphenol mono- and diethoxylates (NPEs) and polychlorinated biphenyls (PCBs) are organic pollutants in sewage sludge which have to be monitored in the European Union according to a future Sludge Directive. In the present work, an analytical method for the simultaneous extraction and determination of DEHP, NPEs and PCBs is proposed for the routine analysis of these compounds in sludge from wastewater treatment plants. All the compounds were simultaneously extracted by sonication with hexane and analysed by gas chromatography-mass spectrometry (GC-MS) in electronic impact mode. Recoveries achieved were 105% for DEHP, 61.4-88.6% for NPEs and 55.8-108.3% for PCBs with relative standard deviation bellow 10%. Limits of quantification were 65 μg kg⁻¹ for DEHP, from 630 to 2504 μg kg⁻¹ for NPEs and from 5.4 to 10.6 μg kg⁻¹ for PCBs in dried sludge. The applicability of the proposed method was evaluated by the determination of these compounds in sludge from wastewater treatment plants in Seville (South Spain).     

Method Development for the Speciation of Chromium in River and Industrial Wastewater Using GFAAS

A simple, sensitive and inexpensive method for the speciation of Cr(VI) and Cr(III) in river and industrial wastewater was developed, optimized and validated. Samples were collected, filtered and then chromium species were determined in the filtrate. In the filtrate, total Cr was determined directly by Graphite Furnace Atomic Absorption Spectrometry (GFAAS). A portion of the filtered sample was buffered to pH 6.4, extracted with Amberlite LA-2/MIBK and finally Cr(VI) was determined in the organic extract and Cr(III) in the aqueous phase using GFAAS. The method was evaluated by analysis of the certified reference material, CRM 544, and good accuracy was obtained. The limit of detection for Cr(VI) and Cr(tot)/Cr(III) was found to be 0.30 and 0.08 µg L⁻¹, respectively, and a precision expressed as relative standard deviation of better than 11% was achieved for nine replicates. A number of water samples from the Tinishu Akaki River, Ethiopia, and wastewater samples from a chemical plant in Germany, were analysed. In addition to the GFAAS method, Cr(tot) was also determined using ICP-MS (in CRM 544, lyophilized water, and Tinishu Akaki River water samples) and Cr(tot) and Cr(VI) using UV-VIS spectrophotometry (in CRM 544 and industrial wastewater samples). Good agreement between the different methods was found.     

Attachment of nickel hexacyanoferrates nanoparticles on carbon nanotubes: preparation, characterization and bioapplication

Anilinemethyltriethoxysilane (AMTEOS) was first used as precursor as well as selective stationary phase to prepare the sol-gel derived anilinemethyltriethoxysilane/polydimethylsiloxane (AMTEOS/PDMS) solid-phase microextraction (SPME) fibers. The novel SPME fiber exhibits high extraction efficiency, good thermal stability and long lifetime compared with commercial SPME coatings. In addition, the phenyl groups in the porous layer can exhibit π-π interactions with aromatic compounds, such as monocyclic aromatic hydrocarbons (MAHs) and polycyclic aromatic hydrocarbons (PAHs). Therefore, SPME using the AMTEOS/PDMS sol-gel fiber coupled with GC-FID was recommended as a sensitive and selective method towards the analysis of these compounds in environmental water samples. The optimal extraction conditions were investigated by adjusting extraction time, salt addition, extraction temperature, and desorption time. The method showed linearity between 2 and 4000 μg l⁻¹ for MAHs and 1 and 1000 μg l⁻¹ for PAHs. The limit of detection (LOD) was 0.6-3.8 μg l⁻¹for MAHs and 0.2-1.5 μg l⁻¹ for PAHs. The novel AMTEOS/PDMS fiber was applied to extract small amount of aromatic compounds in wastewater and river water respectively. The recovery of the method was acceptable for quantitative analysis.     

Dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry for the determination of nitro musks in surface water and wastewater samples

A new, simple, fast and high sensitive analytical method based on dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS) for the simultaneous determination of nitro musks in surface water and wastewater samples is presented. Different parameters, such as the nature and volume of both the extraction and disperser solvents and the ionic strength and pH of the aqueous donor phase, were optimized. Under the selected conditions (injection of a mixture of 1 mL of acetone as disperser solvent and 50 μL of chloroform as extraction solvent, no salt addition and no pH adjustment) the figures of merit of the proposed DLLME-GC-MS method were evaluated. High enrichment factors, ranging between 230 and 314 depending on the target analyte, were achieved, which redound to limits of detection in the ng L⁻¹ range (i.e., 4-33 ng L⁻¹). The relative standard deviation (RSD) was below 5% for all the target analytes. Finally, the recoveries obtained for different water samples of diverse origin (sea, river, irrigation channel and water treatment plant) ranged between 87 and 116%, thus showing no matrix effects.     

Chemometric tools improving the determination of anti-inflammatory and antiepileptic drugs in river and wastewater by solid-phase microextraction and liquid chromatography diode array detection

An analytical method for the simultaneous determination of seven non-steroidal anti-inflammatory drugs (naproxen, ketoprofen, diclofenac, piroxicam, indomethacin, sulindac and diflunisal) and the anticonvulsant carbamazepine in river and wastewater is reported. The method involves pre-concentration and clean-up by solid-phase microextraction using polydimethylsiloxane/divinylbenzene fibers, followed by liquid chromatography with diode array detection analysis. Owing to the fact that river water samples did not contain interferences and no sensitivity changes due to sample matrix were observed, external calibration was implemented. Standardization was also applied in order to carry out the prediction step by preparing only two diluted standards that were subjected to the pre-concentration step and a set of standards prepared in solvent. For the analysis of wastewater samples, in contrast, it was necessary to implement standard addition calibration in combination with the multivariate curve resolution-alternating least squares (MCR-ALS) algorithm, which allowed us to overcome matrix effect and exploit the second order advantage. Recoveries ranging from 72% to 125% for all pharmaceuticals proved the accuracy of the proposed method in river water samples. On the other hand, wastewater sample recoveries ranged from 83% to 140% for all pharmaceuticals, showing an acceptable performance – considering this sample contains no modeled interferences.     

Determination and comparison of polybrominated diphenyl ethers in primary,secondary, and tertiary wastewater treatment plants

A concurrent comparison of the concentration, occurrence, and removal efficiency of polybrominated diphenyl ethers (PBDEs) in wastewater from primary, secondary and tertiary wastewater treatment plants was examined. The study area was composed of all three types of wastewater treatment plants in two countries, the United States of America and Mexico. Nineteen PBDEs were analyzed by an environmentally friendly technique, Stir Bar Sorptive Extraction coupled with thermal desorption and gas chromatography and mass spectrometry. This method required no organic solvent and was proven to be effective and sensitive. The most detected PBDEs found in wastewater influent and effluent were BDE-47, BDE-99, BDE-100 and BDE-119. The total concentration of PBDEs (∑BDE_{47,99,100,119}) in the influents ranged from 115.3 to 595.0?ng?L^?1, and from below method detection limit to 388.2?ng?L^?1 in the effluent. It was observed that tertiary treatment was the most effective process to remove BDE-47, 99, and 100, while the primary treatment only rendered an average of 27% removal of total PBDEs. Owing to the incomplete removal in wastewater processes, PBDEs are constantly released into the environment, which implies possible hazardous effects on the environment and human health.     

Analysis of tetrabromobisphenol A and other phenolic compounds in water samples by non-aqueous capillary electrophoresis coupled to photodiode array ultraviolet detection

Non-aqueous capillary electrophoresis (NACE) with large-volume sample stacking injection using the electroosmotic flow pump (LVSEP) has been developed for the determination of tetrabromobisphenol A (TBBPA) and other phenolic compounds in environmental matrices. Methanol has been used as run buffer solvent to reduce the electroosmotic flow (EOF). Identification and quantification of the analytes was performed by photodiode array ultraviolet detection. LVSEP-NACE improved sensitivity of the peak height by 90-300-fold. The method developed was applied to the analysis of TBBPA in river water and wastewater samples, using solid-phase extraction (SPE) as sample pretreatment process. The average recoveries of the analytes were in the range of 96-106% and 73-103% for 1 L of river water and 0.5 L of wastewater samples, respectively. When the method was based on off line SPE-LVSEP-NACE, sensitivity was improved by 3300-4500-fold and 1600-2200-fold for river water and wastewater samples, respectively.     

The maintenance of the second-order advantage: second-order calibration of excitation-emission matrix fluorescence for quantitative analysis of herbicide napropamide in various environmental samples

A rapid non-separative spectrofluorometric method based on the second-order calibration of excitation-emission matrix (EEM) fluorescence was proposed for the determination of napropamide (NAP) in soil, river sediment, and wastewater as well as river water samples. With 0.10 mol L⁻¹ sodium citrate-hydrochloric acid (HCl) buffer solution of pH 2.2, the system of NAP has a large increase in fluorescence intensity. To handle the intrinsic fluorescence interferences of environmental samples, the alternating penalty trilinear decomposition (APTLD) algorithm as an efficient second-order calibration method was employed. Satisfactory results have been achieved for NAP in complex environmental samples. The limit of detection obtained for NAP in soil, river sediment, wastewater and river water samples were 0.80, 0.24, 0.12, 0.071 ng mL⁻¹, respectively. Furthermore, in order to fully investigate the performance of second-order calibration method, we test the second-order calibration method using different calibration approaches including the single matrix model, the intra-day various matrices model and the global model based on the APTLD algorithm with nature environmental datasets. The results showed the second-order calibration methods also enable one or more analyte(s) of interest to be determined simultaneously in the samples with various types of matrices. The maintenance of second-order advantage has been demonstrated in simultaneous determinations of the analyte of interests in the environmental samples of various matrices.