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Biomedical subjects

D Barceló

Publications and source records attributed to D Barceló.

At least 73 records · Page 4Linked to original sources
PubMed2000

Determination of anionic and nonionic surfactants, their degradation products, and endocrine-disrupting compounds in sewage sludge by liquid chromatography/mass spectrometry.

A comprehensive analytical method based on reversed-phase liquid chromatography and mass spectrometry using both atmospheric pressure chemical ionization and electrospray ionization has been developed for the simultaneous determination of anionic and nonionic surfactants, their polar degradation products, and endocrine-disrupting compounds (EDCs) in sewage sludge. Extraction of target compounds, with recovery rates from 86% to nearly 100% for polyethoxylates and from 84 to 94% for polar degradation products, was achieved applying ultrasonic solvent extraction with a mixture of methanol/ dichloromethane (7:3, v/v). Cleanup of sample extracts was performed on octadecyl solid-phase extraction cartridges. Determination of less polar compounds: alcohol ethoxylates (AEOs), nonylphenol ethoxylates (NPEOs), coconut diethanol amides, poly(ethylene glycol)s, and phthalate esters was accomplished by reversed-phase LC-APCI-MS in positive ionization mode, while more polar compounds: nonylphenolcarboxylates, nonylphenol (NP), octylphenol, and bisphenol Awere analyzed by ion-pair LC-ESI-MS under negative ionization conditions. This protocol was successfully applied to the trace determination of anionic and nonionic surfactants, polar degradation products, and EDCs in sewage sludge collected from different sewage treatment plants. The analysis revealed the presence of NP at high concentration levels ranging from 25 to 600 mg/kg. Polyethoxylates (AEOs and NPEOs) were also found in all samples at parts-per-million levels (10-190 mg/kg AEOs and 2-135 mg/kg NPEOs, respectively).

Chromatography, Liquid↗
PubMed2000

Determination of steroid sex hormones and related synthetic compounds considered as endocrine disrupters in water by liquid chromatography-diode array detection-mass spectrometry.

In this study, a procedure for the determination of various naturally occurring hormones and of some related synthetic chemicals, commonly used for birth control and treatment of certain hormonal disorders and cancers, in water is described. The procedure includes solid-phase extraction of 0.5 l of water and subsequent analysis of the extract by liquid chromatography with diode array detection and mass spectrometric detection in series (LC-DAD-MS). DAD has been performed at 197, 225, and 242 nm for quantification and confirmatory identification purposes. For MS detection two interfaces--electrospray and atmospheric pressure chemical ionization--in both the positive and the negative ion mode have been tested and the MS parameters influencing the MS signal optimized. DAD and MS have been intercompared for selectivity, sensitivity, precision, and linearity of response. Selected conditions have been applied to the determination of six estrogens (17beta-estradiol, estriol, estrone, ethynylestradiol, mestranol, and diethylstilbestrol) and four progestogens (progesterone, levonorgestrel, norethindrone and ethynodiol diacetate) in several types of water bodies, including sewage influents and effluents, surface water and drinking water. Recoveries greater than 83% and detection limits in the ng/l range have been achieved for most compounds.

Chromatography, Liquid↗
PubMed2000

Solid-phase extraction of polar hydrophilic aromatic sulfonates followed by capillary zone electrophoresis-UV absorbance detection and ion-pair liquid chromatography-diode array UV detection and electrospray mass spectrometry.

A comprehensive comparison of four different polymeric solid-phase extraction (SPE) materials for the extraction of 22 different aromatic sulfonates of environmental concern was performed. The investigated adsorbents were the polystyrene-divinylbenzene materials LiChrolut EN from Merck, Isolute ENV+ from International Sorbent Technology, HR-P from Macherey-Nagel and the new Oasis HLB poly(divinylbenzene-co-N-vinylpyrrolidone) copolymer from Waters. Different SPE parameters like the elution solvent and the drying step of the cartridges were optimized. Analyses were performed by capillary zone electrophoresis-UV absorbance detection (CZE-UV) and ion-pair liquid chromatography-diode array UV detection coupled in series with electrospray mass spectrometry (IP-LC-DAD-ESI-MS) in the negative ionization mode. LC-MS offers a higher separation efficiency than CZE. The best adsorbents were LiChrolut EN and HR-P followed by Isolute ENV+ and Oasis HLB. The recoveries for most of the onefold negatively charged aromatic sulfonates were >50% for the extraction from spiked ground water at 50 microg/l. Recoveries for LiChrolut EN and HR-P were approximately 20% higher than for Isolute ENV+. Very hydrophilic sulfonates containing more than one negative sulfonate group could not be extracted by any of the tested adsorbents.

Calibration↗
PubMed2000

Determination of glucosinolates in rapeseed and Thlaspi caerulescens plants by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

Liquid chromatography-atmospheric pressure chemical ionization mass spectrometry was used to identify glucosinolates in plant extracts. Optimization of the analytical conditions and the determination of the method detection limit was performed using commercial 2-propenylglucosinolate (sinigrin). Optimal values for the following parameters were determined: nebulization pressure, gas temperature, flux of drying gas, capillar voltage, corona current and fragmentor conditions. The method detection limit for sinigrin was 2.85 ng. For validation of the method the glucosinolates in reference material (rapeseed) from the Community Bureau of Reference Materials (BCR) were analyzed. The method was applied for the determination of glucosinolates in Thlaspi caerulescens plants.

Atmospheric Pressure↗
PubMed2000

Inter-laboratory comparison of liquid chromatographic techniques and enzyme-linked immunosorbent assay for the determination of surfactants in wastewaters.

Seven laboratories participated in an inter-laboratory comparison exercise within the framework of the PRISTINE, SANDRINE and INEXsPORT European Union Projects. Solid-phase extraction (SPE) methodologies were used for the extraction of target analytes from wastewaters. The analytical strategies were based on liquid chromatography (LC) coupled to mass spectrometric (MS) or to fluorescent (FL) detection in all cases with the exception of one laboratory using a test-tube enzyme-linked immunosorbent assay kit. Samples were spiked with the surfactants nonylphenolpolyglycol ether, coconut diethanolamide, linear alkylbenzene sulfonate, nonylphenolpolyglycol ether sulfate, alkylpolyglycol ether and secondary alkane sulfonate. After enrichment on previously conditioned SPE cartridges, the SPE cartridges were distributed among the participating laboratories without the information about the amount of spiked surfactants. In addition, SPE cartridges loaded with a real-world environmental sample containing a tannery wastewater were also analyzed. The results of the programme showed that SPE followed by LC-MS techniques are reliable for the surfactants determination at submicrogram to microgram per liter levels in wastewaters. Inter-laboratory precision values were calculated as the reproducibility relative standard deviation (RSD(R)) which was determined from the reproducibility standard deviation (sR) and the average concentration at a particular concentration level. When data from all laboratories were pooled, the RSD(R) values ranged from 5.1 to 28.3% for the determination of target analytes. The most accurate result corresponded to that given for linear alkylbenzene sulfonates. Taking into account that different methodologies were used (including non-chromatographic techniques) and the complexity of the samples analyzed, it can be considered that acceptable reproducibility values were obtained in this inter-laboratory study.

Chromatography, Liquid↗
PubMed2000

Determination of linear alkylbenzenesulfonates in wastewater treatment plants and coastal waters by automated solid-phase extraction followed by capillary electrophoresis-UV detection and confirmation by capillary electrophoresis-mass spectrometry.

Linear alkylbenzenesulfonates (LASs) were determined in wastewaters and coastal waters by solid-phase extraction, using two different sample preparation protocols depending on the sample treated, followed by capillary electrophoresis and ultraviolet detection (CE-UV). The linear range of the proposed method varied from 3 to 53 and from 25 to 495 microg/l, depending on the compound, with a limit of detection of 1 microg/l when 250 ml of coastal water was preconcentrated. [M-H]- ions were used for CE-MS confirmation after quantification by CE-UV. CE-MS diagnostic ions were the same ones used in LC-electrospray (ESI) MS and corresponded to m/z 297, 311, 325 and 339 for C10, C11, C12 and C13 LASs, respectively. LASs were determined in wastewater samples of the influent and effluent of three wastewater treatment plants (WWTPs), two of them using biological treatment with secondary settlement and receiving mainly domestic wastewaters whereas one of the plants was operated with physicochemical treatment and received mainly industrial wastewaters. LASs were also analyzed in two samples from coastal waters of the bay of Cadiz (Spain) receiving untreated domestic effluents. All samples were also analyzed by LC-ESI-MS and the results are compared with the CE-UV method developed in this work. The concentration levels of total LASs varied from 988 to 1309 microg/l in the influents of WWTPs, whereas in the effluents the concentrations varied from 136 to 197 microg/l. The levels of LASs in coastal wastewaters of the bay of Cadiz varied from 739 to 911 microg/l, indicating that the wastewaters discharged into the bay did not undergo any treatment at all.

Alkanesulfonic Acids↗
PubMed2000

Stability of sulfonated derivatives of benzene and naphthalene on disposable solid-phase extraction pre-columns and in an aqueous matrix.

The stability of 14 sulfonated benzene and naphthalene compounds was investigated using polymeric solid-phase extraction cartridges, based on the styrene-divinylbenzene polymer Isolute ENV+. Several different storage conditions were tested to carry out the stability study in polymeric cartridges, which included storage at room temperature, at 4 degrees C and at -20 degrees C, during a period of up to 3 months. An additional stability study was carried out, not with the polymeric solid matrix, but in an aqueous matrix. This study was performed storing the samples at 4 degrees C, during 2 months under three different conditions: acidifying the water sample to pH 2.5-3 with sulfuric acid, adding 1% of formaldehyde (additive used in waste water analyses), and storing the water sample at 4 degrees C without any additives. The extraction of the SPE process is analyzed by ion-pair chromatography-electrospray mass spectrometry, in the negative ion mode. This study showed that the stability of polar aromatic sulfonic acids on disposable polymeric cartridges and in the water matrix is related to temperature and pH, respectively. Target aromatic sulfonated compounds stored in polymeric solid-phase extraction cartridges, are more stable at lower temperatures. The target analytes showed also good stability when stored in water at acidic pH. From the different analytes studied, substituted naphthalenesulfonates suffered more degradation than mononaphthalenesulfonates or benzenesulfonates under the experimental conditions of this work.

Benzene↗
PubMed2000

Determination of aldicarb, aldicarb sulfoxide and aldicarb sulfone in some fruits and vegetables using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

An analytical method for the determination of aldicarb, and its two major metabolites, aldicarb sulfoxide and aldicarb sulfone in fruits and vegetables is described. Briefly the method consisted of the use of a methanolic extraction, liquid-liquid extraction followed by solid-phase extraction clean-up. Afterwards, the final extract is analyzed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS). The specific fragment ion corresponding to [M-74]+ and the protonated molecular [M+H]+ ion were used for the unequivocal determination of aldicarb and its two major metabolites. The analytical performance of the proposed method and the results achieved were compared with those obtained using the common analytical method involving LC with post-column fluorescence detection (FL). The limits of detection varied between 0.2 and 1.3 ng but under LC-FL were slightly lower than when using LC-APCI-MS. However both methods permitted one to achieve the desired sensitivity for analyzing aldicarb and its metabolites in vegetables. The method developed in this work was applied to the trace determination of aldicarb and its metabolites in crop and orange extracts.

Aldicarb↗
PubMed2000

Determination of rice herbicides, their transformation products and clofibric acid using on-line solid-phase extraction followed by liquid chromatography with diode array and atmospheric pressure chemical ionization mass spectrometric detection.

A simultaneous method for the trace determination of acidic, neutral herbicides and their transformation products in estuarine waters has been developed through an on-line solid-phase extraction method followed by liquid chromatography with diode array and mass spectrometric detection. An atmospheric pressure chemical ionization (APCI) interface was used in the negative ionization mode after optimization of the main APCI parameters. Limits of detection ranged from 0.1 to 0.02 ng/ml for 50 ml of acidified estuarine waters preconcentrated into polymeric precolumns and using time-scheduled selected ion monitoring mode. Two degradation products of the acidic herbicides (4-chloro-2-methylphenol and 2,4-dichlorophenol) did not show good signal response using APCI-MS at the concentration studied due to the higher fragmentor voltage needed for their determination. For molinate and the major degradation product of propanil, 3,4-dichloroaniline, positive ion mode was needed for APCI-MS detection. The proposed method was applied to the determination of herbicides in drainage waters from rice fields of the Delta del Ebro (Spain). During the 3-month monitoring of the herbicides, 8-hydroxybentazone and 4-chloro-2-methylphenoxyacetic acid were successively found in those samples.

Atmospheric Pressure↗
PubMed2000

Part-per-trillion level determination of antifouling pesticides and their byproducts in seawater samples by off-line solid-phase extraction followed by high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

A new method for the simultaneous determination of antifouling pesticides and some of their byproducts such as dichlofluanid, diuron and its byproducts [demethyldiuron and 1-(3,4-dichlorophenyl)urea], (2-thiocyanomethylthio)ben: zothiazole, chlorothalonil, Sea-nine 211, Irgarol 1051 and one of its byproducts (2-methylthio-4-tert.-butylamino-s-triazine) in seawater was developed. The extraction of these compounds from the filtered seawater samples was performed off-line with different solid-phase extraction sorbents using (I) a 500 mg graphitized carbon black cartridge (ENVI-Carb) and (II) 200 mg polymeric cartridges (LiChrolut EN and Isolute ENV+) and passing 500 ml of the sample through these cartridges. The detection was carried out by reversed-phase high-performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry both in the negative and positive ion modes. The recovery ranged from 76 to 96% for the whole antifouling group with the ENVI-Carb cartridges and the detection limit was at the part-per-trillion level except for TCMTB. The method utilizing the polymeric cartridge proved to be very useful, time saving and with good recoveries when only Irgarol and its byproduct, Sea-nine 211 and diuron and its byproducts, have to be analyzed. The different cartridges were applied to the analysis of these pesticides in different marinas of the Catalan coast; diuron, dichlofluanid, Sea-nine 211, Irgarol as well as demethyldiuron and the Irgarol byproduct being the must ubiquitous pollutants. Maximum concentration levels were 2-3.5 microg/l of diuron and Sea-nine 211, respectively.

Atmospheric Pressure↗
PubMed2000

Monitoring of priority pesticides and other organic pollutants in river water from portugal by gas chromatography-mass spectrometry and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-APCI-MS) were optimized and applied for the trace-level determination of 42 priority pesticides and 33 priority organic pollutants from European Union Directive EC 76/464. First, off-line solid-phase extraction of 200 ml of river water using an OASIS solid-phase extraction cartridge, followed by GC-MS was used. Next, selected samples that were positive to GC-MS were analyzed by LC-APCI-MS in order to detect further polar byproducts or to improve the determination of previously detected polar analytes. The transformation products of triazine pesticides like deethylatrazine (DEA) and deisopropylatrazine (DIA) and compounds such as diuron and several chlorophenols were positively identified by LC-APCI-MS. The present methodology has also been used for searching for new analytes not included in the EC 76/464 list, like Irgarol, DEA and DIA. In addition it was applied to target pollutants in 43 river water samples from Portugal during a pilot survey from April to July 1999. Atrazine followed by simazine and 2,4,6-trichlorophenol were the most ubiquitous compounds detected in this area. The levels detected of the different compounds were in the range of: 0.01-2.73 microg/l, 0.05-0.74 microg/l, 0.02-1.65 microg/l, 0.02-5.43 microg/l, 0.01-0.40 microg/l, 0.01-0.26 microg/l, 0.02-0.61 microg/l, 0.01-3.90 microg/l, 0.01-1.24 microg/l, 0.02-2.3 microg/l, 0.01-0.13 microg/l and 0.01-0.5 microg/l for atrazine, simazine, terbuthylazine, alachlor, metolachlor, Irgarol, propanil; tributhylphosphate, diuron, 2,4,6-trichlorophenol, deisopropylatrazine and deethylatrazine, respectively.

Atmospheric Pressure↗
PubMed2000

Analysis of polar hydrophilic aromatic sulfonates in waste water treatment plants by CE/MS and LC/MS.

The present work describes the development and optimization of a capillary (zone) electrophoresis/mass spectrometric (CE/MS) analysis method for polar hydrophilic aromatic sulfonates (ASs). The compounds were detected by negative ion electrospray ionization (NIESI) and selected ion monitoring (SIM). In comparison with CE/UV, for CE/MS a lower-concentration volatile ammonium acetate buffer (5 mM) without organic modifier and a higher separation voltage were better suited for separation. Sensitivity of CE/MS was slightly better than for CF/UV, with the limit of detection (LOD) ranging between 0.1 and 0.4 mg l(-1). For verification of the CE/MS results, ASs were also analysed by ion-pair liquid chromatography/diode array UV detection coupled in series with electrospray mass spectrometry (IPC/DAD/ESI-MS). Real water samples of different waste water treatment plants (WWTPs) in Catalonia (NE Spain) were extracted by solid-phase extraction (SPE) with LiChrolut EN and analysed with CE/MS and LC/MS. ASs were found in influent and effluent water samples of the WWTPs in the microg l(-1) concentration range. LC/MS offered a higher separation efficiency and sensitivity than CE/MS. Therefore with LC/MS more compounds could be identified in the WWTPs. The persistency of the ASs was distinct: some compounds were well degraded during the water treatment process, while others were quite persistent.

Arylsulfonates↗
PubMed2000

The stability of non-ionic surfactants and linear alkylbenzene sulfonates in a water matrix and on solid-phase extraction cartridges.

The stability of nonylphenol ethoxylates (NPEO), alcohol ethoxylates (AEO), coconut diethanol amides (CDEA) and linear alkylbenzene sulfonates (LAS) in a water matrix and preconcentrated on SPE cartridges was studied. A stability study was carried out in a water matrix (spiked ground water and real-world waste water) comparing different pretreatment procedures (addition of sulfuric acid to pH = 3, preservation with 1% and 3% of formaldehyde). When stored in a water matrix serious qualitative and quantitative changes occurred in waste water during the period of time studied (30 days). The losses of C12-C14 alcohol ethoxylates ranged from 72% to 88% when the sample was preserved with acid and from 17% to 86% when the sample was preserved with formaldehyde (3%). Simultaneously, an enrichment of the shorter alkyl chain homologues (C7EO and C10EO) was observed. The losses of NPEO were from 45% (sample preserved by acidification or by addition of 3% of formaldehyde) to 85% (sample preserved with 1% of formaldehyde). Additionally, an increase in concentration of polyethylene glycols (PEGs) and formation of different acidic forms, such as monocarboxylated (MCPEGs) and dicarboxylated polyethylene glycols (DCPEGs) were observed. The stability of surfactants preconcentrated on SPE cartridges was studied as a function of storage time and storage conditions (room temperature, 4 degrees C and -20 degrees C). The results indicate that disposable SPE cartridges can be recommended for the stabilization of non-ionic surfactants and LAS. Storage at -20 degrees C is feasible for long periods (up to 3 months for ground water and up to 2 months for waste water), while storage at 4 C can be recommended for a maximum of 1 month. When cartridges were kept at -20 degrees C the losses of AEOs (n = 12, 13 and 14), preconcentrated from waste water, ranged from 17 to 29% (after 60 days) and other compounds suffered small losses (maximum of 14% for C13LAS). At room temperature, after 7 days, the losses were less than 11%, indicating that shipping of samples by mail can be done without any special requirements.

Alkanesulfonates↗
PubMed2000

Vitellogenin induction and other biochemical responses in carp, Cyprinus carpio, after experimental injection with 17 alpha-ethynylestradiol.

Prespawning, adult male and female carp, Cyprinus carpio, were intraperitoneally injected with a single dose of 500 microg/kg of 17alpha-ethynylestradiol (EE2). Blood samples were taken and vitellogenin levels were recorded previous to the injection and 8 days afterward. Western blot analysis of plasma VTG showed a marked response in both males (90-fold) and females (67-fold) after EE2 injection. Also, a significant inhibition of the cytochrome P450 monooxygenase system, namely, 7-ethoxyresorufin O-deethylase (EROD) activity, as well as immunodetected CYP1A protein was observed in the EE2-injected fish. Other cytochrome P450 isozymes, such as CYP3A or NADH cyt (b5) reductase, did not indicate any particular trend; whereas NADPH cyt (P450) reductase was significantly induced in EE2-injected animals. Total cytochrome P450, glutathion S-transferase (GST), and total glutathion peroxidase (GPX) fluctuated in a similar manner, but differences among treated and nontreated animals were not statistically significant. UDP glucuronyl transferase (UDPGT), similar to the antioxidant enzymes catalase, superoxide dismutase (SOD), and Se-GPX, progressively decreased in carrier and injected animals in comparison to the controls, although this trend did not reach statistical significance either.

Animals↗
PubMed2000

Determination of non-ionic surfactants and polar degradation products in influent and effluent water samples and sludges of sewage treatment plants by a generic solid-phase extraction protocol.

Non-ionic polyethoxylated surfactants (nonylphenol polyethoxylates, alcohol polyethoxylates), their breakdown products (polyethylene glycol, polyethoxylated nonylphenol carboxylates and polyethoxylated alcohol carboxylates) and other compounds were identified and measured in various waste-water treatment samples (influent, effluent and sludge). A generic protocol involving the use of sequential solid-phase extraction (SSPE) with octadecylsilica and styrene-divinylbenzene cartridges in series and differential elution was used. Fractionated extracts were analyzed by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionization (APCI) in the positive and negative ionization modes. For sewage treatment plant (STP) sludge, the extraction protocol involved lyophilization of the sludge followed by sonication with MeOH-CH2Cl2 (7 + 3) and final clean-up using the SSPE protocol. Limits of detection for target analytes ranging from 1.1 to 4.1 micrograms L-1 for water samples and from 0.11 to 0.28 mg kg-1 for sludge were achieved. The results obtained demonstrated the inefficient removal of the target analytes in physico-chemical STPs whereas their elimination factors in STPs with biological treatment reached average values of 77, 92 and 98% for alcohol polyethoxylates, nonylphenol polyethoxylates (NPEOs) and polyethylene glycols (PEGs), respectively. Quantitative elimination of coconut fatty acid diethanolamide (CDEA) surfactants in the activated sludge process occurred. In contrast, total removal of NPEOs led to the formation of persistent and toxic metabolites such as nonylphenol which was present in treated effluent as well as in sludge samples with average concentrations ranging from 15.0 to 251.2 micrograms L-1 and from 13.5 to 74.2 mg kg-1, respectively. Polyethoxylated carboxylates and short chain NPEOs were also detected at similar levels in the effluents and sludges. In addition, a linear correlation between the total phenolic concentration (Total Ph) measured by the 4-aminoantipyrine method and the total concentration of nonylphenolic compounds (Total NP) measured by SSPE-LC-APCI-MS was observed.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

Efficient solid-phase extraction procedures for trace enrichment of priority phenols from industrial effluents with high total organic carbon content.

Polymeric solid-phase extraction (SPE) cartridges and Speedisks were used to extract 17 phenols from HPLC-grade water, tap water, river water and industrial effluents. With SPE cartridges, recoveries between 60 and 120% were obtained for waters with a total organic carbon (TOC) content below 20 mg C/l. However, when extracting industrial effluent waters with higher TOC values (75 mg C/l), only the polar phenols were recovered from the water fraction. Nonpolar compounds (di-, tri- and tetrachlorophenols) remained attached to the particulate matter and were recovered from the 0.45-microm filter membrane disks by Soxhlet extraction. Speedisks offered a high efficiency and permitted one to extract phenols without a prior filtration step. Acceptable recoveries were obtained when processing heavily charged industrial effluents with a TOC of 505 mg C/l. Liquid chromatography with electrochemical detection was used for the routine determination of 17 priority phenols.

Carbon↗
PubMed1999

Identification of polar toxicants in industrial wastewaters using toxicity-based fractionation with liquid chromatography/mass spectrometry.

An efficient and novel method for the identification of toxic compounds in industrial wastewater was developed. In the first step, the samples collected were tested for toxicity using the recently developed ToxAlert 10 system based upon luminescence inhibition of freeze-dried Vibrio fischeri. In the second step, sequential solid-phase extraction (SSPE) and liquid chromatography/mass spectrometry (LC/MS) for compound identification were employed to isolate and identify compounds in the waters. Average recoveries ranging from 72 to 95% were obtained using the SSPE methodology for ubiquitous analytes such as poly(ethylene glycol)s, nonylphenol and alcohol polyethoxylates, phenols, linear alkylbenzenesulfonates, and benzene- and naphthalenesulfonates. In the third step, all the extracts obtained after SSPE followed by LC/MS identification were tested again with the ToxAlert system. The procedure was applied to influent and effluent samples of a sewage treatment plant (STP) and to a raw tannery effluent that constitutes the main type of influent in the receiving waters of the STP. This method has shown that, despite the complexity of the untreated tannery wastewaters with an average total organic carbon (TOC) value of 1960 mg of C/L, the biological treatment of the STP eliminates compounds that inhibit luminiscence of V. fischeri. In the final step, the chemical toxicity of the tentatively identified chemicals was tested to identify the toxicants in the waters. Comparison of the toxicities of the sample, the extracts, and individual components has shown that diverse classes of pollutants were responsible for toxicity, as all fractions of toxic samples gave significant bioluminescence inhibition values. Toxicity of the two intermediate-polarity SSPE fractions was attributed to alcohol ethoxylates, nonylphenol ethoxylates, bis(2-ethylhexyl)phthalate, and linear alkylbenzenesulfonates. In the most nonpolar and most polar fractions, identification of the compounds responsible for toxicity was unclear. By the toxicity-based fractionation, followed by LC/MS methodology, it was feasible to identify between 1.4 and 7.5% of the TOC, thus expanding the number of toxicants identified in these complex wastewaters as compared to those identified by conventional gas chromatography/mass spectrometric (GC/MS) methods. When artificial water samples were reconstituted using similar concentrations of the chemicals detected in the wastewaters, nonsynergetic toxicity effects were observed for all analytes with the exception of 2,6-naphthalenedisulfonate (2,6-NPS), which promoted the bioluminescence inhibition. The toxicity-directed identification was successful for the STP's samples and showed 1400 times higher toxicity for the raw tannery wastewaters as compared to the mixed industrial and domestic wastewaters by applying the Weibull model.

Chromatography, Liquid↗