Determination of alkyl, chloro and mononitrophenols in water by sample-acetylation and automatic on-line solid phase extraction-gas chromatography-mass spectrometry

Separation of Polyphenols from Jordanian Olive Oil Mill Wastewater

This research aims at separation of polyphenols from Jordanian olive mill wastewater which have possible applications in pharmaceutical industry. The phenolic compounds were isolated using silica column chromatography based on using different solvents after extracting the acidified solution with n-hexane and ethyl acetate. The structural elucidation of the separated compounds was achieved using 1H-NMR, 13C-NMR and mass spectrometry. The concentrations of these compounds were determined by GC-MS after derivatization with N, O-bis(trimethylsilyl)trifluoroacetamide (BSTFA). The concentrations of the main isolated phenolic compounds in the Jordanian olive mill wastewater were ferulic acid (93.6 mg/L), trans-cinnamic acid (105.3 mg/L), p-coumaric acid (117.0 mg/L), vanillic acid (128.7 mg/L), caffeic acid (140.4 mg/L), tyrosol (210.6 mg/L), and hydroxytyrosol (315.9 mg/L).

Determination of endocrine disrupting compounds using temperature-dependent inclusion chromatography: I. Optimization of separation protocol

In the present work we optimised the separation of battery of key UV non-transparent low-molecular-mass compounds having possible endocrine disrupting compounds (EDCs) activity or which may be used as the endocrine effect biomarkers. Simple optimization strategy was based on strong temperature effect that is driven by electrostatic interactions between macrocyclic mobile phase additives like cyclodextrins and eluted components of interest under C18 stationary phase and acetonitrile/water mobile phase conditions. Particularly, the effect of temperature involving native beta-cyclodextrin and its hydroxypropyl derivative to improve separation of number of natural (d-equilenin, equilin, estetrol, estriol, estrone, 17beta-estradiol, 17alpha-hydroxyprogesterone, 20alpha-hydroxyprogesterone, cortisol, cortisone, progesterone, testosterone, tetrahydrocortisol and tetrahydrocortisone) and artificial steroids (ethynylestradiol, norgestrel isomers, medroxyprogesterone, mestranol, methyltestosterone, norethindrone, 17alpha-estradiol) as well as non-steroidal compounds (diethylstilbesterol, bisphenol A, 4-tert-butylphenol, dimethyl phthalate, dibutyl phthalate and dioctyl phthalate) was investigated. It has been found that successful isocratic separation of 27 chemicals can be achieved using acetonitrile/water eluents modified with beta-cyclodextrin or hydroxypropyl-beta-cyclodextrin at concentration of 10 mM and temperature of 47 degrees C. Separation protocol is simple, reliable, direct and non-radioactive and may be easily adapted for rapid separation and quantification of wide range of given steroids and related EDCs in environmental samples, particularly those that are characterised by unstable biological matrix and components of interest load.

Principles, developments and applications of on-line coupling of extraction with chromatography

On-line coupling of extraction and chromatographic separation allows the whole analysis to be performed in a closed system. On-line systems are particularly useful when the analytes are labile, the amount of sample is limited, or very high sensitivity is required. Many on-line systems have been developed both for liquid and for solid samples. This review discusses the different instruments that have been constructed and the factors that need to be considered in the coupling. Selected illustrative applications are described to illustrate the potential of the on-line systems.

Injection Port Derivatization Following Ion-Pair Hollow Fiber-Protected Liquid-Phase Microextraction for Determining Acidic Herbicides by Gas Chromatography/Mass Spectrometry

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction (LPME) for the trace determination of acidic herbicides (2,4-dichlorobenzoic acid, 2,4-dichlorophenoxyacetic acid, 2-(2,4-dichlorophenoxy)propionic acid, 3,5-dichlorobenzoic acid, 2-(2,4,5-trichlorophenoxy)propionic acid) in aqueous samples by gas chromatography/mass spectrometry (GC/MS) was developed. Prior to GC injection port derivatization, acidic herbicides were converted into their ion-pair complexes with tetrabutylammonium chloride in aqueous samples and then extracted by 1-octanol impregnated in the hollow fiber. Upon injection, ion pairs of acidic herbicides were quantitatively derivatized to their butyl esters in the GC injection port. Thus, several parameters related to the derivatization process (i.e., injection temperature, purge-off time) were evaluated, and main parameters affecting the hollow fiber-protected LPME procedure such as extraction organic solvent, ion-pair reagent type, pH of aqueous medium, concentration of ion-pair reagent, sodium chloride concentration added to the aqueous medium, stirring speed, and extraction time profile, optimized. At the selected extraction and derivatization conditions, no matrix effects were observed. This method proved good repeatability (RSDs <12.3%, n = 6) and good linearity (r2 > or = 0.9939) for spiked deionized water samples for five analytes. The limits of detection were in the range of 0.51-13.7 ng x L(-1) (S/N =3) under GC/MS selected ion monitoring mode. The results demonstrated that injection port derivatization following ion-pair hollow fiber-protected LPME was a simple, rapid, and accurate method for the determination of trace acidic herbicides from aqueous samples. In addition, this method proved to be environmentally friendly since it completely avoided open derivatization with potentially hazardous reagents.

Determination of trace concentrations of bromophenols in water using purge-and-trap after in situ acetylation

An analytical method that enables detection and quantification of bromophenols (BPs) at taste threshold concentrations (2,6-DBP: 0.5 ng/L) was developed. This method involves conversion of the BPs to their acetates, followed by isolation of the acetates by a modified purge-and-trap procedure, and analysis by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Bromophenyl acetates were synthesized so that each of the two steps in the method could be developed and optimised in isolation to the other. Deuterated BPs (phenol-d5, 2-BP-d4, 4-BP-d2, 2,6-DBP-d3, 2,4-DBP-d3 and 2,4,6-TBP-d2) were synthesized to enable quantification of analytes using the deuterated analogues of analytes as internal standards. This method allowed quantification of BPs at concentrations ranging from the detection limits (3 ng/L for phenol and 0.1-0.5 ng/L for each of the BPs) to 1000 ng/L for each analyte, with repeatabilities of < or =14% (RSD) for concentrations of 1 ng/L and < or =9% (RSD) for concentrations of 10-1000 ng/L, with recoveries ranging from 91 to 97%.

Polymer-coated hollow-fiber microextraction of estrogens in water samples with analysis by gas chromatography–mass spectrometry

A novel sorbent, dihydroxylated polymethylmethacrylate (DHPMM), coated on hollow-fiber membrane, is used for the polymer-coated hollow-fiber microextraction of trace amounts of natural and synthetic estrogens, such as diethylstilbestrol, estrone, 17beta-estradiol and 17alpha-ethynylestradiol, in aqueous samples. In this procedure, estrogens were extracted using the functionalized polar DHPMM polymer with derivatization using N-methyl-N-(trimethylsilyl)trifluoroacetamide followed by gas chromatography-mass spectrometric analysis. The detection limits for estrogens in aqueous sample were between 0.03 and 0.8 ng l(-1) and the calibration curves were linear over the concentration range 0.05-10 microgl(-1) and had correlation coefficients of >0.994. The relative standard deviations (RSDs) were <15% (n = 3). This simple, accurate, sensitive and selective analytical method is applicable to the determination of trace amounts of estrogens in reservoir and potable water samples.

Simultaneous determination of alkylphenols and bisphenol A in river water by stir bar sorptive extraction with in situ acetylation and thermal desorption–gas chromatography–mass spectrometry

A method for the determination of seven alkylphenols and bisphenol A by stir bar sorptive extraction (SBSE) with in situ derivatization-thermal desorption (TD)-gas chromatography (GC)-mass spectrometry (MS) is described. SBSE was performed with in situ acetylation and without derivatization for comparison. For 4-tert-butylphenol and bisphenol A, in situ acetylation improved the responses in SBSE-TD-GC-MS. The method detection limits ranged from 0.1 to 3.2 ng/l. The recoveries of the analytes from a river water sample spiked with standards at 10 and 100 ng/l were 85.3-105.9% (R.S.D., 3.0-11.0%) and 88.3-105.8% (R.S.D., 1.6-8.3%), respectively.

Determination of natural and synthetic estrogens in water by gas chromatography with mass spectrometric detection

A procedure for the determination of six natural and synthetic estrogens (diethylstilbestrol, estrone, 17beta-estradiol, mestranol, 17alpha-ethinylestradiol and estriol) in water samples is described. Samples, up to 2000 ml, were concentrated using Oasis HLB solid-phase extraction cartridges. Analytes were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide and determined by GC-MS or GC-MS-MS. The reactivity of several silylation reagents versus aliphatic and aromatic hydroxyl groups contained in the structure of the selected analytes was evaluated. Influence of parameters such as sample pH, nature of the water samples and derivatization conditions on the performance of the whole analytical procedure was systematically studied. Under optimal conditions, quantification limits between 1 and 3 ng/l were achieved for the determination of the considered estrogens in sewage water.

Recent advances in the mass spectrometric analysis related to endocrine disrupting compounds in aquatic environmental samples

An overview of mass spectrometric methods used for the determination of endocrine disrupting compounds (EDCs) in environmental samples is presented. Among the EDCs we have selected five groups of compounds that are of priority within European Union and US research activities: alkylphenols, polychlorinated compounds (dioxins, furans and biphenyls), polybrominated diphenyl ethers, phthalates and steroid sex hormones. Various aspects of current LC-MS and GC-MS methodology, including sample preparation, are discussed.

Determination of phenols in landfill leachate-contaminated groundwaters by solid-phase extraction

A solid-phase extraction method for phenols in landfill leachates was developed and optimized in order to solve the expected and observed problems associated with an anaerobic matrix containing high concentrations of salts and organic matter. Isolute ENV+ cartridges exhibited the best retention of phenols of the four sorbents examined, and was the only cartridge which a 1 L leachate sample could pass through. With the other cartridges, clogging made this impossible. The final method, which included 27 different phenols, gave detection limits of <0.1 microg/L (drinking water concentration limit for pesticides) for most phenols (25), and for 12 phenols <0.01 microg/L. Recovery rates (determined for four concentrations in the range 1-25 microg/L, two replicates of each) were in the range 79-104% (SD 1-12%), except for phenol (26+/-1.3%) and 2-methoxyphenol (62+/-4.2%). Up to 12 different phenols could be identified in leachates from three Danish landfills, ranging in concentration from 0.01 to 29 microg/L, which is at the lower end of the concentration range usually found for phenols in landfill leachates (sub-microg/L to mg/L).

Sensitive determination of bisphenol A and alkylphenols by high performance liquid chromatography with pre-column derivatization with 2-(4-carboxyphenyl)-5,6-dimethylbenzimidazole

A new and sensitive high-performance chromatographic method for the determination of bisphenol A and 8 alkylphenols with fluorescence detection is reported. Each phenol was derivatized by reaction with 2-(4-carboxyphenyl)-5,6-dimethylbenzimidazole at 40 degrees C for 60 min. The fluorescence derivatives were separated on a Wakosil 5C18 column (4.0 i.d. x 300 mm, 5 microm) with methanol:water (10:90) as mobile phase (detection wavelength: lambda(ex) 336 nm, lambda(em) 440 nm). The detection limits were in the range of 0.1-10.0 pg/mL in serum. The calibration graphs were linear to 1.0 microg/mL. The relative standard deviations were 7.2-8.9%, respectively. The proposed method was applied to the determination of bisphenol A in mother and infant rat serum.

Liquid-liquid-liquid microextraction of nitrophenols with a hollow fiber membrane prior to capillary liquid chromatography

A simple liquid-liquid-liquid microextraction device utilizing a 2 cm x 0.6 mm I.D. hollow fiber membrane was used to preconcentrate nitrophenols from water sample prior to capillary liquid chromatography (cLC) analysis. The extraction procedure was induced by the pH difference inside and outside the hollow fiber. The donor phase outside the hollow fiber was adjusted to pH approximately 1 with HCl; the acceptor phase was NaOH solution used at various concentrations. Organic solvent was immobilized into the pores of the hollow fiber. With stirring, the neutral nitrophenols outside the fiber were extracted into the organic solvent, then back extracted into 2 microl of basic acceptor solution inside the fiber. The acceptor phase was then withdrawn into a microsyringe and injected into the cLC system directly. This technique used a low-cost disposable extraction "device" and is very convenient to operate. Up to 380-fold enrichment of analytes could be achieved. This procedure could also serve as a sample clean-up step because large molecules and basic compounds were not extracted into the acceptor phase. The RSD (n=6) was less than 6.2%, while the linear calibration range was from 1 to 200 microg/ml with r>0.998. The procedure was applied to the analysis of seawater.

Determination of steroid sex hormones and related synthetic compounds considered as endocrine disrupters in water by fully automated on-line solid-phase extraction-liquid chromatography-diode array detection

In this study, a procedure for the simultaneous determination in water of six estrogens (estradiol, estriol, estrone, ethynyl estradiol, mestranol, and diethylstilbestrol) and three progestogens (progesterone, norethindrone, and levonorgestrel), selected based on their abundance in the human body, their estrogenic potency, and the extent of their use in contraceptive pills, was developed. The procedure, based on the on-line solid-phase extraction (SPE) of the water sample and subsequent analysis by liquid chromatography/diode array detection (LC/DAD), allows for the monitoring of up to 16 samples in a completely automated, unattended way. The SPE experimental conditions were optimized and the polymeric cartridge PLRP-S selected out of four different cartridges evaluated. The chromatographic separation was carried out on a LiChrospher 100 RP-18 and detection was performed at 200, 225, and 240 nm. The applicability of the method to the analysis of various environmental water samples, including drinking water, groundwater, surface water and sewage treatment plant effluents, was evaluated. Method detection limits were in the range 10-20 ng/l. The method precision and accuracy were satisfactory with recovery percentages ranging from 96 to 111% and relative standard deviations lower than 3%. The technique is also considerably cheap, fast, and easy, and, therefore, very adequate for routing monitoring. To the authors' knowledge it constitutes the first work describing a fully automated, on-line methodology for the continuous monitoring of these compounds in water.

Cloud point preconcentration of rather polar compounds: application to the high-performance liquid chromatographic determination of priority pollutant chlorophenols

The potential of the cloud point methodology for the preconcentration of relatively polar compounds was studied using the non-ionic surfactant Triton X-114 and five EPA chlorophenols as test analytes. Analyte determination was performed using reversed-phase gradient LC with electrochemical and spectrophotometric detection. The amount of surfactant used is a critical variable in the preconcentration factor because it determines the extraction yield and the volume of surfactant-rich phase obtained. These values were determined as a function of the Triton X-114 concentration, together with the phase ratio, which allows prediction of the maximum preconcentration factor under given conditions.

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.

Efficiency through combining high-performance liquid chromatography and high resolution gas chromatography: progress 1995-1999

Progress during the last 5 years in on-line LC-GC and related techniques is reviewed. In normal-phase LC-GC, the wire interface proved to have advantages over the loop type interface. Further investigations on the solvent evaporation process in an uncoated precolumn under conditions of an early vapour exit revealed that the rules for the transfer by the retention gap techniques must be modified. For reversed-phase LC-GC, approaches with a phase transfer compete with direct evaporation. Eluents were extracted into a bed of Tenax located in a programmed-temperature vaporiser and thermally desorbed. Direct evaporation is possible when a hot vaporising chamber is used and solvent/solute separation occurs in a separate compartment, a coated precolumn possibly in combination with packed beds. As a future strategy, LC-GC transfer techniques should be adjusted to those of large volume injection and involve a single device. It is believed that on-column injection/transfer is the choice. This requires that concurrent evaporation in LC-GC is performed by the on-column interface.

Determination of endocrine disruptors in water after derivatization with N-methyl-N-(tert.-butyldimethyltrifluoroacetamide) using gas chromatography with mass spectrometric detection

The combined gas chromatographic determination of a number of hydroxyl-group containing endocrine disruptors, including 4-octylphenol, 4-nonylphenol, 2,4-dichlorophenol, pentachlorophenol, 4-tert.-butylbenzoic acid, bisphenol-A, 17beta-estradiol and 17alpha-ethynylestradiol, was investigated. Derivatization, required for sensitive determination of these compounds, was carried out using N-methyl-N-(tert.-butyldimethyltrifluoroacetamide). A number of parameters affecting the derivatization reaction, like temperature, time, matrix, solvent, and amount of reagent were studied in detail. Quantitative yields were obtained for real-life extracts after optimization, but the hormones were only mono-substituted. Both solid-phase extraction (SPE) and liquid-liquid extraction were studied as extraction methods, with emphasis on SPE material and effect of pH. Recoveries and RSD for analysis of surface water samples were 58-106 and 6-16% (n=4), respectively, when using SPE, and 109-117 and 6-14% (n=6) when using liquid-liquid extraction. The method developed allows routine analysis of surface water for traces of endocrine disruptors. The limits of detection of were 4-6 ng/l but higher for the hormones.

Development of an immunochemical technique for the analysis of trichlorophenols using theoretical models

An immunoassay has been developed for trichlorophenol analysis on the basis of theoretical chemistry modeling studies. These data have allowed us to choose the optimum chemical structure of the immunizing hapten according to realistic similarities with the target analyte. The synthesis of this hapten and the subsequent application of an appropriate immunization protocol have lead to the production of polyclonal antibodies against the target analyte. A homologous direct competitive ELISA has been developed that can be carried out in about 1 h. It has a limit of detection of 0.2 +/- 0.06 microg/L (1.01 +/- 0.3 nM) and it has been proven to tolerate a wide range of ionic strengths and pH values. Thus, the assay has acceptable features in samples with ionic strength between 4 and 56 mS/cm and pH values between 5.5 and 9.5. Studies on the selectivity of this immunoassay have demonstrated a high recognition of the corresponding brominated analogues. Other phenolic compounds do not interfere significantly in the analysis of 2,4,6-trichorophenol using this immunochemical technique. The accuracy of the assay has been evaluated using certified and spiked samples.

On-line coupling of solid-phase extraction with mass spectrometry for the analysis of biological samples. II. Determination of clenbuterol in urine using multiple-stage mass spectrometry in an ion-trap mass spectrometer

Solid-phase extraction (SPE) was coupled to ion-trap mass spectrometry to determine clenbuterol in urine. For SPE a cartridge exchanger was used and, after extraction, the eluate was directly introduced into the mass spectrometer. For two types of cartridges, i.e. C18 and polydivinylbenzene (PDVB), the total SPE procedure (including injection of 1 mL urine, washing, and desorption) has been optimised. The total analysis, including SPE, elution, and detection, took 8.5 min with PDVB cartridges, while an analysis time of 11.5 min was obtained with C18 cartridges. A considerable amount of matrix was present after extraction of urine over C18 cartridges, resulting in significant ion suppression. With PDVB cartridges, the matrix was less prominent, and less ion suppression was observed. For single MS, a detection limit (LOD) of about 25 ng/mL was found with PDVB cartridges. With C18 cartridges an LOD of only about 50 ng/mL could be obtained. Applying tandem mass spectrometry (MS/MS) did not lead to an improved LOD due to an interfering compound. However, a considerable improvement in the LOD was obtained with MS3. The selectivity and sensitivity were increased by the combination of efficient fragmentation of clenbuterol and reduction of the noise. Detection limits of 2 and 0.5 ng/mL were obtained with C18 and PDVB cartridges, respectively. The ion suppression was 4 to 45% (concentration range: 250 to 1.0 ng/mL) after extraction of urine using PDVB cartridges, and up to 70% ion suppression was observed using C18 cartridges. With MS4, no further improvement in selectivity and sensitivity was achieved, due to inefficient fragmentation of clenbuterol and no further reduction of noise.

Coupling device for desorption of drugs from solid-phase extraction-pipette tips and on-line gas chromatographic analysis

Solid-phase extraction-pipette tips were used for micro solid-phase extraction of lidocaine and diazepam. Off-line desorption was done after in-vial collection for reference purposes, whereas with on-line desorption the eluate was directly introduced in the gas chromatograph. With both methods the total eluate (100 microl) was introduced into the GC system, which was equipped with a programmed-temperature vaporiser (PTV) for large volume injection. For on-line desorption a laboratory-made coupling device was developed to connect the pipette tips with the injector of the PTV. The coupling device was applied successfully since no leakage occurred at the connection of the coupling device and the pipette tip. No significant differences in recovery of lidocaine and diazepam and in presence of impurities were observed between chromatograms obtained with either off-line or on-line desorption. Preliminary experiments with standard solutions showed recoveries of about 75% for a concentration level of 1 microg/ml. The system seems particularly suitable for high-throughput analysis.

On-line combination of aqueous-sample preparation and capillary gas chromatography

Methods currently in use to combine the preparation of aqueous samples on-line with capillary gas chromatography (GC) comprise heartcut-orientated reversed-phase liquid chromatography-GC and analyte-isolation-orientated analyte extraction-GC. These approaches either use techniques in which water is directly introduced onto the GC column, or an indirect approach in which water is eliminated, i.e., by solid-phase extraction, solid-phase microextraction or liquid-liquid extraction, prior to introduction of the analytes onto the GC column. The latter type of approach is much more successful and user-friendly, and many applications have been reported.

On-line combination of aqueous-sample preparation and capillary gas chromatography

An overview is presented of methods currently in use to combine the preparation of aqueous samples on-line with capillary gas chromatography. Two approaches can be distinguished: heartcut-orientated reversed-phase liquid chromatography-gas chromatography (GC) and analyte-isolation-orientated analyte extraction-GC. These approaches either use techniques in which water is directly introduced onto the GC column, or an indirect approach in which water is eliminated, i.e., by solid-phase extraction, solid-phase microextraction or liquid-liquid extraction, prior to introduction of the analytes onto the GC column. The latter type of approach is much more successful and user friendly, and many applications have been reported.