[Show abstract][Hide abstract] ABSTRACT: An immunoaffinity solid-phase-extraction sorbent has been developed by raising polyclonal antibodies against propanil and covalently bonding them to activated silica. This immunosorbent (IS) had high affinity for propanil and for structurally related phenylurea herbicides whereas structurally related chloroanilines were retained only poorly. Studies of breakthrough volumes, capacity, and calibration ranges of selected pesticides showed that the antibodies have different affinities for each compound. Propanil and phenylureas could be quantitatively recovered by elution with methanol–water; average recoveries were close to 100%. The IS was also packed in a precolumn and coupled on-line to HPLC–UV. The high selectivity provided by the IS was demonstrated by comparing results with those obtained by use of a non-selective polymeric sorbent when both were used for direct extraction of propanil and phenylureas from a 50-mL sample of river-Seine water spiked at 0.1 g L–1 or from lemon juice spiked at 50 g L–1.
[Show abstract][Hide abstract] ABSTRACT: Direct, selective solid-phase extraction of triazines from aqueous samples is presented using a molecularly imprinted polymer (MIP) made with terbutylazine as template molecule. After optimization of the steps of the procedure, 14 triazines including degradation products were studied and satisfactory extraction recoveries were obtained except for thiotriazines. By comparing results obtained with the terbutylazine MIP and a similar non-imprinted polymer, it was determined that retention was achieved via specific interactions except for hydroxyterbutylazine. Selectivity of the extraction procedure was also verified by applying the MIP for the extraction of phenylureas that were not retained on it. The effects of the charge distribution and of molecular volume of the triazines (obtained by molecular modeling) on the selectivity of interactions between the analytes and the MIP were studied. However, when the optimized procedure was applied to real samples, low extraction recoveries were obtained due to strong matrix effects: ion-exchange occurs between the carboxylate groups of the MIP and the ionic species of the sample, that prevents subsequent specific interactions. By introducing an acid wash step, the procedure was successfully applied for the class-selective extraction of triazines from industrial effluent and surface water samples. Finally, increased extraction recoveries were achieved for the polar degradation products of triazines by using a mixed-phase composed of a polymeric sorbent and the MIP.
Journal of Chromatography A 06/2003; 999(1-2):23-33. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is a need for a better characterization of sludges from wastewater treatment plants which are destined to be spread on agricultural lands. Inorganic pollutants are regularly controlled but organic pollutants have received few attention up to now. On this paper, we have been interested on the analysis of the 16 polycyclic aromatic hydrocarbons (PAHs) listed in the US Environmental Protection Agency (US EPA) priority list and more particularly of the six PAHs listed in the European community list (fluoranthene, benzo[b and k]fluoranthene, benzo[a]pyrene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene). The analysis step consists on liquid chromatography with both fluorescence and UV detections as described in the EPA Method 8310. As for the extraction step, several techniques such as supercritical fluid extraction, pressurized liquid extraction, focused microwave extraction in open vessels, Soxhlet and ultrasonic extractions are compared after optimization of the experimental conditions (solvent nature and quantity, temperature, pressure, duration, ... ) and validation with certified sludges. When optimized, these five extraction techniques are as much efficient with similar relative standard deviation. Whatever the extraction techniques used, the whole analysis protocol permits to quantify PAHs in the range of 0.09 to 0.9 mg/kg of dried sludges.
Journal of Chromatography A 06/2003; 995(1-2):87-97. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Phenolic compounds present in olive mill wastewater (OMW) need to be quantified because of their pollution capacity toward the environment. In the present study, six representative phenolic compounds of OMW were chosen to develop a LC-MS method. The high polarity of the compounds caused problems when using traditional reversed-phase liquid chromatography (RPLC). Consequently, a method was developed on another kind of chromatographic phase: Porous Graphitic Carbon (PGC) involving the use of a tetrahydrofuran (THF) gradient. The influence of THF as mobile phase in LC-MS coupling, which is not common practice, was evaluated. In Atmosperic Pressure Chemical Ionisation (APCI) in the negative ion mode, the presence of THF in the mobile phase did not degrade the MS signal of the target compounds in the conditions studied. On the contrary, an improvement was even observed when the percentage of THF increased. The proposed PGC-LC-MS method was selective and linear for the six phenolic compounds analysed with limits of quantification lower than 5 ppm in all cases. The precision was satisfactory (pooled RSD around 6%). The analyses of OMW matrix spiked sample confirmed the good performance of the proposed method.
Journal of Chromatography A 01/2002; 937(1-2):21-9. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: PAHs and their nitrated derivatives (Nitro-PAHs) have been analyzed in extracts from particulate matter by GC-MS and GC-MS-MS. Using GC-MS, most of these compounds could not be detected in raw extracts or their confirmation was uncertain because of interfering compounds from the matrix. Detection and quantification was greatly improved by using GC-MS-MS. Limits of detection were lower than 40 pg (injected) in standard solution and in diesel particulate matter extracts (for 10 mg of particles extracted). Low traces of PAHs and Nitro-PAHs, in the range of a few pg·m–3, could be detected without purification or fractionation of the extract.
[Show abstract][Hide abstract] ABSTRACT: O-PAHs have been analyzed in extracts of particulate matter by GC-MS-MS and GC-MS. Using GC-MS, most O-PAHs could not be detected
in raw extracts, or their confirmation was uncertain due to interfering compounds from the matrix. Detection and quantification
was greatly improved by using GC-MS-MS. Linearity was observed in the range from 10 to 1000 pg injected. Low traces of O-PAHs,
in the range of a few pg·m−3 of air, could be detected without purification or fractionation of the extract.
[Show abstract][Hide abstract] ABSTRACT: Adsorbents involving antigen-antibody interactions, so-called immunosorbents, have high affinity and class-selective extraction
properties. Although most studies of immunosorbents are based on the use of polyclonal antibodies, to ensure a good repeatability
with this kind of sorbent monoclonal antibodies are required. This study shows that the cross-reactivity of monoclonal anti-isoproturon
antibodies is similar to that of polyclonal anti-isoproturon antibodies. To reduce the price of the resulting immunosorbent,
the bonding density has been optimized. The choice of activated silica rather than Sepharose as solid support is discussed.
The effect of sample volume and of the amount of immunosorbent on extraction recoveries for some phenylureas has been studied.
It appears that the amount of immunosorbent can be readily adapted to the detection limit required.
[Show abstract][Hide abstract] ABSTRACT: A selective clean-up procedure using immunoaffinity solid-phase extraction was applied for the trace-level determination of polycyclic aromatic hydrocarbons (PAHs) in urban waste water and sewage sludges used for soil amendment. Anti-pyrene antibodies have been immobilized on a silica-based sorbent and the cross-reactivity of the antibodies towards structurally related compounds were allowed to extract the whole class of priority PAHs. The selectivity of the antibodies provided clean extracts from sludges and, therefore, the identification and quantification were shown to be easier using either liquid chromatography (LC) with UV diode array and fluorescence detection in series or gas chromatography-mass spectrometry (GC-MS), although some loss of up to 50% was observed for the clean-up. The identification of the PAHs by matching of UV and MS spectra was greatly improved. The procedure, including immunoclean-up and LC coupled to diode array and fluorescence detection, was validated using certified reference materials with native PAHs of concentrations in the range of 0.57-2.16 mg/kg (dry sludges).
Journal of Chromatography A 11/1999; 859(1):29-39. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The objective of this review is to provide updated information about the most important features of the new solid-phase extraction (SPE) materials, their interaction mode and their potential for modern SPE. First, the recent developments are given in formats, phases, automation, high throughput purpose and set-up of new types of procedures. Emphasis is then placed on the large choice of sorbents for trapping analytes over a wide range of polarities, such as highly cross-linked copolymers, functionalized copolymers, graphitized carbons or some specific n-alkylsilicas. The method development is given which is based on prediction from liquid chromatographic retention data or solvation parameters in order to determine the main parameters of any sequence (type and amount of sorbent, sample volume which can be applied without loss of recovery, composition and volume of the clean-up solution, composition and volume of the desorption solution). Obtaining extracts free from matrix interferences in a few steps--one step when possible--is now included in the development of SPE procedure. New selective phases such as mixed-mode and restricted access matrix sorbents or emerging phases such as immunosorbents or molecularly imprinted polymers are reviewed. Selectivity obtained by combining two sorbents is described with the use of ion-exchange or ion-pair sorbents. Special attention is given to complete automation of the SPE sequence with its on-line coupling with liquid chromatography followed by various detection modes. This represents a fast, modern and reliable approach to trace analysis. Many examples illustrate the various features of modern SPE which are discussed in this review. They have been selected in both biological and environmental areas.
Journal of Chromatography A 10/1999; 856(1-2):3-54. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A new extraction immunosorbent involving antigen-antibody interactions was coupled on-line to liquid chromatography for the selective extraction in aqueous samples of benzidine and congeners, widely used as intermediate compounds in the manufacturing of dyes and pigments. Due to the cross-reactivity of the antibodies for analytes with chemical structures closely related to that of the analyte used for immunization, the immunoextraction sorbent was shown to be able to extract aminoazobenzene and related azo dyes with good recoveries. The on-line coupling was optimized for the trace determination of benzidine, dichlorobenzidine, aminoazobenzene and some azo dyes with detection limits in the range 0.1 to 1 microgram/l. The high selectivity of the immunoextraction was shown by comparing the analysis of an industrial textile effluent obtained using precolumns packed either with a non-selective polymeric sorbent or with the anti-benzidine immunosorbent. In such complex samples, extraction and clean-up are achieved in the same step.
Journal of Chromatography A 07/1999; 846(1-2):317-29. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A phosphatase inhibition assay using commercially available components has been developed for the detection of cyanobacterial toxins in drinking and surface water samples. The assay is simple, economic and rapid. Results are obtained in 1h on a 96-well microtitre plate. The test uses a type 2A protein phosphatase whose activity is inhibited proportionally to the toxin concentration and is measured by means of a colourimetric reaction. Two procedures of the tests have been optimised using the same phosphatase, but different working conditions. The first one allows a direct estimation of the concentration of microcystin-LR in the range 0.4–10μg/l and is used to calculate the sample dilution required for the second procedure, which has been optimised in order to be much more accurate with a working range between 0.2 and 0.8μg/l (concentration in the sample, which corresponds to 0.1–0.4μg/l in the well). An enrichment using solid phase extraction on octadecyl silica has been described for samples containing less than 0.2μg/l of microcystin. A repeatability of 8% at the IC50 level has been obtained and the IC50 value is 0.21±0.02μg/l (concentration in the well). Inhibition of enzyme activity by other toxins such as microcystin-YR and microcystin-RR has also been evaluated. Particular attention has been paid to the effect of the sample matrix on the assay. Several drinking and surface waters have thus been investigated. Validation of the assay has been performed by comparing the phosphatase inhibition assay results to the liquid chromatography results for the same samples. A good correlation (R2=0.96) has been observed for samples containing microcystin-LR.
[Show abstract][Hide abstract] ABSTRACT: The selective isolation of PAHs from complex environmental mixtures was accomplished by means of a new methodology based on antigen--antibody interactions. This method consists on the extraction of PAHs from water samples onto an anti-fluorene immunosorbent (IS) followed by liquid chromatography with diode array detection. Environmental sediments and a sludge reference material containing PAHs were analyzed using this methodology in order to validate the performance of the IS for the cleanup procedure of such materials. Sediments were extracted by sonication with dichloromethane/methanol (2:1), and the extracts were brought to a volume of 100 mL of water in order to perform the extraction with the anti-fluorene IS. The reliability of the cleanup achieved by the IS was well demonstrated in the analysis of sediment and sludge complex samples containing the priority PAHs established by the U.S. EPA at concentrations varying from 56 micrograms/kg to 26 mg/kg. Results were compared to those obtained with conventional cleanup procedures showing a better selectivity for PAHs. The chromatograms presented a clear baseline allowing the determination and quantification of PAHs at the ppb level. Using immunosorbents, extraction, trace enrichment, and cleanup were accomplished in only one step.
[Show abstract][Hide abstract] ABSTRACT: There is a need for a better characterization of sludges from wastewater treatment plants which are destined to be spread on agricultural land. Inorganic pollutants are regularly controlled, but organic pollutants have received little attention up to now. The main problem for trace analysis of organic pollutants comes from the complexity of the various matrices of sludges, which depends on their origins. Therefore, methods described for soils and sediments cannot be directly applied to sludges which contain high amount of lipids. This paper provides a method for trace-determination of polycyclic aromatic hydrocarbons in the range of mg/kg of dried sludge including an extraction step, and an analysis step by liquid chromatography with fluorescence detection for sensitive quantification and UV-diode-array detection for confirmation. The extraction step was optimized by a selection of the solvent used for both Soxhlet and supercritical-fluid extraction and by setting the experimental conditions (temperature, pressure, modifier, etc.) used for SFE. Extraction recoveries were found similar and quantitative for the two procedures. However supercritical-fluid extraction appears to be a good alternative to Soxhlet extraction because of the consumption of less time and solvent. Detection limits were obtained in the range of 0.1-1 mg/kg of dried sludges, with possible confirmation by UV spectra. The whole method (extraction/quantification/confirmation) was validated using sludges which have been certified by the Community Bureau of Reference from Brussels (CRM No. 088). Application to the determination of PAHs in urban sludges is presented.
Journal of Chromatography A 11/1998; 823(1-2):219-30. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A method development is given for predicting the main solid-phase extraction parameters with emphasis to polar analytes which are poorly extracted using popular C18 silicas. Recoveries and breakthrough curves have been modelled according to the sample volume. From the knowledge of the sample volume to be handled for the required detection level in the sample, the prediction of the necessary retention factor in water, log kw, can be done in order to have recoveries at least above 85%. The selection of the sorbents and amounts of sorbents allowing the predicted log kw values is discussed according to the knowledge of interactions between analyte, matrix and common reversed-phases sorbents (standard C18 silicas, specifically designed C18 silica for polar analytes, apolar copolymers, carbon-based sorbents).
Journal of Chromatography A 10/1998; · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Some physicochemical parameters of three microcystin standards, known to be potent hepatotoxins produced by cyanobacteria, were determined using well defined chromatographic measurements. The logarithm of their retention factor on octadecylsilica (ODS) with water as the eluent, which is an estimation of the hydrophobicity of a molecule, was assessed at pH 7 at 3.9, 4.2 and 4.4 for microcystins-YR, -LR and -RR, respectively. Though being rather hydrophobic, microcystins also possess polar functions, namely carboxylic acids, amino and amido groups. The ionization of carboxylic groups occurs at pH values of 3.3-3.4. In environmental waters, microcystins are neutral or anionic. They are readily soluble in water, the solubility of microcystin-LR being higher than 1 g/l. Owing to their hydrophobicity and their polar functions, microcystins remain in the aqueous phase rather than being adsorbed on sediments or on suspended particulate matter. In a river water spiked with microcystins at 5 micrograms/l, only 10% was adsorbed on particles and 7% on the sandy sediment after three days. A method using solid-phase extraction on ODS followed by high-performance--or micro--liquid chromatography was optimized to detect microcystins at trace level in water. A clean-up was introduced to eliminate part of the interfering compounds coextracted during the sample percolation. Good recoveries (75-80%) were obtained. The method was linear, reproducible (with relative standard deviations ranging from 5 to 8%) and enabled the determination of microcystins at levels as low as 30 ng/l in drinking water and 100-200 ng/l in surface waters. The production of toxins by two strains of cyanobacteria was evaluated. Variations in the microcystin-LR content in the cells and in the medium of Microcystis aeruginosa PCC7806 were recorded over a five-week period. Toxin production was not correlated to the biomass but depended on the growth stage and was maximal at the end of the exponential growth phase. The release of toxin in water occurred essentially in old cultures where microcystin-LR was determined at concentrations of 170 and 280 micrograms/l in the media of M. aeruginosa PCC7806 and M. aeruginosa PCC7813, respectively. Other microcystins are likely to be synthesized by these strains. But owing to the lack of standards, mass spectrometric detection is required for further identification. This study points out the need of having other standards for water quality monitoring.
Journal of Chromatography A 03/1998; 799(1-2):155-69. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The national French lists of priority pesticides to be monitored in drinking and/or surface water contain various pesticides with a wide range of physico-chemical properties and can be modified on a regional scale with the addition of other pesticides, depending on local agricultural usage. A multiresidue extraction method is presented using new disk formats engineered for high throughput that are particularly well adapted to the extraction of compounds from high volumes of dirty samples. However, because of the occurrence of very polar and very apolar compounds in the lists, two procedures are required for the extraction step. Divinylbenzene disks were used to extract the more polar compounds, as well as the moderately polar or acidic ones. For apolar pesticides, a C18 silica disk was used, and 10% methanol was added to the water sample before percolation in order to avoid adsorption on the flasks and connecting tubes. Since 1 l of surface water is extracted in less than 5 min without previous filtration using these new laminar disks, the percolation time is no longer a limiting factor in the analysis scheme of surface water samples containing suspended matter. The sample volume can be easily increased in order to reach lower detection limits, provided that the extraction conditions have been optimized in order to minimize the amount of co-extracted and interfering substances. A considerable decrease in the effect of the humic and fulvic substances was achieved using divinylbenzene disks, which allows the samples to be handled at pH 6, for the polar pesticides. Moreover, the necessary addition of 10% methanol in the samples for the extraction of the apolar ones also considerably decreases the amount of co-extracted analytes. The time of the whole sample preparation sequence, i.e., conditioning of the disks, sample extraction, sample clean-up and desorption, is achieved within 10 min for six simultaneous samples. Detection limits in the range 0.01-0.05 microgram l-1 are easily obtained for most pesticides contained in the national lists from 1 l of real surface water samples. The two procedures described in this work allow the handling of any compounds having a water-octanol constant, log Kow, in the range 1-6.
Journal of Chromatography A 01/1998; 795(1):83-92. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The parameters governing solid-phase microextraction (SPME) are investigated, with emphasis on the determination of the partition coefficients, K, and their use to predict the selection of a fibre, depending on the respective characteristics of the fibres and the analytes. Film thickness and stability of the compounds can interfere with the determination of K values. The time profile curves were determined for twelve pesticides having a wide range of water solubilities and polarities and using four fibres (polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, Carbowax-divinylbenzene and polyacrylate). Although the affinity order was different for the four coatings, no correlation was found between the respective characteristics of the fibres and solutes. The two fibres containing divinylbenzene were shown to have the highest affinities and the polydimethylsiloxane had the lowest affinity. The polyacrylate fibre which is the more polar commercial fibre did not provide the highest affinities for the more polar and water-soluble analytes. The important parameters for quantitative analysis have been evaluated. The calibration curves were similar when one analyte of interest was present on its own in a drinking water sample, or when eleven other pesticides were present at the same concentration or when much higher concentrations of other analytes were present in the sample. Linearity was obtained over a wide range of concentrations in drinking water samples. Detection limits are in agreement with European regulatory levels in drinking water for most of the analytes using solid-phase microextraction-gas chromatography-nitrogen-phosphorus detection (SPME-GC-NPD). In contaminated surface water samples, the chromatograms are relatively clean and most of the compounds can be detected at levels lower than 0.5 microgram/l.
Journal of Chromatography A 01/1998; 795(1):27-42. · 4.61 Impact Factor