The objective of this study was to develop and validate a 96-well plate solid phase extraction method for analysis of 23 lipophilic persistent organic pollutants (POPs) in low-volume plasma and serum samples which is applicable for biomonitoring and epidemiological studies. The analysis of selected markers for internal exposure: 16 polychlorinated biphenyls (PCBs), 5 organochlorine pesticides (OCPs), octachlorinated dibenzo-p-dioxin (OCDD), and polybrominated diphenylether 47 (BDE 47) was evaluated by comparing two SPE sorbents and GC-HRMS or GC-MS/MS detection. The final method extracted 23 POPs from 150 μL of serum and plasma using a 96-well extraction plate containing 60 mg Oasis HLB sorbent per well prior to GC-HRMS magnetic sector analysis. The extraction method was applied to 40 plasma samples collected for an epidemiological study. The recovery of selected POPs ranged from 31% to 63% (n = 48), and detection limits ranged from 2.2 to 45 pg/mL for PCBs, 4.2 to 167 pg/mL for OCPs, 7.8 pg/mL for OCDD and 6.1 pg/mL for BDE 47. This method showed good precision with relative standard deviations of selected POP concentrations in quality control samples (n = 48) ranging from 11% to 25%. The trueness was determined with standard reference material serum (n = 48) and the deviation from certified values ranged from 1 to 27%. Of the 23 POPs analyzed, 18 were detected in 43% to 100% of plasma samples collected for the epidemiological study. The method showed good robustness with low inter-well plate variation (11-31%) determined by twelve 96-well plate extractions, and can extract 96 samples, including quality controls and procedural blanks in 2-3 days. Comparison with GC-MS/MS analysis showed that similar concentrations (within 0.5% to 30%) of most POPs could be obtained with GC-APCI-MS/MS. Larger deviations were observed for PCB 194 (60%) and trans-nonachlor (43%). The developed method produces accurate concentrations of low-level marker POPs in plasma and serum, providing a suitable high-throughput sample preparation procedure for biomonitoring and epidemiological studies involving large sample size and limited sample volume. GC-HRMS was chosen over GC-MS/MS, however the latter showed promising results, and could be used as an alternative to GC-HRMS analysis for most POPs.
- MeSH
- Solid Phase Extraction instrumentation methods MeSH
- Environmental Pollutants blood MeSH
- Humans MeSH
- Limit of Detection MeSH
- Environmental Monitoring methods MeSH
- Organic Chemicals blood MeSH
- Gas Chromatography-Mass Spectrometry MeSH
- Reproducibility of Results MeSH
- Tandem Mass Spectrometry MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
The magnetic metal-organic framework Fe3O4@(Fe-(benzene-1,3,5-tricarboxylic acid) (MMOF) was prepared, characterized and studied as a magnetic sorbent for the dispersive solid-phase extraction (DSPE) of several widely used blood lipid regulators (i.e., bezafibrate, clofibric acid, clofibrate, gemfibrozil and fenofibrate) from water samples. Characterization of the synthesized Fe3O4@Fe-BTC magnetic nanomaterial was performed by Fourier transform infrared spectroscopy, powder X-ray diffractometry, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The magnetic nanocomposite was found to be chemically stable and to possess a large surface area (803.62 m2/g) and pore volume (0.59 cm³/g). The concentrations of fibrates in different water samples were determined using HPLC-UV-Vis and confirmed by UPLC-MS/MS. Parameters affecting the extraction efficiency of magnetic-DSPE were studied and optimized. The maxima absorption capacities (Qmax) were determined to be (in mg/g) 197.0 for bezafibrate, 620.3 for clofibric acid, 537.6 for clofibrate, 288.7 gemfibrozil and 223.2 for fenofibrate. Validations of the optimized magnetic DSPE method for analyses at two fibrate concentrations in spiked water samples produced relative recovery values ≤ 70% for clofibrate and within the range of 80-100% for bezafibrate, clofibric acid, gemfibrozil and fenofibrate. LODs ranging from 4 μg/L for fenofibrate to 99 μg/L for gemfibrozil were obtained. The validated methodology produced recovery values ranging from 70 to 112% (relative standard deviations < 7%).
- MeSH
- Benzene chemistry MeSH
- Water Pollutants, Chemical isolation & purification MeSH
- Solid Phase Extraction methods MeSH
- Tricarboxylic Acids chemistry MeSH
- Lipid Regulating Agents blood isolation & purification MeSH
- Magnetite Nanoparticles chemistry MeSH
- Metal-Organic Frameworks chemistry MeSH
- Water chemistry MeSH
- Iron chemistry MeSH
- Publication type
- Journal Article MeSH
We report on a Lab-On-Valve (LOV) configuration for analyte preconcentration from milliliter sample volumes using confluent mixing in the holding coil for in-line addition of loading buffer. The system was applied to the spectrophotometric determination of iron(II) in acidified seawater using 1,10-phenanthroline as color reagent. A cellulose-based chelating sorbent containing 8-hydroxyquinoline was used for the first time in LOV and excellent retention behavior and loading capacity were found. The flow system employs a syringe pump for handling all solutions (sorbent suspension, loading buffer, water, eluent, and color reagent) and a peristaltic pump for sample propulsion and includes a fit-for-purpose 14 cm long detection glass flow cell and a bubble trap for in-line carrier degasification. Advantage was taken of the LOV flow-through port to keep the eluted analytes for re-aspiration for subsequent chromogenic reaction. In effect, a universal analyzer configuration and preconcentration procedure was developed, which is combinable with other analytes, sorbents, and reagents. Among the studied parameters were the compositions, pH, volumes, and flow rates of loading buffer, eluent, and color reagent, as well as the microcolumn size, repeatability, and system stability. Reproducibility of 4.1% RSD over the entire working range, a LOD of down to 5 nmol L(-1), sampling frequency of 12h(-1), and linearity up to 1 µmol L(-1) for 3.3 mL of sample were obtained and applicability to real samples was demonstrated. It was proven that both Fe(III) and Fe(II) were retained and yielded similar recovery and sensitivity values. The method was applied to coastal seawater samples and spiking experiments yielded recovery values close to 100%.
- MeSH
- Color MeSH
- Cellulose chemistry MeSH
- Chelating Agents chemistry MeSH
- Solid Phase Extraction MeSH
- Phenanthrolines chemistry MeSH
- Hydrogen-Ion Concentration MeSH
- Limit of Detection * MeSH
- Analytic Sample Preparation Methods instrumentation methods MeSH
- Seawater chemistry MeSH
- Oxyquinoline chemistry MeSH
- Buffers MeSH
- Reproducibility of Results MeSH
- Iron analysis chemistry isolation & purification MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Polymeric nano- and microfibers were tested as potential sorbents for the extraction of five neonicotinoids from natural waters. Nanofibrous mats were prepared from polycaprolactone, polyvinylidene fluoride, polystyrene, polyamide 6, polyacrylonitrile, and polyimide, as well as microfibers of polyethylene, a polycaprolactone nano- and microfiber conjugate, and polycaprolactone microfibers combined with polyvinylidene fluoride nanofibers. Polyimide nanofibers were selected as the most suitable sorbent for these analytes and the matrix. A Lab-In-Syringe system enabled automated preconcentration via online SPE of large sample volumes at low pressure with analyte separation by HPLC. Several mat layers were housed in a solvent filter holder integrated into the injection loop of an HPLC system. After loading 2 mL sample on the sorbent, the mobile phase eluted the retained analytes onto the chromatographic column. Extraction efficiencies of 68.8-83.4% were achieved. Large preconcentration factors ranging from 70 to 82 allowed reaching LOD and LOQ values of 0.4 to 1.7 and 1.2 to 5.5 μg·L-1, respectively. Analyte recoveries from spiked river waters ranged from 53.8% to 113.3% at the 5 μg·L-1 level and from 62.8% to 119.8% at the 20 μg·L-1 level. The developed methodology proved suitable for the determination of thiamethoxam, clothianidin, imidacloprid, and thiacloprid, whereas matrix peak overlapping inhibited quantification of acetamiprid.
- Publication type
- Journal Article MeSH
We report on the hyphenation of the modern flow techniques Lab-In-Syringe and Lab-On-Valve for automated sample preparation coupled online with high-performance liquid chromatography. Adopting the bead injection concept on the Lab-On-Valve platform, the on-demand, renewable, solid-phase extraction of five nonsteroidal anti-inflammatory drugs, namely ketoprofen, naproxen, flurbiprofen, diclofenac, and ibuprofen, was carried out as a proof-of-concept. In-syringe mixing of the sample with buffer and standards allowed straightforward pre-load sample modification for the preconcentration of large sample volumes. Packing of ca. 4.4 mg microSPE columns from Oasis HLB® sorbent slurry was performed for each sample analysis using a simple microcolumn adapted to the Lab-On-Valve manifold to achieve low backpressure during loading. Eluted analytes were injected into online coupled HPLC with subsequent separation on a Symmetry C18 column in isocratic mode. The optimized method was highly reproducible, with RSD values of 3.2% to 7.6% on 20 µg L-1 level. Linearity was confirmed up to 200 µg L-1 and LOD values were between 0.06 and 1.98 µg L-1. Recovery factors between 91 and 109% were obtained in the analysis of spiked surface water samples.
A new on-line SPE-HPLC method using fused-core columns for on-line solid phase extraction and large volume sample injection for increasing the sensitivity of detection was developed for the determination of insecticides fenoxycarb and cis-, trans-permethrin in surface waters. The separation was carried out on fused-core column Phenyl-Hexyl (100×4.6 mm), particle size 2.7 µm with mobile phase acetonitrile:water in gradient mode at flow rate 1.0 mL min(-1), column temperature 45°C. Large volume sample injection (1500 µL) to the extraction dimension using short precolumn Ascentis Express RP C-18 (5×4.6 mm); fused-core particle size 2.7 µm allowed effective sample preconcentration and efficient ballast sample matrix removal. The washing mobile phase consisting of a mixture of acetonitrile:water; 30:70, (v/v) was pumped at flow rate of 0.5 mL min(-1) through the extraction precolumn to the waste. Time of the valve switch for transferring the preconcentrated sample zone from the extraction to the separation column was set at 3rd min. Elution of preconcentrated insecticides from the extraction precolumn and separation on the analytical column was performed in gradient mode. Linear gradient elution started from 40% of acetonitrile at time of valve switch from SPE column (3rd min) to 95% of acetonitrile at 7th min. Synthetic dye sudan I was chosen as an internal standard. UV detection at wavelength 225 nm was used and the method reached the limits of detection (LOD) at ng mL(-1) levels for both insecticides. The method showing on-line sample pretreatment and preconcentration with highly sensitive determination of insecticides was applied for monitoring of fenoxycarb and both permethrin isomers in different surface water samples in Czech Republic. The time of whole analysis including on-line extraction, interferences removal, chromatography separation and system equilibration was less than 8 min.
- MeSH
- Water Pollutants, Chemical analysis MeSH
- Solid Phase Extraction MeSH
- Phenylcarbamates analysis MeSH
- Insecticides analysis MeSH
- Lakes analysis MeSH
- Environmental Monitoring MeSH
- Online Systems MeSH
- Permethrin analysis MeSH
- Rivers chemistry MeSH
- Chromatography, High Pressure Liquid MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
Separation of major environmental pollutants as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) by capillary electrophoresis is reported for the first time. It is not possible to resolve the solutes in an aqueous media. However, the use of methanol and acetonitrile as the background electrolyte (BGE) solvents allowed their rapid separation in an uncoated capillary. A major effort was put into BGE optimization in respect to both separation efficiency and detection for further on-line preconcentration. 5 mmol.L⁻¹ naphthalene-1-sulfonic acid and 10 mmol.L⁻¹ triethylamine dissolved in ACN/MeOH (50:50 v/v) provided best separation and detection conditions. Next, the large-volume sample stacking and the field-amplified sample injection were applied and compared. Large-volume sample stacking improved limits of detection (LODs) with regard to the standard injection by 69 times for PFOA and 143 times for PFOS with LODs of 280 and 230 nmol.L⁻¹, respectively. Field-amplified sample injection improved LODs 624 times for PFOAand 806 times for PFOS with LODs 31 and 40 nmol.L⁻¹, respectively. Both preconcentration methods showed repeatabilities of migration times less than 1.2% RSD intraday and 6.6% RSD interday. The method was applied on PFOA and PFOS analysis in a sample of river water treated with solid-phase extraction, which further improved LOD toward 5.6 × 10⁻¹⁰ mol.L⁻¹ for PFOS and 6.4 × 10⁻¹⁰ mol.L⁻¹ for PFOA and allows the method to be used for river water contamination screening or decomposition studies.
- MeSH
- Acetonitriles MeSH
- Water Pollutants, Chemical isolation & purification MeSH
- Electrophoresis, Capillary methods MeSH
- Solid Phase Extraction MeSH
- Fluorocarbons isolation & purification MeSH
- Caprylates isolation & purification MeSH
- Alkanesulfonic Acids isolation & purification MeSH
- Limit of Detection MeSH
- Methanol MeSH
- Rivers chemistry MeSH
- Solvents MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
- Research Support, Non-U.S. Gov't MeSH
A new HPLC column-switching method using large volume sample injection and fused-core columns for on-line solid phase extraction have been developed for the determination of the following carbamates and pyrethroids: aldicarb, carbaryl, pirimicarb, carbofuran, kadethrin, flumethrin, fenpropathrin, fenoxycarb, tau-fluvalinate and fenvalerate, in surface water samples. Sudan I was used as internal standard. The proposed method was performed using 100 µl sample injection followed by an on-line solid phase extraction procedure and finally the compounds were identified and quantified by liquid chromatography with ultraviolet detection. The separation was carried out on C-18 reversed phase column based on fused-core particle technology. The influence of the injected sample volume, the variables affecting to SPE process and the conditions for the separation on an analytical column, were studied and optimized. The limits of detection ranged from 5.5 to 8.9 µg L(-1), and limits of quantification from 18.4 to 29.7 µg L(-1), while inter- and intra-day variability was under 15%. This new analytical procedure was satisfactorily applied for the determination of these organic pollutants in surface water samples located in Czech Republic. Concentration levels were found for some of these pollutants up to 26.11 µg L(-1) in the river Elbe and up to 34.53 µg L(-1) in the closed lakes samples.
- MeSH
- Water Pollutants, Chemical analysis MeSH
- Chromatography, Liquid MeSH
- Solid Phase Extraction methods MeSH
- Insecticides analysis MeSH
- Lakes MeSH
- Carbamates analysis MeSH
- Environmental Monitoring methods MeSH
- Online Systems MeSH
- Organic Chemicals analysis MeSH
- Pyrethrins analysis MeSH
- Rivers MeSH
- Reproducibility of Results MeSH
- Spectrophotometry, Ultraviolet MeSH
- Water chemistry MeSH
- Chromatography, High Pressure Liquid methods MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
The method employing molecularly imprinted polymers for the extraction and clean up of endocrine-disrupting compounds (estrogens, bisphenol A, and alkylphenols) from water and sediment is described. The identical extraction/clean-up and LC-MS/MS condition were used for the analysis of both types of samples. The method showed high recoveries ranging from 90 to 99% with excellent precision (intrabatch: 3.6-9.3%; interbatch: 5.6-11.4% for water; intrabatch: 4.3-8.5%; interbatch: 6.1-9.6% for sediment). The LOD was in the range of 0.7-1.9 ng/L and 0.3-0.6 ng/g for water and sediment, respectively. Overall extraction on molecularly imprinted polymers substantially enhanced sample clean-up. The difference in efficiency of clean-up was particularly pronounced when a large sample volume/weight was extracted and analyzed. Finally, the method was successfully applied for the analysis of 20 water and sediment samples.
- MeSH
- Water Pollutants, Chemical analysis isolation & purification MeSH
- Endocrine Disruptors analysis isolation & purification MeSH
- Solid Phase Extraction instrumentation methods MeSH
- Geologic Sediments analysis MeSH
- Molecular Imprinting MeSH
- Polymers chemical synthesis chemistry MeSH
- Tandem Mass Spectrometry methods MeSH
- Chromatography, High Pressure Liquid methods MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
- Research Support, Non-U.S. Gov't MeSH
Magnetic techniques based on the application of magnetic nanoparticles and microparticles and films have been successfully used for the determination and detection of different types of xenobiotics (e.g. herbicides, insecticides, fungicides, aromatic and polyaromatic hydrocarbons, pentachlorophenol and heavy metal ions) as well as viruses, microbial pathogens and protozoan parasites in water samples. Preconcentration of xenobiotics from large volumes of samples can be performed using magnetic solid-phase extraction, stir-bar sorptive extraction and related procedures. This review provides basic information about these techniques. Published examples of successful applications document the importance of these simple and efficient procedures employing magnetic materials.
- MeSH
- Adsorption MeSH
- Water Pollutants chemistry isolation & purification MeSH
- Magnetics methods MeSH
- Water Microbiology * MeSH
- Water parasitology MeSH
- Xenobiotics chemistry isolation & purification MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
