Line Solid Phase Extraction Research Articles

Size–controllable synthesis of large–size spherical 3D covalent organic frameworks as efficient on–line solid-phase extraction sorbents coupled to HPLC

BackgroundCovalent organic frameworks (COFs) have found promising applications in separation fields due to their large surface area and high adsorption capacity, but the exiting COFs can not be directly used as the packing materials of on–line solid-phase extraction (SPE) coupled to HPLC and HPLC because their nano/submicron size or irregular shapes might cause ultrahigh column back pressure and low column efficiency. To synthesize the large-size spherical COFs larger than 3 μm as sorbents might be able to address these problems, however it is still a great challenge till now. ResultsIn this work, two large-size spherical 3D COFs (COF–320 and COF–300) were size–controllably synthesized within 10–90 μm via a two–step strategy. These two spherical COFs showed large surface area, fine crystallinity, good chemical/mechanical stability, and good reproducibility. As an application case, when used as the on–line SPE sorbents coupled to HPLC, the large–size spherical COF–320 displayed high binding capacity for bisphenol F (Qmax of 452.49 mg/g), low column back pressure (6–8 psi at flow rate of 1 mL/min), and good reusability (at least 30 cycles). The developed on–line–SPE–HPLC–UV method presented good analytical performance with enrichment factor of 667 folds, linear range of 1.0–400 ng/mL, limit of detection (LOD, S/N = 3) of 0.3 ng/mL, limit of quantification (LOQ, S/N = 10) of 1.0 ng/mL, and recoveries of 100.3–103.2 % (RSDs of 2.0–3.5 %) and 95.2–97.0 % (RSDs of 4.3–5.6 %) for tap water and lake water samples, respectively. SignificanceThis is the first case to synthesize the large–size spherical COFs within 10–90 μm, and this work made it possible to directly use COFs as the filling materials of on–line SPE coupled to HPLC and HPLC. The developed analytical method can be potentially applied to the rapid and sensitive detection of trace bisphenol F in environmental water samples.

A coupled method of on-line solid phase extraction with the UHPLC‒MS/MS for detection of sulfonamides antibiotics residues in aquaculture

The use of a variety of antibiotics in fish farming raises serious concern about the development of antibiotic resistance. Sulfonamides antibiotics (SAs), which are widely used in aquaculture and generate large eco‒toxicological effects with significant mutagenicity and teratogenic consequences, are still difficult to determine in aquatic organisms. In this study, an automatic technology was developed by coupling on‒line solid phase extraction system (on‒line SPE) with ultra‒high‒performance liquid chromatography spectrometry‒mass spectrometry (UHPLC‒MS/MS). Particularly, using a single on‒line column in the process of sample pretreatment, e.g., HLB or C18, phospholipids that potentially caused the matrix effect cannot be removed form biological sample. We applied a mixed cation exchange column (Oasis® MCX) connected with a hydrophilic lipophilic balance column (Oasis® HLB) in series in on‒line SPE clean‒up to remove interferences and finally obtained a clear and stable eluant. The on‒line SPE working conditions and UHPLC‒MS/MS parameters were optimized for their sensitivity, accuracy, decision limit, and detection capability, which were further calibrated for fish, shrimp and crab. The results showed that the limits of detection and limits of quantification ranged from 1.46 to 15.5 ng/kg, and 4.90–51.6 ng/kg, respectively. Accuracy values covered 71.5%–102% at the three concentration levels (0.1, 0.5, 1.0 μg/kg) for all compounds and average repeatability (relative standard deviation, RSD%) ranged from 3.47% to 14.2%. This on‒line SPE coupled with UHPLC‒MS/MS method is a way forward for an automatic, powerful detection technology for determination of antibiotics from complex matrix.

Automated fluorimetric determination of the genotoxic impurity hydrazine in allopurinol pharmaceuticals using zone fluidics and on-line solid phase extraction

In the present study we report a fully automated method for the determination of low levels of the genotoxic impurity hydrazine in allopurinol active pharmaceutical ingredient (API) and formulations based on the concept of zone-fluidics. Hydrazine reacts on-line with o-phthalaldehyde in a unique way, that is in acidic medium (pH < 1.5) and in the absence of nucleophilic reagents, to form a highly fluorescent hydrazone (λex/em = 318 / 376 nm). The adaptation of a 120 s long stopped-flow step at elevated temperature (70 °C) offered adequate sensitivity (LOD =0.9 μg L−1 or 0.1 ppm in the solid API) to meet the pharmacopoeia limits for the selected application. The analyte was separated efficiently from the excess of the API by on line solid phase extraction using a Hydrophilic-Lipophilic technology sorbent that provided direct retention of the more hydrophobic API without the need of wetting/conditioning steps. Percent recoveries ranged between 93.3 and 105.8%.

Rapid determination of ultra-trace levels of atrazine in surface water by on line solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry

A method for the determination of ultra-trace atrazine in surface water was developed based on on line solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (on line SPE-UPLC-MS/MS). The water sample was directly injected into an on line SPE system after filtering using a 0.22 μm filter membrane. An HLB Direct Connect HP column was used for the enrichment and purification of the water sample and eluted using a methanol solution. The analyte was separated on an Acquity BEH 130 column, and then detected by tandem mass spectrometry. The analyte was quantified with external standard method. There was a good linear relationship in the range of 1.0-5000 ng/L. The correlation coefficient (r) was 0.9989. The method detection limit was 0.2 ng/L. The recoveries of atrazine ranged from 83.0% to 105.1%. The relative standard deviation was 1.6%-5.3% (n=7), which met the requirements of trace analysis. The method is sensitive, fast and effective, and it is suitable for the determination of atrazine in surface water. It is important to ensure the safety of the water environment, provide timely pollution information, and effectively respond to environmental emergencies.

Arsenic speciation in environmental waters by a new specific phosphine modified polymer microsphere preconcentration and HPLC–ICP-MS determination

A new specific phosphine modified polymer microsphere (PPMs) was designed and used as the core adsorbent to comprehensively enrich both inorganic and organic arsenic species in environmental waters by on line solid-phase extraction (SPE). Avoiding any redox reagent, all the four arsenic species have been quantitatively retained on the home made mini-column with large number of positively charged adsorption groups, and then eluted rapidly (within seconds) with a mixed solution of ammonium nitrate and ammonium dihydrogen phosphate. The trace separation and determination of As(III), DMA, MMA and As(V) species have been simultaneously achieved by high performance liquid chromatography hyphenated to inductively coupled plasma spectrometry (HPLC–ICP-MS) technique. This work has developed a versatile tri-n-butylphosphine functionalized polymer microsphere for an efficient and reliable on-line of simultaneous preconcentration and detection of inorganic and organic arsenic speciation. Under the optimized experimental conditions, the enrichment factors obtained for As(III) and DMA with 25mL sample solution were 28, while for MMA and As(V) reached 30. The low detection limits of 1.2ngL−1, 0.96ngL−1, 0.82ngL−1 and 0.91ngL−1, with the relative standard deviations (RSDs) of 3.9%, 5.6%, 3.2% and 4.5% were obtained for As(III), DMA, MMA and As(V), respectively. The developed method was validated by analyzing Certified Reference Materials GSBZ 07-3171-2014, promising for routine monitoring of arsenic species in lake water, river water and seawater samples.

Development of a novel, fast, sensitive method for chromium speciation in wastewater based on an organic polymer as solid phase extraction material combined with HPLC–ICP-MS

Speciation analysis of inorganic chromium in wastewater is of great significance for the monitoring of environmental pollution. In this work, N,N-bis(2-aminoethyl)ethane-1,2-diamine functionalized poly(chloromethyl styrene-co-styrene) was synthesized, characterized and used as the adsorbent to preconcentrate chromium species in environmental waters by on line solid-phase extraction (SPE). The trace speciation analysis of Cr(III) and Cr(VI) in wastewater has been used by short-column high-performance liquid chromatography hyphenated to inductively coupled plasma spectrometry (HPLC–ICP-MS) after on-line SPE. Cr(III) and Cr(VI) have been adsorbed on the anion exchange column after transforming the cationic Cr(III) to an anionic [Cr(III)–EDTA]− complex devoid of re-dox reagent, and then eluted rapidly (within seconds) with a very low concentration of tetrabutylammonium hydroxide (TBAH) solution. This method provides a reliable on-line preconcentration method and detection coupled technique. Under the optimized conditions, high enrichment factors have been obtained for Cr(VI) and [Cr(III)–EDTA]− with 30mL sample solution up to 105 and 128, respectively. The low detection limits of 0.0068ngmL−1 and 0.0041ngmL−1, with the relative standard deviations (RSDs) of 4.3% and 3.6% were obtained for Cr(VI) and [Cr(III)–EDTA]−, respectively. The developed method was validated by analyzing Certified Reference Materials GSBZ50027-94, and the spike tests were also performed. At the same time, thanks to the merit of simple operation, rapid adsorption/desorption dynamics, high enrichment and low LODs, the established method was applied to analyze three wastewater samples from different discharge port.

Fast and Selective Determination of Pesticides in Water by Automated On-Line Solid Phase Extraction Liquid Chromatography Tandem Mass Spectrometry

An automated on line-solid phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 17 polar pesticides in water. Minimizing sample pretreatment and using a fast chromatographic separation, the method allowed a sample to be processed in 15 minutes. The MS analysis was performed by Data Dependent Acquisition, using the triggered Multiple Reaction Mode function that provided analyte confirmation, thus enhancing selectivity without compromising sensitivity. In fact, the optimized method enabled the determination of the considered pesticides at the ultratrace level, with detection limits in the range 0.07–1.65 ng/L (propazine and atrazine-desisopropyl, respectively); the only exception was linuron that showed a slightly higher detection limit (12.2 ng/L). The optimized method was then applied to real water samples; five pesticides were determined in river water, in the range 1.17–14.2 ng/L, while four were measured in drinking water, in the range 0.91–2.25 ng/L.

Use and Environmental Occurrence of Antibiotics in Freestall Dairy Farms with Manured Forage Fields

Environmental releases of antibiotics from concentrated animal feeding operations (CAFOs) are of increasing regulatory concern. This study investigates the use and occurrence of antibiotics in dairy CAFOs and their potential transport into first-encountered groundwater. On two dairies we conducted four seasonal sampling campaigns, each across 13 animal production and waste management systems and associated environmental pathways: application to animals, excretion to surfaces, manure collection systems, soils, and shallow groundwater. Concentrations of antibiotics were determined using on line solid phase extraction (OLSPE) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) with electrospray ionization (ESI) for water samples, and accelerated solvent extraction (ASE) LC/MS/MS with ESI for solid samples. A variety of antibiotics were applied at both farms leading to antibiotics excretion of several hundred grams per farm per day. Sulfonamides, tetracyclines, and their epimers/isomers, and lincomycin were most frequently detected. Yet, despite decades of use, antibiotic occurrence appeared constrained to within farm boundaries. The most frequent antibiotic detections were associated with lagoons, hospital pens, and calf hutches. When detected below ground, tetracyclines were mainly found in soils, whereas sulfonamides were found in shallow groundwater reflecting key differences in their physicochemical properties. In manure lagoons, 10 compounds were detected including tetracyclines and trimethoprim. Of these 10, sulfadimethoxine, sulfamethazine, and lincomycin were found in shallow groundwater directly downgradient from the lagoons. Antibiotics were sporadically detected in field surface samples on fields with manure applications, but not in underlying sandy soils. Sulfadimethoxine and sulfamethazine were detected in shallow groundwater near field flood irrigation gates, but at highly attenuated levels.

Existence of Pharmaceutical Compounds in Tertiary Treated Urban Wastewater that is Utilized for Reuse Applications

Research on the effects of chemical pollution in the environment that is related to urban wastewaters’ discharge and reuse until recently was focused almost exclusively on conventional pollutants. During the last several years though there has been a growing level of concern related to the hypothesis that various chemicals may exhibit endocrine disrupting effects. In addition, thousands of tons of pharmacologically active substances are used annually ending up in the wastewaters. In many countries facing prolonged droughts and implementing wastewater reuse schemes for irrigation and groundwater discharge, the existence of xenobiotic compounds in the tertiary treated wastewaters constitutes a new concern. This study describes the application of a recently developed multi-residue method for the determination of 29 multi-class pharmaceuticals using off line solid phase extraction followed by liquid chromatography–triple quadrupole mass spectrometry (LC–MS–MS). The method was applied for the analysis of pharmaceutical residues at three sewage treatment plants in Cyprus serving major coastal Mediterranean cities. The presence of 19 pharmaceuticals was confirmed. For some of the compounds high concentrations were obtained for the final effluents (e.g. ofloxacin: 4.82 μg/L, diclofenac: 5.51 μg/L, carbamazepine: 27.27 μg/L, metoprolol: 9.59 μg/L). Concerning the elimination potential, what was derived from the study is that the biological treatment step contributes the most to the removal of the compounds while sand filtration and chlorination steps reduce slightly the residual concentrations.

Validation of an off line solid phase extraction liquid chromatography–tandem mass spectrometry method for the determination of systemic insecticide residues in honey and pollen samples collected in apiaries from NW Spain

The use of pesticides to protect crops against plagues and insects is one of the most important ways to assure agricultural quality and productivity. However, bad application practices may cause the contamination of different environmental compartments and animal species, as a consequence of migration or accumulation of those compounds. Fipronil, imidacloprid and thiametoxam are systemic or systemic-like insecticides widely used in maize crops. Their heavy action in the nervous system of target insects also means a high toxicity to non-target pollinator insects such as honey bees which can get in touch with them through pollen and nectar during foraging activities. These insecticides have even been suspected to cause a significant decrease of honeybee colonies that has been observed in many countries since the past decade. Since September 1st 2008, the European Commission set new MRLs in food and feed of plant and animal origin. The pesticides included in this study have MRLs in honey and pollen between 10 and 50 ng g −1. In the present work, an analytical method was developed with the aim of determining residues of fipronil and some of its metabolites (fipronil sulfone, fipronil sulfide, fipronil desulfinyl and fipronil carboxamide), thiamethoxam and imidacloprid in honey and pollen samples. The extraction optimization was performed using a Doehlert experimental design by studying two factors, the mixture and the ratio of solvents used. Prior to the extraction procedure, raw hive samples containing honey, pollen and wax were centrifuged at 4000 rpm. The upper solid material was removed, and 1 g of the lower phase was mixed with 3 mL of the optimized mixture of methanol/water (10/90). The extract was passed through a florisil cartridge and the target compounds were eluted with methanol and analysed by LC–MS/MS in selective reaction monitoring (SRM) mode. The method was validated according to the guidelines included in the SANCO/10684/2009 document and the ISO 11843 standard for the following parameters: decision limit (CCα), detection capability (CCβ), recovery, repeatability and reproducibility at 0.5, 1 and 1.5 folds the MRLs. Ion suppression/enhancement effects into the ion source were also assessed. The CCβ values were included between 0.83 and 4.83 ng g −1, well below the current MRLs. The validated method was applied to the determination of the target pesticides in 91 samples collected in colonies from 73 apiaries of NW Spain (two sampling campaigns during 2008). None of the target insecticides were detected among all the collected samples.

Preparation of a Novel Emulsion-Templated MIP Monolith and its Application for on Line Assay of Nifedipine in Human Plasma

A novel nifedipine molecularly imprinted polymer (MIP) monolith was prepared by radical polymerization of the water in oil (W/O) emulsions, using vinyl ester resin and methacrylic acid (MAA) as the monomers and nonionic surfactants such as Polyethylene glycol 400 (PEG 400) and Pluronic F68 (PF 68) as the emulsifying agents. The properties of the material were investigated. The MIP monolithic column was installed in the high performance liquid chromatography (HPLC) system and used as the selective sorbent for on line solid-phase extraction of nifedipine in human plasma due to the good selectivity to nifedipine. For this method, the calibration curve was linear in the concentration range of 5-150 ng/mL (r2=0.998) for nifedipine in human plasma and the limit of detection (LOD) was 2 ng/mL. Accuracy, precisions and recovery was acceptable for screening nifedipine in plasma samples. The results indicated that the novel material could be used as pre-column for on line clear-up and screening of nifedipine in plasma samples, which provided a simple and rapid assay of the drugs in plasma.

Automated Determination of Linear Alkylbenzene Sulphonate (LAS) in Wastewater Treatment Plants Effluents Using on Line Solid-phase Extraction Followed by HPLC with Fluorescence Detection

Abstract An on line SPE (solid-phase extraction) method followed by HPLC with fluorescence detection has been developed and validated for determining the LAS in inlet and outlet effluents of wastewaters treatment plants. Filtered effluent samples were on line concentrated on a small polymeric reversed phase column, then the trapped LAS are separated on a specialty polar-embedded reversed-phase column and detected by a fluorimeter. The on line SPE method with fluorescence detection showed very good repeatability (from 1.5 to 11.7% depending on the sample loading volume) and robustness with detection limits of 1.5 μg l−1 for total C10–13 LAS loading a 5 ml sample volume. This automated method is a cost-effective way to determine LAS also in routine monitoring of inlets and outlets of wastewater treatment plants allowing to optimize treatment procedures.

Determination of lamotrigine in whole blood with on line solid phase extraction

A simple, sensitive and reproducible method was developed for the determination of lamotrigine in whole blood with on-line solid phase extraction followed by HPLC separation with UV detection. Whole blood samples were diluted 1:1 with water and then injected directly on a clean-up column dry-packed with 40 μm C8 silica and separated on a C18 reversed-phase column (150 × 4.6 mm) at room temperature. The extraction column was activated with methanol and conditioned with phosphate buffer of pH 4.5. Mobile phases consisted of phosphate buffer of pH 4.5 for the extraction column and of phosphate buffer of pH 4.5 – acetonitrile (60:40, v/v) for the analytical column. At a flow rate of 1.0 ml/min and a connection time of 1.0 min, the complete cycle time was 10.0 min. Detection was carried out at 260 nm. No internal standard was necessary. The method was linear over concentration range 0.2–20.0 μg/ml for lamotrigine. Recovery was 98%. Within-day and between-day coefficients of variation ranged from 1.8 to 6.7%.

Development of a multi-residue analytical methodology based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) for screening and trace level determination of pharmaceuticals in surface and wastewaters

This paper describes development, optimization and validation of a method for the simultaneous determination of 29 multi-class pharmaceuticals using off line solid phase extraction (SPE) followed by liquid chromatography–triple quadrupole mass spectrometry (LC–MS–MS). Target compounds include analgesics and non-steroidal anti-inflammatories (NSAIDs), lipid regulators, psychiatric drugs, anti-histaminics, anti-ulcer agent, antibiotics and β-blockers. Recoveries obtained were generally higher than 60% for both surface and wastewaters, with exception of several compounds that yielded lower, but still acceptable recoveries: ranitidine (50%), sotalol (50%), famotidine (50%) and mevastatin (34%). The overall variability of the method was below 15%, for all compounds and all tested matrices. Method detection limits (MDL) varied between 1 and 30 ng/L and from 3 to 160 ng/L for surface and wastewaters, respectively. The precision of the method, calculated as relative standard deviation (R.S.D.), ranged from 0.2 to 6% and from 1 to 11% for inter and intra-day analysis, respectively. A detailed study of matrix effects was performed in order to evaluate the suitability of different calibration approaches (matrix-matched external calibration, internal calibration, extract dilution) to reduce analyte suppression or enhancement during instrumental analysis. The main advantages and drawbacks of each approach are demonstrated, justifying the selection of internal standard calibration as the most suitable approach for our study. The developed analytical method was successfully applied to the analysis of pharmaceutical residues in WWTP influents and effluents, as well as in river water. For both, river and wastewaters, the most ubiquitous compounds belonged to the group of anti-inflammatories and analgesics, antibiotics, the lipid regulators being acetaminophen, trimethoprim, ibuprofen, ketoprofen, atenolol, propranolol, mevastatin, carbamazepine and ranitidine the most frequently detected compounds.

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

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

Direct determination of anabolic steroids in human urine by on-line solid-phase extraction/liquid chromatography/mass spectrometry.

A fully automated method is presented for the determination of anabolic steroids in human urine. On line solid-phase extraction with automatic cartridge exchange is used for sample clean-up followed by an high-performance liquid chromatographic isocratic separation. A narrow-bore 5 microns reversed-phase column (250 x 2.1 mm i.d.) at a flow rate of 0.2 ml min-1 is connected to a particle beam interface linked to a single-quadrupole mass spectrometer. No derivatization is needed and normal electron impact mass spectra are obtained for a series of up to 28 steroids and metabolites. Urine samples collected following the ingestion of therapeutic doses of some of the steroids were analysed and the detection and confirmation of excreted compounds accomplished. A dramatic reduction in human intervention and overall analysis time was achieved compared with other common approaches.