Conventional Solid-phase Extraction Research Articles

Quechers methodologies as an alternative to solid phase extraction (SPE) for the determination and characterization of residues of cephalosporins in beef muscle using LC–MS/MS

This work was focused on the comparison of two clean-up methods to be used for the simultaneous determination of seven cephalosporins in cow muscle. In particular, the performance of novel dispersive solid phase extraction (d-SPE) procedures based on QuEChERS methodologies was assessed and compared with conventional SPE. The separation and detection of the analytes using both methods was carried out by LC–MS/MS to reach enough sensitivity to be compatible with the detection of the maximum residue limits (MRL) of cephalosporins as regulated by EU directives. The optimization of the clean-up step relied on experimental design in order to find the most suitable conditions with a reduced number of assays. Besides, multi-objective responses were used to reach an overall compromise in the recovery of all analytes simultaneously. The validation of the two methods was done according to the Directive 2002/657/EC. Linearity, decision limit, detection capability, detection and quantification limits (4–50μgkg−1), precision (RSD less than 15% except for PIR) and recoveries were determined and adequate results with comparable values using QuEChERS and SPE methodologies. LOQ were better for SPE method (0.1–10μgkg−1) but both methods show LOQ below MRL values. Precision was slightly better for the QuEChERS method, that also presents better recoveries, higher than 85% except for cephalexin.

Preconcentration of trace amounts of lead in water samples with cetyltrimethylammonium bromide coated magnetite nanoparticles and its determination by flame atomic absorption spectrometry

A sensitive and simple magnetic solid phase extraction procedure was presented for the preconcentration of lead ions in environmental water samples. In the present study, lead ions form complexes with 1-(2-pyridilazo)-2-naphthol reagent (PAN) in basic medium, and then are quantitatively extracted to the surface of cetyltrimethylammonium bromide (CTAB)-coated magnetite nanoparticles (Fe3O4 NPs). After magnetic separation of adsorbent, the adsorbent was eluted with 0.5% (v/v) HCl in methanol prior to its analysis by flame atomic absorption spectrometry (FAAS). The pH of sample, concentrations of PAN, amounts of CTAB and Fe3O4 NPs, sample volume and desorption conditions were optimized. Under optimum conditions, the calibration curve was linear in the range of 0.05–100ngmL−1 with R2=0.9996. Detection and quantification limits of the proposed method were 0.005 and 0.05ngmL−1, respectively. Enhancement factor of 1050 was achieved using this method to extract 1000mL of different environmental water samples. Compared with conventional solid phase extraction methods, the advantages of this method still include easy preparation of sorbents, short times of sample pre-treatment, high extraction yield, and high breakthrough volume. It shows great analytical potential in preconcentration of lead from large volume water samples.

An enzyme-based DNA preparation method for application to forensic biological samples and degraded stains

Extraction of DNA from forensic samples typically uses either an organic extraction protocol or solid phase extraction (SPE) and these methods generally involve numerous sample transfer, wash and centrifugation steps. Although SPE has been successfully adapted to the microdevice, it can be problematic because of lengthy load times and uneven packing of the solid phase. A closed-tube enzyme-based DNA preparation method has recently been developed which uses a neutral proteinase to lyse cells and degrade proteins and nucleases [14]. Following a 20min incubation of the buccal or whole blood sample with this proteinase, DNA is polymerase chain reaction (PCR)-ready. This paper describes the optimization and quantitation of DNA yield using this method, and application to forensic biological samples, including UV- and heat-degraded whole blood samples on cotton or blue denim substrates. Results demonstrate that DNA yield can be increased from 1.42 (±0.21)ng/μL to 7.78 (±1.40)ng/μL by increasing the quantity of enzyme per reaction by 3-fold. Additionally, there is a linear relationship between the amount of starting cellular material added and the concentration of DNA in the solution, thereby allowing DNA yield estimations to be made. In addition, short tandem repeat (STR) profile results obtained using DNA prepared with the enzyme method were comparable to those obtained with a conventional SPE method, resulting in full STR profiles (16 of 16 loci) from liquid samples (buccal swab eluate and whole blood), dried buccal swabs and bloodstains and partial profiles from UV or heat-degraded bloodstains on cotton or blue denim substrates. Finally, the DNA preparation method is shown to be adaptable to glass or poly(methyl methacrylate) (PMMA) microdevices with little impact on STR peak height but providing a 20-fold reduction in incubation time (as little as 60s), leading to a ≥1h reduction in DNA preparation time.

Validation of an on-line solid-phase extraction method coupled to liquid chromatography–tandem mass spectrometry detection for the determination of Indacaterol in human serum

Indacaterol has been recently approved in Europe for the treatment of chronic obstructive pulmonary disease (COPD). In the present study, we have developed and validated a rapid and sensitive on-line solid phase extraction (SPE) method coupled to liquid chromatography–tandem mass spectrometry (LC–MS/MS) detection for the determination of Indacaterol in human serum. The sample preparation involves the serum dilution with a 0.2% acetic acid solution prior to the on-line SPE on a mixed-mode cationic (MCX) polymer based sorbent. The samples were then eluted on a reversed phase column with a mobile phase made of acidified water and methanol and detection was performed by MS using electrospay ionization in positive mode. The analysis time between 2 samples was 7.0min. Standard curves were linear over the range of 10.0pg/mL (LLOQ) to 1000pg/mL with correlation coefficient (r2) greater than 0.990. The method specificity was demonstrated in six different batches of human serum. Intra-run and inter-run precision and accuracy within ±20% (at the LLOQ) and ±15% (other levels) were achieved during a 3-run validation for quality control samples (QCs). The stability at room temperature (38h) was determined and reported. In addition, the comparison between an off-line SPE procedure and our method gave equivalent results. The results of the present work demonstrated that our on-line SPE–LC–MS/MS method is rapid, sensitive, specific and could be applied to the quantitative analysis of Indacaterol in human serum samples. Our method effectively eliminated the tedious conditioning and rinsing steps associated with conventional off-line SPE and reduced the analysis time. The on-line SPE approach appears attractive for supporting the analysis of several hundreds of clinical samples.

Gold nanoparticles for specific extraction and enrichment of biomolecules and environmental pollutants

Because of their high surface-to-volume ratio, easy surface modification, and simple synthesis methods, gold nanoparticles (AuNPs) are becoming an attractive material as an alternative to conventional solvent extraction and solid-phase extraction column for the selective extraction and enrichment of target analytes from a large sample volume. Through covalent bond formation (Au-S bonds), electrostatic attraction, hydrophobic adsorption, and molecular recognition, AuNPs have been applied successfully to the extraction/removal of a variety of compounds from biological fluids and environment waters, including thiol-containing compounds, peptides, proteins, heavy metal ions, polycyclic aromatic hydrocarbons, and melamine. This review summarizes the recent advances in properties, synthesis, and surface modification of AuNPs for the preconcentration of biomolecules and environmental pollutants.

Magnetic multi-walled carbon nanotubes assisted dispersive solid phase extraction of nerve agents and their markers from muddy water

The multi-walled carbon nano-tubes (MWCNT) were magnetized with iron oxide nanoparticles and were characterized by SEM and EDX analyses. These magnetized MWCNT (Mag-CNT) were used as sorbent in dispersive solid phase extraction (DSPE) mode to extract nerve agents and their markers. Mag-CNT were dispersed in water and collected with the help of an external magnet. From Mag-CNT, the adsorbed analytes were eluted and analyzed by GC-FPD in phosphorus mode. DSPE was found to be advantageous over conventional solid phase extraction (SPE) in terms of operational simplicity, speed, handling of large sample volume and recoveries. Extraction parameters such as eluting solvent, sorbent amount, pH and salinity of aqueous samples were optimized. Optimized extraction conditions included 40mg of Mag-CNT as sorbent, chloroform as eluent, pH 3–11 and salinity 20%. Under the optimized conditions, recoveries from distilled water ranged from 60 to 96% and were comparable in tap and muddy water. Limits of quantification and limits of detection of 0.15ng/ml and 0.05ng/ml, respectively, were achieved. Superiority of Mag-CNT over conventional C18 SPE was also established.

Immunoaffinity-Based Solid Phase Extraction for the Determination of Melamine in Animal-Derived Foods Followed by LC

An immunoaffinity chromatography (IAC) column was prepared and optimized to purify melamine in animal-derived foods followed by determination with a liquid chromatography method. The column showed high binding capacity of 1,250 ng for melamine with recovery higher than 96%, and the column could be renewed and repeatedly used for at least 30 cycles. The extracts of chicken, egg and milk samples were directly loaded onto IAC column for purification, and the analyte retained on the column was eluted with 4 mL of modified Tris buffer without carryover. The purification effect was satisfactory and better than that of the conventional solid phase extraction. Recoveries from the melamine-fortified blank samples were between 82.5 and 101.4% with coefficient of variation (CV) lower than 10.6%.

Application of Nanoscale Poly(divinyl-Benzene Vinylpyrrolidone) as Solid-Phase Extraction Adsorbent Prior to LC-MS-MS for the Determination of Paralytic Shellfish Poisoning Toxins in Shellfish

In the present study, the feasibility of the poly(divinyl-benzene vinylpyrrolidone) as solid-phase extraction (SPE) nanoscale adsorbent prior to LC-MS-MS method for the sensitive and selective determination of eight paralytic shellfish poisoning (PSP) (GTX1, GTX2, GTX3, GTX4, GTX5, dcGTX2, dcGTX3 and dcNEO-b) toxins in the shellfish was investigated. Various parameters affecting SPE efficiency including the eluent and its volume, and sample volume were studied. The application of the SPE can remove most of the ematrix interference compared with the conventional SPE procedure. By using slected reaction monitoring (SRM) mode in LC-MS-MS analysis, the acquired calibration curves were strictly linear (r2 > 0.996) for the eight targeted analyses. The feasibility of the proposed method was finally validated by quantifing the eight PSPs in the shellfish samples (scallop, Crassostrea gigas and Ruditapes philippinarum) with the satisfitory recoveries of more than 80% with RSDs less than 10%.

Establishment of trace determination method of pyrethroid pesticides with TiO2 nanotube array micro-solid phase equilibrium extraction combined with GC-ECD

This paper described a new method for the enrichment and determination of pyrethroid pesticides from environmental water samples with ordered TiO(2) nanotube array micro-solid phase equilibrium extraction (μ-SPEE) prior to gas chromatography (GC) with electron capture detection (ECD). Several factors such as the anodization voltage, the kind of organic solvents, sample pH, equilibrium extraction time, desorption time and salting-out effect were optimized. Under the optimal conditions, ordered TiO(2) nanotube arrays demonstrated excellent merits on the preconcentration of pyrethroid pesticides and good detection limits were achieved as 0.018, 0.020, 0.031, 0.041, and 0.070 μg L(-1) for bifenthrin, fenpropathrin, cyhalothrin, fenvalerate, and deltamethrin, respectively. Four real water samples were used to validate the proposed method and the spiked recoveries were over the range of 81.9-110.6%. Compared to conventional solid phase extraction (SPE), the present method showed better recoveries and good reproducibility. These results showed that this μ-SPEE technique could be an important alternative to multistep SPE for the extraction and determination of such analytes in complex samples and become a useful tool in monitoring such analytes in the environment.

Monolithic silica with HPLC separation and solid phase extraction materials for determination of drugs in biological materials

During the last one or two decades, monolithic polymers and silica have been developed for use as a new separation material or as a solid phase extraction sorbent and the applications with monoliths have been dramatically increased to separate the analytes by HPLC and to extract the analytes by solid phase extraction. The structure of monoliths differs from those of conventional particle materials. Specifically, the porosity of monoliths is over 80% and is larger than that of silica particle materials; therefore, columns packed with monoliths provide fast and high throughput analysis. Furthermore, high flow analysis is possible using monoliths because they produce very low back pressure. The applications of HPLC using monoliths for separation of bio-active compounds have gradually increased. In this review, these applications are summarized so that researchers can be introduced to the advantages of using monolithic silica. In addition, monolithic materials have the potential to be used as conventional solid phase extraction sorbents for the extraction of analytes in a sample matrix. The analytes in the sorbent can be eluted with a small volume because the monolith has wider surface area for each unit volume than those in other silicas or polymers and the required volume of the sorbents to extract the analytes is smaller in comparison with the conventional methods. To utilize these advantages of monoliths, new devices have been developed. In this review, the applications of monolithic silica for the extraction of drugs and medicines in biological materials are summarized.

Microextração em sorvente empacotado (MEPS) para a determinação de fármacos em fluidos biológicos

Microextraction by packed sorbent (MEPS) is a new sample preparation technique developed in 2004. Actually, MEPS is a miniaturization of conventional solid phase extraction (SPE) packed bed devices from mililitre bed volumes to microlitre volumes. The key factor in MEPS is that the volume of solvent used to elute the analytes from the extraction process is of a suitable order of magnitude to be injected directly on-line into Liquid Chromatography, Gas Chromatography or Capillary Electrophoresis systems, without any modification of the instrument. This review focuses on MEPS theory and applications. MEPS procedure with different steps (sample preparation, analytes pre-concentration, sorbent washing, and analytes elution) is discussed for biological samples. A short overview of recent and successful applications of MEPS for determination of drugs and their metabolites in different biological matrices (plasma, urine, blood, hair) for therapeutic drug monitoring, doping inspection, biomarkers analysis, and forensic toxicology are also summarized.

Rapid and sensitive drug metabolism studies by SU-8 microchip capillary electrophoresis-electrospray ionization mass spectrometry

Monolithically integrated, polymer (SU-8) microchips comprising an electrophoretic separation unit, a sheath flow interface, and an electrospray ionization (ESI) emitter were developed to improve the speed and throughput of metabolism research. Validation of the microchip method was performed using bufuralol 1-hydroxylation via CYP450 enzymes as the model reaction. The metabolite, 1-hydroxybufuralol, was easily separated from the substrate ( R s = 0.5) with very good detection sensitivity (LOD = 9.3 nM), linearity (range: 50–500 nM, r 2 = 0.9997), and repeatability (RSD Area = 10.3%, RSD Migration time = 2.5% at 80 nM concentration without internal standard). The kinetic parameters of bufuralol 1-hydroxylation determined by the microchip capillary electrophoresis (CE)-ESI/mass spectrometry (MS) method, were comparable to the values presented in literature as well as to the values determined by in-house liquid chromatography (LC)-UV. In addition to enzyme kinetics, metabolic profiling was demonstrated using authentic urine samples from healthy volunteers after intake of either tramadol or paracetamol. As a result, six metabolites of tramadol and four metabolites of paracetamol, including both phase I oxidation products and phase II conjugation products, were detected and separated from each other within 30–35 s. Before analysis, the urine samples were pre-treated with on-chip, on-line liquid-phase microextraction (LPME) and the results were compared to those obtained from urine samples pre-treated with conventional C18 solid-phase extraction (SPE, off-chip cartridges). On the basis of our results, the SU-8 CE-ESI/MS microchips incorporating on-chip sample pre-treatment, injection, separation, and ESI/MS detection were proven as efficient and versatile tools for drug metabolism research.

Dispersive solid-phase extraction for in-sorbent Fourier-transform infrared detection and identification of nerve agent simulants in analysis for verification of chemical weapon convention

The combination of dispersive solid-phase extraction (DSPE) and Fourier-transform infrared (FTIR) spectroscopy is presented for detection and quantification of markers and simulants of nerve agents. Hydrophilic-lipophilic balance (HLB) sorbent was used for extraction and enrichment of organophosphonates from water. When the extraction efficiency of DSPE was compared with that of conventional solid-phase extraction (SPE), DSPE was more efficient. Extraction conditions such as extraction time, and type and quantity of sorbent material were optimized. In DSPE, extracted analytes are detected and quantified on the sorbent using FTIR as analytical technique. Absorbance in FTIR due to P-O-C stretching was used for detection and quantification. Infrared absorbance of different analytes were compared by determining their molar absorptivities (ε (max)). Quantitative analyses were performed employing modified Beer's law, and relative standard deviations (RSDs) for intraday repeatability and interday reproducibility were found to be in the range 0.30-0.90% and 0.10-0.80% respectively. The limit of detection (LOD) was 5-10μg mL(-1). The applicability of the method was tested with an unknown sample prepared by mimicking the sample obtained in an international official proficiency test.

Determination of parabens in cosmetic products using multi-walled carbon nanotubes as solid phase extraction sorbent and corona-charged aerosol detection system

The potential of carbon nanotubes for the solid phase extraction of parabens in cosmetic products and the detection using a corona-charged aerosol detector (C-CAD) is presented in this work. The analytical procedure is based on a conventional solid phase extraction step for which 20mg of multi-walled carbon nanotubes were packed in a 3-mL commercial SPE cartridge. Methylparaben, ethylparaben, propylparaben and butylparaben were thus isolated and preconcentrated from the pre-treated samples and subsequently separated on a RP-C18 column using acetonitrile:water, 50:50 (v/v) as mobile phase. The analytical signals for the individual parabens were obtained using C-CAD. The experimental variables affecting the extraction procedure and the instrumental detection have been deeply studied. Limits of detection were in the range of 0.5-2.1mgL(-1), while the linear range was extended up to 400mgL(-1). The average precision of the method varied between 3.3-3.8% (repeatability) and 4.3-7.6% (reproducibility). Finally, the optimized procedure was applied to the determination of the target preservatives in a variety of cosmetic products with satisfactory results.

Application of Conventional Solid-Phase Extraction for Multimycotoxin Analysis in Beers by Ultrahigh-Performance Liquid Chromatography−Tandem Mass Spectrometry

A new analytical method has been developed and validated for the simultaneous analysis of mycotoxins (aflatoxins B1, B2, G1, G2, and M1, fumonisins B1 and B2, deoxynivalenol, ochratoxin A, HT-2 and T-2 toxins, and zearalenone) in beers. Mycotoxins were extracted by solid-phase extraction (SPE) using C18 as the cartridge. Several parameters such as type of sorbent, elution solvent, and dilution of the sample were evaluated. The separation and determination were carried out by ultrahigh performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The method was validated, and mean recoveries ranging from 70 to 106% were obtained. Repeatability and intermediate precision, expressed as relative standard deviations, were lower than 21% for all mycotoxins and levels assayed. The limits of quantification were lower than 0.5 microg/L. The developed method has been applied for the analysis of several types of beers with different alcoholic content (nonalcoholic, normal, and special), and T2, HT-2 toxins, aflatoxin B1, and fumonisin B2 were detected. This methodology combines the simplicity of SPE using conventional cartridges and UHPLC-MS/MS, producing a rapid, sensitive, and reliable procedure.

Bag-SPE—a convenient extraction method for screening of pharmaceutical residues in influent and effluent water from sewage treatment plants

Bag-SPE is a solid-phase extraction (SPE) technique here applied to sample pharmaceutical residues in wastewater. The device, consisting of 20 mg polystyrene-divinylbenzene (PS-DVB) enclosed in a woven polyester fabric was immersed into a 20-mL sample. Extraction of the analytes was performed under gentle rotation (25 rpm) until distribution equilibrium was achieved (4 h). The extraction efficiency for thirteen pharmaceuticals was evaluated for the bag-SPE sampler compared to a conventional SPE cartridge (Oasis HLB). All analyses were determined on an ultra-performance liquid chromatography (UPLC) coupled to a quadrupole time-of-flight (QToF) mass spectrometer. The detection limit of the bag-SPE technique for the analytes in wastewater ranged from 15-100 ng/L with recoveries between 20.7% and 58.2% and ion suppressions between 2.2% and 53.2%. Although the extraction efficiencies were lower with the bag-SPE sampler compared to the SPE technique, the two methods showed similar detection limits due to the lower ion suppression experienced with the bag-SPE. The results demonstrate that bag-SPE is an attractive alternative to the more, in terms of manual handling, demanding SPE technique.

Recent developments and applications of microextraction techniques in drug analysis

Sample preparation is important for isolating desired components from complex matrices and greatly influences their reliable and accurate analysis. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, online coupling with analytical instruments, and low-cost operation through extremely low or no solvent consumption. Microextraction techniques, such as liquid-phase microextraction and solid-phase microextraction, have these advantages over the traditional approaches of liquid-liquid extraction and conventional solid-phase extraction. This review focuses primarily on these microextraction techniques developed over the last decade, and presents a summary of the characteristics of various approaches in drug analysis.

Preparation of magnetic molecularly imprinted polymer for rapid determination of bisphenol A in environmental water and milk samples

A magnetic molecularly imprinted polymer (M-MIP) of bisphenol A (BPA) was prepared by miniemulsion polymerization. The morphological and magnetic characteristics of the M-MIP were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometry. The adsorption capacities of the M-MIP and the nonimprinted polymer were investigated using static adsorption tests, and were found to be 390 and 270 mg g(-1), respectively. Competitive recognition studies of the M-MIP were performed with BPA and the structurally similar compound DES, and the M-MIP displayed high selectivity for BPA. A method based on molecularly imprinted solid-phase extraction assisted by magnetic separation was developed to extract BPA from environmental water and milk samples. Various parameters such as the mass of sorbent, the pH of the sample, the extraction time, and desorption conditions were optimized. Under selected conditions, extraction was completed in 15 min. High-performance liquid chromatography with UV detection was employed to determine BPA after the extraction. For water samples, the developed method exhibited a limit of detection (LOD) of 14 ng L(-1), a relative standard deviation of 2.7% (intraday), and spiked recoveries ranging from 89% to 106%. For milk samples, the LOD was 0.16 microg L(-1), recoveries ranged from 95% to 101%, and BPA was found in four samples at levels of 0.45-0.94 microg L(-1). The proposed method not only provides a rapid and reliable analysis but it also overcomes problems with conventional solid-phase extraction (SPE), such as the packing of the SPE column and the time-consuming nature of the process of loading large-volume samples.

Simple water analysis of golf link pesticides by means of batch-wise adsorption and supercritical fluid extraction

Here, a simple new method is proposed to evaluate water for the presence of pesticides. Specifically, pesticides for golf link maintenance were used as the targets for this investigation. Water samples containing the pesticides were mixed with particulate adsorbent, after which the pesticides were extracted from the adsorbents using supercritical fluid carbon dioxide and then analyzed by gas chromatography–mass spectrometry. The recoveries of pesticides were examined with several types of adsorbents and found to be related to their octanol/water partition coefficients ( K ow) for most of the adsorbents. Good recoveries were obtained when the water samples were mixed with octadecylsilane (ODS) and stylene-divinylbenzene copolymer (XAD) resins for 15 and 30 min, respectively. In the supercritical fluid extraction, extraction pressure affected the efficiency of extraction from XAD while a little effect on extraction from ODS, probably due to the internal structure of the adsorbents. The limit of detection ranged from 0.002 to 2.3 μg L −1 and the method is suitable for the measurement of golf link pesticides in μg L −1 order to 100 μg L −1. The procedure of the proposed method was simpler than the conventional solid-phase extraction method. Finally, the method presented here was used to identify pesticides present in actual wastewater from golf links.

High performance liquid chromatography–tandem mass spectrometry for the analysis of 10 pesticides in water: A comparison between membrane-assisted solvent extraction and solid phase extraction

This work describes the application of two sample preparation methods: membrane-assisted solvent extraction (MASE) and solid phase extraction (SPE) in combination with high performance liquid chromatography–tandem mass spectrometry (HPLC–MS–MS) for the determination of 10 pesticides in surface and ground water. Optimal extraction conditions for MASE were 60 min extraction time at 30 °C with a solvent volume of 100 μL toluene. 5 μL of the toluene extract were directly injected in the HPLC–MS–MS system. Concerning SPE, two materials were tested and C18 was superior to Oasis HLB. Complete desorption was ensured by desorbing the SPE (C18) cartridge with 3 mL of an acetonitrile/methanol mixture (1:1). After evaporation, the extract was injected in the analytical system. Analyte breakthrough was not found for the investigated compounds. For both methods, high extraction yields were achieved, in detail 71% (metalaxyl) till 105% (linuron) for MASE and 52% (ethiofencarb) till 77% (prometryne) for SPE (C18). Detection limits were in the low ng/L range for both methods and precision, expressed as the relative standard deviation (RSD) of the peak areas was below 13%. Five real water samples were analyzed applying both extraction methods. The results were in good agreement and standard addition proved that no matrix effects (such as ion suppression) occurred. In this comparison SPE has the potential of larger sensitivity whereas faster analysis and slightly better recoveries were achieved with MASE. MASE shows potential to be a promising alternative to the conventional off-line SPE concerning low to medium polar compounds.