Solid Phase Microextraction System Research Articles

High throughput and automated solid-phase microextraction and determination by liquid chromatography-mass spectrometry for the analysis of mycotoxins in beer.

There is high demand for rapid screening of toxics in food analysis. In this study, a new high-throughput and automated solid-phase microextraction (SPME) system was employed for the sample preparation of mycotoxins in beers. Matrix compatible SPME blades with thin coating layer were used, which significantly decreased the matrix effects in beer samples (≤ 12%). This SPME system allows 96 samples to be processed automatically and simultaneously with average preparation time of 57s per sample. After sample preparation, the 96-well plate with desorption solution was sealed with a thin film and put into the LC-MS sampler for analysis via positive/negative ESI switching mode. The results also showed good sensitivity (limits of detection between 0.02 and 3ng/mL) with R2≥ 0.9971, reproducibility (intra- and inter-day ≤ 8% and ≤ 13%, respectively), and accuracy (recoveries between 79% and 121%).

Rapid solid phase microextraction of DNA using mesoporous metal-organic framework coating for PCR-based identification of meat adulteration.

A rapid, convenient, low-cost, and selective DNA isolation method was developed for identifying meat adulteration. A mesoporous metal organic framework (Meso-UIO-66)-coated solid phase microextraction system was employed as an isolation device to simplify DNA isolation into three steps (lysis, washing, and elution). Meso-UIO-66 was utilized as the adsorbent because of its positively charged surface, high chemical stability, and mesoporous structure. Meso-UIO-66 was characterized by scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet‒visible spectroscopy, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption tests. Parameters that affected DNA isolation were optimized. This method can be used to isolate and purify DNA from meat in 60s, and the DNA concentration and purity are comparable to those of samples isolated with a commercial kit. Multiple DNA detection was achieved by coupling this method with the multiplex polymerase chain reaction technique, and the detection limit was lower than 1% (w/w).

Rapid Screening and Quantitation of Drugs of Abuse by Both Positive and Negative Modes via Coated Blade Spray-Mass Spectrometry.

Solid-phase microextraction (SPME)-direct mass spectrometry (MS) has proven to be an efficient tool for the rapid screening and quantitation of target compounds at trace levels. However, it is challenging to perform screening using both positive and negative modes in one analytical run without compromising scanning speed and detection sensitivity. To take advantage of the special geometry of a coated blade spray (CBS) blade, which consists of two flat sides coated with the same SPME coating, we developed a CBS-MS method that enables desorption and ionization to be performed in positive ionization mode on one side of a coated blade and negative ionization mode on the other side of the same blade. By simply flipping the blade 180°, MS analysis in both ionization modes on different sides can be completed in 40 s. Combining this approach with an automated Concept 96-blade-based SPME system allowed analysis for one sample in positive and negative modes to be completed in less than 1 min. The workflow was optimized by using a biocompatible polyacrylonitrile as an undercoating layer and a binder of polyacrylonitrile/hydrophilic-lipophilic balance (HLB) particles, which enabled the rapid analysis of 20 drugs of abuse in saliva samples in both positive and negative modes. The proposed method provided low limits of quantification (between 0.005 and 10 ng/mL), with calibration linear correlation coefficients ⩾ 0.9925, accuracy between 72% and 126%, and relative precision < 15% for three validation points.

Simultaneous determination of three herbicide residues in wheat flour based on the hollow fiber supported carbon dots

A solid-phase micro extraction (SPME) coupled high performance liquid chromatography (HPLC) strategy was explored for trace concentrations of dicamba, 2,4-dichlorophenoxyacetic acid (2,4-D), and picloram residues simultaneous determination from complex matrix of food samples. The SPME system was established by immobilizing flavonoid moiety incorporated carbon dots (CDs) into the wall-pores of hollow fiber (HF) based on their electrostatic interactions, and as an effective extractant, functional groups incorporated CDs exhibited desirable sensitivity and selectivity to carboxyl contained aromatic herbicides. Associated SPME extraction parameters were investigated, and the proposed SPME-HPLC analytical method was proved to have satisfactory reproducibility with the RSD less than 6.9 %, feasible linearity with the linear coefficients above 0.99, low limits of detection (LOD) that were 0.96, 1.21, and 0.83 ng/g for dicamba, 2,4-D, and picloram, desirable accuracy with the recoveries in the range of 76.4–106.9 %. The analytical method has promising potentials for carboxyl contained aromatic herbicides sensitive and selective determination from food samples.

Inside-tube solid-phase microextraction as an interlink between solid-phase microextraction and needle device for n-hexane evaluation in air and urine headspace.

Monitoring the trace amount of chemicals in various samples remains a challenge. This study was conducted to develop a new solid-phase microextraction (SPME) system (inside-tube SPME) for trace analysis of n-hexane in air and urine matrix. The inside-tube SPME system was prepared based on the phase separation technique. A mixture of carbon aerogel and polystyrene was loaded inside the needle using methanol as the anti-solvent. The air matrix of n-hexane was prepared in a Tedlar bag, and n-hexane vapor was sampled at a flow rate of 0.1 L/min. Urine samples spiked with n-hexane were used to simulate the sampling method. The limit of detection using the inside-tube SPME was 0.0003 μg/sample with 2.5 mg of adsorbent, whereas that using the packed needle was 0.004 μg/sample with 5 mg of carbon aerogel. For n-hexane analysis, the day-to-day and within-day coefficient variation were lower than 1.37%, with recoveries over 98.41% achieved. The inside-tube SPME is an inter-link device between two sample preparation methods, namely, a needle trap device and an SPME system. The result of this study suggested the use of the inside-tube SPME containing carbon aerogel (adsorbent) as a simple and fast method with low cost for n-hexane evaluation.

Modified headspace solid-phase microextraction for the determination of quantitative relationships between components of mixtures consisting of alcohols, esters, and ethers - impact of the vapor pressure difference of the compounds.

The quantitative relationship between analytes established by the headspace solid-phase microextraction procedure for multicomponent mixtures depends not only on the character and strength of interactions of individual components with solid-phase microextraction fiber but also on their vapor pressure in the applied headspace solid-phase microextraction system. This study proves that vapor pressure is of minor importance when the sample is dissolved/suspended in a low-volatility liquid of the same physicochemical character as that of the used solid phase microextraction fiber coating. It is demonstrated for mixtures of alcohols, esters, ethers and their selected representatives by applying a headspace solid-phase microextraction system composed of Carbowax fiber and sample solutions in polyethyleneglycol. The observed differences in quantitative relations between components of the examined mixtures established by their direct analysis and by modified headspace solid-phase microextraction are insignificant (Fexp <Fcrit ). It is explained by a significant diminution in vapor pressure difference between individual components of the examined mixture in the applied headspace solid phase microextraction system due to low components concentration in polyethyleneglycol suspensions (Raoult's law) and due to strong specific interactions of analyte molecules with polyethyleneglycol molecules.

A convenient approach for the determination of multiple trace BPs using an in-syringe-assisted solid phase microextraction system packed with elastic spongy graphene rods coupled with HPLC

An elastic cylindrical three-dimensional porous spongy graphene rod (3D-PSGR) was synthesized by a facile one-step hydrothermal method and applied in a syringe system as a solid phase adsorbent for the extraction of nine trace bisphenol analogs (BPs) from environmental samples.

Spectrophotometric determination of dithizone–mercury complex by solid phase microextraction in micropipette tip syringe packed with activated carbon xerogel

A new simple miniaturized solid phase microextraction system in a syringe was developed for mercury (Hg) preconcentration of in water samples based on the adsorption of its dithizone complex on a microcolumn. The syringe system contains a micropipette tip packed with activated carbon xerogel. The influence of acidity, eluting agents, amount of adsorbent, complex stability and interfering ions was studied in detail. The complex retained on activated carbon xerogel in the micropipette tip–syringe system could be eluted using ethanol and the concentration was determined by visible spectrophotometry.The method showed good linearity in the range of 30–280μgL−1, with a limit of detection of 7.6μgL−1. The relative standard deviation (RSD%) for six replicate measurements of 280μgL−1 of Hg2+ ion was 1.36%.The proposed method was successfully applied to quantitative determination of Hg2+ in ground water and mineral water with satisfactory results.

Rapid Separation of Elemental Species by Fast Multicapillary Gas Chromatography with Multichannel Optical Spectrometry Detection following Headspace Solid Phase Microextraction

A method for conducting fast and efficient gas chromatography based on short multicapillaries in straight alignment combined with atomic emission detection was developed for field analysis. The strategy enables for speciation analysis of organometallic compounds. The analytes are simultaneously ethylated and preconcentrated on a solid phase microextraction (SPME) fiber placed in the headspace over the sample for 25 min. The ethylated species are then completely separated and selectively quantified within 25 s under isothermal conditions. A new miniaturized speciation analyzer has been constructed and evaluated. The system consists of a GC injection port and a lab-made miniaturized GC unit directly coupled with miniaturized plasma excitation source. The emitted light is transferred via optical fiber and registered with a miniaturized charged coupled device (CCD) based spectrometer. Working parameters for multicapillary column gas chromatography with atomic emission detector, including carrier gas flow rate, desorption temperature, and GC column temperature, were optimized to achieve good separation of analytes. Basic investigations of the fundamental properties of 5 cm-long multicapillary column, to evaluate its potential and limitations as a rapid separation unit, are presented. The adaptation of the technique for use with a SPME system and with a multichannel element-selective plasma-emission detector is highlighted.

Determination of trace Cd, Cu, Fe, Pb and Zn in diesel and gasoline by inductively coupled plasma mass spectrometry after sample clean up with hollow fiber solid phase microextraction system

This study reports a simple and efficient method for the determination of trace Cd, Cu, Fe, Pb and Zn in diesel and gasoline samples by inductively coupled plasma mass spectrometry after matrix removal and analyte pre-concentration using hollow fiber-solid phase microextraction (HF–SPME). The optimization of HF-SPME procedure was carried out using two-level full factorial and central composite designs. Four factors (variables), that are, sample solution pH, acceptor phase amount, extraction time and eluent concentration were optimized. Under the optimized experimental conditions, the precision was ≤3% (C=10μgL−1, n=15), limits of detection and quantification ranged from 0.1 to 0.3μgL−1 and 0.3–0.9μgL−1, respectively, and the maximum preconcentration factor was 30. The HF-SPME method was applied for the determination of trace metals in real gasoline and diesel samples.

A sequential solid phase microextraction system coupled with inductively coupled plasma mass spectrometry for speciation of inorganic arsenic

A sequential solid phase microextraction (SPME) system consisting of two monolithic capillary columns was developed for simultaneous separation and preconcentration of inorganic arsenic, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection.

Carboxylated multiwalled carbon nanotubes/polydimethylsiloxane, a new coating for 96-blade solid-phase microextraction for determination of phenolic compounds in water

A new thin-film, carboxylated multiwalled carbon nanotubes/polydimethylsiloxane (MWCNTs-COOH/PDMS) coating was developed for 96-blade solid-phase microextraction (SPME) system followed by high performance liquid chromatography with ultraviolet detection (HPLC-UV). The method provided good extraction efficiency (64–90%) for three spiked levels, with relative standard deviations (RSD)≤6%, and detection limits between 1 and 2μg/L for three phenolic compounds. The MWCNTs-COOH/PDMS 96-blade SPME system presents advantages over traditional methods due to its simplicity of use, easy coating preparation, low cost and high sample throughput (2.1min per sample). The developed coating is reusable for a minimum of 110 extractions with good extraction efficiency. The coating provided higher extraction efficiency (3–8 times greater) than pure PDMS coatings.

A novel organic–inorganic hybrid monolithic column prepared in-situ in a microchip and its application for the determination of 2-amino-4-chlorophenol in chlorzoxazone tablets

γ-Alumina nanoparticles (γ-Al2O3) were introduced to the conventional poly(methacrylic acid-co-ethylene glycol dimethacrylate) (MAA-co-EGDMA) monolith to prepare a novel organic-inorganic hybrid monolith, poly(MAA-co-EGDMA)-Al2O3 monolith. The polymerization was induced in-situ with UV irradiation in an ultraviolet transparent polymethyl methacrylate (PMMA) microfluidic chip. The monolith-based solid phase microextraction system was used for the on-line determination of 2-amino-4-chlorophenol (ACP) in chlorzoxazone tablets coupled with an optical fiber spectrophotometer. Several parameters affecting the adsorption/desorption, including sample pH value, sample flow rate, sampling time, eluent flow rate, and eluting time, were investigated in detail. Under the optimized conditions, limit of detection (LOD) and limit of quantification (LOQ) of the method were calculated to be 2.8 and 9.1µgL−1, respectively, with the relative standard deviation (RSD) of 3.1%.

Automated determination of phenolic compounds in wine, berry, and grape samples using 96-blade solid phase microextraction system coupled with liquid chromatography–tandem mass spectrometry

An automated 96-thin-film solid phase microextraction system was optimized for high throughput analysis of phenolic compounds in wine, berry, and grape samples. Liquid chromatography and tandem mass spectrometry methods were optimized and applied for separation and detection of compounds. Evaluation of five different stationary phases showed that polystyrene-divinylbenzene-polyacrylonitrile (PS-DVB-PAN) is the optimum extraction phase for the extraction of phenolic compounds under study. The thin-film PS-DVB-PAN SPME coating provided almost exhaustive extraction recovery for all phenolics compounds under study, except for naringenin with 80% recovery. Extraction efficiency, inter- and intra-day reproducibility, sensitivity, linearity, limit of detection and quantitation, and matrix effect were evaluated. Intra-day and inter-day reproducibility were in the respective range of 4–8 and 7–13% relative standard deviation (RSD) for all eight phenolic compounds. Limits of detection and quantitation of the proposed SPME-LC–MS/MS system for the analysis of analytes under study were found in the range of 0.2–3 and 0.5–10ng/mL, respectively. Standard addition calibration was applied for the quantitative determination of unknown phenolic compounds from wine, berry, and grape samples. The assessment of matrix effect showed significant reduction of ion suppression/enhancement using SPME method in comparison with that of solvent extraction technique.

Determination of selected pharmaceutical residues in wastewater using an automated open bed solid phase microextraction system

The detection of trace levels of pharmaceuticals in environmental matrices requires an analyte pre-concentration procedure to obtain the required sensitivity for quantitative determination. This research aims to develop a simple automated analytical method based on C18 thin film solid phase microextraction (TF-SPME) for the simultaneous extraction of pharmaceutical compounds detected in surface waters. As a sample preparation method, solid phase microextraction, is a rapid, environmentally friendly, and a sensitive analytical technique which isolates and pre-concentrates trace organic pollutants from environmental water samples in a single step. High throughput analysis was achieved with the use of a robotic auto sampler which enabled parallel analyte extraction in a 96-well plate format. Application of the method was demonstrated using wastewater from pilot-scale municipal treatment plants and environmental water samples from wastewater-dominated reaches of the Grand River (adjacent Waterloo, ON) which were analysed using a liquid chromatography–mass spectrometry (LC–ESI–MS/MS) technique. The proposed method successfully determined concentrations of carbamazepine, fluoxetine, sertraline, and paroxetine in treated effluent at concentrations ranging from 240 to 3820ng/L with a method detection limit of 2–13ng/L with a relative standard deviation of less than 16%. Matrix effect was not observed with this method; therefore internal standards are not necessary for quantification of target compounds. The results suggest that this method is capable of detecting and quantifying many compounds present in both wastewater and wastewater-influenced surface water from multiple municipal sources. In this study, automated TF-SPME system is demonstrated as a simple and fast alternative method for high throughput analysis of pharmaceutical contaminants in environmental matrices.

Bioanalysis Young Investigator: Dajana Vuckovic

Dajana currently has 21 peer-reviewed articles published or accepted for publication in top analytical chemistry journals including Analytical Chemistry and Angewandte Chemie International Edition. She has co-authored eight book chapters, and made 22 presentations at international conferences such as Pittcon and ASMS conferences. Dajana's commitment to excellence is also illustrated by the awards she has won to date, including a Postdoctoral Fellow Award offered by the Natural Science and Engineering Research Council of Canada (2010-2012) and the Douglas E Ryan Analytical Chemistry Student Award of the Canadian Society for Chemistry (2010). During her PhD in my group, Dajana excelled in very diverse areas of interest including the development of targeted LC-MS assays for drugs and metabolites, application of in vivo solid-phase microextraction (SPME) in mice and LC-MS metabolomics for the first time, and evaluation of a high-throughput 96-well plate automated SPME system. Since her graduation from my group she has further extended her bioanalytical expertise to proteomics. I think Dajana's excellent research productivity, accomplishments to date, willingness to address complex bioanalytical challenges and extensive expertise in both small molecule and protein bioanalysis make her an excellent candidate for the Bioanalysis Young Investigator Award.

Thin-film octadecyl-silica glass coating for automated 96-blade solid-phase microextraction coupled with liquid chromatography–tandem mass spectrometry for analysis of benzodiazepines

A thin-film octadecyl (C18)-silica glass coating was developed as the extraction phase for an automated 96-blade solid-phase microextraction (SPME) system coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS). Various factors (e.g., sol–gel composition and aging time, coating preparation speed, coating thickness, and drying conditions) affecting the quality of C18-silica glass thin-film coating were studied and optimized. The results showed that the stability and durability of the coating are functions of the coating thickness and drying conditions. Coating thickness is controlled by sol–gel composition, aging time and the withdrawal speed in the dipping method. Automated sample preparation was achieved using a robotic autosampler that enabled simultaneous preparation of 96 samples in a 96-well plate format. Under the optimum SPME conditions the proposed system requires a total of 140min for preparation of all 96 samples (i.e., 30min preconditioning, 40min equilibrium extraction, 40min desorption and 30min carry over step). The performance of the C18-silica glass 96-blade SPME system was evaluated for high-throughput analysis of benzodiazepines from phosphate-buffered saline solution (PBS) and human plasma, and the reusability, repeatability, and validity of the system were evaluated. When analysing spiked PBS and human plasma, the inter-blade reproducibility for four benzodiazepines was obtained in the ranges of 4–8% and 9–11% RSD (relative standard deviation), respectively, and intra-blade reproducibility were in the ranges of 3–9% and 8–13% RSD, respectively. The limits of detection and quantitation for plasma analysis were in the ranges of 0.4–0.7ng/mL and 1.5–2.5ng/mL for all four analytes.

Optimization of the Coating Procedure for a High-Throughput 96-Blade Solid Phase Microextraction System Coupled with LC–MS/MS for Analysis of Complex Samples

Biocompatible C18-polyacrylonitrile (PAN) coating was used as the extraction phase for an automated 96-blade solid phase microextraction (SPME) system with thin-film geometry. Three different methods of coating preparation (dipping, brush painting, and spraying) were evaluated; the spraying method was optimum in terms of its stability and reusability. The high-throughput sample preparation was achieved by using a robotic autosampler that enabled simultaneous preparation of 96 samples in 96-well-plate format. The increased volume of the extraction phase of the C18-PAN thin film coating resulted in significant enhancement in the extraction recovery when compared with that of the C18-PAN rod fibers. Various factors, such as reusability, reproducibility, pH stability, and reliability of the coating were evaluated. The results showed that the C18-PAN 96-blade SPME coating presented good extraction recovery, long-term reusability, good reproducibility, and biocompatibility. The limits of detection and quantitation were in the ranges of 0.1-0.3 and 0.5-1 ng/mL for all four analytes.

Automated study of ligand–receptor binding using solid-phase microextraction

An automated ligand–receptor binding study was performed for the first time using solid-phase microextraction (SPME) coupled to liquid chromatography–tandem mass spectrometry. A new multi-fibre SPME system, which relies on multi-well plate technology and allows parallel preparation of up to 96 samples was used in order to obtain all data points of the binding curve in a single experiment. The binding of diazepam to human serum albumin was used as the model system in order to evaluate the performance of automated SPME. The time required to establish equilibrium was 30 min; this was verified experimentally by constructing extraction time profiles in the presence and absence of receptor molecules. Fibre constant calibration was used to remove inter-fibre variability from the binding data. Using a simple one-site binding model, a binding constant of 9.1 × 10 5 ± 3 × 10 5 l/mol was obtained. This result is in excellent agreement with values for equilibrium dialysis and manual SPME procedures reported in the literature. The proposed method can be further extended to study plasma–protein binding or drug binding to whole blood. In comparison to other methods, SPME is simpler, faster and fully automated, can be combined with any analytical detection method, and can be used to directly study complex samples.

Influence of Albumin on Sorption Kinetics in Solid-Phase Microextraction: Consequences for Chemical Analyses and Uptake Processes

Because of its simplicity, solid-phase microextraction (SPME) is an increasingly popular technique to use in experiments measuring freely dissolved concentrations of compounds in biological and environmental samples. However, a number of studies have shown that sorption kinetics of compounds in such SPME systems is dependent on the presence of a binding matrix. This affects the interpretability of nonequilibrium SPME data. In this study, this phenomenon was investigated by measuring the rate of depletion of pyrene from a "loaded" poly(dimethylsiloxane) fiber into surrounding cell culture medium containing different concentrations of bovine serum albumin (BSA). The rate of depletion was found to steadily increase with increasing concentrations of BSA. It was postulated that BSA facilitated the transport of pyrene through the medium. This phenomenon was modeled by considering diffusion of BSA-bound pyrene in addition to diffusion of unbound pyrene in the aqueous boundary layer (BL) around the fiber. The model closely fit the experimental data and illustrated that diffusion in the BL was rate limiting because the analyte's affinity for the fiber was high and the BL thickness significant. The concentration of binding matrix and the analyte's affinity for the matrix further determined the extent to which BSA-facilitated transport contributed to the kinetics of the system.