Extraction Tube Research Articles

Resorcinol-formaldehyde aerogel coating for in-tube solid-phase microextraction of estrogens.

Resorcinol-formaldehyde aerogel coating was in situ prepared on the surface of basalt fibers. The aerogel coating is uniformly modified onto basalt fibers, and it is very porous according to the characterization by using scanning electron microscopy. An extraction tube was prepared for in-tube solid-phase microextraction by placing the aerogel-coated basalt fibers into a polyetheretherketone tube. To evaluate the extraction performance toward five estrogenic compounds, the tube was connected with high performance liquid chromatography, the important extraction and desorption conditions were investigated. An online analytical method for detection of estrogens was developed and presented low limits of detection (0.005-0.030 µg/L), wide linear ranges (0.017-20, 0.033-20, and 0.099-20 µg/L), good linearity (r>0.9990), and satisfactory repeatability (relative standard deviation<2.7%). The method was successfully applied to detect trace estrogens in real water samples (bottled pure water and bottled mineral water), satisfactory recoveries were ranged from 80 to 125% with two spiking levels of 2 and 6µg/L.

CFD-based process optimization of a dissolved air flotation system for drinking water production.

Dissolved air flotation (DAF) has received more attention recently as a separation technique in both drinking water as well as wastewater treatment. However, the process as well as the preceding flocculation step is complex and not completely understood. Given the multiphase nature of the process, fluid dynamics studies are important to understand and optimize the DAF system in terms of operation and design. The present study is intended towards a comprehensive computational analysis for design optimization of the treatment plant in Kluizen, Belgium. Setting up the modelling framework involving the multiphase flow problem is briefly discussed. 3D numerical simulations on a scaled down model of the DAF design were analysed. The flow features give better confidence, but the flocs escape through the outlet still prevails which is averse to the system performance. In order to improve the performance and ease of maintenance, design modifications have been proposed by using a perforated tube for water extraction and are found to be satisfactory. The discussion is further reinforced through validating the numerical model against the experimental findings for stratified flow conditions.

Triazine-based organic polymers@SiO2 nanospheres for sensitive solid-phase microextraction of polycyclic aromatic hydrocarbons.

Triazine-based organic polymers@SiO2 nanospheres were prepared and applied as an extraction coating onto stainless steel wires and the wires were filled into polyetheretherketone tube for in-tube solid-phase microextraction. Taking polycyclic aromatic hydrocarbons as targets, main factors affecting extraction performance of the tube were investigated through coupling to high performance liquid chromatography. Under the optimum conditions, an online analytical method for polycyclic aromatic hydrocarbons was established with large linear ranges (0.010-20µg/L), low limits of detection (0.003-0.010µg/L), high enrichment factors (533-2954), and good repeatability (relative standard deviations<1.7% for intraday test,<5.0% for interday test). The analysis method was successfully applied to the detection of trace targets in real water samples and the relative recoveries ranged from 82.9 to 119.9%, which demonstrated the applicability of extraction tube in sample preparation.

Balls-in-tube matrix solid phase dispersion (BiT-MSPD): An innovative and simplified technique for multiresidue determination of pesticides in fruit samples

Sample preparation of complex matrices, like food samples, continues to be a challenge demanding great effort for improvements. In this study, a new technique named balls-in-tube matrix solid-phase dispersion (BiT-MSPD) is proposed based on a simplification of the conventional MSPD technique being all sample preparation performed directly in a closed extraction tube with the assistance of steel balls. An innovative method using BiT-MSPD was successfully established for the determination of 133 pesticide residues in apple, peach, pear and plum by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). Several sorbents were evaluated as solid support in different proportions with the sample. The homogenization step using mortar, glass rod or steel balls, with methanol and acetonitrile as extraction solvent, was evaluated. Vortex and ultrasound assisted extractions were also tested. Best results were obtained with C18, homogenization with steel balls, acetonitrile as solvent and ultrasound assisted extraction. Validation presented adequate trueness and precision results for the evaluated pesticides with recovery results ranging from 72 to 113% and RSD ≤ 17%. Practical limit of detection (LOD) and quantification (LOQ) for the compounds were 3 and 10 µg kg−1, respectively. The developed method proved to be easier and faster to perform than the MSPD, considering that extraction and clean-up are performed in the same tube without the need to transfer to cartridges, recipients or to use a separate clean-up step. The proposed BiT-MSPD technique was successfully applied to fruit samples and has great potential to be applied in other matrices, like cereals and meat, since the steel balls promote an efficient sample dispersion and extraction of pesticides. The BiT-MSPD permit a fully automation of the entire sample preparation step.

Carbonized silk fibers for in-tube solid-phase microextraction to detect polycyclic aromatic hydrocarbons in water samples.

Silk fibers were carbonized to develop a biomass carbon material as an adsorbent for solid-phase microextraction. The surface structure of the carbonized silk fibers was characterized by scanning electron microscopy, and the graphitization degree was determined by Raman spectrometry. After carbonization under high temperature, the orderliness and structural regularity of carbon atoms on silk fibers were promoted. Extraction tube packed with carbonized silk fibers was prepared for in-tube solid-phase microextraction. Coupled with high performance liquid chromatography, it exhibited good extraction performance for hydrophobic polycyclic aromatic hydrocarbons. Main parameters including sampling volume, sampling rate, methanol content in sample, and desorption time were systematically investigated. Under the optimum conditions, the analysis method was established and it exhibited wide linear range (0.016-20 μg/L) with good linearity (correlation coefficient ≥ 0.9947), low limits of detection (0.005-0.050 μg/L), and high enrichment factors (1189-2775). Relative standard deviations (n=3) for intraday (≤3.3%) and interday (≤9.6%) tests indicated that the extraction material had satisfactory repeatability. Finally, the analytical method was successfully applied to detect trace polycyclic aromatic hydrocarbons in real water samples, demonstrating its satisfactory practicability.

Nano-MoO3 for highly selective enrichment of polycyclic aromatic hydrocarbons in in-tube solid-phase microextraction.

Nano-molybdenum trioxide was prepared from nano-molybdenum disulfide by simple firing in muffle furnace. Nano-molybdenum trioxide was used as the extraction coating on the stainless steel wire. Four wires were filled in a polyetheretherketone tube to get an extraction tube. The tube was connected to the six-port valve of a high performance liquid chromatograph, and the online analysis system was constructed. Extraction selectivity of the tube for different types of compounds, including polycyclic aromatic hydrocarbons, plasticizers, estrogens, anilines and neonicotinoids, was studied. Good enrichment ability for polycyclic aromatic hydrocarbons, but the extraction efficiency of others was not satisfactory. Using eight polycyclic aromatic hydrocarbons as the targets, an analytical method was established after optimizing main factors such as sampling volume, sampling rate, methanol content, and desorption time. The established method exhibited wide linear range to 0.016-20.00μg/L and low limits of detection to 0.005μg/L, and the enrichment factors can be up to 2443. The method was applied to the detection of trace polycyclic aromatic hydrocarbons in tap water and river water, and a good recovery was obtained. The tube showed good durability and chemical stability, and it still remained good extraction effect after more than 140 run.

Simultaneous determination of 75 abuse drugs including amphetamines, benzodiazepines, cocaine, opioids, piperazines, zolpidem and metabolites in human hair samples using liquid chromatography–tandem mass spectrometry

A liquid chromatography-tandem mass spectrometric method for the simultaneous determination of 75 abuse drugs and metabolites, including 19 benzodiazepines, 19 amphetamines, two opiates, eight opioids, cocaine, lysergic acid diethylamide, zolpidem, three piperazines and 21 metabolites in human hair samples, was developed and validated. Ten-milligram hair samples were decontaminated, pulverized using a ball mill, extracted with 1 mL of methanol spiked with 28 deuterated internal standards in an ultrasonic bath for 60 min at 50°C, and purified with Q-sep dispersive solid-phase extraction tubes. The purified extracts were evaporated to dryness and the residue was dissolved in 0.1 mL of 10% methanol. The 75 analytes were analyzed on an Acquity HSS T3 column using gradient elution of methanol and 0.1% formic acid and quantified in multiple reaction monitoring mode with positive electrospray ionization. Calibration curves were linear (r ≥ 0.9951) from the lower limit of quantitation (2-200 pg/mg depending on the drug) to 2000 pg/mg. The coefficients of variation and accuracy for intra- and inter-assay analysis at three QC levels were 4.3-12.9% and 89.2-109.1%, respectively. The overall mean recovery ranged from 87.1 to 105.3%. This method was successfully applied to the analysis of 11 forensic hair samples obtained from drug abusers.

Bare polyprolylene hollow fiber as extractive phase for in-tube solid-phase microextraction to determine estrogens in water samples.

Polypropylene hollow fibers as the adsorbent were directly filled into a polyetheretherketone tube for in-tube solid-phase microextraction. The surface properties of hollow fibers were characterized by a scanning electron microscope. Combined with high performance liquid chromatography, the extraction tube showed good extraction performance for five environmental estrogen hormones. To achieve high analytical sensitivity, four important factors containing sampling volume, sampling rate, content of organic solvent in sample, and desorption time were investigated. Under the optimum conditions, an online analysis method was established with wide linear range (0.03-20µg/L), good correlation coefficients (≥0.9998), low limits of detection (0.01-0.05µg/L), low limits of quantitation (0.03-0.16µg/L), and high enrichment factors (1087-2738). Relative standard deviations (n=3) for intraday (≤3.6%) and interday (≤5.1%) tests proved the stable extraction performance of the material. Durability and chemical stability of the extraction tube were also investigated, relative standard deviations of all analytes were less than 5.8% (n=3), demonstrating the satisfactory stability. Finally, the method was successfully applied to detect estrogens in real samples.

Polydopamine-coated cotton fibers as the adsorbent for in-tube solid-phase microextraction.

Polydopamine was coated onto cotton fibers as the adsorbent to improve the extraction efficiency. Polydopamine-coated cotton fibers were placed into a polyetheretherketone tube for in-tube solid-phase microextraction. To develop an online analysis system, the extraction tube was connected with high-performance liquid chromatography. The tube was evaluated with five estrogenic analytes, and the extraction and desorption conditions were optimized to get high extraction efficiency. Under the optimum conditions, the enrichment factors of five analytes were 143-1745. An online analysis method was established, it had large linear ranges (0.10-40 and 0.16-40 μg/L), low limits of detection (0.03, 0.05 μg/L) and satisfactory repeatability (≤3.2%). The analysis method was applied to detect targets in the real samples like as hot water in new plastic cup and tap water. The relative recoveries spiked at 1 and 5 μg/L in these samples were investigated and the results were in the range of 83.7-109%.

Carbonized cotton fibers via a facile method for highly sensitive solid-phase microextraction of polycyclic aromatic hydrocarbons.

Cotton fiber is an environmentally friendly and natural material with a certain extraction capacity, while its enrichment ability is poor. In order to improve the extraction efficiency of cotton fibers, it was carbonized to form a layer of amorphous carbon as the sorbent by a simple carbonization method. Carbonized cotton fibers were filled into a polyetheretherketone tube for in-tube solid-phase microextraction. The carbonization time was investigated to obtain high extraction efficiency. Coupled to high-performance liquid chromatography, the extraction tube was evaluated with polycyclic aromatic hydrocarbons, estrogens and phthalates, and it exhibited best extraction efficiency for polycyclic aromatic hydrocarbons. Under the optimum conditions, an online analysis method for several polycyclic aromatic hydrocarbons was established with large linear ranges (0.016-0.20 μg/L), low limits of detection (0.005-0.020 μg/L), and high enrichment factors (948-2874). Analysis method was successfully applied to the detection of targets in the real samples and shown satisfactory durability and chemical stability. Moreover, the relative recoveries ranged from 82 to 119.2%, which demonstrated the applicability of carbonized cotton fibers in sample preparation. Compared with other reported methods, the proposed method provided shorter extraction time, higher enrichment factors, comparable limits of detection, and recoveries.

Dispersive Solid Phase Extraction Using Magnetic Nanoparticles Performed in a Narrow-Bored Tube for Extraction of Atorvastatin, Losartan, and Valsartan in Plasma.

Purpose: In this investigation, a new version of magnetic solid phase extraction (MSPE) performed in a narrow–bore tube has been proposed. In this study, hydrophobic octyl (C8) functionalized Fe3O4 magnetic nanoparticles (MNPs) stabilized by SiOH groups (Fe3O4@SiO2@C8) are used as magnetic nano–sorbents for the extraction of cardiovascular drugs from human plasma prior to their determination by high performance liquid chromatography–photodiode array detection. Methods: After precipitation of the plasma proteins, the supernatant is diluted with deionized water and filled into the narrow–bore tube. Then mg–level of the sorbent is added into the tube. The sorbent is dispersed and moved down through the solution instead of passing the solution from the cartridge. Using an external magnet, the collected nano–sorbents at the bottom of the tube are transferred on top of the solution and released to move down through the solution for three times to increase the extraction efficiency. Results: The linearity of the assay was ranging from 0.4–500 mg mL-1. The limits of detection and quantification of the method were obtained in the ranges of 0.05–0.07 and 0.16–0.24 mg L-1, respectively. The extraction recoveries were obtained in the range of 31–49%. Intra– and inter–day precisions were calculated and obtained in the ranges of 5–8 and 7%–9% for 0.5 mg L-1 of each analyte, and 5–6 and 6%–8% for 2 mg L-1 of each analyte, respectively. Conclusion: The proposed method was successfully used in determination of the studied drugs in patient’s plasmas.

Diamond nanoparticles coating for in-tube solid-phase microextraction to detect polycyclic aromatic hydrocarbons.

Diamond nanoparticles were coated onto stainless steel wires as a extraction material, then it was filled into a poly(ether ether ketone) tube for in-tube solid-phase microextraction. Coupled with high-performance liquid chromatography, the extraction tube was evaluated with different types of analytes including polycyclic aromatic hydrocarbons, estrogens and plasticizers. As the coating, diamond nanoparticles exhibited greater extraction capacity for hydrophobic analytes. Several polycyclic aromatic hydrocarbons were used as model analytes, four main extraction and desorption factors were optimized, including sampling volume, sampling rate, methanol content in sample and desorption time. A sensitive analysis method was established with wide linear range (0.016-20μg/L), good correlation coefficients (0.9991-0.9997), low limits of detection (0.005-0.020μg/L), low limits of quantitation (0.016-0.070μg/L) and high enrichment factors (305-2396). Relative standard deviations for intra- and interday were less than 2.4% (n=3) and 8.4% (n=3), respectively. Durability and chemical stability were satisfactory with relative standard deviations less than 7.9% (n=3). Finally, the method has been successfully applied to the detection of polycyclic aromatic hydrocarbons in real samples.

Melamine–formaldehyde aerogel coating for in-tube solid-phase microextraction

A melamine–formaldehyde (MF) aerogel coating was prepared on basalt fibers (BFs) for in-tube solid-phase microextraction (SPME). MF aerogel-coated BFs were placed in a polyetheretherketone tube to obtain the extraction tube. To build an in-tube SPME–high performance liquid chromatography (HPLC) online system, the extraction tube was connected with HPLC equipment by replacing the sample loop of a six-port valve. The extraction tube was evaluated using eight polycyclic aromatic hydrocarbons (PAHs) as model analytes. After the optimization of important factors, an online analysis method was established. Wide linear ranges (0.03–25 μg L−1, 0.06–30 μg L−1) and low detection limits (0.01, 0.02, and 0.05 μg L−1) were observed. High sensitivity resulted from large enrichment factors ranging from 2070 to 3246. To validate the analysis method, two real water samples were detected. Most of the analytes were not detected in tap water and rainwater, and relative recoveries spiked at 2 and 5 μg L−1 were in the range of 80%–117%. The extraction repeatability on one tube and the preparation repeatability among three tubes were also tested, and their RSDs (n = 3) were in the range of 0.77%–2.04% and 0.88%–9.17%, respectively. As a result of the high surface area of the MF aerogel and π-π interactions with PAHs, the MF aerogel coating exhibits a superior extraction performance than other SPME materials, including wider linear ranges, lower LODs and higher enrichment factors.

Barium Sulfate Nanoparticles as a Coating for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons in Aqueous Samples

Owing to the high toxicity of polycyclic aromatic hydrocarbons (PAHs) and their low content in the environment, the development of efficient analysis methods is very important. In this work, an extraction tube was developed through filling barium sulfate nanoparticle-coated basalt fibers (BFs) in a poly(ether ether ketone) (PEEK) tube. According to the characterization result by scanning electron microscopy, BFs were evenly covered with barium sulfate nanoparticles, and their diameter was about 11 µm. To sensitively determine PAHs, the extraction tube was connected to a high-performance liquid chromatography instrument with diode array detector for an online enrichment and detection method. By optimizing sampling volume, sampling rate, the content of methanol in sample and desorption time, the analysis method provided a wide linear range (0.30–20 µg L− 1) and high enrichment ratio (71–2095), and was useful for the efficient detection of PAHs in environmental aqueous samples.

Basalt fibers grafted with a poly(ionic liquids) coating for in-tube solid-phase microextraction.

To improve the durability and extraction efficiency of an ionic liquid coating, 1-dodecyl-3-vinylimidazolium bromide was polymerized and grafted onto basalt fibers for in-tube solid-phase microextraction. To develop an extraction tube, basalt fibers grafted with the poly(ionic liquids) coating were filled into a polyether ether ketone tube with a 0.75mm inner diameter. The extraction tube was connected to high-performance liquid chromatography system equipped with a sampling pump to build an online enrichment and analysis system. Using four common phthalates as model analytes, the extraction tube was investigated by the online analysis system. Good enrichment performance was exhibited by high enrichment factors ranging from 851 to 1858. Under the optimum conditions, an online analysis method was established, and good linearity (0.03-12 and 0.15-12 μg/L) and low limits of detection (0.01-0.05 μg/L) were achieved. This analysis method was applied to real samples including water in a disposable plastic box and the bottled water, some targets were detected but not quantified, and the relative recoveries spiked at 2, 5 and 10 μg/L were in the range of 86.4-119.5%.

Simple ICP-OES based method for determination of selected elements in brewed ground and soluble coffees prior to evaluation of their intake and chemical fractionation

A simple method of simultaneous determination of aluminum (Al), barium (Ba), calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), nickel (Ni), strontium (Sr) and zinc (Zn) in brews of ground and soluble coffees was proposed. It relied on acidification of brews with HNO3 to 1.3 mol L−1 and their analysis by inductively coupled plasma optical emission spectrometry. Precision of 0.1–9% and detection limits from 0.07 ng mL−1 (Sr) to 3 ng mL−1 (Ni) were achieved. Trueness of the method was verified by comparison of results with those achieved with wet digestion and by the recovery study, and was better than 5%. Additionally, chemical fractionation by tandem solid phase extraction with reverse-phase and strong cation-exchange extraction tubes was carried out. Differences in chemical fractionation patterns, particularly the residual fraction, was useful for differentiation of ground and soluble coffees by analysis of variance, principle component analysis and hierarchical clustering analysis.

Determination of 24 personal care products in fish bile using hybrid solvent precipitation and dispersive solid phase extraction cleanup with ultrahigh performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry

Personal care products (PCPs) are ubiquitous in aquatic environments owing to the continuous discharge of domestic wastewater from highly urbanized regions. These PCPs can be adsorbed by fish and thereafter usually enter the bile of the fish through biliary excretion. In this study, a sensitive method based on a combination of hybrid solvent precipitation and dispersive solid phase extraction (d-SPE) purification was developed to simultaneously extract and detect 24 PCPs, namely, 16 biocides, 4 synthetic musks, and 4 benzotriazoles, from fish bile. Hybrid precipitation on solid phase extraction (SPE) tubes was applied to remove phospholipids and proteins, and a d-SPE procedure was used for further purification. The extraction solvents for the hybrid precipitation/SPE tubes and d-SPE materials were optimized. The method performance for bile samples both with and without enzyme hydrolysis using β-glucuronidase/aryl-sulfatase were validated. The 24 PCPs in fish bile were spiked with standard concentrations of 10 ng/mL, 20 ng/mL, 100 ng/mL, and 200 ng/mL to evaluate recoveries, which ranged from 70 to 120% for 16, 16, 22, and 21 analytes with hydrolysis, respectively, and 70–120% for 14, 15, 23, and 23 analytes without hydrolysis, respectively. The quantification limits for target PCPs were in the range 0.26–7.38 ng/mL [excluding musk xylene (MX) and musk ketone (MK)] and 0.20–9.48 ng/mL (excluding MX and MK) for bile samples with and without enzyme hydrolysis, respectively. After enzyme hydrolysis, 12 PCPs were detected in bile from fish collected from the Yangtze River, with a maximum detected concentration of 460 ng/mL, for triclosan (TCS). The hydrolysis reaction indicated that high percentages of glucuronide and sulfate metabolites for some PCPs, i.e. four parabens and TCS, existed in the bile.

Co-Al bimetallic hydroxide nanocomposites coating for online in-tube solid-phase microextraction

The Co-Al bimetallic hydroxide nanocomposites were synthesized and used as in-tube solid-phase microextraction coating. The nanocomposites-coated fibers were packed in a PEEK tube and tested for the extraction of eight polycyclic aromatic hydrocarbons (PAHs) coupled with high performance liquid chromatography. Several parameters affecting the PAHs extraction including the sampling volume, sampling flow rate, methanol content and desorption time were investigated. Under the optimized conditions, the extraction tube with nanocomposites coating exhibited remarkable extraction performance towards PAH targets. An online analysis method was achieved with the limits of detection less than 0.02 μg L−1 and the linearity in the range from 0.03 to 15 μg L−1. The recoveries of the method for two water samples with spiking levels of 1 and 10 μg L−1 ranged from 83 to 121%. Extraction repeatability and preparation repeatability were less than 4.0% and 10.9%, respectively.

Development of electrochemically controlled packed-in-tube solid phase microextraction method for sensitive analysis of acidic drugs in biological samples

In the present research, for the first time, a novel “packed-in-tube” configuration has been applied to electrochemically controlled in-tube solid phase microextraction, followed by high performance liquid chromatography. In order to prepare a mini packed column, small beads of stainless steel were first placed into the stainless steel column. Then, a nanostructured polypyrrole film was prepared on the internal surface of a stainless steel tube and the surface of stainless steel particles through a facile in-situ electrodeposition method. Filling the column with tiny particles of stainless steel effectively reduces the dead volume of the extraction tube and increases the extraction phase volume. The column was used for separation and preconcentration of diclofenac and mefenamic acid as model analytes from biological samples. Several important factors affecting extraction efficiency, such as extraction and desorption times, flow rates of the sample solution and eluent, and extraction and desorption voltages were investigated and optimized. This method showed good linearity for the drugs in the range of 0.3–200.0 μg L−1, 1.1–200.0 μg L−1, and 1.8–200.0 μg L−1 with coefficients of determination better than 0.9986, 0.9973, and 0.9973 in water, urine, and plasma samples, respectively. Intra- and inter-assay precisions (RSD%, n = 3) were in the range of 2.6–4.8% and 2.9–5.1, respectively, at three concentration levels of 10, 25, and 75 µg L−1. In addition, the limits of detection were in the range of 0.02–0.04 μg L−1. The validated method was successfully applied to the analysis of diclofenac and mefenamic acid in some biological samples. Finally, it is concluded that this method can be a general and reliable alternative to the analysis of ionic compounds in biological matrices.

Direct ICP-OES multielement analysis of infused black and green teas and chemical fractionation of selected essential and non-essential elements prior to evaluation of their bioavailability and classification of teas by pattern recognition

Operationally defined chemical fractionation of Al, Ba, Ca, Cu, Fe, Mg, Mn, Ni, Sr and Zn in infusions of loose leaf and bagged black and green teas was carried out. It was based on tandem-column solid phase extraction using reverse-phase and strong cation-exchange extraction tubes connected in series. Concentrations of elements in resultant infusions as well as column effluents and eluates were determined with the aid of inductively coupled plasma optical emission spectrometry and a newly developed simplified sample preparation procedure. It was established that information on separated chemical fractions, particularly the fraction of residual species of elements, had better discrimination power than information about total concentrations of these elements. Differences in chemical fractionation patterns of elements in infusions of analyzed four types of tea led to simple classification of different black and green teas by principal component analysis and linear discriminant analysis.