Use In Solid-phase Microextraction Research Articles

Fabrication of UMCM-1 based monolithic and hollow fiber – Metal-organic framework deep eutectic solvents/molecularly imprinted polymers and their use in solid phase microextraction of phthalate esters in yogurt, water and edible oil by GC-FID

In this study, for the first time, hollow fiber and monolithic fiber were fabricated based on metal-organic framework deep eutectic solvents/molecularly imprinted polymers (MOF- DES/MIPs) and were used for microextraction of phthalate esters under termed hollow fiber liquid membrane-protected solid-phase microextraction (HFLMP-SPME) followed by gas chromatography- flame ionization detection. Several parameters influencing extraction recoveries of phthalate esters including adsorption and desorption parameters were investigated and optimized using fabricated MOF- DES/MIPs monolithic fiber. Under optimal conditions, detection limits (S/N = 3) of the method were in a range of 0.008–0.03 µg L−1 and limits of quantification (S/N = 10) were between 0.028 and 0.12 µg L−1. RSD (%) for intra-day and inter-day precisions were between 2.4–4.7% and 2.6–3.4%, respectively. Subsequently, this procedure was successfully applied with satisfactory results in the determination of phthalate esters in yogurt, water, and soybean oil samples. The R (%) ranged from 95.5 to 100.0% in different samples.

Braid solid-phase microextraction of polycyclic aromatic hydrocarbons by using fibers coated with silver-based nanomaterials in combination with HPLC with fluorometric detection.

Authors propose a novel braid support configuration for use in solid-phase microextraction (SPME) fibers. Two different braided supports (double and triple) were prepared and compared with the conventional single support configuration. Three kinds of silver-based nanomaterials that serve as coatings on these supports are described. They included silver dendrites, silver nanoparticles (AgNPs), and silver dendrites decorated with AgNPs (Ag-dendrites@AgNPs). They were prepared by electrodeposition, a layer-by-layer (LBL) method, and a hybrid strategy, respectively. Fibers were used in the direct-immersion (DI) mode of SPME. Five polycyclic aromatic hydrocarbons (PAHs) were studied as model analytes by DI-SPME when analyzing (spiked) underground waters. PAHs were further determined with high-performance liquid chromatography (HPLC) and fluorescence detection. The analytical performance of the fibers was compared to that of the commercial polydimethylsiloxane (PDMS) fiber of 100μm thickness. AgNPs obtained by LBL was the best coating and the double braid was the best support configuration. The configuration of the SPME support always played an important role independently on the coating material, being always beneficial the use of double-braids. Despite the low coatings volumes of the silver-based fibers compared to that of PDMS, the analytical features of the method were adequate. Figures of merit include: (a) limits of detection down to 20ng·L-1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) of <13%, <12%, and < 13%, respectively; and (c) adequate operational lifetime (>60 extractions). Graphical abstract Schematic presentation of braided solid-phase microextraction support configurations together with different silver-based nanomaterials as coatings.

Oriented ZnO nanoflakes on nickel-titanium alloy fibers for solid-phase microextraction of polychlorinated biphenyls and polycyclic aromatic hydrocarbons.

ZnO nanoflakes (ZnONFs) were electrochemically grown on a nickel-titanium alloy (NiTi) wire for use in solid-phase microextraction. Prior to the growth of ZnONFs, the NiTi wire was hydrothermally treated for in-situ growth of TiO2/NiO nanoflakes as a seeding base. The applied potential was used to control the dimensions of vertically oriented hexagonal ZnONFs. After annealing at 600°C, the resulting fiber display fairly selective affinity for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons. The fibers were applied to the preconcentration of PCBs which then were quantified by HPLC with UV detection. Compared to commercial polydimethylsiloxane coatings, the new coating displays high extraction capability, rapid extraction kinetics and superior cycling stability. This is assumed to be due to its high surface-to-volume ratio, double-sided open access structure, and enhanced structural stability. The assay excels by (a) a wide analytical range (0.10 to 200μgL-1 of PCBs), (b) low limits of detection (20-17ngL-1), and (c) low standard deviations for the single fiber repeatability (<9.8%) and for the fiber-to-fiber reproducibility (<7.5%). Satisfactory accuracy and precision were achieved when PCBs were determined by this method in spiked rain water, river water and wastewater samples. Graphical abstract ZnO nanoflakes were fabricated on a superelastic nickel-titanium alloy wire in desired orientation with enhanced extraction capability and good extraction selectivity. The fabricated fiber was suitable for the determination of PCBs in environmental water samples.

Silver nanoparticles supported onto a stainless steel wire for direct-immersion solid-phase microextraction of polycyclic aromatic hydrocarbons prior to their determination by GC-FID.

The authors describe a new coating for use in solid-phase microextraction (SPME). Silver nanoparticles (AgNPs) were prepared by using gallic acid or glucose as the reducing agents, and then supported onto a stainless steel wire that was previously coated with a silver mirror. Coating with AgNPs was performed by a layer-by-layer approach of up to eight cycles of consecutive deposition of AgNPs and the thiol linker 1,8-octanedithiol. This procedure allows proper control of the coating thickness. Thicknesses are 3.2μm and 3.5μm with AgNPs obtained with gallic acid and glucose, respectively. This is in agreement with theoretical estimations (3.8μm). The fibers were used in the direct-immersion SPME-GC-FID determination of 16 polycyclic aromatic hydrocarbons (PAHs) from different waters. The performance of the method was compared to the one using polydimethylsiloxane fibers (100μm), which is the most suitable commercial SPME fiber for PAHs. Despite the low thickness of the AgNP coatings (compared to PDMS), the analytical features of the method using the most adequate coating (AgNPs prepared with gallic acid) include: (a) limits of detection down to 0.6ng·mL-1; (b) intra-day, inter-day, and inter-fiber precisions (expressed as RSDs) lower than 22, 26 and 25%, respectively; and (c) an operational lifetime of ~150 extractions/desorption cycles. The analysis of various spiked environmental waters using these fibers resulted in adequate analytical performance. Graphical abstract Silver nanoparticle based coatings for solid-phase microextraction fibers were prepared by a layer-by-layer approach. They were used for determination of 16 PAHs in waters by gas chromatography. Limits of detection are < 14μg·L-1 and intra-day, inter-day, and inter-fiber precisions are <26%.

A silica fiber coated with a ZnO-graphene oxide nanocomposite with high specific surface for use in solid phase microextraction of the antiepileptic drugs diazepam and oxazepam.

A novel ZnO-graphene oxide nanocomposite was prepared and is shown to be a viable coating on fused silica fibers for use in solid phase microextraction (SPME) of diazepam and oxazepam from urine, this followed by thermal desorption and gas chromatographic quantitation using a flame ionization detector. A central composite design was used to optimize extraction time, salt percentage, sample pH and desorption time. Limits of detection are 0.5μg·L-1 for diazepam and 1.0μg·L-1 for oxazepam. Repeatability and reproducibility for one fiber (n = 4), expressed as the relative standard deviation at a concentration of 50μg·L-1, are 8.3 and 11.3% for diazepam, and 6.7 and 10.1% for oxazepam. The fiber-to-fiber reproducibility is <17.6%. The calibration plots are linear in the 5.0-1000μg·L-1 diazepam concentration range, and from 1.0-1000μg·L-1 in case of oxazepam. The fiber for SPME has high chemical and thermal stability (even at 280°C) after 50 extractions, and does not suffer from a reduction in the sorption capacity. Graphical abstract A hydrothermal method was introduced for preparation of ZnO- GO nano composite on a fused silica fiber as solid phase microextraction with high mechanical, chemical stability and long service life.

Solid-phase microextraction of sulfonylurea herbicides by using borate-reinforced multiple monolithic fibers.

Boron-nitrogen coordination is a useful interaction for use in the extraction of amino-nitrogen-containing compounds. A new monolithic adsorbent is described here that consisted of poly(acrylamidophenyl boronic acid/vinyl-3-octylimidazolium tetrafluroborate-co-divinylbenzene/ethylene dimethacrylate) polymer. It was synthesized with the aim to obtain a new kind of extraction phase for multiple monolith based fiber solid-phase microextraction of sulfonylurea herbicides. Results indicate that boron-nitrogen coordination interaction plays a key role in the efficient extraction. It is also found that soaking the sorbent in a borate solution further improves the enrichment performance. The preparation conditions and extraction parameters were optimized. Following extraction with the adsorbent, the sulfonylurea herbicides were submitted to quantitation by HPLC with DAD detection. The limits of detection are in the range of 9.0-18ng·L-1. The method was applied to monitor the herbicides in samples of tap, river and waste waters. Recoveries at spiking levels of 1.0, 10 and 100μg·L-1 are in the range of 70.1-108%, and the values for relative standard deviation are less than 10% for all analytes in all cases. Graphical abstract Schematic of the monolith-based adsorbent (MBA) on a multiple monolith based fiber (MMF) for use in solid-phase microextraction of sulfonylurea herbicides (SUs).

A chromium(III) oxide-coated steel wire prepared by arc ion plating for use in solid-phase microextraction of aromatic hydrocarbons.

The authors introduce an arc ion plating method for the deposition of chromium oxide (Cr2O3) on a steel wire substrate, and its use as a coating for solid phase microextraction. The coating has a micro- and nano-scaled structure after annealing at 700°C. It is found that Cr2O3 exhibits a good extraction capability for the aromatic hydrocarbons naphthalene, anthracene, fluorene, fluoranthene, and biphenyl. Following desorption by high temperature at 300°C, the analytes were quantified by gas chromatography (GC). The limits of detection are in the range between 20 and 200ng·L-1, and calibration plots are linear within a wide range (0.2 to 400μg·L-1). The coating has excellent mechanical properties, with a hardness is as high as 31.7GPa, and the adhesion strength between coating and substrate reaches 20.1N (corresponding to the critical Hertzian contact stress of 10GPa). This, along with the chemical and thermal stability of the Cr2O3 coating, endows the wire with a long operational life. It was used for at least 100 times without any obvious decline of extraction capability. Graphical abstract An arc ion plating method was introduced for the deposition of chromium oxide (Cr2O3) on a steel wire substrate, and its use as a coating for solid phase microextraction with high mechanical strength, stability, and long operational lifetime.

A nanoporous carbon material coated onto steel wires for solid-phase microextraction of chlorobenzenes prior to their quantitation by gas chromatography.

A nanoporous carbon material was synthesized by heating potassium citrate without using a template or an activating agent. It is shown to represent a viable coating for use in solid-phase microextraction. The material is thermally stable and mainly consists of amorphous sheets of sp2-bonded carbon. It has an extensive pore structure and a surface area as large as 1236 m2·g-1. The nanoporous carbon was deposited on the surface of steel wires, and the resulting fibers were applied to the extraction of trace levels of chlorobenzenes in water samples. Following extraction by absorbing, the chlorobenzenes were quantified by gas chromatograph in combination with electron capture detection. Extraction temperature and time, and desorption temperature were optimized (80 °C, 10 min and 310 °C). Under optimized conditions, the calibration plots are linear in thefollowing concentration ranges: 2.5 to 100 ng·L-1 (pentachlorobenzene), 5 to 200 ng·L-1 (1,2,3,4-tetrachlorobenzene), 10 to 100 ng·L-1 (hexachlorobenzene) and 10 to 500 ng·L-1 (1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene). Other figures of merit include (a) high enrichment factors (8324 to 9920), (b) low limits of detection (0.10-1.03 ng·L-1), and (c) good reproducibility (relative standard deviations including intra-day and inter-day with a single fiber and fiber-to-fiber were below 6.4% at a mixed concentration level of 2.5, 5, and 10 ng·L-1 respectively in ultra-water). This method was successfully applied to the determination of chlorobenzenes in (spiked) lake waters where it gave recoveries between 82.3% and 104.5%. Graphical abstract A nanoporous carbon material was synthesized by heating potassium citrate without using a template or an activating agent and used as a viable coating of solid-phase microextraction for chlorobenzenes.

Preparation of a porous aromatic framework via the Chan-Lam reaction: a coating for solid-phase microextraction of antioxidants and preservatives

The Chan-Lam reaction was applied to the preparation of a porous aromatic framework (PAF) at room temperature in air without employing expensive noble metal catalysts. The PAF is shown to be a viable sorbent for use in solid-phase microextraction of antioxidants and preservatives as contained in cosmetics. The material was characterized by FT-IR, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. Effects of various experimental parameters on the extraction efficiency were investigated. The analytes were extracted by using a fiber coated with the PAF. Following extraction, the fiber was directly inserted into a GC analyzer with flame ionization detection. Specifically, the following antioxidants and preservatives were extracted and detected: 2-tert-butyl-4-methoxyphenol (BHA), 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT), methylparaben (MP), and propylparaben (PP). Under the optimum experimental conditions, the method has a low limit of detection (0.12–0.22 μg L−1 for antioxidants and 0.19–0.30 μg L−1 for preservatives) and a linear response in the 0.02 to 500 mg L−1 for concentration range. Relatives standard deviations (RSDs) for one fiber ranged from 1.2% to 7.2% (n = 6) while those for three different fibers (n = 3) were in the range between 4.3% and 11.0%. The fiber was successfully employed to the determination of antioxidants and preservatives in cosmetic samples with recoveries of 81.5%–110.2%.

A magnetic multifunctional dendrimeric coating on a steel fiber for solid phase microextraction of chlorophenols

A polyamidoamine dendrimer was synthesized, placed on magnetite nanoparticles, and the resulting material was then employed as a fiber coating for use in solid phase microextraction of chlorophenols. The polyamidoamine was expected to be an efficient extracting medium due to the presence of multipolar groups and its inner porosity. A thin stainless steel wire was coated with the dendritic polyamidoamine polymer via electrolysis and chemical reactions. The coated fiber was investigated in terms of headspace solid phase microextraction of chlorophenols from aqueous samples followed by GC-MS quantitation. The calibration plots are linear in the 2–1000 ng⋅L−1 chlorophenol concentration ranges. The LOD values (for an S/N ratio of 3) are between 0.6 and 10 ng⋅L−1. The relative standard deviations (RSDs) for spiked distilled water samples (for n = 3) are <7% at a level of 100 ng⋅L−1. The RSDs for fiber to fiber variations at the same concentration are <9%. The method was applied to spiked tap water, well water and Caspian Sea water samples. Relative recoveries are between 80 and 97%. The method shows good repeatability, sensitivity, long operational lifetime, and the fibers are physically stable.

A platinum wire coated with a composite consisting of poly pyrrole and poly(ɛ-caprolactone) for solid phase microextraction of the antidepressant imipramine prior to its determination via ion mobility spectrometry

A poly(ɛ-caprolactone) deposited on a platinum wire by electrochemical polymerization of pyrrole in the presence of poly(ɛ-caprolactone) is introduced for use in solid-phase microextraction. The resulting fibers were analyzed by FTIR and scanning electron microscopy and are found to be thermally stable up to 280 °C. They were applied to the direct solid-phase microextraction and subsequent ion mobility spectrometric determination of the anti-depressant imipramine. The extraction capability of the fibers was compared to polypyrrole fibers. The effect of four parameters on peak height was investigated by d-optimal experimental design. Under optimized conditions, the detection limits for imipramine are 0.23 μg⋅L−1 (in urine) and 0.45 μg⋅L−1 (in plasma). The intra-day and inter-day relative standard deviations obtained at 100 μg L−1, using a single fibre, were found to be 2.5 % and 3.1 %, respectively. The method was successfully applied to the analysis of imipramine in urine and plasma real samples showing recoveries from 105 to 120 % and 91 to 101 %, respectively.

A review on procedures for the preparation of coatings for solid phase microextraction

Introduced in the 1990s, solid-phase microextraction (SPME) has found numerous applications. This is due to the solventless nature of SPME and the large variety of sorbents and coatings available. Highly diverse procedures have been applied to coat supports such as fused silica fibers or metal wires with sorbents in order to enhance capability, selectivity and robustness of SPME. Lately, research also is directed towards more simple methods for deposition of different types of coatings. Several of these methods have resulted in better stability and higher effective surface areas of the coatings. This review (with 128 references) covers the state of the art in methods for coating materials for use in SPME. It is divided into the following sections: (a) Dip methods and physical agglutination methods, (b) sol-gel technology, (c) chemical grafting, (d) electrochemical methods for coating (such as electrodeposition, anodizing and electrophoretic deposition), (e) electrospinning, (f) liquidphase deposition, and (g) hydrothermal methods. A final section covers conclusions and future trends.

Polyoxotungstate nanoclusters supported on silica as an efficient solid-phase microextraction fiber of polycyclic aromatic hydrocarbons

A highly porous silica-supported tungstophosphoric acid (PW) nanocluster was prepared for use in solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs). The PWs represent a class of discrete transition metal-oxide nanoclusters and their structures resemble discrete fragments of metal-oxide structures of definite size and shape. Transition metal-oxide nanoclusters display large structural diversity, and their monodisperse sizes can be tuned from several Angstroms up to 10 nm. The highly porous silica-supported tungstophosphoric acid nanocluster material is found to be capable of efficiently extracting PAHs from aqueous sample solutions. The nanomaterial was immobilized on a stainless steel wire for fabrication of the SPME fiber. Following thermal desorption, the PAHs were quantified by GC-MS. Analytical merits include limits of detection that range from 0.02 to 0.1 pg mL−1 and a dynamic range as wide as from 0.001 to 100 ng mL−1. Under optimum conditions, the repeatability for one fiber (n = 3), expressed as the relative standard deviation, is between 4.3 % and 8.6 %. The method is simple, rapid, and inexpensive. The thermal stability of the fiber and the high relative recovery make this method superior to conventional methods of extraction.

Polypyrrole/graphene composite‐coated fiber for the solid‐phase microextraction of phenols

A polypyrrole (Ppy)/graphene (G) composite was developed and applied as a novel coating for use in solid-phase microextraction (SPME) coupled with gas chromatography (GC). The Ppy/G-coated fiber was prepared by electrochemically polymerizing pyrrole and G on a stainless-steel wire. The extraction efficiency of Ppy/G-coated fiber for five phenols was the highest compared with the fibers coated with either Ppy or Ppy/graphene oxide (GO) using the same method preparation. Significantly, compared with various commercial fibers, the extraction efficiency of Ppy/G-coated fiber is better than or comparable to 85 μm CAR/PDMS fiber (best extraction efficiency of phenol, o-cresol, and m-cresol in commercial fibers) and 85 μm polyacrylate (PA) fiber (best extraction efficiency of 2,4-dichlorophenol and p-bromophenol in commercial fibers). The effects of extraction and desorption parameters such as extraction time, stirring rate, and desorption temperature and time on the extraction/desorption efficiency were investigated and optimized. The calibration curves were linear from 10 to 1000 μg/L for o-cresol, m-cresol, p-bromophenol, and 2,4-dichlorophenol, and from 50 to 1000 μg/L for phenol. The detection limits were within the range 0.34-3.4 μg/L. The single fiber and fiber-to-fiber reproducibilities were <8.3 (n=7) and 13.3% (n=4), respectively. The recovery of the phenols spiked in natural water samples at 200 μg/L ranged from 74.1 to 103.9% and the relative standard deviations were <3.7%.

Solid phase microextraction using new sol–gel hybrid polydimethylsiloxane-2-hydroxymethyl-18-crown-6-coated fiber for determination of organophosphorous pesticides

A new sol–gel hybrid coating, polydimethylsiloxane–2-hydroxymethyl-18-crown-6 (PDMS–2OHMe18C6) was prepared in-house for use in solid phase microextraction (SPME). The three compositions produced were assessed for its extraction efficiency towards three selected organophosphorus pesticides (OPPs) based on peak area extracted obtained from gas chromatography with electron capture detection. All three compositions showed superior extraction efficiencies compared to commercial 100 μm PDMS fiber. The composition showing best extraction performance was used to obtain optimized SPME conditions: 75 °C extraction temperature, 10 min extraction time, 120 rpm stirring rate, desorption time 5 min, desorption temperature 250 °C and 1.5% (w/v) of NaCl salt addition. The method detection limits (S/N = 3) of the OPPs with the new sol–gel hybrid material ranged from 4.5 to 4.8 ng g −1, which is well below the maximum residue limit set by Codex Alimentarius Commission and European Commission. Percentage recovery of OPPs from strawberry, green apple and grape samples with the new hybrid sol–gel SPME material ranged from 65 to 125% with good precision of the method (%RSD) ranging from 0.3 to 7.4%.

Solid-phase microextraction using silica fibers coated with tenax-TA films

Silica fibers (125 μm×1cm) were coated with 3 μm-thick Tenax-TA films and investigated for possible use in solid-phase microextraction. The performance of these fibers was evaluated by comparing them with commercially available polydimethylsiloxane/divinylbenzene (PDMS/DVB) SPME fibers. Performance was evaluated using static headspace extraction of n-alkanes at 25∘C. Results indicate the high performance of Tenax-TA coated fibers in terms of adsorption capacity and uptake saturation time. The PDMS/DVB fiber saturated after 25 minutes while Tenax-TA fiber saturated after 40 minutes. The uptake capacity of the Tenax-TA fibers was only half of what was retained with the 65 μm-thick PDMS/DVB fiber.

A novel multiwalled carbon nanotubes bonded fused-silica fiber for solid phase microextraction–gas chromatographic analysis of phenols in water samples

The present work reports on the synthesis of chemically bonded multiwalled carbon nanotubes (MWCNTs)/fused-silica fibers and their use in solid phase microextraction of seven phenols from water samples coupled with gas chromatography (GC). The synthetic strategy was verified by infrared (IR) spectroscopy and field emission scanning electron microscopy. Adsorption factors (pH, ionic strength, stirring rate, adsorption time and temperature) and desorption factors (time and temperature) of the fibers were systematically investigated. Detection limits to seven phenols were less than 0.05 μg L −1, and their calibration curves were all linear ( R 2 ≥ 0.9984) in the range from 0.05 to 5000 μg L −1. This method was then utilized to analyze two real water samples from Yellow River and sanitary wastewater, resulting in satisfactory results. Compared with normal solid phase materials, this MWCNTs-bonded fused-silica fibers showed a number of advantages: wide linear range and low detection limit for extracting phenols couple with GC, and good stability in acid, alkali, organic solvents and at high temperature.

Application of an NiTi alloy coated with ZrO2 solid-phase microextraction fiber for determination of haloanisoles in red wine samples

This study describes an application of ZrO2 electrolytically deposited onto an NiTi alloy (NiTi-ZrO2) as a solid-phase microextraction (SPME) fiber to the determination of 2,4,6-trichloroanisole, 2,4,6-tribromoanisole and pentachloroanisole in red wine samples at the ng L−1 level. Separation and detection was carried out by gas chromatography and electron capture, respectively. The parameters affecting extraction efficiency, such as extraction time and temperature, salting-out effect and sample pH, were simultaneously optimized firstly by means of a two-level full factorial experimental design including a center point, and subsequently through a Doehlert design for three-variables. Excellent robustness, evaluated through a factorial design study, was obtained for all variables considered in the extraction procedure. Detection limits in the range of 6.8 to 8.0 ng L−1 were obtained. Precision was excellent, relative standard deviations being lower than 7.0%. Good accuracy was obtained with calibration against a synthetic solution and 25% dilution of wine samples. The extraction capability of the fiber was stable for more than 700 extractions. Thus, it is an excellent alternative for use in SPME.

Glass fibers coated with Nb 2O 5 for use in SPME

Fiberglass with a composition of 29% Li 2O, 1% ZrO 2, 5% BaO, and 65% Si 2O was coated with Nb 2O 5 using the metallo-organic decomposition (MOD) technique. The morphology and coating homogeneity of the fibers was evaluated, using the scanning electron microscopy (SEM) technique, which revealed the presence of niobium distributed uniformly over the surface of the fibers. The efficiency of the fiber coating process was evaluated by phenol adsorption and by solid phase micro extraction (SPME) applied to gaseous chromatography. The fibers displayed a high capacity for adsorption and selectivity, as well as high durability.