Polydimethylsiloxane Phase Research Articles

Diels-Alder Network Blends as Self-Healing Encapsulants for Liquid Metal-Based Stretchable Electronics.

Two dynamic covalent networks based on the Diels-Alder reaction were blended to exploit the properties of the dissimilar polymer backbones. Furan-functionalized polyether amines based on poly(propylene oxide) (PPO) FD4000 and polydimethylsiloxane (PDMS) FS5000 were mixed in a common solvent and reversibly cross-linked with the same bismaleimide DPBM. The morphology of the phase-separated blends is primarily controlled by the concentration of backbones. Increasing the PDMS content of the blends results in a dilute droplet morphology at 25 wt %, with a growing size and concentration of droplets and the formation of two separate PPO- and PDMS-rich layers at 50 wt %. Further increasing the PDMS content to 75 wt % leads to larger droplets and a thicker layer of the secondary phase. The hydrophobic PDMS phase creates a barrier against water, while the more hydrophilic PPO phase enhances the resistance against oxygen diffusion. Lowering the maleimide-to-furan stoichiometric ratio resulted in a decrease in cross-link density and thus more flexible and stretchable encapsulants. Changes in the stoichiometric ratio also affected the phase morphology due to resulting changes in phase separation and network formation kinetics. Lowering the stoichiometric ratio also resulted in enhanced self-healing properties of 96% at room temperature as a consequence of the increased chain mobility in the blended networks. The self-healing blends were used to encapsulate liquid metal circuits to create stretchable strain sensors with a linear electro-mechanical response without much drift or hysteresis, which could be efficiently recovered by 90% after the damage-healing cycles.

Development of a novel microdevice for sorptive extraction under a green analytical chemistry approach: Application for bioanalytical determination of Ibuprofen

This study proposes a novel device called micro polymeric magnetized bar adsorptive extraction (µ-PMBAE), as an extraction and enrichment technique for trace analysis in aqueous samples. These micro-bar absorbent devices were prepared using easily accessible and low-cost materials, incorporating different sorbent materials into a polymer and introducing a small piece of neodymium magnet. Several stability tests were applied to determine their robustness, stability, and weight variation; finally, ibuprofen concentration in urine samples was determined, demonstrating the applicability of extraction devices under a green analytical chemistry approach. The µ-PMBAE showed remarkable advantages since different sorbents can be added to the hot melt glue. This tunes the interaction with the analytes to become more specific in the extraction. Likewise, the magnetic ability makes it possible to carry out extraction without using an extra stir bar, matching its performance with the traditional commercially based on polydimethylsiloxane phase. The proposed analytical method demonstrated excellent performance concerning high recovery percentages, adequate coefficients of variation, and low detection limits.

Development of a novel microdevice for sorptive extraction under a green analytical chemistry approach: Application for bioanalytical determination of Ibuprofen

This study proposes a novel device called micro polymeric magnetized bar adsorptive extraction (µ-PMBAE), as an extraction and enrichment technique for trace analysis in aqueous samples. These micro-bar absorbent devices were prepared using easily accessible and low-cost materials, incorporating different sorbent materials into a polymer and introducing a small piece of neodymium magnet. Several stability tests were applied to determine their robustness, stability, and weight variation; finally, ibuprofen concentration in urine samples was determined, demonstrating the applicability of extraction devices under a green analytical chemistry approach. The µ-PMBAE showed remarkable advantages since different sorbents can be added to the hot melt glue. This tunes the interaction with the analytes to become more specific in the extraction. Likewise, the magnetic ability makes it possible to carry out extraction without using an extra stir bar, matching its performance with the traditional commercially based on polydimethylsiloxane phase. The proposed analytical method demonstrated excellent performance concerning high recovery percentages, adequate coefficients of variation, and low detection limits.

Tuning of antifouling active PDMS domains tethered to epoxy/amine surface

Biocides in marine coatings provide superior antifouling properties, although harmful effects on the eco system are inevitable. Environmentally friendly polydimethylsiloxane (PDMS) alternatives rely on biorepulsion, but inherently lack in durability due to their low E-Modulus making them unsuited for mechanical cleaning. We employ the commercially available 2K epoxy-amine system Beckopox™ EP 128 and Beckopox™ EH 637, which we modify with Bis(3-aminopropyl) terminated polydimethylsiloxane. This approach incorporates a robust 2K epoxy resin as a basis for reactive PDMS species combining the environmentally benign biorepulsion with mechanical stability. The immiscibility between epoxy and PDMS phases causes a spontaneous separation process thereby forming circular PDMS enriched surface domains as verified via EDX. A Key factor in improving the antifouling performance is to carefully tune the interstitial domain distances and ensure domain formation over the whole surface. Since control over these parameters has proven to be challenging, we introduce an amphiphilic polyglycol-PDMS compatibilizer (COMP) to the system specifically fit to balance out the internal interfacial tensions. Prepared coatings have shown to withstand even high-pressure cleaning with no sign of significant erosion. The use of 5.1 wt% COMP guarantees surface coverages up to 60%. Further domain control is gained by the variation of the time between application and cured state (pre-curing time). Specific topography and interstitial distance design were correlated to the coatings antifouling performance under real-life conditions in the North Sea (Norderney, Germany). Retardation of the biological growth is demonstrated to be present for 117 days after submersion until foulants settlement matches the control.

Interdigitated Three-Dimensional Heterogeneous Nanocomposites for High-Performance Mechanochromic Smart Membranes.

Mechanochromic smart membranes capable of optical modulation have great potential in smart windows, artificial skins, and camouflage. However, the realization of high-contrast optical modulation based on light scattering activated at a low strain remains challenging. Here, we present a strategy for designing mechanochromic scattering membranes by introducing a Young's modulus mismatch between the two interdigitated polydimethylsiloxane phases with weak interfaces in a periodic three-dimensional (3D) structure. The refractive index-matched interfaces of the nanocomposite provide a high optical transparency of 93%. Experimental and computational studies reveal that the 3D heterogeneity facilitates the generation of numerous nanoscale debonds or "nanogaps" at the modulus-mismatching interfaces, enabling incident light scattering under tension. The heterogeneous scatterer delivers both a high transmittance contrast of >50% achieved at 15% strain and a maximum contrast of 82%. When used as a smart window, the membrane demonstrates effective diffusion of transmitting sunlight, leading to moderate indoor illumination by eliminating extremely bright or dark spots. At the other extreme, such a 3D heterogeneous design with strongly bonded interfaces can enhance the coloration sensitivity of mechanophore-dyed nanocomposites. This work presents insights into the design principles of advanced mechanochromic smart membranes.

Fast and opposite temperature responsivity in release behavior of cocontinuous hydrogel composites

For practical implementation, numerous attempts have been made to improve the mechanical durability and response rate of temperature-responsive hydrogels. In this study, the introduction of a cocontinuous structure with polydimethylsiloxane (PDMS), which successfully improved both the properties, was found to reverse the temperature dependence of release behavior. The cocontinuous composites of poly(N-isopropylacrylamide) (PNIPAm) and PDMS were prepared via directional melt crystallization and subsequent infiltration of PDMS. The compressive moduli of composites were more than 30 times higher than those of PNIPAm. Further, the existence of soft hydrophobic PDMS walls against the PNIPAm phases accelerated the deswelling process, and thus, it was more than 2,000 times faster than that of PNIPAm. The deswelling rate increased as the size of PDMS phases increased. The release rate accelerated above the lower critical solution temperature (LCST) and slowed below the LCST, reversibly, thereby opposing the behavior of PNIPAm. Therefore, the fast volume shrinkage of PNIPAm phases confined between PDMS phases is responsible for the unique release behavior of the composites, and not the molecular diffusion processes through hydrogel mesh structures. Collectively, these findings highlight a versatile tool for engineering the release behavior of smart drug carriers based on temperature-responsive hydrogels.

Partition, Reaction, and Diffusion Coefficients of Bromine in Elastomeric Polydimethylsiloxane.

Experiments and models were used to determine the extent to which aqueous bromine permeated into, and reacted with, the elastomer polydimethylsiloxane (PDMS). Thin films of PDMS were immersed in bromine water, and the absorbance of bromine in the aqueous phase was measured as a function of time. Kinetics were studied as a function of mass and thickness of the immersed PDMS films. We attribute the decrease of bromine in solution to permeation into PDMS, followed by a combination of diffusion, reversible binding, and an irreversible reaction with PDMS. In order to decouple the irreversible reaction from the reversible processes, kinetics were also studied for bromine-passivated PDMS films. Fits of the models to a variety of experiments yielded the partition coefficient of bromine between the water and PDMS phases, the diffusion constant of bromine in PDMS, the irreversible reaction constant between bromine and PDMS, the molar concentration of the reactive sites within PDMS, and the on and off rates of reversible binding of bromine to PDMS. Developing a quantitative reaction-diffusion model accounting for the transport of bromine through PDMS is necessary for the design of microfluidic devices fabricated using PDMS, which are used in experimental studies of the nonlinear dynamics of reaction-diffusion networks containing Belousov-Zhabotinsky chemical oscillators.

Pigment printing of polyester fabric using a single step synthesized PDMS-modified polyurethane-acrylic/pigment hybrid emulsion

A novel, waterborne polydimethylsiloxane (PDMS)-modified polyurethane-acrylic (Si-PUA)/pigment hybrid emulsion was synthesized by one-step miniemulsion polymerization for the pigment printing of polyester fabric. The phase structure, hydrophobicity, and thermal and mechanical properties of the formed films with different PDMS contents from the hybrid emulsion were investigated. The results indicated that the pigment particles were uniformly distributed in the homogeneous phase polymer substrate without phase separation occurring between the PDMS phase and polyurethane-acrylic. The hydrophobicity and toughness of the Si-PUA/pigment hybrid latex films gradually increased with the increase of PDMS content. Moreover, the obtained hybrid emulsion was used as a self-curable hybrid pigment that was applied to polyethylene terephthalate fabric for pigment printing. This showed that the Si-PUA/pigment hybrid latex particles yielded similarly good values in terms of color strength, and dry- and wet-rubbing fastness to the PDMS-free hybrid latex particles. Furthermore, use of the Si-PUA/pigment hybrid latex avoided certain problems related to printed fabric, such as poor air permeability and softness.

Evaluation of gas chromatography for the separation of a broad range of isotopic compounds

The separation of deuterated compounds from their protiated counterparts is essential in areas of drug discovery and development, investigating kinetic isotope effects and quantitative methods of non-mass spectrometry-based stable isotope dilution assay (non-MS SIDA). The separations of 47 isotopologue pairs of common compounds and drugs were achieved by gas-liquid chromatography, employing twelve different stationary phases. Polydimethylsiloxane phase, phenyl substituted polydimethylsiloxane phases, wax phases, ionic liquid phases, and chiral stationary phases were selected to encompass a wide polarity range and diverse chemical interactions. The best-performing stationary phases are presented for separation of protic-polar, aprotic-dipolar, nonpolar analytes. Overall, the IL111i, SPB-20, and PAG stationary phases were remarkable in their ability to separate the isotopologues. The isotope effect was also evaluated. It was observed that nonpolar stationary phases often exhibit an inverse isotope effect in which heavier isotopic compounds elute earlier than their lighter counterparts. Conversely, polar stationary phases often show a normal isotope effect, while those of intermediate polarities can show both effects depending on the isotopologues. The location of deuterium atoms, however, affects isotopologue retention times. Deuterium substituted aliphatic groups appear to have a greater inverse isotope effect on retention than aromatic substituents.

Effect of Piezoelectric Phase on Electrical Properties of PDMS-Based Nanocomposites

In this work, nanocomposite between polydimethylsiloxane (PDMS) and barium titanate (BT) are prepared in order to use as piezoelectric nanogenerator. Barium titanate phase with various amounts and shapes such as nanoparticles and nanowires are synthesized via appropriated methods. The PDMS and BT phases are homogeneously mixed and casted into 3 cm x 4 cm rectangle. Phase formation, chemical property and microstructure of these nanocomposites are identified via XRD, FTIR and SEM methods, respectively. Both frequency and temperature dependences of dielectric properties for all samples are measured by LCR meter. The piezoelectric properties of these nanocomposites are performed by study the generated output voltage and current after applying the mechanical force to the samples. From those results, it is concluded that the electrical properties of these BT/PDMS nanocomposites strongly depend on amounts and forms of piezoelectric filler. The orientation of polarization within the BT crystal shows an important role for piezoelectric properties of these nanocomposites.

Novel PDMS based semi-interpenetrating networks (IPNs) for the extraction of phenolic compounds

Four Semi-Interpenetrating Networks (semi-IPN) based on polydimethylsiloxane (PDMS) were developed for the sorptive extraction of polar phenolic compounds (log Kow ≤ 3). Their preparation is based on the hydrosilylation crosslinking reaction of dihydrosilane terminated polydimethylsiloxane with its homologue divinyl, followed by the addition of inert various polyethylene oxide derivatives (PEO). The physico-chemical properties of the semi-IPN were controlled by Differential Scanning Calorimetry (DSC), Scanning Electronic Microscopy (SEM), RAMAN spectroscopy and contact angle measurements, showing the homogeneity of the semi-IPN and their higher hydrophilicity. Under optimum extraction conditions of phenolic molecules as target analytes and using liquid chromatography as analysis techniques, the novel modified PDMS phases showed good extraction rate against polar analytes with an excellent relative recovery average (69–100 %) for phenolic molecules. The higher retention rates were obtained with 30 % interpenetrated copolymer PEO/PPO in PDMS. Moreover, five adsorption/desorption cycles led to a loss of 5.8 % of the adsorption efficiency, showing a good stability of these PDMS-based IPN phases.

Recent Developments of Stir Bar Sorptive Extraction for Food Applications: Extension to Polar Solutes.

Stir bar sorptive extraction (SBSE) is a miniaturized and solvent-less sample preparation method for extraction and concentration of organic compounds from aqueous samples. The method is based on sorptive extraction, whereby the solutes are extracted into a polymer, such as polydimethylsiloxane (PDMS), coated on a stir bar. Using an apolar PDMS coating, SBSE provides high recoveries for apolar solutes; however, SBSE recoveries for polar solutes are low. Although several more polar coatings for SBSE were developed, these extraction phases are mostly not compatible with thermal desorption (TD) and/or have inferior performance characteristics related to robustness, bleeding, stability, etc. compared to PDMS. In this perspective, two recently introduced SBSE approaches are described that can be used to extend the applicability of a PDMS coating to more polar solutes: (1) SBSE with freeze concentration [ice concentration linked with extractive stirrer (ICECLES)], which is based on the concentration of analytes by gradually reducing the phase ratio (sample/extraction phase), and (2) SBSE using a solvent-swollen PDMS [solvent-assisted SBSE (SA-SBSE)], which is based on a combination of polarity modification and volume increase by PDMS phase swelling using certain types of solvents while maintaining the original characteristics of the PDMS phase.

Tunable wrinkle structure formed on surface of polydimethylsiloxane microspheres

Soft materials with controlled surface patterns are useful for a range of applications, including microdevices, sensors and adhesives. In this work, the spontaneously wrinkled morphologies on the surfaces of crosslinked polydimethylsiloxane (PDMS) microspheres were observed. These wrinkled microspheres may have great potentials for construction of high-performance functional materials. They were fabricated in curable PDMS/water emulsions stabilized by surfactants. After curing and drying, the PDMS droplets in the emulsions formed microspheres with different surface wrinkling morphologies, including dimples and labyrinth patterns. The buckling patterns could be well tuned by the surfactant concentration, curing temperature, evaporation and compositions of PDMS phase. A power-law dependence of the wrinkling wavelength on microsphere radius was also observed. Furthermore, the wrinkling morphologies showed good reversibility by simply drying after wetting with water. It is speculated that the evaporation of dissolved water in the PDMS phase triggers interfacial instabilities and result in the wrinkled morphologies. This work gives new insights into the surface wrinkling behavior of soft microspheres, and provides a simple, efficient and environmentally friendly route to fabricate microspheres with complex surface patterns.

Janus and Strawberry-like Particles from Azo Molecular Glass and Polydimethylsiloxane Oligomer.

This study investigated Janus and strawberry-like particles composed of azo molecular glass and polydimethylsiloxane (PDMS) oligomer, focusing on controllable fabrication and formation mechanism of these unique structures and morphologies. Two materials, the azo molecular glass (IA-Chol) and PDMS oligomer (H2pdca-PDMS), were prepared for this purpose. The Janus and strawberry-like particles were obtained from the droplets of a dichloromethane (DCM) solution containing both IA-Chol and H2pdca-PDMS, dispersed in water and stabilized by poly(vinyl alcohol). Results show that the structured particles are formed through segregation between the two components induced by gradual evaporation of DCM from the droplets, which is controlled by adding ethylene glycol (EG) into the above dispersion. Without the addition of EG, Janus particles are formed through the full segregation of the two components in the droplets. On the other hand, with the existence of EG in the dispersion, strawberry-like particles instead of Janus particles are formed in the phase separation process. The diffusion of EG molecules from the dispersion medium into the droplets causes the PDMS phase deswelling in the interfacial area due to the poor solvent effect. Caused by the surface coagulation, the coalescence of the isolated IA-Chol domains is jammed in the shell region, which results in the formation of the strawberry-like particles. For the particles separated from the dispersion and dried, the PDMS oligomer phase of the Janus particles can adhere and spread on the substrate to form unique "particle-on-pad" morphology due to its low surface energy and swelling ability, while the strawberry-like particles exist as "standstill" objects on the substrates. Upon irradiation with a linearly polarized laser beam at 488 nm, the azo molecular glass parts in the particles are significantly deformed along the light polarization direction, which show unique and distinct morphologies for these two types of the particles.

PHARMACEUTICAL COMPOUNDS DETERMINATION IN WATER SAMPLES: COMPARISON BETWEEN SOLID PHASE EXTRACTION AND STIR BAR SORPTIVE EXTRACTION

A variety of organic compounds and their metabolites used in pharmaceutical and personal care products (PPCP´s) are continuously introduced into the environment by domestic or industrial wastewater. Solid phase extraction (polymeric dinivylbenzene cartridge) and stir bar sorptive extraction (polydimethylsiloxane phase) methodologies were optimized for the determination of some selected PPCP´s in aqueous matrices. Carbamazepine, β estradiol, 3-(4-methylbenzylidene) champhor, benzophenone-1 and ibuprofen were extracted from aqueous samples and methanol was used as conditioning/eluting solvent. The variables involved in the extraction of the analytes in the original sample were studied, pH between 3 and 6 and sample volume between 50 and 500 mL were considered. Three concentration levels were extracted at the optimal conditions of pH 5 and 500 mL of sample volume with a recovery up to 89%. The determination was performed in a GC-MS, and a derivatization step using BSTFA+TMCS (99:1) was needed previous to the injection. Real samples from Maipo River and Villarrica Lake were analyzed with the optimized method, and concentrations below the detection limit were detected.

Determining equilibrium partition coefficients between lipid/protein and polydimethylsiloxane for highly hydrophobic organic contaminants using preloaded disks

Bioaccumulation of hydrophobic organic contaminants is of great concern and understanding their partitioning to biological phases is crucial for estimating their bioaccumulation potential. The estimation, however, was of large uncertainty for highly hydrophobic organic contaminants (HHOCs) with log KOW>9 due to the challenge of quantifying their water concentrations. In the present study, partition coefficients between polydimethylsiloxane (PDMS) and storage lipid (KSL,PDMS), membrane lipid (KML,PDMS) and protein (Kpro,PDMS) were measured for 21 polychlorinated biphenyls (PCBs), 14 polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP) and decabromodiphenyl ethane (DBDPE), covering log KOW from 5.07 to 11.6, using a preloaded PDMS depletion method. The values of KSL,PDMS, KML,PDMS and Kpro,PDMS were in the ranges of 5.36–52.5, 0.286–11.8 and 0.067–2.62g/g, respectively, being relatively constant although their KOW values extend more than six orders of magnitude. The relative sorption capacity of the biological phases showed storage lipid was the dominant sorption phase in biota, followed by membrane lipid and protein was the lowest. The KPDMS,pro values of the compounds with log KOW<9 were similar (0.382–14.9g/g) regardless of the thickness of preloaded PDMS disks (58–209μm). For HHOCs, however, KPDMS,pro values dropped when thinner PDMS disks were used, as a result of slow diffusion of HHOCs in PDMS. The KPDMS,pro values of HHOCs measured by 58-μm PDMS disks ranged from 1.78 to 6.85g/g, which was consistent with compounds with log KOW<9. This validated that partition coefficients between PDMS and biological phases were independent of chemical hydrophobicity, showing the advantage of using PDMS-based methods to directly estimate bioaccumulation potential of HHOCs.

EFFECT OF ELECTRON BEAM IRRADIATION ON THE STRUCTURE–PROPERTY RELATIONSHIP OF ETHYLENE OCTENE COPOLYMER AND POLYDIMETHYL SILOXANE RUBBER BLENDS

ABSTRACT The effects of electron beam irradiation on the structure–property relationship of blends can be studied based on ethylene octene copolymer (EOC) and polydimethyl siloxane (PDMS) rubber at three different blend ratios prepared with a melt mixing technique. Irradiation with 2.5 MeV electron beam accelerating energy, over a radiation dose varying from 25 to 150 kGy, causes cross-linking in both the EOC and the PDMS phases. However, cross-linking of the EOC phase without affecting the crystallinity of the EOC polymer leads to tremendous improvement in the physicomechanical properties, including the tensile strength, which improves by nearly 35% for 70:30 EOC:PDMS blends. Morphology of the blends before and after irradiation can be analyzed by scanning electron microscopy and atomic force microscopy and correlated with the physicomechanical properties. The physicomechanical properties of the individual polymer components after irradiation show that radiation cross-linking is more effective for PDMS rubber than it is for EOC. However, at higher radiation doses, chain scissions are possible in both EOC and PDMS rubber, which affect the physicomechanical properties. Through blending and subsequent radiation cross-linking, the maximum degradation temperature of EOC can be increased from 488.6 to 512.8 °C.

Preparation and characterization of graphene oxide/PMMA nanocomposites with amino-terminated vinyl polydimethylsiloxane phase interfaces

Abstract Graphene oxide (GO) was prepared by the Hummers method and was grafted by an amino-terminated vinyl polydimethylsiloxane (AP). The AP-modified GO (GO-AP) was incorporated in poly(methylmethacrylate) (PMMA) to prepare nanocomposites. Raman microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and thermogravimetric analysis were used to characterize the particles. The mechanical properties, thermal stability, thermal conductivity, and dispersing status of the PMMA-based nanocomposites were also investigated. The results indicated that AP was grafted on the surface of GO via the amidation reaction, and the quantity of the grafted AP was approximately 20 wt% that of GO-AP. With the addition of GO-AP, the three-point bending strength of GO-AP/PMMA increased to approximately 58 MPa, and the dispersion of the particles was also enhanced. GO wrapped by AP could not form thermal conducting networks at the percolation thresholds. The increasing amount of AP prevented the formation of thermal conduction network and decreased the thermal conductivity of the composites. The thermal stability of the composites was affected by three main reasons, and the total effect of the three reasons on thermal stability illustrated a negative trend.

Molecular Modelling of Selected Phthalates and Their Interactions with Stationary Phases in Solid-Phase Microextraction

In this work, solid-phase microextraction of six phthalates from methanol and aqueous solutions were carried out. Polar polyacrylate (PA) and non-polar polydimethylsiloxane (PDMS) were used as stationary phases. HyperChem 8.0 software was used for the optimization of the geometry of these six phthalates and their interactions with stationary phases. Extracted samples were analyzed using gas chromatography coupled with mass spectrometry. In the analysis of phthalates extracted from methanol solution, the best extraction efficiency was obtained for the PA phase, whereas for the extraction from aqueous solution, higher efficiency was obtained for the PDMS phase.

Separation and enhanced detection of anesthetic compounds using solid phase micro-extraction (SPME)-Raman spectroscopy.

Polydimethylsiloxane (PDMS)-based solid-phase micro-extraction (SPME) was used along with Raman spectroscopy (RS) to separate and enhance the detection of five anesthetic compounds (halothane, propofol, isoflurane, enflurane, and etomidate) from aqueous and serum phases. Raman signals in the spectral ranges 250-450 cm(-1) and 950-1050 cm(-1) allowed the unique characterization of all five compounds when extracted into the PDMS phase. The SPME-RS detection of clinically relevant concentrations of aqueous propofol (6.5 μM) and halothane (200 μM) is shown. We quantify the partition coefficient for aqueous halothane in PDMS as log K = 1.9 ± 0.2. Solid-phase micro-extraction of the anesthetics makes their detection possible without the strong autofluorescent interference of serum proteins. Because of low solubility and/or weak Raman scattering, we found it challenging to detect enflurane, isoflurane, and etomidate directly from the aqueous phase, but could we do so with SPME enhancement. These studies show the potential of SPME-RS as a method for the direct detection of anesthetics in blood.