Application of Functionalized Fe3O4 Magnetic Nanoparticles Using CTAB and SDS for Oil Separation from Oil-in-Water Nanoemulsions.

Using magnetic nanoparticles (MNPs) for emulsified oil separation from wastewater is becoming increasingly widespread. This study aims to synthesize MNPs using amphiphilic coatings to stabilize the MNPs and prevent their agglomeration for efficiently breaking oil-in-water nanoemulsions. We coat two different sizes of Fe3O4 nanoparticles (15-20 and 50-100 nm) using cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) with surfactant-to-MNP mass ratios of 0.4 and 0.8. We study the effect of various variables on the demulsification performance, including the MNP size and concentration, coating materials, and MNP loading. Based on the oil-water separation analysis, the smaller size MNPs (MNP-S) show a better demulsification performance than the larger ones (MNP-L ) for a 1000 ppm dodecane-in-water emulsion containing nanosized oil droplets (250-300 nm). For smaller MNPs (MNP-S) and at low dosage level of 0.5 g/L, functionalizing with surfactant-to-MNP mass ratio of 0.4, the functionalization increases the separation efficiency (SE) from 57.5% for bare MNP-S to 86.1% and 99.8 for the SDS and CTAB coatings, respectively. The highest SE for MNP-S@CTAB and the zeta potential measurements imply that electrostatic attraction between negatively charged oil droplets (-55.9 ± 2.44 mV) and positively charged MNP-S@CTAB (+35.8 ± 0.34 mV) is the major contributor to a high SE. Furthermore, the reusability tests for MNP-S@CTAB reveal that after 10 cycles, the amount of oil adsorption capacity decreases slightly, from 20 to 19 mg/g, indicating an excellent stability of synthesized nanoparticles. In conclusion, functionalized MNPs with tailored functional groups feature a high oil SE that could be effectively used for oil separation from emulsified oily wastewater streams.

Single-use porous polymer thin-film device: A reliable sampler for analysis of drugs in small volumes of biofluids.

The response to the demand for biomedical testing on small volumes of biofluids has led to a range of new microsampling devices and related techniques. Simple cost-effective sampling devices are available, but most do not incorporate sample clean-up and necessitate extensive sample processing by the analyst. To address both cleanup and analyte stability, a porous polymeric thin film made of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) coated (5 × 18 mm2) on a stainless steel substrate was used for the extraction of seven tricyclic antidepressants (TCAs) from plasma spots, with analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Essential factors such as sample volume, extraction time, matrix effects, and the desorption process were investigated. The optimized method is comprised of a quick 3-min extraction from 10 µL of plasma, a wash (10 s in 1 mL of 1% aqueous triethylamine (TEA) to remove plasma matrix interferences, and 2-min desorption (200 µL of ACN with 0.1% formic acid (FA)). For the purpose of sample archiving, thin film devices containing extracted TCAs were stored for 30 days at room temperature and showed a consistent analyte recovery. Inter-device reproducibility was evaluated without internal standard (%RSD 8.2-19.3%), and using two methods of introducing a single deuterated internal standard (imipramine-D3) either prior to (%RSDs 5.6-13.9%) or after (%RSDs 4.9-10.2%) sample loading to the device. Although the intention of this study was to introduce a single use device for rapid and easy analysis, reusability showed the feasibility of 15 consecutive extractions using same device without any performance loss. The optimized method revealed excellent linearity (R2 > 0.99) in the range of 1-1000 ng mL-1, with good intra- and inter-day accuracy (81.4-118%) and precision (≤12%) in human plasma.

Biological matrix compatible porous thin film for quick extraction of drugs of abuse from urine prior to liquid chromatography-mass spectrometry analysis.

An efficient analytical method is developed using a porous sorptive polymer for thin film microextraction (PSP-TFME) of 8 model drugs from human urine samples. The analysis is conducted with ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). The composition of the porous extraction phase, prepared on a stainless steel substrate, has been optimized for basic drugs of abuse and comprises methacrylic acid (MMA) as the monomer and ethylene glycol methacrylate (EGDMA) as the crosslinker. Factors influencing the analyte recovery and method precision (i.e., sample agitation, pH, extraction and washing time, desorption solvent and time) were assessed. The optimized method includes 5 min of direct immersion of the device into the sample, followed by a quick wash in water (1 min) to remove matrix interferences, and then 5 min in acidified methanol for analyte desorption. The extraction devices demonstrated acceptable inter-device variability (2.9-9.3 %RSD for 8 analytes and n = 10 devices) and no detectable difference between batches of devices (p > 0.05 for a 2-sample t-test). The analytical method was linear over a pharmacologically relevant range for each drug (i.e., 0.05-100 ng mL-1 for MDMA and methadone and 2.5-500 ng mL-1 for morphine with R2 varied from 0.9960 to 0.9996). A matrix effect study showed the devices have a high tolerance for complex variable biological matrices. The method also demonstrated excellent data accuracy in the range of 85.3-117.2% for intra-day assays and 88.8-117.9% for inter-day assays. The precision of the method was acceptable and in the range of 0.9-18.6% for intra- and 2.8-16.4% for inter-day assays, respectively.

Micro-gel thin film molecularly imprinted polymer coating for extraction of organophosphorus pesticides from water and beverage samples.

Molecularly imprinted polymers (MIPs) have become an important class of materials for selective and efficient adsorption of target analytes. Despite versatility of MIPs for fabrication in numerous formats, these materials have been primarily reported as solid phase extraction packing materials. An effective thin film MIP prepared on stainless steel substrate is reported here for high throughput enrichment of organophosphorus pesticides (OPPs) from water and beverage samples followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. The key factors controlling performance as well as best practices for optimized fabrication of thin film MIPs are presented. A pseudo-phase diagram is introduced to evaluate and predict the effect of the ratio of porogen (solvent, 1-octanol) volume to relative crosslinker mass on the desired polymer features (i.e., porosity, surface area, capacity, and selectivity). At low porogen ratios, a macroporous polymer with insignificant selectivity is formed, whereas at high porogen ratios a micro-gel polymer with superior selectivity towards targets is obtained. The porosity and morphology determined with nitrogen adsorption and scanning electron microscopy were attributed to specific regions in the pseudo-phase diagram. Other factors influencing selectivity and stability of the polymer, such as type of the template and its ratios with monomer (methacrylic acid) and crosslinker (ethylene glycol dimethacrylate) were optimized. The prepared thin film MIPs were characterized using adsorption isotherms and adsorption kinetics, and evaluated for matrix effects (high humic acid content) and cross-reactivity in presence of other pesticides and pharmaceuticals. The optimized method provided limits of quantitation (LOQs) ranged from 0.002 to 0.02 ng mL-1 in water and from 0.095 to 0.48 ng g-1 in apple juice. Regarding inter-device variability (CV∼10% without normalization), excellent linearity (R2 > 0.99), satisfactory accuracies (90-110%) and precisions (<15%) were obtained.

Thin film molecularly imprinted polymer (TF-MIP), a selective and single-use extraction device for high-throughput analysis of biological samples.

Enhancing selectivity, reducing matrix effects and increasing analytical throughput have been the main objectives in the development of biological sample preparation techniques. A thin film molecularly imprinted polymer (MIP) is employed for extraction and analysis of tricyclic antidepressants (TCAs) as a model class of compounds in human plasma for the first time to reach the abovementioned goals. The thin film MIPs prepared on a metal substrate can be used directly for extraction from biological matrices with no sample manipulation steps and no pre-conditioning. This method was validated with good linearity (R2 > 0.99 in 1.0-500.0 ng mL-1 range), excellent accuracy (90% -110%) and precision (RSD % value less than 15%) in pooled human plasma samples (N = 3). The limits of quantitation (LOQ) for TCAs in plasma samples were between 1.0-5.0 ng mL-1 which are lower than the therapeutic ranges of these drugs. Kinetic and isotherm studies showed the superior performance of MIP sorbent compared to a non-imprinted polymer (NIP) sorbent in extracting TCAs from a bovine serum albumin (BSA) solution. The optimized and validated method for pooled human plasma was utilized for monitoring the concentration of TCAs in three patient samples who had been prescribed TCAs. These selective single-use thin film extraction devices are promising for efficient and fast procedures for analyzing biological samples.

Magnetic molecularly imprinted polymers prepared by reversible addition fragmentation chain transfer polymerization for dispersive solid phase extraction of polycyclic aromatic hydrocarbons in water.

Magnetic molecularly imprinted polymers (MMIPs) combine nanotechnology and molecular imprinting technology to offer selective and tunable enrichment for water analysis. In this paper, a selective sorbent was prepared by surface polymerization onto magnetic Fe3O4@SiO2 nanoparticles through reversible addition fragmentation chain transfer (RAFT) polymerization. The MMIPs were used for dispersive solid phase extraction (DSPE) of 16 PAHs as priority pollutants in aqueous matrices. After preconcentration, the analysis was performed using gas chromatography with an atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS). The extraction method is based on the dispersion of MMIPs in an aqueous sample using an ultrasonic bath which provides rapid equilibrium of analytes between the sorbent and sample solution. The enriched analytes were retrieved by collecting MMIP particles and desorbed into an organic solvent before instrumental analysis. A design of experiment (DOE) approach was applied to optimize several extraction parameters including the mass of MMIPs, the sample volume, salt addition, collection time, desorption volume, and desorption time. A fractional factorial design (FFD) (26-2) was performed to assess the influence of the selected factors on the extracted amount of analytes. The most effective factors including the mass of MMIPs, the volume of sample solution, and salt content was further investigated using central composite design (CCD) and yielded quadratic models between dependent and independent variables. The optimum conditions of DSPE obtained by desirability function (DF) were employed for preconcentration of PAHs in water samples. The evaluation showed that the MMIPs provide higher extraction efficiency compared to nanoparticles such as Fe3O4, Fe3O4@SiO2 and non-imprinted polymer, demonstrating the creation of selective recognition binding sites at the surface of magnetic nanoparticles. The LODs and LOQs ranged from 1 to 100 pg mL-1 and 2 to 200 pg mL-1, respectively. Finally, the MMIP-DSPE method was successfully applied for preconcentration and trace quantification of PAHs in real samples such as produced water and river water samples.

Single-use porous thin film extraction with gas chromatography atmospheric pressure chemical ionization tandem mass spectrometry for high-throughput analysis of 16 PAHs.

The need for high throughput, reliable analytical methods for environmental analysis has driven our development of novel sampling technologies that can be used in microextraction devices and integrated into chromatographic systems for fast analysis. Here we report a new method of water analysis for 16 EPA priority polycyclic aromatic hydrocarbons (PAHs) that relies on a tailor made porous polymeric film for extraction with analysis by gas chromatography with atmospheric pressure chemical ionization-tandem mass spectrometry (APGC-MS/MS). The extraction device is user friendly, single-use and gives exhaustive extraction from a relatively small volume (20 mL). The films show good stability, with excellent analytical performance. Critical factors affecting the extraction efficiency such as desorption solvent, desorption time, extraction agitation, and extraction time were studied and optimized. These thin films are cost effective and efficient for single use analysis, but carry-over studies showed that the films can be reused at least 10 times without extensive washing and with no loss in performance. The 16 PAHs were measured with excellent limits of detection ranging from 1 pg mL-1 for BaA to 100 pg mL-1 for Flu and linearity (R2 > 0.997) over the 1-50,000 pg mL-1 concentration range. This high throughput method (1-h extractions, which can be completed simultaneously) showed good reproducibility (<20%) with recoveries in the range of 19.0-40.6% and concentration factors varying between 37.9 and 81.1. Analysis of real seawater and river water samples using matrix-matched calibration in synthetic seawater and river water showed only small matrix effects maintaining high sensitivity (LODs:1-100 pg mL-1), demonstrating that the films are suitable for analysis of real samples without the need for standard addition.

High throughput direct analysis of water using solvothermal headspace desorption with porous thin films.

Sample preparation has remained a bottleneck in analysis of biological and environmental samples. Thus, microextraction techniques to reduce time, cost, labor, and environmental impacts as compared to traditional solid phase or liquid-liquid extractions are appealing. In this work, a high throughput extraction method coupled with a novel desorption technique has been developed for the analysis of eight regulated PAHs in water. The targeted analytes were extracted by thin film microextraction (TFME) using single-use sorbents. The enriched analytes on thin films were directly introduced into a gas chromatography with a flame ionization detector (GC-FID) through solvothermal headspace desorption (ST-HD). The desorption of analytes was accelerated by adding a small volume of solvent into the headspace vial. The parameters that influence desorption, such as type and volume of solvent, oven temperature, and desorption time, were studied. As well, the key parameters (stirring rate, extraction time, and salt content) for TFME of PAHs from water were assessed and optimized. Reusability and durability of the film and background noise due to polymer decomposition were also assessed. The method was validated using standards in 3.5% aqueous NaCl. The limits of detection (LODs) were between 0.2 and 2.0 ng mL-1, with linear ranges of 0.4-200.0 ng mL-1 with R2 > 0.99, and satisfactory accuracy and repeatability at three concentrations (low, mid, and high) within the linear range of the calibration curves. The calibration curves were also assessed for suitability as a matched matrix in the analysis of PAHs in a seawater sample. The technique was also applied for determination of PAHs in a produced water sample without the need for pretreatment and filtration of the sample. Although the complexity of produced water required the use of standard addition, we demonstrated that this approach is a useful tool for the analysis of complicated environmental samples.