A flow injection μ-solid phase extraction system based on electrospun polyaniline nanocomposite

Comparison of ZrO2 Particles and Polyaniline as Additives in Polystyrene-Based Sorbents for the Micro-Solid Phase Extraction of Psychoactive Drugs from Biofluids

The intensive development of extraction methods based on μ-SPE extraction contributes to the increased interest in the synthesis of new sorption materials. This work presents the characterization of polystyrene fibers and polystyrene fibers blended with ZrO2 particles or polyaniline obtained by electrospinning and their use in the extraction of selected psychoactive drugs from biological samples. The characteristic of produced fibers is made by performing SEM images, measuring average fiber diameter, and examining their sorption abilities. Among the fibers based on pure polystyrene, tested in the first stage, the best sorption properties are demonstrated for the fibers obtained from a polystyrene solution in DMF with a concentration of 17.5 wt%. In the next stage, this material was modified with synthesized ZrO2 particles and polyaniline. Among the tested materials, the sorbent based on polystyrene with polyaniline shows the best sorption properties of the tested substances. The use of this material in the μ-SPE in a needle enables the extraction of selected compounds from aqueous and biological samples such as urine and human plasma.

The geometrical characteristics of nickel-based metal organic framework on its entrapment capability

Here, a three dimensional nickel-based metal organic framework (MOF) was synthesized via solvothermal and room temperature protocols. In order to study the effects of the synthesis conditions on the physical properties such as pore sizes and shapes of the prepared MOFs, their extraction capabilities were examined. Both MOFs were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller and thermogravimetric analyses. Brilliant properties such as porous structure, high surface area and considerable thermal stability make them reasonable candidates to be employed as efficient extractive phases. The efficiency of the superior nickel-based MOF was evaluated for headspace needle trap extraction of chlorobenzenes as model compounds in conjunction with gas chromatography-mass spectrometry (GC-MS). The MOF-based extractive phase was conveniently packed in a needle trap device and after extraction, the desorption process was performed via direct insertion of needle into the GC inlet. After optimizing the extraction/desorption conditions, the figures of merit such as linear dynamic range was in the range of 5-1000 ng L^-1 (R² > 0.987) while the limits of detection and quantification values were 2-10 and 6-30 ng L^-1, respectively. The intra- and inter-day relative standard deviations for three replicates at the concentration level of 50 ng L^-1 were in the range of 7-9% and 9-12%, respectively. The needle-to-needle reproducibility was also found to be in the range of 5-11%. Acceptable relative recovery values at the concentration level of 50 ng L^-1 ranged from 85 to 96%, showing no significant matrix effect.

Porphyrin-functionalized graphene oxide sheets: An efficient nanomaterial for micro solid phase extraction of non-steroidal anti-inflammatory drugs from urine samples

In this work, porphyrin-functionalized graphene oxide nanosheets (GO@meso-tetrakis(4-hydroxyphenyl)porphyrin) were synthesized and employed as the sorbent. Porphyrins owing to their unique structures and tunable terminal functional groups are expected to be promising media for extraction of the desired analytes. Also, GO with a high specific surface area has exhibited good potential for the extraction purposes. Inspired by these intriguing properties, the combination of GO and porphyrin can benefit both of these amazing features. The synthesized sorbent was utilized for micro solid phase extraction of non-steroidal anti-inflammatory drugs followed by HPLC-UV. Optimization of the experimental factors including sorbent amount, sample pH, sample and eluent flowrates, eluent volume, and the number of desorption cycles were performed with the aid of central composite design. Under the optimal conditions, the calibration curves were linear within the range of 2.0-600 ng mL^-1 and limits of detection were found between 0.5-2.0 ng mL^-1. The preconcentration factors and absolute recoveries were obtained in the range of 4.80-9.79 and 29%-59%, respectively. The matrix effect for the urine samples varied between 81.9%-91.6% at two concentrations of 50 and 300 ng mL^-1, respectively. Intra- and inter-day RSD% (n = 3) of the spiked urine samples at three level concentrations of 25, 100, and 300 ng mL^-1 were less than 10%. The relative recoveries of the urine samples were calculated in the range of 85.2-98.6%. Eventually, the method exhibits proper sensitivity, excellent repeatability, high reusability, and acceptable precision and accuracy.

Review of geometries and coating materials in solid phase microextraction: Opportunities, limitations, and future perspectives

The development of new support and geometries of solid phase microextraction (SPME), including metal fiber assemblies, coated-tip, and thin film microextraction (TFME) (i.e. self-supported, fabric and blade supported), as well as their effects on diffusion and extraction rate of analytes were discussed in the current review. Application of main techniques widely used for preparation of a variety of coating materials of SPME, including sol-gel technique, electrochemical and electrospinning methods as well as the available commercial coatings, were presented. Advantages and limitations of each technique from several aspects, such as range of application, biocompatibility, availability in different geometrical configurations, method of preparation, incorporation of various materials to tune the coating properties, and thermal and physical stability, were also investigated. Future perspectives of each technique to improve the efficiency and stability of the coatings were also summarized. Some interesting materials including ionic liquids (ILs), metal organic frameworks (MOFs) and particle loaded coatings were briefly presented.

Portable and low cost fluorescence set-up for in-situ screening of Ochratoxin A

The present article describes a portable and low cost fluorescence set-up designed and characterized for in-situ screening of Ochratoxin A (OTA) in cocoa samples at field settings. The sensing module (the set up) consists of a LED with the wavelength of 370-380nm and a color complementary metal oxide semiconductor (CMOS) micro-camera inbuilt at upright position of a black box to obtain an image of the sensing molecule. It allows the user to get an image of the sensing analytes under excitation conditions and process the image in order to predict the toxicity of the samples. The image capturing and processing of the system was based on the OTA concentration in the sample and analyzed data can be presented as RGB values. For each concentration of the OTA, the R, G, B co-ordinates were obtained and plotted to quantify actual OTA presents in the sample. Moreover, the system was tested for real sample analysis using cocoa contaminated with OTA. The system could detect OTA as low as 1.25ng/ml with the maximum recovery of 87.5% in cocoa samples. The OTA was extracted in 1% NaHCO3 and cleaned up using molecular imprinted polymer column (MIP). The method demonstrated a good linear range between 1.25 and 10ng/ml. The obtained results were cross validated using chromatographic method HPLC and also compared with commercially available fluorescence instrument. The developed fluorescence setup is simple, economical, and portable with added advantages of digital image processing. The system could be deployable to cocoa fields for monitoring of OTA in quick successions. It is noteworthy to mention that this is the first report of such portable fluorescence setup where, OTA sensing was explored.