Electrospun terpolymeric nanofiber membrane for micro solid‐phase extraction of diazinon and chlorpyrifos from aqueous samples

The present study deals with the synthesis and electrospining of a new terpolymer nanofiber in order to determine the amount of diazinon and chlorpyrifos in water and fruit juice samples. The synthesized terpolymer and the prepared nanofiber were characterized using ¹H NMR spectroscopy, FTIR spectroscopy, scanning electron microscopy, and gel permeation chromatography. The performance of terpolymer nanofiber, prepared as a sorbent for micro solid phase extraction was investigated for the extraction of diazinon and chlorpyrifos from aquaeous media. Then, the target analytes were desorbed from the coating with an organic solvent and analyzed by gas chromatography with flame ionization detector. Extraction efficiencies were significant (>90%) under the optimum condition. The proposed method also demonstrated good linear dynamic ranges for diazinon and chlorpyrifos (3–250 and 5–200 µg/L), and low limit of detections (0.5 and 0.7 µg/L) respectively. Moreover, under optimum condition for extraction of diazinon and chlorpyrifos, square of correlation coefficients (R²) of 0.9978 and 0.9953 and relative standard deviations of 4.6 and 5.1% were achieved, respectively. The recoveries for diazinon and chlorpyrifos were in the range of 85–97%.     

Extraction and determination of flavonoids in fruit juices and vegetables using Fe3O4/SiO2 magnetic nanoparticles modified with mixed hemi/ad‐micelle cetyltrimethylammonium bromide and high performance liquid chromatography

Extraction and determination of three flavonoids (morin, quercetin, and kaempferol) were performed by dispersive magnetic solid phase extraction based on mixed hemi/ad‐micelles and high‐performance liquid chromatography with UV detection. The Fe₃O₄/SiO₂ nanoparticles were synthesized and characterized by X‐ray diffraction, FTIR, scanning electron microscopy, and thermogravimetric analysis. Fe₃O₄/SiO₂ nanoparticles coated with mixed hemi/ad‐micelles cetyltrimethyl ammonium bromide was applied as a sorbent and used for extraction of flavonoids. Effective parameters on the extraction recovery such as amount of magnetic nano particles, volume of cetyltrimethyl ammonium bromide solution with specific concentration, pH of sample solution, adsorption equilibrium time, volume of desorption solvent, and desorption times were evaluated and optimized using fractional factorial design and central composite design. Under the optimum condition limit of detection and linearity were 0.83, 2.7–500.0 for morin, 0.18, 0.7–500.0 for quercetin and, 0.37, 1.3–500.0 µg/L for kaempferol. The extraction recovery with relative standard deviation were 97.88, 1.94 for morin, 95.77, 0.80 for quercetin, and 93.35, 1.45 for kaempferol. The proposed method was applied for simultaneous extraction and determination of flavonoids in several fruit juices and vegetable samples.     

A prototype of an extrapolation chamber for beta radiation beams of 90Sr+90Y

Extrapolation chamber is the only primary standard dosimeter for beta radiation. With the aim to test new configurations and materials using easily-available and low-cost materials and fulfill the need of a chamber for scientific metrological purposes, in this paper the prototype of an extrapolation chamber has been built and its performance has been investigated in the beta radiation field of ⁹⁰Sr+⁹⁰Y. The main differences between the chamber and commercially available chambers are the geometry, constituent material and configuration. The obtained results were compared with those of the calibration certificate of the source and an agreement within 4 % was verified. The depth-dose curve was also obtained and compared with the curve published in ISO 6980, showing a good agreement. Moreover, Monte Carlo simulation was undertaken using MCNP4C code and the relative difference of 0.3 % was observed compared to the experiment. All of the results proved the suitability of the chamber in the beta radiation field of ⁹⁰Sr+⁹⁰Y.     

A Rapid Determination of Taurine in Human Plasma by LC

Taurine is an amino acid which is not incorporated into proteins but found in the cytosol of many mammalian cells, in high concentrations (2–30 mM). Increase in plasma taurine concentration has already been reported after surgical trauma, X-radiation, muscle necrosis, carbon tetrachloride-induced liver damage, and paracetamol overdose. Plasma taurine concentration was measured using LC with fluorescence detection following derivatization by o-phtalaldehyde plus 3-mercapto-propionic acid and α-aminobutyric acid as internal standard. Under these conditions the retention time of taurine was 10 min. This method was sensitive enough, to quantify 150 pg mL⁻¹ and detect 50 pg mL⁻¹ of taurine ranging normally between 65 and 179 mmol L⁻¹ (8–22 μg mL⁻¹). The validated method allowed simple determination of human plasma taurine in pharmacokinetic and biomarker studies.

     

Matrix‐less laser desorption/ionisation mass spectrometry of polyphenols in red wine

Matrix‐assisted laser desorption/ionisation (MALDI) of small molecules is challenging and in most cases impossible due to interferences from matrix ions precluding analysis of molecules <300–500 Da. A common matrix such as ferulic acid belongs to an important class of compounds associated with antioxidant activity. If the shared phenolic structure is related to the propensity as an active MALDI matrix then it follows that direct laser desorption/ionisation should be possible for polyphenols. Indeed matrix‐less laser desorption/ionisation mass spectrometry is achieved whereby the analyte functions as a matrix and was used to monitor low molecular weight compounds in wine samples. Sensitivity ranging from 0.12–87 pmol/spot was achieved for eight phenolic acids (4‐coumaric, 4‐hydroxybenzoic, caffeic, ferulic, gallic, protocatechuic, syringic, vanillic) and 0.02 pmol/spot for trans‐resveratrol. Additionally, 4‐coumaric, 4‐hydroxybenzoic, caffeic, ferulic, gallic, syringic, vanillic acids and trans‐resveratrol were identified in wine samples using accurate mass measurements consistent with reported profiles based on liquid chromatography (LC)/MS. Minimal sample pre‐treatment make the technique potentially appropriate for fingerprinting, screening and quality control of wine samples. Copyright © 2009 John Wiley & Sons, Ltd.     

SALDI-MS Signal enhancement using oxidized graphitized carbon black nanoparticles

The signal intensity of low-molecular-weight compounds analyzed using surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF-MS) was significantly enhanced when oxidized graphitized carbon black (GCB) particles were used as the desorption/ionization surface. The surface of oxidized GCB contains more carboxylic acid groups than non-oxidized GCB. Carboxylic acid groups enhance the efficiency of the ionization process and the desorption of more hydrophobic compounds. A common pharmaceutical compound, propranolol, was successfully extracted from Baltic Sea blue mussels and quantified using oxidized GCB as the SALDI surface, whereas deuterated propranolol was used as the internal standard. The calibration curve showed a wide linear dynamic range of response (0.1–20 μg/mL) and good reproducibility (RSD < 10%). It was not possible to detect propranolol in Baltic Sea blue mussels when non-oxidized GCB was used as the SALDI surface.     

Back‐propagation artificial neural network and attenuated total reflectance‐Fourier transform infrared spectroscopy for diagnosis of basal cell carcinoma by blood sample analysis

A diagnostic method for the cancer, based on investigation of infrared spectra of blood samples, has been developed. The two‐layer modified principal component feed forward back‐propagation artificial neural network (BP‐ANN) was used to classify the attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectra of blood samples obtained from healthy people and those with basal cell carcinoma (BCC). Results showed 98.33% of accuracy, in comparison with the current clinical methods. In the first step, 20 blood samples (10 normal and 10 cancer cases) were applied to construct the calibration model. Spectroscopic studies were performed in 900–1800 cm⁻¹ spectral region with 3.85 cm⁻¹ data space. In order to modify the capability of ANN in prediction of test samples, two different algorithms were applied. The obtained results confirmed the compatibility of the proposed network with the architecture of 20‐8‐2 (input‐hidden‐output) with the pattern model. It was concluded that analysis of blood samples by ATR‐FTIR spectroscopy and ANN chemometric technique would be a reliable approach for detection of BCC. Copyright © 2009 John Wiley & Sons, Ltd.