Electrospun nanofibers as a new solid phase microextraction coating for determination of volatile organic impurities in biological products.

In this study, preparation of a solid-phase microextraction fiber of polydimethylsiloxane (PDMS) polymer in its blends with polystyrene (PS) via electrospinning process, on a stainless steel wire has been reported. The electrospining enhancement of PDMS solutions in the presence of PS is found due to the increase in the viscosity of the mixed solutions. Characteristics of the fibers were inspected by energy dispersive X-ray spectroscopy, scanning electron microscopy and field emission scanning electron microscopy. The applicability of the coating was assessed for headspace solid phase microextraction (SPME) of some residual solvents (Diethyl Ether, Toluene and Chloroform) from biological products (Anti venin and Foot-and-mouth disease vaccine) followed by gas chromatography-mass spectrometry. The effects of extraction time and temperature, desorption time and temperature, agitation rate and ionic strength on the extraction efficiency were investigated. Under optimized conditions, limits of detection in the range of 2-10 µg L-1 and limits of quantification in the range of 10-50 µg L-1 were obtained. The method showed linearity in a wide range with a correlation coefficient greater than 0.99. In addition, the obtained inter-day and intra-day precisions were in the range of 1.57-8.28% and 4.87-11.72%, respectively. The thermal stability of the fiber was also investigated and it was found to be durable at 230 °C for 450 min. Furthermore, the proposed method was successfully applied for quantification of chloroform in Foot-and-mouth disease vaccine and diethyl ether and toluene in Anti-venin with recoveries in the range of 78.84-123.01%.

New nanostructure of polydimethylsiloxane coating as a solid-phase microextraction fiber: Application to analysis of BTEX in aquatic environmental samples.

Electrospinning technique was used to convert polydimethyl siloxane (PDMS) sol-gel solution to a new nanostructure on a stainless steel wire. The surface morphology of the fiber was observed by scanning electron microscopy (SEM). It showed a diameter range of 30-60nm for PDMS nanoparticles with a homogeneous and porous surface structure. The applicability of this coating was assessed for the headspace SPME (HS-SPME) of benzene, toluene, ethylbenzene and xylenes (BTEX) from water samples followed by gas chromatography-mass spectrometry. The important parameters affecting extraction efficiency such as extraction time and temperature, desorption conditions, agitation rate and ionic strength were investigated and optimized. Under the optimized conditions, LODs and LOQs of 0.3-5µgL(-1) and 1-10µgL(-1) were obtained, respectively. The method showed linearity in the broad range of 1-5000µgL(-1) with correlation coefficient of >0.99. Inter-day and intra-day precisions of the developed method ranged from 2.43% to 6.54% and from 5.24% to 13.73%, respectively. The thermal stability of the fiber was investigated on stainless steel wire. It was found to be durable at 260°C for more than 360min. Furthermore, the proposed method was successfully applied for quantification of BTEX in real water samples.

Electrospun nanostructured polystyrene as a new coating material for solid-phase microextraction: Application to separation of multipesticides from honey samples.

For the first time, electrospun polystyrene nanostructure was used as coating material on a stainless steel wire for solid-phase microextraction. Surface morphology of the coating was studied by scanning electron microscopy which showed the formation of nanofibers on the wire. The coating was stable after conditioning at 250°C for 2h. The efficiency of the polystyrene coating was approved by extracting a mixture of seven pesticides (polar and apolar) from head space of honey samples followed by gas chromatography-mass spectrometry. The important parameters affecting extraction efficiency such as, extraction time and temperature, desorption conditions, agitation rate and ionic strength were investigated. Under optimized experimental conditions, detection limits for the investigated pesticides ranged from 0.1-2µgL(-1). The intra- and inter-day precisions of the developed method were 3.5-17.6% and 10.0-25.0%, respectively. Finally, all the investigated pesticides were spiked to honey samples and extracted by the proposed method. The accuracies of determination of all the species were found to be in the range of 81-125%.

Determination of free formaldehyde in vaccines and biological samples using solid-phase microextraction coupled to GC-MS.

A headspace solid-phase microextraction method coupled to GC-MS was successfully developed for the trace determination of formaldehyde in veterinary bacterial and human vaccines, and diphtheria-tetanus antigen. The formaldehyde was derivatized by means of the Hantzsch reaction prior to extraction and subsequent determination. Three different types of solid-phase microextraction fibers, polar, and nonpolar poly(dimethylsiloxane) and polyethylene glycol were prepared by using a sol-gel technique. The effects of different parameters such as type of fiber coating, extraction time and temperature, desorption conditions, agitation rate, and salt effect were investigated. Under the optimized conditions, the detection limit of the method was 979 ng/L using the selected ion-monitoring mode. The interday and intraday precisions of the developed method under the optimized conditions were below 13%, and the method shows linearity in the range of 1.75-800 µg/L with a correlation coefficient of 0.9963. The optimized method was applied to the determination of formaldehyde from some biological products. The results were satisfactory compared to the standard method.