Abdulrahman Bahrami

Chlorobenzene degeradation by non-thermal plasma combined with EG-TiO2/ZnO as a photocatalyst: Effect of photocatalyst on CO2 selectivity and byproducts reduction

The non-thermal plasma (NTP) technique, which suffers from low selectivity in complete oxidation of volatile organic compounds to CO2 and H2O, creates unwanted and harmful byproducts. NTP in concert with photocatalyst can resolve this limitation due to additional oxidation. TiO2 and ZnO nanoparticles were coated on the surface of the expanded graphite and placed downstream of the NTP reactor under UV light. In this study, to compare the performance of NTP and the combined system, chlorobenzene removal, selectivity of CO2 and byproducts formation were investigated. The results showed that the combined system enhanced both the removal efficiency and CO2 selectivity. The output gas of the NTP reactor contained chlorobenzene, phosgene, O3, NO, NO2, CO, CO2, HCL and CL. The bulk of these byproducts was oxidized on the surface of the nanocomposite; as a result, the content of the byproducts in the output gas of the combined system decreased dramatically. The removal efficiency and CO2 selectivity increased by rising the applied voltage and residence time because the collision between active species and pollutant molecules increases. Based on these results, the combined system is preferred due to a higher performance and lower formation of harmful byproducts.

Field application of SPME as a novel tool for occupational exposure assessment with inhalational anesthetics

Occupational exposure to inhalational anesthetics occurs routinely in operating rooms. It could induce serious health hazards and diseases. This exposure assessment is a crucial step in determining risks. In this study, a pen-shaped holder for solid-phase microextraction (SPME) sampler was successfully applied as a time-weighted average sampling tool for workshift exposure assessment of operation room staff to halothane. It proved to be very convenient for use in occupational environments such as operation rooms. Samples were analyzed by a gas chromatography–mass spectrometry. The validity of the SPME method was checked in real-world conditions with Occupational Safety and Health Administration (OSHA) 103 standard method for the determination of inhalational anesthetics. A good agreement between OSHA 103 and SPME methods was obtained and results demonstrated no statistically significant differences in anesthetic concentrations determined by the two analytical methods (p ≥ 0.05). It is concluded that SPME in retracted mode could successfully be applied in occupational exposure assessment purposes.

Determination of Inhalational Anesthetics in Field and Laboratory by SPME GC/MS

Exposure to inhalational anesthetics in health care workers could lead to several diseases and disorders. This study examined the applicability of solid phase microextraction for sampling and quantification of three inhalational anesthetics including; halothane, isoflurane, and sevoflurane in operating room air. Carboxen-Polydimethylsiloxane in retracted mode was selected and the effects of environmental parameters including temperature, humidity, and air velocity, were studied. There were no significant differences between sampling rates determined at different temperatures and air velocities. On the opposite, relative humidity has a significant effect on sampling rates. Comparison of the results between the developed SPME method and OSHA 103 method on standard test atmosphere and field showed satisfactory agreement.

Development of diffusive solid phase microextraction method for sampling of epichlorohydrin in air

Epichlorohydrin is used frequently in many industrial processes. Exposure to this pollutant could induce harmful effects. The present work developed a novel solid phase microextraction (SPME) method for time weighted average determination of epichlorohydrin in the air by GC/MS. CAR/PDMS in 0.5 cm retracted mode was selected and the effect of environmental parameters on sampling properties of SPME was examined. Experimental sampling rate for epichlorohydrin (8.89 × 10−3 cm3/min) was slightly less than theoretical value (9.059 × 10−3 cm3/min). There was no significant difference among sampling rates at different temperature and velocities but relative humidity had a significant effect on the sampling rate. Limit of detection for SPME method was 0.8 ng per sample, which is good enough in comparison with the NIOSH 1010 method. Comparison of the results between the developed SPME and the NIOSH 1010 method on standard test atmosphere and field showed satisfactory agreement (y = 1.162x + 1.8 r 2 = 0.992 and y = 1.009x+0.76 r 2 = 0.98 respectively).

Determination of urinary trans,trans-muconic acid using molecularly imprinted polymer in microextraction by packed sorbent followed by liquid chromatography with ultraviolet detection

trans,trans-Muconic acid (tt-MA) has been introduced as biological exposure index for workers exposed to benzene. In the present study, for the first time, a novel and easy-to-use analytical method based on molecularly imprinted polymer (MIP) in microextraction by packed sorbent (MEPS), followed by high-performance liquid chromatography with ultra-violet detection (MIMEPS-HPLC-UV) was developed to determine tt-MA in urine samples. Fourier transform infrared spectroscopy was used for MIP characterization. The imprinting effect on the MIP was also evaluated. Furthermore, various parameters that affect the MEPS performance were investigated, including extraction cycles, sample volume, as well as the type and volume of washing and elution solvents. The optimised procedure was selective, sensitive, rapid and both user- and environmentally-friendly. A seven-point calibration curve was obtained in the range of 0.015-2μg/mL (R2=0.9986). The extraction recovery was >89.8%. The limit of detection and limit of quantitation for tt-MA were 0.015 and 0.05μg/mL, respectively. The within- and between-day precisions, given as percent relative standard deviation, were in the range of 3.4-4.7% and 3.5-6.6%, respectively. Accuracy was -8.4 to -10.2% in urine samples. The developed method is suggested as an alternative to existing conventional SPE methods for biomonitoring of benzene-exposed subjects.

Development of Hollow-Fiber Liquid-Phase Microextraction Method for Determination of Urinary trans,trans-Muconic Acid as a Biomarker of Benzene Exposure

For the first time, hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography–ultraviolet was used to extract trans,trans-muconic acid, in urine samples of workers who had been exposed to benzene. The parameters affecting the metabolite extraction were optimized as follows: the volume of sample solution was 11 mL with pH 2, liquid membrane containing dihexyl ether as the supporter, 15% (w/v) of trioctylphosphine oxide as the carrier, the time of extraction was 120 minutes, and stirring rate was 500 rpm. Organic phase impregnated in the pores of a hollow fiber was extracted into 24 µL solution of 0.05 mol L−1 Na2CO3 located inside the lumen of the fiber. Under optimized conditions, a high enrichment factor of 153–182 folds, relative recovery of 83%–92%, and detection limit of 0.001 µg mL−1 were obtained. The method was successfully applied to the analysis of ttMA in real urine samples.

Hollow-fiber liquid-phase microextraction based on carrier-mediated transport for determination of urinary methyl hippuric acids

ABSTRACT Hollow-fiber liquid-phase microextraction based on carrier-mediated transport for analysis of methyl hippuric acids in aqueous samples is described. Under optimized conditions, relative recoveries of 83%–98% and limits of detection of 2–3 µg L−1 were obtained, with linear calibration curves for the three isomers in the range of 10–50,000 µg L−1. The method was applied for the determination of urine samples of volunteers at various working environments.

Analysis of xylene in aqueous media using needle‐trap microextraction with a carbon nanotube sorbent

This paper describes a new extraction technique with needles and a sorbent based on carbon nanotubes to analyze trace amounts of three isomers of xylenes in aqueous samples. In this research, results have been compared with one commercial sorbent. The synthesized sorbent was prepared using sol-gel technology and was packed into 20 gauge needles, and the same size needle was used for packing the commercial sorbent. In the extraction process, a purge and trap sampling methodology is developed, so purging and trapping cycles were performed by a sampling pump. Optimized conditions for standard xylene samples have been obtained, and eight urine samples from workers that were exposed to xylene in the workplace were collected and analyzed. Experimental parameters such as limits of detection and quantification were investigated, and these two parameters were <1 μg/L.

Development of Carbotrap B-packed needle trap device for determination of volatile organic compounds in air

Carbotrap B as a highly pure surface sorbent with excellent adsorption/desorption properties was packed into a stainless steel needle to develop a new needle trap device (NTD). The performance of the prepared NTD was investigated for sampling, pre-concentration and injection of benzene, toluene, ethyl benzene, o-xylene, and p-xylene (BTEX) into the column of gas chromatography-mass spectrometry (GC-MS) device. Response surface methodology (RSM) with central composite design (CCD) was also employed in two separate consecutive steps to optimize the sampling and device parameters. First, the sampling parameters such as sampling temperature and relative humidity were optimized. Afterwards, the RSM was used for optimizing the desorption parameters including desorption temperature and time. The results indicated that the peak area responses of the analytes of interest decreased with increasing sampling temperature and relative humidity. The optimum values of desorption temperature were in the range 265-273°C, and desorption time were in the range 3.4-3.8min. The limits of detection (LODs) and limits of quantitation (LOQs) of the studied analytes were found over the range of 0.03-0.04ng/mL, and 0.1-0.13ng/mL, respectively. These results demonstrated that the NTD packed with Carbotrap B offers a high sensitive procedure for sampling and analysis of BTEX in concentration range of 0.03-25ng/mL in air.

Single-walled carbon nanotube/silica composite as a novel coating for solid-phase microextraction fiber based on sol-gel technology

Single-walled carbon nanotubes (SWCNTs)/silica composite coating for solid phase microextraction synthesized by sol-gel technology was developed for air sampling and determination of perchloroethylene, benzotrichloride, chloromethyl methyl ether and trichloroethylene. Application of this method was investigated under different laboratory conditions. Predetermined concentrations of each analyte were prepared in a homemade standard chamber and the influence of temperature, humidity, extraction time, storage time, desorption temperature and desorption time was investigated. Under optimal conditions, the use of SWCNTs/silica composite fiber showed high sensitivity and fast sampling of halogenated volatile organic compounds from air. For linearity test, the regression correlation coefficient was more than 98% for analytes of interest and linear dynamic range for the proposed fiber and the applied gas chromatography-flame ionization detector (GC-FID) technique was from 1 to 100 ng/mL Method detection limits ranged from 0.11 to 0.2 ng/mL and method quantification limits were between 0.34 and 0.7 ng/mL. SWCNTs/silica composite fiber was highly reproducible; relative standard deviations were between 5.6 and 11.7%. The developed method was applied to determine perchloroethylene concentration of real air samples of a dry cleaning shop and the results compared with the data obtained with commercially available carboxen/polydimethylsiloxane (CAR/PDMS).