Publications by authors named "Seyyed Hamid Ahmadi"

Aim: This study aimed to compare the elemental composition of traditional and flavored hookah tobacco, with a focus on heavy metals.

Methods: We used inductively coupled plasma mass spectrometry (ICP-MS) to analyze the concentrations of 29 elements in the raw tobacco, tobacco ash, hookah water after smoking, and tobacco smoke.

Results: The results showed that the traditional tobacco had significantly higher metal concentrations than the flavored tobacco in all samples.

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Early and on-site detection of environmental contaminations and physicochemical parameters of seawater is increasingly preferred to guarantee hazard minimization in many settings. In this paper, we describe a combination of microfluidic paper-based sensors (µPADs) and an Android-based smartphone application (App) for simultaneous on-site quantification of phosphate (PO-P), silicate (SiO-Si) and nitrite (NO-N) in coastal seawater samples. The developed App can on-site capture, process, and quantify the µPAD colorimetric outputs.

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In this study, prometryne and prometon were extracted and preconcentrated from aqueous media using an online solid-phase extraction-thermal desorption method coupled with gas chromatography-flame ionization detector (GC-FID), equipped with two different inlets: split and programmable temperature vaporizer (PTV). For this purpose, the applicability of Tenax and a metal-organic framework were investigated as solid-phase sorbents. Several effective parameters on the extraction efficiency, such as the amount of sorbent, sample volume, sample pH and thermal desorption procedure were optimized.

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Bottled water is most well liked within the world and attention is drawn due to its health issues. Oxyhalides is one amongst the foremost important by-products in bottled water which is produced by disinfection process such as "ozonation". International standards have been set and justified to permissible levels for chlorate, chlorite and bromate as 700, 700 and 10 μg/l.

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Solid phase microextraction on a screw was utilized for the extraction of hexanal and heptanal as lung cancer biomarkers from urine samples. Reduced graphene oxide (rGO) was coated on the surface of a stainless-steel set screw by electrophoretic deposition method. The screw was located inside a glass cover, and the created channel acted as the sample solution flow pass.

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This study introduces micrometric carbon strands as a suitable fiber for headspace solid phase microextraction. Compared to previous supports, carbon fibers have mechanical flexibility, wide thermal expansion, and a large surface area, which is an important factor in headspace solid phase microextraction. The electrophoretic technique was applied to modify the surface of stainless steel and carbon fibers with polypyrrole.

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One of the concerns of parents in the first days of their baby's birth is the baby's risk of jaundice/hyperbilirubinemia. This is because more than 60% of babies are born with jaundice that, if not timely diagnosed and subsequently treated, can lead to serious damage to their health. On the other hand, despite recent progress in sensor technology for clinical applications, the development of easy-to-use, cost-effective, sensitive, specific, and portable diagnostic devices, which use nontoxic and biodegradable materials in their design and fabrication, is still in high demand.

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A new ionic liquid-based high-performance liquid chromatography stationary phase is reported. A derivative of -methyl pyrrolidinium tetrafluoroborate was covalently immobilized on the surface of silica particles to prepare silica-based -methyl pyrrolidinium tetrafluoroborate (SilprMP BF4) stationary phase. The obtained ionic liquid-modified silica was evaluated and confirmed by elemental analysis, infrared spectroscopy, and thermogravimetric analysis.

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We report the synthesis and enantioseparation characteristics of two novel covalently immobilized deoxycholic acid derivatives as chiral stationary phases for high-performance liquid chromatography. In the structure of the first stationary phase, the 3-position of deoxycholic acid is substituted with a 3,5-dinitrophenylcarbamoyl group and the second one has an additional calix[4]arene attached to the carboxylic group of the deoxycholic acid. The chromatographic performance of the stationary phases was evaluated with enantioseparation of N-(3,5-dinitrobenzoyl)-dl-leucine, N-(3,5-dinitrobenzoyl)-dl-valine, omeprazole, diclofop-methyl, dl-mandelic acid and (RS)-pregabalin.

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Here we report a new chiral stationary phase (CSP) immobilized on silica gel based on cone calix[4]arene functionalized at the upper rim with two l-alanine units as new chiral selector that has been used in high-performance liquid chromatography. The CSP was prepared by covalently bonding the allyl groups at the lower rim of calix[4]arene to silica gel by thiol-ene click chemistry reaction. Elemental analysis of the CSP showed that 120 μmol of chiral selector bonded per gram of silica gel.

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In-tube magnetic solid phase microextraction (in-tube MSPME) of fluoroquinolones from water and urine samples based on the use of sodium dodecyl sulfate (SDS) coated Fe3O4 nanoparticles packed tube has been reported. After the preparation of Fe3O4 nanoparticles (NPs) by a batch synthesis, these NPs were introduced into a stainless steel tube by a syringe and then a strong magnet was placed around the tube, so that the Fe3O4 NPs were remained in the tube and the tube was used in the in-tube SPME-HPLC/UV for the analysis of fluoroquinolones in water and urine samples. Plackett-Burman design was employed for screening the variables significantly affecting the extraction efficiency.

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We report a new in-tube solid phase microextraction approach named electrochemically controlled in-tube solid phase microextraction (EC in-tube SPME). This approach, which combined electrochemistry and in-tube SPME, led to decrease in total analysis time and increase in sensitivity. At first, pyrrole was elctropolymerized on the inner surface of a stainless steel tube.

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A new in-tube solid phase microextraction approach named electrochemically controlled in-tube solid phase microextraction (EC in-tube SPME) has been reported. In this approach, in which electrochemistry and in-tube SPME were combined, the total analysis time was decreased and the sensitivity was increased. After electropolymerization of pyrrole on the inner surface of a stainless steel tube, the polypyrrole (PPy)-coated in-tube SPME was coupled on-line to high performance liquid chromatography (HPLC) to achieve automated in-tube SPME-HPLC analysis.

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In this study, a new method for the simultaneous determination of penicillin G salts in pharmaceutical mixture via FT-IR spectroscopy combined with chemometrics was investigated. The mixture of penicillin G salts is a complex system due to similar analytical characteristics of components. Partial least squares (PLS) and radial basis function-partial least squares (RBF-PLS) were used to develop the linear and nonlinear relation between spectra and components, respectively.

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A simple and selective method for the determination of cadmium in water samples by FAAS after solid phase extraction has been developed. The method is based on the sorption of cadmium as CdI(4)(2-) on octadecyl silica membrane disks modified by cationic surfactant of methyltrioctylammonium chloride in the pH range of 1-8. The sorbed cadmium is then eluted with 10ml of 1moll(-1) nitric acid in ethanol and is measured by flame atomic absorption spectrometry.

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In the present work, the relationship between residual solvents concentration and ampicillin trihydrate crystals stability has been investigated. The amounts of residual solvents determined by GC, X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FT-IR) were used for characterization of solid state. The obtained results have shown good relationship between concentration of methylene chloride (as a critical residue solvent) and degree of ampicillin trihydrate crystallinity.

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