Validation of an Analytical Method for Simultaneous Determination of 18 Persistent Organic Pollutants in Trout Using LLE Extraction and GC-MS/MS.

Persistent organic pollutants, (POPs), are vast distributed compounds in environment which are recognized as one of the global pollution problems. These groups of materials being dangerous due to their high stability are accumulated in animal tissues and occurring in the food chain. One of the major paths through which persistent organic combinations access to human body is consuming polluted foods, particularly, fishes. Among aquatic animals, trout as one of the mostly consumed fishes in Tehran's food basket was studied. In this study, two categories of persistent organic pollutants: Organochlorine pesticides (OCPs) including HCB, Dieldrin, Methoxychlor, α-, ϒ-Chlordane, α-, ß-Endosulfan and o,p'-DDE, p,p'-DDE, o,p'-DDT, p,p'-DDT and the second group Polychlonitated biphenyls (PCBs) including seven PCB congeners which are called indicator PCBs (IUPAC nos.: 28,52,101,118,138,153 and 180) were determined in trout by GC-MS/MS in MRM monitoring mode and LLE extraction. The average recoveries of OCPs and PCBs at five concentration levels (1, 2, 5, 10 and 20 ng/g for PCBs and 5 times for OCPs) were in the range of 73-112%. The relative standard deviations of POPs in fish were in the range of 1.4-17.9% for all of the concentration levels. The limit of detections (LODs) and the limit of quantitations (LOQs) were between 0.6-8.3 and 2-25 µg/kg, respectively. The results indicated the presence of organochlorine pesticides in trout and the levels of p,p'-DDE and p,p'-DDT were within the range of < LOQ -12.83 and < LOQ -10.2 ng/g ww (wet weight), respectively. According to the results, OCPs residues were lower than maximum residue levels set by European Council Directives.

Providing hyper-branched dendrimer conjugated with ß-cyclodextrin based on magnetic nanoparticles for the separation of methylprednisolone acetate.

This study introduced a developed approach for dendritic ß-cyclodextrin (ß-CD) in order to obtain high sorption capacity. Synthetic strategy exploits the reactivity between acrylic acid and allyl glycidyl ether for high-yielding assembly via grafting on to the magnetic nanoparticles that are modified using 3-mercaptopropyltrimethoxysilane for various building branches and host-guest molecules of ß-CD. The methodology has been applied for the preparation of a series of ß-CD conjugated magnetic nanoparticles with dendrimers as a nano-sorbent for the extraction of methylprednisolone acetate. This study allowed us to probe (i) the effects of the dendric-cyclodextrin architecture on the affinity of sorption capacity, (ii) the drug influence between the cyclodextrin core and the polyester dendrimer, and (iii) the result of sorbent formation for using the anti-inflammatory drug as a target guest into the ring of ß-CD on biological extraction. It was found that the adsorption behavior could be fitted by the Langmuir adsorption isotherm model. The adsorption capacity of MPA is found to be 12.4 mg g-1 and indicated the homogeneous sites onto polymer grafted magnetite nano-sorbent surface. Our results confirm the high capability of this type of dendrimer-ß-CD for drug extraction in biological fluids and pharmaceutical samples. This nano-sorbent assists the magnetic solid phase extraction technique represented in the high extraction yield (up to 97%) for methylprednisolone acetate in biological human fluids and pharmaceutical samples. Moreover, the achieved polymeric nano-sorbent of the reaction combination was facilitated by a magnetic field and reusability was performed without any notable loss in the sorbent activity.

Facile preparation of multifunctional carbon nanotube/magnetite/polyaniline nanocomposite offering a strong option for efficient solid-phase microextraction coupled with GC-MS for the analysis of phenolic compounds.

The aim of this study was to synthesize a highly efficient organic-inorganic nanocomposite. In this research, the carbon nanotube/magnetite/polyaniline nanocomposite was successfully prepared through a facile route. Monodisperse magnetite nanospheres were prepared through the coprecipitation route, and polyaniline nanolayer as a modified shell with a high surface area was synthesized by an in situ growth route and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The prepared nanocomposite was immobilized on a stainless-steel wire for the fabrication of the solid-phase microextraction fiber. The combination of headspace solid-phase microextraction using carbon nanotube/magnetite/polyaniline nanocomposite fiber with gas chromatography and mass spectrometry can achieve a low limit of detection and can be applied to determine phenolic compounds in water samples. The effects of the extraction and desorption parameters including extraction temperature and time, ionic strength, stirring rate, pH, and desorption temperature and time have been studied. Under the optimum conditions, the dynamic linear range was 0.01-500 ng/mL and the limits of detection of phenol, 4-chlorophenol, 2,6-dichlorophenol, and 2,4,6-trichlorophenol were the lowest (0.008 ng/mL) for three times. The coefficient of determination of all calibration curves was more than 0.990.

A novel strategy to increase performance of solid-phase microextraction fibers: electrodeposition of sol-gel films on highly porous substrate.

In the present work, the effect of substrate porosity for preparation of solid-phase microextraction (SPME) fibers was investigated. The fibers were prepared by electrodeposition of sol-gel coatings using negative potentials on porous Cu wire and compared with previous reported technique for preparation of SPME fibers using positive potentials on smooth gold wire. Porous substrate was prepared by electrodeposition of a thin layer of Cu on a Cu wire. The extraction capability of prepared fibers was evaluated through extraction of some aromatic hydrocarbons from the headspace of aqueous samples. The effect of substrate porosity and some operating parameters on extraction efficiency was optimized. The results showed that extraction efficiency of SPME fibers highly depends on porosity of the substrate. The LOD ranged from 0.005 to 0.010 ng/mL and repeatability at the 1 ng/mL was below 12%. Electrodeposited films were characterized for their surface morphology and thermal stability using SEM and thermogravimetric analysis, respectively. SEM analysis revealed formation of porous substrate and subsequently porous coating on the wire surface and thermogravimetric analysis showed high thermal stability of the prepared fiber.

A rapid, simple, liquid chromatographic-electrospray ionization, ion trap mass spectrometry method for the determination of finasteride in human plasma and its application to pharmacokinetic study.

A fast, accurate, sensitive, selective and reliable method using reversed-phase high performance liquid chromatography coupled to electrospray ionization ion trap mass spectrometry was developed and validated for the determination of finasteride in human plasma. After protein precipitation with perchloric acid, satisfactory separation was achieved on a Zorbax Eclipse(®) C8 analytical column using a mobile phase consisted of acetonitrile, 2 mM ammonium formate buffer (58:42, pH adjusted at 2.5 using formic acid); the flow rate was 0.25 mLmin(-1) and the column oven was set to 50°C. Tamoxifen citrate was used as internal standard. This method involved the use of [M +H](+) ions of finasteride and IS at m/z 373 and 372 respectively with the selected ion monitoring (SIM) mode. The calibration curve was linear over the range of 0.1-60 ng mL(-1). The limit of quantification for finasteride in plasma was 0.1 ng mL(-1). The intra-day and inter-day repeatability (precision) were 2.68-13.87% and 2.14-14.69% respectively. Intra-day and inter-day accuracy were 98-101.57% and 99.7-110%. The assay method has been successfully used to estimate the pharmacokinetics of finasteride after oral administration of a 5 mg tablet of finasteride in 12 healthy volunteers.

ß-cyclodextrin-bonded silica particles as novel sorbent for stir bar sorptive extraction of phenolic compounds.

A stir bar coated with ß-cyclodextrin-bonded-silica (CDS) as novel sorbent has been developed and used to analyze seven phenolic compounds in aqueous samples, followed by thermal desorption and gas chromatography-mass spectrometric detection. Significant parameters affecting sorption process such as the time and temperature of sorption and desorption, ionic strength, pH and stirring rate have been optimized and discussed. The coating has a high thermal stability up to 300°C and long application lifetime (80 times). The porous structure of CDS coating provides high surface area and allows high extraction efficiency. Under the selected conditions, linearity range of 0.1-400 µg/L, limit of quantifications of 0.08-3.3 µg/L and method detection limits of 0.02-1.00 µg/L have been obtained. A satisfactory repeatability (RSD ≤ 6.5, n = 7) with good linearity (0.9975 ≤ r(2) ≤ 0.9996) of results illustrated a good performance of the present method. The recovery of different natural water samples was higher than 81.5%.

Pre-concentration of phenolic compounds in water samples by novel liquid-liquid microextraction and determination by gas chromatography-mass spectrometry.

Pre-concentration and determination of 8 phenolic compounds in water samples has been achieved by in situ derivatization and using a new liquid-liquid microextraction coupled GC-MS system. Microextraction efficiency factors have been investigated and optimized: 9 microL 1-undecanol microdrop exposed for 15 min floated on surface of a 10 mL water sample at 55 degrees C, stirred at 1200 rpm, low pH level and saturated salt conditions. Chromatographic problems associated with free phenols have been overcome by simultaneous in situ derivatization utilizing 40 microL of acetic anhydride and 0.5% (w/v) K(2)CO(3). Under the selected conditions, pre-concentration factor of 235-1174, limit of detection of 0.005-0.68 microg/L (S/N=3) and linearity range of 0.02-300 microg/L have been obtained. A reasonable repeatability (RSD< or =10.4%, n=5) with satisfactory linearity (0.9995> or =r(2)> or =0.9975) of results illustrated a good performance of the present method. The relative recovery of different natural water samples was higher than 84%.