Majid Haji Hosseini
Abstract
The rapid expansion of a supercritical solution (RESS) process has limited commercial applicability due to the extremely low solubility of polar drugs in supercritical CO2 (sc CO2). To overcome this major limitation, a modified process of rapid expansion of supercritical solution with solid cosolvent ...
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The rapid expansion of a supercritical solution (RESS) process has limited commercial applicability due to the extremely low solubility of polar drugs in supercritical CO2 (sc CO2). To overcome this major limitation, a modified process of rapid expansion of supercritical solution with solid cosolvent (RESS-SC) is proposed. Here, the RESS-SC is examined for clozapine using menthol solid as a cosolvent to reduce particle size and to increase drug solubility. In addition, the effect of extraction pressure and extraction temperature was investigated on the size and morphology of precipitated particles of clozapine. The properties of the micronized clozapine were assessed using scanning electron microscopy (SEM) and powder x-ray diffraction (XRD) techniques. In this study, the average particle size of clozapine was reduced from 29.15 (before RESS-SC) to 3.15 μm (after RESS-SC).
Majid Haji Hosseini
Abstract
In the present study a combined analytical method involving ultrasonic extraction (USE) and headspace liquid phase micro extraction (HS- LPME) was used to extract methyl tert-butyl ether (MTBE) in fish tissue for analysis by gas chromatography (GC). Extraction of MTBE from 2 g of fresh fish tissue was ...
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In the present study a combined analytical method involving ultrasonic extraction (USE) and headspace liquid phase micro extraction (HS- LPME) was used to extract methyl tert-butyl ether (MTBE) in fish tissue for analysis by gas chromatography (GC). Extraction of MTBE from 2 g of fresh fish tissue was performed by ultrasonication for 10 min (in 25 ºC after 3.5 h maceration) in the glass barrel that was filled with water and sealed. Headspace solvent microextraction was done for the extraction of MTBE after centrifuge of sonicated sample. The optimized method (under the optimal experimental conditions: ultrasonic extraction time: 10 min, ultrasonic extraction temperature: 25 °C, fish particle size: a particle of 2 grams, media: distilled water, maceration time: 3.5 h and centrifuge of sonicated sample: 2500 rpm in 15 ˚C for 10 min) had good linearity (R2 >0.99) over the range 0.5- 50 µg g-1, and showed satisfactory level of precision, with RSD values in the range of 1.1 to 9.7 %. The LOD about 0.2 µg g-1 was obtained.
Majid Haji Hosseini
Abstract
Minimizing a drug’s size is an effective means to increase its dissolution and hence the bioavailability, which can be achieved by specialized dispersion techniques. This strategy results in increased surface area, the potential to increase saturation solubility, and decreased diffusional distance, ...
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Minimizing a drug’s size is an effective means to increase its dissolution and hence the bioavailability, which can be achieved by specialized dispersion techniques. This strategy results in increased surface area, the potential to increase saturation solubility, and decreased diffusional distance, all of which lead to an increase in the extent and the rate of dissolution. The purpose of this research was to develop antisolvent precipitation system for the preparation of stable aqueous suspension from ultrafine particles of lamotrigine as a poorly water soluble drug. Use of high stream velocities enhances mixing of lamotrigine acetic acid solution with water, that water was containing of polymer or surfactant inhibitor, was prepared a solution with lamotrigine particles with size <250 nm. Several experimental parameters, such as the type of stabilizer, the concentration of stabilizer, the concentration of salt (NaCl) and the concentration of drug that affected on size of the particles were optimized by undertaking Taguchi experimental design methodology. Using different analytical tools, such as X-ray diffraction (XRD), dynamic light scattering (DLS) and differential scanning calorimetry (DSC), the effect of different parameters on the size of the produced particles was investigated. The results showed that the best stabilizer is PEG (poly ethylene glocal) 4 mg ml-1, concentration of lamotrigine 10 mg ml-1 and NaCl concentration: 2 mol L-1, that the produced submicrometer suspension had a mean particle size of 248.5 nm and size distribution 243.9 – 252.2 nm.
Majid Haji Hosseini; Mohammad Reza Rezaei; Mohammad Rezaee; Peyman Asaadi; Khatereh Ashtari
Volume 1, Issue 1 , March 2014, , Pages 20-28
Abstract
This study propose a new analytical protocol for the determination of benzene, xylene, toluene and styrene in water samples using homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA) technique followed by gas chromatography-mass spectrometry (GC-MS). In this research, a special ...
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This study propose a new analytical protocol for the determination of benzene, xylene, toluene and styrene in water samples using homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA) technique followed by gas chromatography-mass spectrometry (GC-MS). In this research, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. No centrifugation was required in this procedure. The water sample solution was added into the extraction cell which contained an appropriate mixture of extraction and homogeneous solvents. By using air flotation, the organic solvent was collected at the conical part of the designed cell. The effects of different variables on the efficiency of the extraction were studied simultaneously using experimental design. Response surface methodology was applied to investigation the optimum conditions of each variable. Using optimized variables in the extraction process, for all target analytes, the detection limits, the precisions and the linearity of the method were found in the range of 0.8-8.2 ng mL-1, 3.09-7.96% (RSD, n=4) and 1-100 ng mL-1, respectively. The headspace method was used for the accuracy of comparison. The performance of the method was evaluated for extraction and determination of analytes in water samples and satisfactory results were obtained (RSD ≤10.06 %).