Papers by Bahram Hemmateenejad
Chemometrics and Intelligent Laboratory Systems, 2015
The use of multivariate curve resolution-alternating least square (MCR-ALS) for determination of ... more The use of multivariate curve resolution-alternating least square (MCR-ALS) for determination of nanoparticles concentration is proposed. The concentration of nanoparticles based on its reaction with a reagent such as a biomolecule, nanoparticles and etc was calculated. The reagent can be considered as an aggregating agent, capping agent and so on. To do so, titration of nanoparticle was achieved by adding variable amounts of reagent to a nanoparticle solution of unknown concentration. A reverse titration was also performed. The UV-Vis spectra of the solutions at different titration steps were recorded. After data collection, chemometrics approach was employed for data analysis. To use MCR-ALS as a quantitative tool, rotational and intensity ambiguities were removed employing unimodality, non-negativity, closure and equality constraints and simultaneous analysis of four spectroscopic titrations: three titrations of reagent by nanoparticles with different concentrations of reagent, and one titration of nanoparticles by reagent. The proposed method was firstly evaluated by simulated data. Then, the concentration of the laboratory-synthesized silver nanoparticles was determined using human serum albumin as reagent. The estimated concentration by the suggested method (1.24 × 10 −8 M) was very close to that obtained by analysis of TEM images (1.19 × 10 −8 M) with a relative error of 4.2%.
Journal of the Iranian Chemical Society, 2015
Semiconductor nanoparticles (quantum dots) are promising fluorescent markers, but very little kno... more Semiconductor nanoparticles (quantum dots) are promising fluorescent markers, but very little known is about interaction of quantum dots with biological molecules. In this study, interactions of ZnS quantum dots doped with different amounts of Mn (1, 2 and 3 %) with human serum albumin (HSA) were studied by fluorescence and UV-Vis spectroscopic techniques. It was observed that fluorescence of HSA was strongly quenched by ZnS QDs. The results of fluorescence quenching at different temperatures and UV-Vis absorption spectra experiments indicated that the quenching mechanism of serum albumin by QDs is static quenching through formation of the complex of QDs-HSA. According to the modified Stern-Volmer equations at different temperatures, the thermodynamic parameters, ΔH 0 , ΔS 0 and ΔG 0 were determined. The number of binding sites (n) was also obtained. It was found that hydrogen bonding and van der Waals interaction played a key role in the interaction process.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2009
A new, rapid, sensitive, non-extraction batch, and flow injection spectrophotometric method for t... more A new, rapid, sensitive, non-extraction batch, and flow injection spectrophotometric method for the determination of cationic surfactants (CSs) such as cetyltrimethyl ammonium bromide (CTAB), tetra-n-butyl ammonium chloride (TBAC) and cetylpyridinium chloride (CPC) is proposed. The method is based on the interaction of cationic surfactants with eriochrome black-T to form an ion-association complex. This complex has strong absorbance at 708 nm. The effects of chemical parameters and FIA variables on the determination of cationic surfactants were studied in detail, especially for CTAB. Under optimum conditions, the two linear calibration ranges of the method are 3.0 x 10(-6) to 5.0 x 10(-3)mol L(-1) CTAB, CPB and DTAB for the batch spectrophotometric method and 2.0 x 10(-6) to 2.0 x 10(-4)mol L(-1) CTAB, CPB and TBC for the flow injection spectrophotometric method. The sample throughput was 35+/-5 samples h(-1) at room temperature. The relative standard deviations for 10 replicates of...
Journal of Photochemistry and Photobiology A: Chemistry, 2015
ABSTRACT Diphenylamine (DPA) photodegradation was studied by applying the optimal response surfac... more ABSTRACT Diphenylamine (DPA) photodegradation was studied by applying the optimal response surface design methodology to the chromatographic data from pollutant solutions exposed to stressing irradiation. The procedure consisted of data analysis of aliquots collected at different reaction times and injected to a high-performance liquid chromatography coupled to diode array detection-mass spectrometry (HPLC–DAD–MS). The variables considered for the process optimization were irradiation power, irradiation time and pH of solution, for a solution with DPA concentration of 100 mg L−1. This methodology allowed assessing and identifying the effects of different factors studied and their interactions in the process response. An appropriate quadratic model was developed in order to plot the response surface and contour curves and to perform the process optimization. The results obtained revealed that DPA photodegradation is strongly dependent on the solution pH and irradiation power. Under the optimal conditions (i.e., pH of 10, irradiation power of 2 × 15 W lamp and irradiation time of 150 min), it was possible to achieve an almost complete photodegradation of DPA. The process was found to follow a pseudo-first-order kinetic model. Mass spectrometric analysis allowed the identification of carbazole (CB) as the major photodegradation product. A possible pathway for the photodegradation of DPA was suggested. The optimized methodology was applied to preparation and separation of CB, as an important mediator in fine chemistry and pharmacy, from DPA by thin layer chromatography.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013
Department of Chemistry, Razi University, Kermanshah, b Medicinal & Natural Products Chemistry Research Center, Shiraz University of Medical Science, Shiraz, 71345, Iran c Department of Chemistry, Shiraz University, Shiraz, Iran
Page 1. Archive of SID Iranian Journal of Medical Hypotheses and Ideas Diabetes foot ulcers: A no... more Page 1. Archive of SID Iranian Journal of Medical Hypotheses and Ideas Diabetes foot ulcers: A novel treatment strategy Khodaberdi Kalavi1, Abdolvahab Moradi1, Abbas Ali Keshtkar1, Mergen Kalavi1, Golnaz Namazi1 and Saleh Mohaghegh Hazrati2 ...
ABSTRACT Starch-coated CdSe quantum dots weresynthesized and utilized as aphotocatalystfor degrad... more ABSTRACT Starch-coated CdSe quantum dots weresynthesized and utilized as aphotocatalystfor degradation of Methyl Green (MG)in ambient condition.Very low quantities of photocatalystfound to be capable ofsignificantly decolorize large amount of MG (ratio of MG to photocatalyst 1000:1) within a few minutesin pH neutral.Simple UV/Vis spectroscopy measurements was coupledwith multivariate curve resolution-alternative least-squares (MCR-ALS) to present a new paradigm in employing MCR-ALS technique for studying reaction kinetic. Five chemical components were detected for decomposition of MG using factor analysis (FA) and concentration profiles and pure spectra of detected components were resolved using MCR-ALS.
A systematic study has been conducted on the effect different factors including relative acidity,... more A systematic study has been conducted on the effect different factors including relative acidity, number of components and added noise on the simultaneous determination of weak acids by multivariate pH-metric titration. For this purpose, partial least squares (PLS) regression was applied on the simulated pH-metric titration data. Large numbers of acid mixture systems composed of different number of acids with varying acidity strengths were examined. The effect of added noise on the prediction ability of the PLS regression was also studied. a linear relationship between the added titrant volumes and analyte's concentration.
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Papers by Bahram Hemmateenejad