Sharif Digital Repository

Comprehensive two-dimensional gas chromatography and flame ionization detection combined with unfolded-partial least squares is proposed as a simple, fast and reliable method to assess the quality of gasoline and to detect its potential adulterants. The data for the calibration set are first baseline corrected using a two-dimensional asymmetric least squares algorithm. The number of significant partial least squares components to build the model is determined using the minimum value of root-mean square error of leave-one out cross validation, which was 4. In this regard, blends of gasoline with kerosene, white spirit and paint thinner as frequently used adulterants are used to make... 

Combination of fast high-performance liquid chromatography–diode array detection (HPLC–DAD) technique and ultrasonic assisted emulsification micro-extraction (USAEME) as extraction method are used for simultaneous determination of sixteen polycyclic aromatic hydrocarbons (PAHs) in river samples. The optimum conditions of USAEME procedure are selected according to the literature. Due to presence of different chromatographic issues and the complexity of water matrices, multivariate curve resolution-alternating least squares (MCR-ALS) is a good resolution technique for simultaneous quantification of PAHs in standard and real samples. On this matter, region-based and whole chromatographic data... 

The Ghotbi-Vera hard sphere equation of state as the reference system, coupled with the mean spherical approximation, (GV-MSA), has been used to accurately correlate the mean ionic activity coefficients of aqueous solutions of single 1:1 electrolytes. The new equation of state considers the ions to be hard spheres in Kelvin tetrakaidekahedron cells. The mean ionic activity coefficients of the electrolytes can be correlated with constant diameter of anions, equal to the crystallographic Pauling diameter and with a concentration dependent relation for the cations. In comparison to their crystallographic Pauling diameters, the new model for the mean ionic activity coefficient produces realistic... 

The non-primitive mean spherical approximation (NP-MSA) based models were used to correlate the individual and the mean ionic activity coefficients of the symmetric and asymmetric aqueous electrolyte solutions. The results of the models for the mean ionic activity coefficients were directly used to calculate the osmotic coefficient for the electrolyte solutions studied in this work. In the NP-MSA models, the Ghotbi-Vera and the Boublik-Mansoori-Carnahan-Starling- Leland hard sphere equation of state as the reference system coupled with the non-primitive mean spherical approximation model (NP-GV-MSA and NP-BMCSL-MSA models, respectively). In correlating the mean ionic activity coefficients of... 

The objective of this work is to extend the Kelvin mean spherical approximation (K-MSA) model to correlate the mean and individual ionic activity coefficients for symmetric and asymmetric electrolyte solutions at different concentrations and at different temperatures. Revised values of the parameters for the mean and individual ionic activity coefficients of 1:1 electrolytes and new values of the parameters for the mean ionic activity coefficients of asymmetric electrolytes are presented. The effect of the short-range electrostatic term (Pn) at different size ratios of the ions is examined. Assuming a constant anion diameter and a composition-dependent diameter for the cation, the K-MSA...