A second virial coefficient correlation suitable for two different temperatures ranges, (T*)(-2)less than or equal to 180 and (T*)(-2)>180, where T* is RT/Delta H-vap is presented The equation of state can be calculated for different complicated nonpolar, and slightly polar Liquid mixtures at any temperature over the range from T-tp to T-c and up to high pressures. The latent heat of vaporization and density at the triple point are the only two parameters that are needed in these calculations. The results indicate that the Liquid densities of Liquid mixtures with quite different acentric factors can be predicted to within about 5%.

In this study, the NonRandom Two-Liquid (NRTL) model was used to calculate the isoactivity equations from the experimental Liquid-Liquid Equilibrium (LLE) data. Additionally, the original Differential Evolution method (DE_rand1) and its modifications involve the self-adaptive control parameters differential evolution (JDE), the adaptive differential evolution with optional external archive (JADE), and the Composite Differential Evolution (CODE) have been used to estimate the binary interaction parameters. Randomization of regression parameters has been used to minimize the fitting objective function. Furthermore, the effectiveness of these optimization methods was tested in a quaternary system of water, acetic acid, 50 % dichloromethane (DCM), and 50 % methyl isobutyl ketone (MIBK) at 301.15 K. Moreover, the optimization process assessment was carried out by regression analysis using Root Mean Square Deviation (RMSD), mean, standard deviation, and the duration of execution time spent on both the activity and the fractional objective functions. Root Mean Square Deviation (RMSD) results that were less than or equal to 0.0107 demonstrated the effectiveness of Differential Evolution methods in estimating NRTL parameters for this specific system. Finally, the original method (DE_rand1) was found to be the most efficient approach among all its variations.

Two convenient sample preparation methods, air-assisted Liquid-Liquid microextraction (AALLME) and dispersive Liquid-Liquid microextraction (DLLME) have been developed for the simultaneous determination of multiclass pesticide residues in vegetable and fruit juice samples with gas chromatography-flame ionization detection and the advantages of each method were investigated. In AALLME, fine droplets of an extraction solvent were immediately formed by suction with a syringe and injection of the mixture of an aqueous sample solution and an extraction solvent into a test tube for several times. In DLLME, the cloudy solution was formed with the aid of a disperser solvent. The effect of main factors, such as type and volume of extraction solvent, salt addition, pH, etc. was studied. Under the optimum conditions, enrichment factors and extraction recoveries were obtained in the ranges of 262-515, 52-103% and 45-438, 9. 2-88% in AALLME and DLLME methods, respectively. Both methods are inexpensive, simple, fast, efficient, reliable and sensitive. Therefore, the proposed methods are suitable for determination of trace levels of multiclass pesticide residues in fruit juice and vegetable samples.