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Accurate determinations of water (H2O) content in natural gases especially in the methane (CH4) phase are highly important for chemical engineers dealing with natural gas processes. To this end, development of a high performance model is necessary. Due to importance of the solubility of methane in the aqueous solutions for natural gas industries, two novel models based on the Decision Tree (DT) and Adaptive Neuro-Fuzzy Interference System (ANFIS) have been employed. To this end, a total number of 204 real methane solubility points in aqueous solution containing NaCl under different pressure and temperature conditions have been gathered. The comparisons between predicted solubility values and experimental data points have been conducted in visual and mathematical approaches. The R2 values of 1 for training and testing phases express the great ability of proposed models in calculation of methane solubility in pure water systems.

Bimetallic catalysts NiCo/CNTs with distribution-controlled Ni and Co species were prepared by modified impregnation method with the assistance of dimethylbenzene and characterized by XRD, N2 adsor...

A novel chemiluminescence (CL) method to determine putrescine was proposed based on the enhanced effect of putrescine on CL emission of the [Ag(HIO6)2]5−–luminol system. The enhanced degree of CL emission was proportional to the putrescine concentration. Under optimal conditions, there was a linear relationship between the increase in CL intensity and the putrescine concentration over a range of 4.0 × 10−8 to 4 × 10−6 g mL with a detection limit (3σ) of 1.76 × 10−8 g mL−1. The relative standard deviation (RSD) was 3.2% for 11 replicate determinations of 1.0 × 10−6 g mL−1 putrescine. The proposed CL reaction systems had potential capability for residue analysis of studied analytes in food samples. A possible mechanism of CL emission and enhanced effect was also suggested.

A sensitive and reliable high performance liquid chromatograph-fluorescence detection (HPLC-FLD) method for the determination of diethylstilbestrol (DES) in human urine is developed. DES was derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl)benzoyl chloride (DIB-Cl) under mild conditions and separated isocratically on a C18 column. The detection limits of DES at a signal-to-noise ratio (S/N) of 3 was 0.5 ng ml−1, and the recoveries for the addition of different concentrations of DES to samples were in the range of 78.5–88.3% with RSD (n = 5) of less than 6.4%. The method was successfully applied to the determination of DES in human urine samples.