Bishydrazone ligand and its Zn-complex: synthesis, characterization and estimation of scalability inhibition mitigation effectiveness for API 5L X70 carbon steel in 3.5% NaCl solutions.

Bishydrazone ligand, 2,2'-thiobis(N'-((E)-thiophen-2-ylmethylene) acetohydrazide), H2TTAH and its Zn- complex were prepared and characterized through elemental analysis and various spectroscopic performances as well as (IR, 1H and 13C NMR, mass and (UV-Vis) measurements. The synthesized complex exhibited the molecular formula [Zn2(H2TTAH)(OH)4(C5H5N)3C2H5OH] (Zn-H2TTAH). To assess their potential as anti-corrosion materials, the synthesized particles were assessed for their effectiveness for API 5L X70 C-steel corrosion in a 3.5% NaCl solution using electrochemical methods such as potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Additionally, X-ray photoelectron spectroscopy (XPS) was employed to examine the steel surface treated with the tested inhibitors, confirming the establishment of an adsorbed protecting layer. The results obtained from the PP plots indicated that both H2TTAH and Zn-H2TTAH act as mixed-type inhibitors. At a maximum concentration of 1 × 10-4 M, H2TTAH and Zn-H2TTAH exhibited inhibition efficiencies of 93.4% and 96.1%, respectively. The adsorption of these inhibitors on the steel surface followed the Langmuir adsorption isotherm, and it was determined to be chemisorption. DFT calculations were achieved to regulate the electron donation ability of H2TTAH and Zn-H2TTAH molecules. Additionally, Monte Carlo (MC) simulations were conducted to validate the adsorption configurations on the steel surface and gain insight into the corrosion inhibition mechanism facilitated by these molecules.

Second-derivative synchronous fluorimetry and time-programmed HPLC-fluorescence detection for simultaneous estimation of flibanserin and sitagliptin phosphate in synthetic mixtures and human plasma samples.

Diabetes Mellitus is directly related to female anaphrodesia. Female Viagra or Flibanserin (FLB), U.S. FDA approved in 2015, is specifically indicated for premenopausal Hypoactive Sexual Desire Disorder, HSDD, which is one of the primary consequences of Diabetes Mellitus. Simultaneous analysis of the concomitantly administered, FLB and oral antidiabetics, as Sitagliptin phosphate (STG), is a crucial demand to investigate mutual drug-drug interaction. The latter is responsible for uncontrolled glycaemia and higher risk of sudden hypoglycemia. Two simple, sensitive, economical and direct analytical methods, namely, Second-Derivative Synchronous Fluorimetric Spectroscopy, D2-SFS, and High Performance Liquid Chromatography with fluorimetric detection, HPLC-FD, are established for simultaneous determination of FLB and STG in their binary mixtures. First method relies on measuring D2-SFS spectra of both drugs, at Δλ = 25 nm, along linearity ranges of 0.05-1 µg/mL for both drugs. The second method is a chromatographic one with gradient elution of FLB and STG on RP-ZORBAX Eclipse C18 column (5 µm, 4.6 × 150 mm). Mobile phase; phosphate buffer: acetonitrile, pH 4.5, with a flow rate of 1 mL/min at room temperature has been used. Time programmed fluorimetric detection is optimized at λem = 305 nm for STG (0.0-5.9 min), at λem = 375 nm for FLB (6-9 min) after both excitation at λex = 257 nm, in the linear ranges of 1-40 µg/mL and 5-60 µg/mL for FLB and STG, respectively. Proposed methods have been validated according to ICH guidelines, then applied for simultaneous quantitation of FLB and STG in their laboratory-prepared mixtures and in spiked human plasma samples. Satisfactory Student's t-value and F-variance ratio have been obtained upon comparing the results of both methods.