Chemometrically Assisted Development of Ultra-High-Performance Liquid Chromatography Method for the Simultaneous Quantification of Sofosbuvir, Daclatasvir and Ledipasvir in Pharmaceutical Dosage Forms.

A new ultra-high-performance liquid chromatography method for the simultaneous quantification of sofosbuvir, daclatasvir and ledipasvir was developed. Two combinations of these direct-acting antivirals are used in hepatitis C virus infection therapy and show high efficacy and safety. Fractional factorial design was used for screening the most influential factors on separation and time analysis.

Factorial design optimization of experimental variables in preconcentration of carbamates pesticides in water samples using solid phase extraction and liquid chromatography-electrospray-mass spectrometry determination.

An experimental design was applied for the optimization of extraction process of carbamates pesticides from surface water samples. Solid phase extraction (SPE) of carbamates compounds and their determination by liquid chromatography coupled to electrospray mass spectrometry detector were considered. A two level full factorial design 2(k) was used for selecting the variables which affected the extraction procedure.

TiO2 nanotubes as solid-phase extraction adsorbent for the determination of polycyclic aromatic hydrocarbons in environmental water samples.

An analytical method based on TiO2 nanotubes solid-phase extraction (SPE) combined with gas chromatography (GC) was established for the analysis of seven polycyclic aromatic hydrocarbons (PAHs): acenaphtylene, acenaphthene, anthracene, fluorene, phenanthrene, fluoranthene and pyrene. Factors affecting the extraction efficiency including the eluent type and its volume, adsorbent amount, sample volume, sample pH and sample flow rate were optimized. The characteristic data of analytical performance were determined to investigate the sensitivity and precision of the method.

Identification of phenyl-N-methylcarbamates and their transformation products in Tunisian surface water by solid-phase extraction liquid chromatography-tandem mass spectrometry.

Liquid chromatography-pneumatically assisted electrospray mass spectrometry with both negative and positive ionization has been used for the determination of carbamates pesticides and their transformation products in Tunisian surface water. Eight pesticides and four of their hydrolysis products were covered in this study. Optimization of electrospray inlet conditions is described as well as results from investigations of the linearity of the detector response.