This paper describes fundamentals and applications of multivariate statistical techniques for the optimization of chromatographic systems. The surface response methodologies: central composite design, Doehlert matrix and Box-Behnken design are discussed and applications of these techniques for optimization of sample preparation steps (extractions) and determination of experimental conditions fo...

An optimized method is presented using liquid-liquid extraction and derivatization for the extraction of iodoacetic acid (IAA) and other haloacetic acids (HAA9) and direct extraction of iodoform (IF) and other trihalomethanes (THM4) from drinking water, followed by detection by gas chromatography with electron capture detection (GC-ECD). A Doehlert experimental design was performed to determine...

The modelling of the parameters that influence the continuous evaporation of an alcoholic extract was considered using Doehlert matrices. The work was performed with a wiped falling film evaporator that allowed us to study the influence of the pressure, temperature, feed flow and dry matter of the feed solution on the dry matter contents of the resulting concentrate, and the productivity of the...

In this work, the effects of N2 addition to SF6 plasma used in isotropic silicon etching Micro-electromechanical systems (MEMS) with Au components are investigated. A four-variables Doehlert design was implemented for optimizing parameters (power, pressure, gas flow rate, and N2/SF6 ratio) maximize lateral etch rate Si using SF6/N2 mixture. The optimized condition founded a 1.8 µm/min was: powe...

A method for the determination of trace amounts of the herbicide oxadiazon was developed using headspace solid-phase microextraction (HS-SPME), gas chromatography-mass spectrometry (GC-MS) and selected ion monitoring. It was applied to determine oxadiazon in ground water, agricultural soil, must, wine and human urine samples. To determine oxadiazon in liquid samples, a response surface methodol...

Throughout dry-cured ham production, salt and water content, pH and temperature are key factors affecting proteolysis, one of the main biochemical processes influencing sensory properties and final quality of the product. The aim of this study was to quantify the effect of these variables (except pH) on the time course of proteolysis in laboratory-prepared pork meat samples. Based on a Doehlert...

A spectrofluorometric method is described for the determination of germanium(IV) based on its complexation reaction with quercetin in presence of Brij-35. The fluorescence is monitored at 552 nm with excitation at 432 nm. The pH, quercetin and Brij-35 concentrations were optimized simultaneously using the response surface methodology from sequential experimental three-variable Doehlert designs....