Nutritional evaluation after copper cloud point extraction in spirulina (Arthrospira sp.) samples with determination by digital image colorimetry.

This study presents the development of a procedure based on copper preconcentration at the cloud point of commercial spirulina dietary supplements, with determination by digital image colorimetry. A fractional factorial design 2 and Doehlert matrix were applied in the method optimization. The developed method presented 0.

An introductory review on the application of principal component analysis in the data exploration of the chemical analysis of food samples.

Principal component analysis (PCA) is currently one of the most used multivariate data analysis techniques for evaluating information from food analysis. In this review, a brief introduction to the theoretical principles that underlie PCA will be given, in addition to presenting the most commonly used computer programs. An example from the literature was discussed to illustrate the use of this chemometric tool and interpretation of graphs and parameters obtained.

A new and accessible instrumentation to determine urea in UHT milk using digital image analysis.

This research demonstrates the development, optimization and application of a new low-cost detection system, based on digital image analysis, for the detection of urea in ultra-high-temperature (UHT) milk samples. The apparatus built in the laboratory, allows the capture of images through a simple system built by polyvinyl chloride (PVC) tubes, a digital microscope and a peristaltic mini-pump, after the colorimetric reaction between urea and diacetylmonoxime (butane-2,3-dionammonoxime). The red, green and blue (RGB) and hue, saturation and value (HSV) color systems were studied, with the saturation channel of the HSV color system selected as the analytical signal.

In-syringe dispersive liquid-liquid microextraction.

Dispersive liquid-liquid microextraction (DLLME) has recently been widely used in the separation and preconcentration of various chemical species. Among the various approaches using DLLME are systems that use a syringe as an extraction environment. In this review, details of some methods that use this approach are presented.

Doehlert design in the optimization of procedures aiming food analysis - A review.

In the present paper is presented a review on the application of Doehlert design in the optimization of some of the steps of analytical procedures aimed the analysis of food samples. The theoretical principles and the main characteristics of this type of design are described. In addition, the main advantages and limitations of Doehlert design over other designs (Central Composite Design and Box-Behnken) and its application in the area of food analysis are discussed.

Multivariate optimization of a dispersive liquid-liquid microextraction method for determination of copper and manganese in coconut water by FAAS.

In this study, multivariate methodologies were applied in the optimization of a dispersive liquid-liquid microextraction (DLLME) method, aiming at the determination of Cu and Mn in coconut water samples by flame atomic absorption spectrometry. Some extractors (chloroform and CCl), dispersants (ethanol, methanol and acetonitrile) and complexing agents (5-Br-PADAP and Dithzone) were previously tested in the extraction. A mixture design was used to optimize the component proportions formed by chloroform (10%), acetonitrile (76%), and 0.

Multivariate optimization of a goat meat alkaline solubilization procedure using tetramethylammonium hydroxide for metals determination using FAAS.

In the present work, multivariate designs were used to optimize an alkaline dissolution, assisted by ultrasound energy, procedure of goat meat using tetramethylammonium hydroxide (TMAH) aiming to determine Ca, Cu, Fe, K, Mg, Na and Zn by flame atomic absorption (FAAS) and emission (FAES) spectrometry. The optimal conditions found for the dissolution were in the following ranges: 0.4-0.

Artificial neural network employment for element determination in Mugil cephalus by ICP OES in Pontal Bay, Brazil.

Fish are important sources of protein, making them very significant in the human diet. Although the consumption of this food is beneficial for health, it is essential that the product does not contain inorganic components above the limits recommended by the current legislation. Therefore, a method for determination of elements in fish (Mugil cephalus) samples was optimized.

An alkaline dissolution-based method using tetramethylammonium hydroxide for metals determination in cow milk samples.

This study approaches the development of a method for the determination of Ca, Mg, Zn, and Fe in liquid and powdered cow milk. The method is based on sample dissolution assisted by ultrasound energy in tetramethylammonium hydroxide (TMAH) media and determination by flame atomic absorption spectrometry (FAAS). Central composite design (CCD) associated with response surface methodology and desirability function allowed the fast and efficient optimization of the variables involved in the performance of the dissolution.

Mineral content of longissimus lumborum from growing lambs fed crude glycerin.

The objective of the study was to evaluate whether crude glycerin (CG), which was supplied as a dietary ingredient for growing lambs, affected the macro- and micromineral contents of the longissimus lumborum (LL). Twenty-four lambs were placed in two treatments: animals that received no CG and animals that received CG as part of their diet. The experiment lasted for 56 days.

Simultaneous optimization of multiple responses and its application in Analytical Chemistry - A review.

This manuscript covers the application of the main techniques for simultaneous optimization of multiple responses generated by the application of multivariate designs (two-factor factorial, Central Composite, Doehlert, etc.) or by chromatographic runs in the development of analytical methods. Special attention will be given to the graphical method, desirability function, multiple response function and chromatographic response functions, since they are more frequently used in the analytical area.

Evaluation of macro and micronutrient elements content from soft drinks using principal component analysis and Kohonen self-organizing maps.

This study approaches the determination of nine elements from Brazilian carbonated soft drinks of several flavors and manufactures using inductively coupled plasma optical emission spectrometry (ICP OES). The concentrations of the elements varied as follows: (in µg L: Cu: 4.00-78.

Doehlert design in the optimization of ultrasound assisted dissolution of fish fillet samples with tetramethyl ammonium hydroxide for metals determination using FAAS.

Doehlert design and desirability function were used in the optimization of an ultrasound assisted dissolution method of fish fillet samples with tetramethyl ammonium hydroxide (TMAH) for the determination of Ca, Fe, Zn and Mg by flame atomic absorption spectrometry. The variables values after optimization were 620 μL (volume of TMAH), 25 min (sonication time) and 46 °C (bath temperature). The quantification limits for Ca, Mg, Fe and Zn were 56, 107, 23 and 2.

Screening of Passiflora L. mineral content using principal component analysis and Kohonen self-organizing maps.

A method using digestion with diluted nitric acid and inductively coupled plasma optical emission spectrometry was applied to determine metal ions in the peel, pulp, and seed of Passiflora edulis f. flavicarpa and Passiflora cincinnata cultivated in the Bahia state, Brazil. Plasma parameters (radio frequency power and argon flow rates) were optimized.

Determination and Evaluation of Metallothionein and Metals in Mugil cephalus (Mullet) from Pontal Bay, Brazil.

To assess environmental contamination, studies have been increasingly carried out using biomarkers to diagnose the effects of toxic metal exposure, such as metallothionein (MT). In this context, the aims of the present study were to determine Cd, Cu, Ni and Pb concentrations, by ICP-MS, in liver samples from Mugil cephalus from the municipality of Ilhéus, located in North-Southeastern Brazil, in the state of Bahia, which has been increasingly suffering from anthropogenic pressure, and to quantify total MT in liver and gills. Among essential metals, copper (199.

Synthesis of a new solid-phase extractor and its application to preconcentration and determination of lead in water samples.

A procedure for preconcentration and determination of lead in water is described. The method is based on the sorption of Pb(II) in a minicolumn packed with a functionalized sorbent and subsequent elution with acidic solution. The determination of lead content in the eluate was carried out using flame atomic absorption spectrometry.

Flow injection preconcentration system using a new functionalized resin for determination of cadmium and nickel in tobacco samples.

A solid-phase extraction method combined with flow injection (FI) on-line flame atomic absorption spectrometry (FAAS) for the determination of cadmium and nickel in tobacco samples is presented. The 2-aminothiophenol functionalized Amberlite XAD-4 (AT-XAD) resin was synthesized by covalent coupling of the ligand with the copolymer through a methylene group. A minicolumn packed with AT-XAD was connected into the automated on-line preconcentration system.