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: 0.4-0.5 g for the sample mass, 12-15 min of sonication and using 700-1000 µL of 25% TMAH at a temperature of 50 °C. The obtained limits of quantification varied between 0.221 (Mg) and 7.60 (Ca) µg g-1. Accuracy was assessed by comparing the results obtained by applying the proposed method with the digestion in an acid medium using a digesting block and by analyzing bovine liver certified reference material. The application of a t-test revealed that, at a 95% confidence level, there were no significant differences between the values obtained.

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. The developed dissolution method allowed Ca, Fe, Zn, and Mg determination in milk samples with adequate analytical characteristics for these determinations. Addition/recovery tests and analysis of a certified reference material of skimmed powdered milk (ERM-BD150) have shown that this method presents enough accuracy to carry out these analyses.

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. The advantages, disadvantages, limitations, and potentialities of these methods will also be addressed, as well as some of their applications, commenting on real examples from the literature. Some less usual methods in multiple response optimization in Analytical Chemistry will also be commented.