An analytical method for multi-elementary determination in powder refreshment, based on sample digestion using dilute mineral acids and detection by inductively plasma coupled optical emission spectrometry (ICP OES) is proposed. Chemometric tools, such as fractional factorial design and principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to optimize the sample preparation conditions in closed block digester, and Doehlert design for spectrometer operation. Addition and recovery tests and analyses of certified reference material were performed to evaluate the precision and accuracy, and the results confirm the reliability of the proposed method. Limits of quantification (LOQ) between 0.02 and 36 µg g−1 were obtained. The analytical method was applied for determination of 24 inorganic constituents in 20 powder refreshment samples. Calcium, K, Mg, Na, P, S and Ti presented the highest concentrations. The analytical method was adequate for the determinations of inorganic constituents in powder refreshment samples by ICP OES.

In this work, an analytical method for determination of Ba, Cu, Ni, V, and Zn, in medicinal herbs, through direct solid sample analysis by energy dispersive X-ray fluorescence spectrometry (EDXRF), was applied. Accuracy and precision (intra and inter day) of the analytical method were confirmed through analysis of certified reference material, tomato leaves (CRM NIST 1573a). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) allowed to observe the formation of two groups. Group I was composed by highest levels of Cu and Zn, and the group II with highest concentrations of Ba, V, and Zn. Group I also was subdivided into two subgroups. The concentration of Ni in some samples exceeded the maximum allowed limit. In all samples, Cu and Zn concentration were below the maximum limit allowed by Brazilian legislation. However, for Ba and V, the evaluation was not possible, because there are no maximum limits in legislation.

Cat and dog feed production has increased worldwide, and much emphasis has been placed on the importance of determining the mineral composition of pet foods. In this work, the concentrations of Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Sr, V and Zn in dry feed for cats and dogs employing inductively coupled plasma-optical emission spectrometry (ICP OES) were determined and evaluated according to regulatory agencies. Forty-one dry feed samples (24 dog feed and 17 cat feed) were analyzed. The obtained concentrations ranged from 2.3 mg kg-1 (Ba) to 2.8 g kg-1 (Ca) in cat feeds, and from 3.8 mg kg-1 (Cu) to 3.4 g kg-1 (Ca) in dog feeds. The concentrations of P are in accordance with the Brazilian legislation, and Mn and Zn contents met the American legislation. The concentration values of Cu, K and Mg presented in some samples were below the limits established by American regulatory agency. Based on multivariate data analysis evaluated from flavors of the products and brands, it was concluded that the feed samples were uniform since there was no trend to group formation and classification according to their mineral composition, except one dog feed brand, which had a significant content of Al and Cu.