Decomposition method in semi-closed system with cold finger for evaluation of Ca, K, Na, Mg, Zn and Fe in colostrum silage by F AAS and F AES

• Concentrations of Ca, K, Na, Mg, Zn and Fe were determined in five colostrum silage.
• The acid decomposition in a semi-closed system was efficient to decompose the samples.
• The method is fast, inexpensive and can be applied for routine analysis.

The objective of this study was to use a method of acid decomposition in a semi-closed system with cold finger in colostrum silage samples, for the determination of Ca, Fe, K, Mg, Na and Zn. Colostrum silage samples from five different bovine were studied. Analyte determinations were carried out by flame techniques. In the decomposing system, 5 mL of sample and 5 mL of HNO3 per 200 °C were used for 2 h, ending with the addition of 1 mL of H2O2 for 30 min at 120 °C. Accuracy was evaluated by recovery tests, with results ranging from 83 to 120%, and by the low RSD values (< 11.2%). Results differed significantly (95% confidence) between samples with higher levels than those found in milk and this fact reveals that the silage process allows the maintenance of minerals compounds present in colostrum. Furthermore, the values for the elements found in the colostrum silage are close to the values found in the literature for colostrum.