AN ECO-FRIENDLY SAMPLE PREPARATION METHOD DEVELOPMENT FOR ANIMAL FEED NUTRIENT ANALYSIS BY MIP OES

LARREGUI, D. N.; SAVIO M.; CORA JOFRE, F.; ROSSINI, A.; SOSA, A. P.

Mendoza

Simposio; 15th Rio Symposium on Atomic Spectrometry; 2019

Feeds for farm animals must contain suitable nutrients concentration, since its composition may affect animal health and its productivity1. Thus, knowing nutrients in feed is of great importance. One of the main analytical chemistry challenges has been to overcome problems to bring samples into solutions, which should be compatible with the spectrochemical instrumental technique for inorganic trace analysis. In the present work, a procedure for sample preparation of pig feeds using commercially available infrared radiation (IR) lamps was evaluated, as this technology could be extensively used based on its ability to promote fast heating. Microwave induced plasma atomic emission spectrometry (MIP OES) was used for Al, Ca, Cd, Co, Cu, Fe, K, Na, Mg, P, Sr and Zn determination in porcine food samples. The proposed procedure consisted in homogenizing and grinding the porcine food samples, adding 1 mL of diluted nitric acid (3.5 mol L-1) to 0.15 g of the sample, and exposing it to IR until dry (this procedure was repeated again). Then, 1 mL of H2O2 -100 volumes- was added and samples were dried by exposing to IR (repeating the procedure twice). To validate the proposed methodology Certified Reference Materials (CRM) were analyzed using the same treatment as the samples; analytical recoveries were between 80-120%. Detection limits were found in the range between 0.87 mg kg-1 (Cd) and 148 mg kg-1 (Fe), and accuracy (expressed in terms of relative standard deviation, RSD) was better than 8%. This treatment of complex samples, rich in organic compounds, through the use of IR was efficient, without residual carbon content and a low acidity in the final digest. In addition, the use of small volumes of diluted nitric acid makes it eco-friendly and recommended to improve the yield and productivity when quantifying the nutritional quality of pork foods. This could be verified by using the analytical eco-scale that is especially important in the search for new green methodologies because it clearly indicates the weaknesses of the analytical procedures.