GREEN AND SIMPLE MICRO-ECTRACTION OF FREE SELENO-AMINO ACID FROM POWDER AND LYOPHILIZED MILK SAMPLES WHIT NATURAL DEEP EUTECTIC SOLVENTS

CERUTTI, S.; PACHECO, P.; LÓPEZ, ROMINA VANESA

Mendoza

Congreso; 15th Rio Simposyum; 2019

Recently, works have been published that apply new deep eutectic natural solvents (NADE) in replacement of conventional solvents for the extraction of proteins in different foods [1]. NADE in combination with ultrasonic energy is an ecological approach for protein solubilization. This research describes a new process for the extraction of free seleno-amino acids from cow´s milk and sheep´s milk samples with NADE. In dairy production, different amino acids are easily incorporated into the milk protein, becoming a good source of Se for humans [2]. Within the framework of a balanced diet, the ingestion of Se in organic form is recommended, mainly as amino acids present in food, since the human body assimilates it more easily than Se in its inorganic form. In this sense, it is important to evaluate in which form of selenium is being enriched in milk.NADEs present a complex organic matrix that represents a challenge for the conventional inductively coupled plasma mass spectrometry (ICP MS) sample introduction system. An appropriate dilution of the NADE becomes an important strategy to overcome these difficulties along with the optimization of gas flow rate (GFR) and radio frequency (RF), to maintain a reproducible analysis without losing sensitivity. Extraction consists of adding the milk powder sample with NADE, shake it, perform an ultrasound extraction, centrifuge and analyze seleno-amino acids by liquid chromatography-ICP MS. The best extraction after different NADEs comparison was reached for the lactate-glucose NADE, reaching a 94% extraction of selenium. After the best NADEs performance for seleno-amino acid extraction, an experimental design was implemented to obtain accurate data on the most influential parameters in the system and the adequate quantities of sample and reagents. Results showed that the optimal working conditions were: 21.94% of LGH concentration (v v-1), the ultrasound time of 33.26 minutes, the amount of sample of 0.94 g and the volume of extractant (NADE solution) of 3.09 mL. After optimization a LoD and LoQ of 2.18 and 6.61 µg kg-1 were obtained respectively. A green extraction procedure developed that eliminates the use of highly polluting organic solvents. ICP-DRC-MS optimization increase sensitivity and precision during Se determination. The system was successfully applied to free seleno-amino acids determination in milk powder and milk lyophilized samples.