Application of LIBS for Identification and Determination of Element Concentrations in Milk

Milk and dairy products in many parts of the world constitute a major part of the human diet. This nutrient is composed of various elements such as calcium, potassium, chlorine, phosphorus, magnesium, zinc, etc. In animal nutrition, some heavy and dangerous metals like lead, arsenic and cadmium are transmitted through animal feed to the milk. The purpose of this study is introducing Laser Induced Breakdown Spectroscopy (LIBS) method for identifying and determining the element concentrations in pasteurized and raw cow milk. This research was done on six types of milk from different milk factories, and raw milk from a dairy industry in 2013. Each of these milks was analyzed 7 times by using LIBSCAN100 system and Plasus Specline software. In this research, the mean concentration of five major elements (calcium, phosphor, potassium, magnesium, and sodium), four partial elements (zinc, copper, and Iron), and three heavy metals (lead, cadmium, and arsenic) was determined. The variations of mean concentration of different elements in the pasteurized samples are as follows: Ca: [1000-11000µg/g], K: [0-13000 µg/g], Mg: [100-3000 µg/g], P: [0-1800 µg/g], Na: [200-3000 µg/g], Zn: [300-28100 µg/g], Cu: [100-10600 µg/g], Se: [1-113 µg/g], Fe: [100-8900 µg/g], Cd: [0.110-0.690 µg/g], Pb: [0.1-0.84 µg/g], As: [0-0.860 µg/g]. In this research, a new high speed non-destructive analytical method with no need to initial preparation is introduced. The results of analyze showed that the concentrations of nutrient elements are close to RDI factor, and the concentrations of toxic elements are under the PTWI threshold.