Detection and comparison of major and trace elements from different species milk by inductively coupled plasma-mass spectrometry

Abstract Text: Milk contains lots of nutrients, such as proteins, lipids, carbohydrates, vitamins and elements. As a complex biological fluid and an excellent source of macro and micro nutrients, milk can play an important way in meeting the nutritional requirements for individuals. The content of 9 major and trace elements in cow (n=20), yak (n=20), buffalo (n=20), Jersey cattle (n=20), goat (n=20), camel (n=8) and horse (n=8) milk samples which were collected around the 4^thmonth of lactation for each species from February to April, 2013 in China have been determined by inductively coupled plasma-mass spectrometry (ICP-MS) (Agilent 7700X, Agilent Corporation, USA) after microwave digestion. Descriptive statistics and Duncan’s multiple comparison of protein contents were obtained by SAS 9.1 via GLM model (SAS Institute Inc., Cary, NC). In order to check the applicability of the proposed method to the analysis, two certified reference materials available for powder skim milk (GBW10017) and for cabbage power (GBW1001) were analysed to obtain satisfactory results in all cases. The result showed that the contents of major elements (Na, Mg, K, Ca, Fe) and trace elements (Mn, Co, Zn, Se) in different species milk were significantly different. All of the major elements were lowest in horse milk. Much higher concentrations of Mg and Ca were found in buffao milk. The content of Fe was highest in cow milk. Na and K were found highest in camel milk and goat milk, respectively. The concentrations of trace elements (Mn, Co, Zn, Se) were almost higher in cow milk than in other species milk, except for Se, which was a little lower than in buffalo milk. The content of Co was found nearly the same in cow, yak, buffalo, Jersey cattle, camel and horse milk, except for in goat milk, which was a little lower. In addition, Se was not detected in horse milk. It was concluded that the contents of major and trace elements in milk from different species were various and the trace element of Se was not detected in horse milk in this study. 

Keywords: major and trace elements, species milk, inductively coupled plasma-mass spectrometry