Quantification of trace elements in raw cow’s milk by inductively coupled plasma mass spectrometry (ICP-MS)

Abstract

The levels of trace elements are an important component of safety and quality of milk. While certain elements such as chromium are essential at low levels, an excess can result in deleterious effects on human health. International quality control standards for milk are published by the Codex Alimentarious Commission and levels of heavy metals in milk intended for human consumption are routinely monitored. This paper describes a new method for demonstrating the levels of V, Cr, Mn, Sr, Cd and Pb in raw cow's milk, using an ICP-MS. Samples (n = 24) of raw cow's milk were collected from dairy farms close to mines in Gauteng and North West Provinces of South Africa. In order to destroy organic matrix, each freeze dried milk sample was mineralised by using a microwave assisted digestion procedure. Concentrations of trace elements in digested milk samples were measured by ICP-MS. A whole milk powder reference material (NIST SRM 8435) was used to evaluate the accuracy of the proposed method. It was found that the levels of V, Cr, Mn, Sr, Cd and Pb obtained using the new method showed concordance with certified values.

Speciation of chromium in cow's milk by solid-phase extraction/dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS)

“…17 The values for three brands (1, 6 and 8) were slightly higher than reported in that paper. The higher concentrations of total Cr in these commercial brands could be influenced by environmental conditions such as proximity to mines, or the equipment processing the milk.…”

“…Samples for quantification of total Cr were prepared by applying the method reported previously. 17 A 0.5 g (AE0.0001) aliquot of freeze-dried and crushed milk sample was accurately weighed and quantitatively transferred to each XP-1500Plus vessel. The sample was reconstituted with 2 ml of 18.2 MU cm de-ionised water.…”

Multivariate optimization of microwave-assisted digestion of copper and zinc from powder milk

“…This method uses less reagent volumes and shorter digestion time. 1 Milk powder sample aliquot (0.5 g) was weighed and then transferred to a closed-vessel. Then, appropriate amount of nitric acid was added.…”

“…Therefore, it is known as an almost complete nutritional product in the human diet. 1 This is especially true in the case of early childhood since milk is a unique food source in the first months of life of the baby and the growing children diet containing a high proportion of milk and dairy products. A sufficient intake of milk is also recommended for adults whereas calcium source for maintaining mass of the bone to prevent fractures and osteoporosis.…”

“…A sufficient intake of milk is also recommended for adults whereas calcium source for maintaining mass of the bone to prevent fractures and osteoporosis. 1,2 It is need to develop the exact analytical methods for analysis of zinc and copper in the milk samples for the quality control.…”