Fast method for the determination of major and trace elements in breast milk: optimization and validation

Breast milk, the first and irreplaceable source of nourishment for the infant, and the wellbeing of both the mother and baby are increasingly threatened by contamination from environmental toxic agents. In particular, elements can be used as good indicators/tracers of environmental and food contamination. In turn, as well as urine [1–3], and serum [4], breast milk can be considered as suitable biological matrix for biomonitoring studies. Taking all the above aspects into account, the aim of this study was to optimize and validate, a fast method for the determination of a total content of 34 elements (Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Se, Si, Sn, Sr, Te, Ti, Tl, U, V, and Zn) in liquid and lyophilized breast milk. The samples (0.5 g) were subjected to HNO3:H2O2 (2:1) digestion in open polypropylene tubes heated in a water bath (80 °C) and subsequently analysed by inductively coupled plasma mass spectrometry (ICP-MS). The analytical performance and quality control of the proposed method were evaluated in terms of selectivity, detection and quantification limits, linearity, accuracy, and robustness by using standard reference materials and filed samples of breast milk. The number of samples that can be handled in parallel was only limited by the number of available electric plates. The proposed method allows a significant reduction in treatment time and sample handling compared to microwave acid digestion, thereby resulting in a precise and accurate method (trueness and recovery percentages 80–111%; coefficient of variation <10%; and relative repeatability <15%) with satisfactory detection limits. Furthermore, simple application and high sample throughput make it suitable for routine and biomonitoring studies. [1] C. Protano, M.L. Astolfi, S. Canepari, M. Vitali, Urinary levels of trace elements among primary school-aged children from Italy: The contribution of smoking habits of family members. Sci. Total Environ. 557 (2016) 378–385. [2] C. Protano, M.L. Astolfi, S. Canepari, R. Andreoli, A. Mutti, F. Valeriani, V. Romano Spica, A. Antonucci, V. Mattei, S. Martellucci, M.Vitali, Exposure to individual and multiple carcinogenic metals during paediatric age: an experience from an Italian urban scenario. Ann. Ig. 29 (2017) 494–503. [3] C. Protano, S. Canepari, M.L. Astolfi, S. D’Onorio De Meo, M.Vitali, Urinary reference ranges and exposure profile for lithium among an Italian paediatric population. Sci. Total Environ. 619 (2018) 58–64. [4] C. Di Dato, D. Gianfrilli, E. Greco, M.L. Astolfi, S. Canepari, A.Lenzi, A.M. Isidori, E. Giannetta, Profiling of selenium absorption and accumulation in healthy subjects after prolonged l-selenomethionine supplementation. J. Endocrinol. Invest. 40 (2017) 1183–1190.