Determination of nutrient and toxic elements in food reference materials by suspension preparation and TXRF analysis

Abstract

There is a need to maintain nutrient element adequacy through food consumption. Due to the risk of toxic element exposure during food consumption, an accurate and precise characterisation approach is required. This makes the development of a simpler and faster procedure a great concern, especially in Indonesia, where time-consuming methods such as atomic absorption spectroscopy (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS) are still dominant. Therefore, ththe present work aimed to evaluate a suspension technique for food matrices in combination with TXRF S4-TSTAR (total reflection X-ray fluorescence) in Indonesia. The examination focused on standard reference materials (SRM) such as 1570a spinach leaves (SL), 1548 typical diet (TD), 1566b oyster tissue (OT), and 8418 bovine muscle (BM). The concentration of elements was determined by mixing each SRM with internal standard gallium (Ga). This was followed by the comparison of the concentration and sensitivity of Ga to each element in SRM. The TXRF performance was evaluated by quantifying nutrients such as calcium (Ca), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), and toxic element namely arsenic (As). The trueness and precision were calculated through %bias, %recovery, coefficient of variance (%CV), and HorRat ratio (r). The recovery of all elements in SRMs was within 81.20 - 103.35%, except for SRM TD and BM which were 61.73 - 91.70 and 73.78 - 99.41%, respectively. The CV of all SRMs was within the range of 0.63 - 9.54%, except for SRM BM and HorRat ratios which were 2.10 - 25.22 and 0.12 - 3.21%. Based on the results, the concentration of Zn was in good agreement with the primary method of neutron activation analysis (NAA). This showed that TXRF S4-TSTAR had good trueness and precision on SRM food matrices, and could be a promising method to be applied for element characterisation in Indonesian nutritional research.