Closed-vessel microwave acid digestion of foodstuffs and trace aluminum determination by graphite furnace atomic absorption spectrometry

Abstract

The estimation of the daily dietary intake of aluminum is part of an ongoing project aimed at the assessment of the daily intake of food constituents by the Belgian population. This requires a reliable analytical method that is applicable to different solid foodstuffs and can easily be implemented in an analytical laboratory. A method is proposed for the dissolution of food samples with microwave digestion (HNOS-H~O~ 2:0.5) and for the subsequent Al determination by graphite furnace atomic absorption spectrometry. The use of closed-vessel microwave acid digestion shortens the time for sample dissolution and improves the analysis quality. A direct calibration against aqueous solutions was used for all of the foodstuff digests. For the method validation, standard reference materials were analyzed. Aluminum was determined in 13 different types of bread and 30 types of fish. The limit of detection in solution is about 3 pg/L (30). Some samples with relatively higher aluminum content were identified.

Estimation of daily aluminum intake in Japan based on food consumption inspection results: impact of food additives

“…Food additives such as sodium aluminum phosphate and sodium aluminum silicate are approved for use as food additives (Jorhem and Haegglund 1992; Yang et al 1994; Leblanc et al 2005; Saiyed and Yokel 2005; Bratakos et al 2012) in the USA and EU countries. However, in Japan, sodium aluminum phosphate and sodium aluminum silicate are not currently approved for use as food additives, whereas aluminum ammonium sulfate and aluminum potassium sulfate are currently used as food additives, without limits on the amounts used.…”

“…In regions and countries such as the EU and the USA, sodium aluminum phosphate, used as a leavening agent in cereals and related products, and/or sodium aluminum silicate used as an anticaking agent in cake mixes and dried products, contribute highly to Al levels in wheat bread, cakes, cookies, and confectionaries. Food additives such as sodium aluminum phosphate and sodium aluminum silicate are approved for use as food additives (Jorhem and Haegglund 1992 ; Yang et al 1994 ; Leblanc et al 2005 ; Saiyed and Yokel 2005 ; Bratakos et al 2012 ) in the USA and EU countries. However, in Japan, sodium aluminum phosphate and sodium aluminum silicate are not currently approved for use as food additives, whereas aluminum ammonium sulfate and aluminum potassium sulfate are currently used as food additives, without limits on the amounts used.…”

Microwave digestion procedures for environmental matrices

“…A combination of nitric acid and hydrogen peroxide was used for the digestion of NIST Wheat Flour, although results for NIST Rice Flour were slightly high. 74 Recoveries were not increased, however, by the inclusion of HF in the procedure. We have reported the successful determination of aluminium in tea leaves following an open nitric and perchloric acid digestion, although low recoveries were obtained with nitric acid, alone and in combination with hydrogen peroxide.…”

New methods for acceleration of meat sample preparation prior to determination of the metal content by atomic absorption spectrometry

“…Destruction or removal of the organic matter is mandatory prior to determination of trace elements. The decomposition or mineralization of the sample can be carried out by different methods, namely: calcination [12], wet digestion with acid mixtures [13] in either open vessels [14] or closed systems [15], etc. These methods involve some shortcomings, such as long manipulation time [12,16,17] large consumption of chemicals, losses of elements by volatilization and fume emissions.…”

“…These methods involve some shortcomings, such as long manipulation time [12,16,17] large consumption of chemicals, losses of elements by volatilization and fume emissions. The use of a domestic microwave oven with containers of either stainless steel or PTFE (polytetrafluoroethylene) equipped with a sealing pressure-resistant system [18,19] provides short lixiviation times and reduces emission of gases, but involves serious safety problems [15,20]. With a view of overcoming these shortcomings, procedures based on either focused microwave-assisted digestion or ultrasound-assisted leaching have been proposed [21].…”