Influence of digestion methods on the determination of total Al in food samples by ICP-ES

Multi-element Analysis of Food by Microwave Digestion and Inductively Coupled Plasma-Atomic Emission Spectrometry

“…The aluminum recovery for oyster tissue was low (65%) probably due to the presence of silicon which is present at about 0.11% (Nadkarni, 1984). Low recovery of aluminum has been reported to be associated with incomplete dissolution of samples containing silica which would require the use of hydrofluoric acid to obtain complete recovery (Hoenig et al, 1998;Schelenz and Zeiller, 1993;Sun et al, 2000). The aluminum recovery for bovine liver was very high (344%) probably due to a contamination problem or the concentration being near the LOQ (2 mg/kg).…”

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

“…This technique has been applied to the dissolution of biological materials prior to Al determination by GFAAS (Skelly and Distefano, 1988;Nicholson et al, 1989). Some researchers have also addressed its application in foodstuff preparation (Schelenz and Zeiller, 1993;Friel et al, 1990; Topper and Kotuby-Amacher, 1990; Xu et al, 1992). However, a low Al recovery has been observed.…”

Microwave digestion procedures for environmental matrices

“…Considerable research has therefore been undertaken to find ways of controlling or reducing pressure build-up during the digestion process. 31,34,42,47,92,101,112,120,123,128,187 One method of avoiding excess pressure is to pre-digest the sample, and thus enable the gases evolved from the decomposition of easily oxidised organic matter to escape before commencing the closed digestion procedure. This may be carried out by leaving the samples to pre-digest at room temperature, often overnight.…”

“…Using this method temperatures greater than 150 °C and pressures in excess of 150 lb in 22 were achieved, sufficient, for example, to digest NIST Bovine Liver. 120 Another technique reported in order to control pressure buildup is to monitor the pressure or temperature throughout the course of the reaction and subsequently apply microwave power only when the readings are below the required level. In this way the pressure can be controlled, thus minimising venting of the digestion vessel.…”

“…Recoveries were improved by employing nitric and hydrofluoric acid in combination with hydrogen peroxide. Low recoveries were also obtained in BCR Spruce Needles following a nitric acid-hydrogen peroxide digestion 25 and in shellfish, 83 total diet samples 120 and NIST Apple and Peach Leaves 80 following closed digestion procedures with just nitric acid. For marine biological tissue (NIST Oyster Tissue), closed digestion procedures with nitric and perchloric acid, and nitric acid and hydrogen peroxide, also resulted in low results for Al.…”