Page 331 - Analytical method for food addtives

3
4
5
using pyrolytically coated graphite tubes.
20 µL injected, temperature programmed
Al standards containing 0, 10, 20, 40,
Zeeman Z7000 GFAAS with normal
Al determined at 309.6 nm using a
% nitric acid without digestion.
Al determined at 309.3 nm using a
ng/mL were prepared in
background correction and THGA
graphite cuvettes. 20 µL injected,
Al determined by GFAAS in the
PE 4100ZL AAS with Zeeman-
temperature programmed with
atomisation at 2700 ºC (6 s)
presence of a Pd modifier
60 and 80
20
g was placed into petri-dishes and put in
(1.7 mL) for powdered sample, or 2 g sample for ready
Samples filtered through a 0.45 µm membrane filter to
to use, into tube. Capped tube and left in water-bath at
low-temperature microwave oxygen plasma processor
homogenised and stored in polyethylene bags at room
a plasma asher chamber for mineralisation in a closed
55 ºC overnight. Cap removed and solution diluted to
remove any sediment and diluted with water either
Added 2 mL conc HNO 3 to sample (0.3 g) + water
Frozen samples were freeze dried, finely ground,
introduced into the graphite furnace
dissolved with 0.2 % HNO 3
Summary of methods for aluminium in foods Reference Method conditions Sample preparation Matrix 1 Various, including ETAAS, Various methods used including dry ashing, wet open Duplicate diets ICP–AES, FAAS, ZETAAS and and wet pressurised and milk powders DCP–AES 2 The slurry was diluted, sonicated and For slurry analyses the sample
20-fold or 50-fold
10 mL with water
temperature. 1
and evaporated
Infant formula
Wine
milk
Fish
Table 25.1 Method ICP and AAS ETAAS GFAAS GFAAS GFAAS