Page 139 - Analytical method for food addtives

88
14,15
16
was added to sample prior to passage through gas diffusion
reaction of SO 2 , formaldehyde and pararosaniline. An acid
from free sulphite and from portions of bound sulphite are
diffuses across Teflon membrane in gas diffusion cell into
interference in spectrophotometric measurement. SO 2 gas
flowing stream of malachite green, which is discoloured
Based on the formation of a coloured product from the
from free sulphite and from portions of bound sulphite
conc citric acid solution (pH ~2) which forms SO 2 gas
unit which was incorporated into manifold to prevent
15 µL injected directly into FIA system, mixed with
that is labile under these conditions. SO 2 gas
and measured spectrophotometrically
determined
Thoroughly mix undiluted wine
Thoroughly mix undiluted wine
Sample preparation Reference Method conditions Analytical methods for food additives 18 Sulphate determined by CE using 75 µm fused capillary Sulphite in samples converted to mM sodium chromate column with a buffer consisting of 5 sulphur dioxide and finally to sulphate mM OFM anion-BT reagent, pH 8.0, with indirect and 0.5 using
Matrix Wines Wines Foods and beverages Grape skin extract and elderberry colour Wines

Table 8.1 cont’d Method FIA Gas diffusion sequential injection system (GDSIS) with spectrometric detection Capillary electrophoresis Capillary electrophoresis FIA