Page 140 - Analytical method for food addtives

88 Analytical methods for food additives

Reference 14,15 16 18 19 20

mM sodium chromate cm fused

conc citric acid solution (pH ~2) which forms SO 2 gas
15 µL injected directly into FIA system, mixed with

that is labile under these conditions. SO 2 gas from free sulphite and from portions of bound sulphite diffuses across Teflon membrane in gas diffusion cell into flowing stream of malachite green, which is discoloured and measured spectrophotometrically Based on the formation of a coloured product from the reaction of SO 2

Method conditions determined and 0.5 UV detection at 254 nm at 200 nm

Sample preparation Thoroughly mix undiluted wine Thoroughly mix undiluted wine Sulphite in samples converted to sulphur dioxide and finally to sulphate using a Monier–Williams distillation Sulphite in samples converted to sulphur dioxide using a Rankine distillation. SO 2 was trapped in 0.6 % hydrogen peroxide solution as sulph

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