Page 174 - Analytical method for food addtives

118 Analytical methods for food additives

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Aqueous extract is treated with sulphanilamide and
Red compound produced is measured at 538 nm N-1(-naphthyl)ethylenediamine dihydrochloride. Nitrate using m-xylenol. After nitration distil into receiver containing NaOH. Transfer distillate to vol flask and dilute with water. Measure colour at 450 nm Add sulphanilamide reagent to an aliquot, after 5 min add NED reagent,

Method conditions blank Griess method g sand in extraction step, and 530 nm for SD-NS

Summary of methods for nitrites in foods Sample preparation Matrix Dispersed in warm water, fat and Milk and milk proteins precipitated, filtered products Mixed in warm water on steam bath, Meat transferred to volumetric flask Mixed with hot water, placed on steam Meat bath for 2 h. Cooled, diluted to volume. Filter Clarifica

Table 9.1 (a) Method Spectrometry Distillation/ spectrometric Colorimetric Reduction/ colorimetric Colorimetric Colorimetric Spectro- photometric